Critique this performance velomobile idea

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The Toecutter   10 kW

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Critique this performance velomobile idea (calling zombiess)

Post by The Toecutter » Feb 08 2015 4:12pm

Greetings.

I need a long-distance, potentially highway-capable vehicle that can accommodate a car-free lifestyle. Due to various reasons, I am unable to obtain an ID or drivers' license in the state with which I reside. I need to be able to travel long distances in a personal vehicle for various needs, as the mass transit available is quite impractical. I have experience building my own electric car conversion, but for a variety of reasons, I am unable to use it(I can provide pictures if you want. It runs and drives, but it has yet to see more than 30 mph nor is it road legal. It's a Triumph GT6 with a 128V/100AH pack of CALB CA100FI batteries, a modified Prestolite MTC4001 series DC motor, and Soliton 1 controller, and another 20 batteries to add when I get the opportunity for a total of 192V/100AH. It smokes its tires in top gear from a stop, and is currently set for 128Vmax, 680Amot, 400Abatt.).

The research I have done indicates ebike performance well exceeding my needs is theoretically possible, but I have no illusions of this being an easy build even at the minimum design parameters, especially considering that I have never built an ebike before. I am going to give you a brief description of my minimum design parameters(needs), and below that, a brief description of possible and desired design parameters that could accompany the minimum(wants), before explaining a vehicle concept I have thought of. I need to know if my concept is possible to construct within the parameters described, and hearing it from some of the most re-known e-bike builders on the planet would be a good place to start:

Minimum Design Parameters(needs)

-Legality: must be street legal as an "electric bicycle" within the state of Texas and able to be legally pedalled without license or registration
-Minimum Range: must cover 300 miles a day, leaving time for the rider to eat, sleep, and rest
-Minimum Efficiency: able to be pedaled at 15+ mph on flat ground with only 150W of pedal effort and no electric assist.
-Minimum Performance: top speed of at least 35 mph, and the capability to continuously and safely maintain 30 mph on smooth pavement all day long with 150W of pedal effort plus the required electric assist.
-Minimum Protection: the rider's body needs to be isolated from the elements
-Minimum Utility: trail-able on an off-road bike trail at 15 mph safely while able to store small tent/sleeping bag/tools(5 cu ft of storage space in one compartment)
-Maximum Build Cost: cannot exceed $4,000 parts/materials cost
-Minimum Safety Features: gauges, front and rear lights, working turn and brake signals, front and rear suspension, front and rear disc brakes

Theoretically Possible Design Parameters(wants)

-Range: ability to be pedaled and maintain 50 mph for 1 hour with 0.8 to 1.2 kW of electric assist
-Speed: top speed of 70 mph is theoretically reachable
-Stability: I want it to be stable at 50 mph on smooth pavement
-Acceleration: possible tire-smoking acceleration with 0-20 mph in 4 seconds or less
-Power: peak electric-assist of no less than 7 kW, continuous electric assist of no less than 2 kW
-Extended autonomy: solar recharging while vehicle is in use of no less than 150W (this plus light 150W pedal input could potentially allow 30 mph continuous as long as sun is shining, without draining battery at all)
-Entertainment center: nothing fancy, maybe a portable mp3 player or portable radio with some small < 15W speaker system, with a way to keep it charged and operational from the traction pack

So now onto the vehicle concept. I am considering a tadpole pedal trike with electric assist and an aerodynamic fairing, much like a velomobile.

The following vehicle put together is something I wish to emulate, but with the addition of all of the bells and whistles of a velomobile:

https://www.electricbike.com/50mph-mons ... ric-trike/

The vehicle weight must be a total of 100 lbs or less fully assembled, and it must not be capable of exceeding 20 mph on electric-only. Why? It has to be legal as a bicycle in the state of
Texas. The above-linked trike weighs in at 90 lbs and is unfaired. I'm sure a way can be found to safely shave some weight off to get the unfaired but otherwise completed vehicle into the 80 lb range, giving me wiggle room for a fully enclosed faring and some thin-film solar panels.

The legal code describing "electric bicycles" within the state of Texas is as follows:

http://bicycleaustin.info/laws/tx-bike.html

Sec. 541.201. Vehicles.

In this subtitle:

... (2) "Bicycle" means a device that a person may ride and that is propelled by human power and has two tandem wheels at least one of which is more than 14 inches in diameter.
The following definition of electric bicycle was passed by the Texas legislature in 2001:

(10) "Motor-driven cycle" means a motorcycle equipped with a motor that has an engine piston displacement of 250 cubic centimeters or less. The term does not include an electric bicycle.
(11) "Motor vehicle" means a self-propelled vehicle or a vehicle that is propelled by electric power from overhead trolley wires. The term does not include an electric bicycle.
(24) "Electric bicycle" means a bicycle that:
(A) is designed to be propelled by an electric motor, exclusively or in combination with the application of human power;
(B) cannot attain a speed of more than 20 miles per hour without the application of human power; and
(C) does not exceed a weight of 100 pounds.
The lack of any peak kW rating or pedal-assisted top speed limitations on "electric bicycles" opens up lots of design possibilities, while still being legally a bicycle.

If I want to legally have a vehicle that can exceed 20 mph that relies on electric assist as well as pedalling, this means I will need an electric drive system that accepts input from a torque sensor either in the pedal crank itself or in the gear cluster. I'm not well-versed in the realm of e-bike controllers, but I am assuming that some top-of-the-line controllers available today allow this feature.

Given my requirement of being able to operate on pedal-only, it will need at least a 7-speed gear set with a derailler system.

I have read of velomobiles that weigh well under 50 lbs, let alone 100 lbs. There are also e-bikes that have been built to exceed highway speeds, wherein they would be legally "electric bicycles" under Texas law. My intent is to combine these two archetypes into a unique vehicle that will basically have close to the functionality of a car(with regard to a single occupant's long-distance needs), but the legal classification of a bicycle.

For the electric drive, here is a list of parts I have considered:

-Batteries: x6 Multistar High Capacity 6S 10000mAh Multi-Rotor Lipo Pack, for a total of 36S1P, 133.2V 10AH, 1332 Wh, rated to 10C continuous 20C peak, 15.8 lbs pack weight, total pack cost $588.66 http://www.hobbyking.com/hobbyking/stor ... ouse_.html

-Controller: Infineon (EC244115-LYEN EDITION). I want to set it to 120A max phase current, 60A max battery current, 125Vmax to motor, for 7.5 kW peak power electrically applied to the motor. Weight is 3.5 lbs and cost is $349. If possible, I would like more power though, as that battery pack is easily capable of 12 kW continuous. http://endless-sphere.com/forums/viewto ... 31&t=19719

-Motor: CroMotor v2. With 9.4 rpm per V, with a 133.2Vnom pack(assume it sags to 125V @ 60A), I should be able to reach 1175 rpm. How much torque will this make at what current and to what rpm? I'm guessing around 35 lb-ft at 1175 rpm for 7.8 horsepower peak, and a peak torque of 70 lb-ft from 0 rpm to ~580 rpm with a 120A max phase current. Weight is 24 lbs and cost is ~$600. http://www.greyborgusa.com

-Battery Charger: Need help with this one. Guessing 2 lbs and $150.

-Torque Sensor: Need help with this as well. Guessing less than 1 lb and $250.

Add $200 misc cost and 5 lbs misc weight to electric drive system including mounting, wiring, containment, fuses, switches, ect.

This gives a total of 50 lbs weight and $2,138 cost for the entire electric powertrain system. I will be using a Cycle Analyis CA-LSA at $170 for instrumentation. This leaves only 50 lbs and around $1,800 for the rest of the bike. I will be using about $500 of that for the solar panels and charge controller system, leaving $1,300 available for the construction of the fared bike by itself.

I realize that I will need some very stout components for this build and that they will not be light at all. This means parts from downhill racing bikes, or even mopeds and motorcycles, become necessary. This will make staying within 50 lbs for the bicycle by itself(no ev components) very difficult. The enclosed faring can easily be made to weigh under 15 lbs, leaving 35 lbs for the rest of the bike. If just one rear tire is a moped or motorcycle wheel and tire, this can easily eat 10 lbs or more of the weight.

Matt Schumaker's 50 mph electric trike linked above came in at 90 lbs, but it uses a solid tubular frame and heavy duty motorcycle parts, but also a very light motor that requires a custom belt drive. I am thinking instead of a solid frame which is going to be heavy, using folding honeycomb/fiberglass sandwhich material to build my chassis, as was done with the following custom electric car:

http://www.autospeed.com/cms/article.html?&A=112925
http://www.autospeed.com/cms/article.html?&A=112926

I will have to drill holes to bolt up the mounts for the electric drive, suspension bits, body, and other components. If the material can hold a car together, it should be good enough to hold a high power electric bike together. Enough material to build this bike's chassis is going to run at about $500, leaving $800 left for suspension, disc brakes, wheels, tires, faring materials, and misc components. Is that reasonable?

If this is doable by going the DIY route, then the following performance becomes theoretically possible under the given parameters:

Parameters:

-Drag coefficient: 0.25 (high end velomobiles come in at 0.12, so I think more that double that is possible without too much headache for a DIY build, although I will obtain lower Cd if I am capable)
-Frontal area: 0.5 m^2 (5.4 sq ft; about 20% more area than a typical touring velomobile, to accomodate a flat planar surface to hold solar panels of at least 10 sq ft)
-Fully laden weight: 136 kg (300 lbs; includes bike, myself, and tools/camping gear)
-Rear wheel diameter(including tire): 0.508m (20")
-Coefficient rolling resistance: 0.006 (road bike tires are like 0.0045, car tires around 0.009, so I picked a figure somewhere in between)
-Assumed max torque curve: 70 lb-ft from 0 to 580 rpm, 7.8 peak horsepower and 35 lb-ft @ 1175 rpm

Performance:

*simulated from a custom spread sheet and http://www.nightrider.com/biketech/accel_sim.htm

0-20 mph: 3.9 seconds
0-30 mph: 6.0 seconds
0-60 mph: 14.3 seconds
Top speed: 70 mph @ 1175 rpm
Total power(pedal + electric) needed for 30 mph: 311W
Total power needed for 40 mph: 621W
Total power needed for 50 mph: 1106W
Total power needed for 60 mph: 1813W
Total power needed for 70 mph: 2783W

Continuous speed with 150W pedal and 150W solar: 29 mph
Continuous speed with 150W pedal only: 21 mph

Range @ 30 mph with 150W pedal input and no solar(80% assumed motor/cont combined eff and 80% depth of discharge): 171 miles
Range @ 50 mph with 250W pedal input: 49 miles
Range @ 70 mph with 500W pedal input: 41 miles

With larger diameter 30" rear tire, 100 mph becomes theoretically possible on only 7 kW to maintain it, at the expense of acceleration and efficiency. That would be nice though, and if it can be worked in without losing acceleration in the case that I am too conservative on expected motor torque values and could fit in a larger wheel, I would gladly take it. Safety at that speed would probably be an issue.

Technology for solar power has gotten a lot better and cheaper, and making an e-bike with the personal transportation capabilities mimicking that of a car, but doesn't require a license to operate, is enticing. 1 kW of solar panels, instead of the planned 150W, would be a true freeway-capable long distance vehicle that is legally a bicycle.

I have some drawings to scan and share, when I get the opportunity.

The build order will be in the following order:

1) Working pedal trike
2) Working electric drive system
3) Aerodynamic body cover
4) Solar charging system

What questions, comments, and concerns do any of you here have with this build? Does this project sound doable and able to be made reasonably safe to operate on the budget imposed? If not, then what is within the realm of possibility that is as close a match to what has been described as possible, based on the personal experiences of the builders here?

xenodius   1 kW

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Re: Critique this performance velomobile idea (calling zombi

Post by xenodius » Feb 08 2015 4:32pm

I am really interested in how your project develops, as I'm trying to start building my own tilting delta velo with similar criteria (~300 mile range, ~1.5hr charges, 80+mph top speed, lots of cargo space).

My first recommendation would be to consider building your own pack of 18650 cells. Better gravimetric and I believe volumetric energy density relative to lipo. But it sounds like the kind of ambition practical transpo needs. You could build a 10kwhr 18650 pack for a few thousand.

I considered a solar-faired velo VERY seriously but after running a test with thin-film panels and an incidence meter I determined that it wouldn't be worth it. The efficiency is not based on simple geometric incidence, so performance is pretty poor. 150W would be possible but I'm not sure you'll be able to spec a module and paired MPPT that fits your fairing. At an incidence of 60 degrees from perpendicular, expect ~20% of rated power. Further subtract from that figure when you're not in full sun.

Second, really think about what top-speed you need, and what performance you want. If you want to rocket up hills (I do) then the cromotor or another high-powered hubmotor is a great choice. The Cro's kV is a little low for 70+, IMO, but it depends on your wheel size obviously. Most velo's have under-20" wheels though 26" rears are around.
If, however, you want to sip 1kw all day long, consider a mid-drive or parallel drive! You can get a little better efficiency for those long trips and you'll see better range.

Your Cd x A of .125 is reasonable, my goal is to stay around .15 but I want a bit more ground clearance and a bit more cargo space. The numbers are crazy. Have you used swbluto's calculator? Here's a link, my stats are in the "Hubmonster" file that's in the folder. It's a convenient tool.

Oh yeah, and regarding legality, that's another key draw of a velo for me personally. No way to prove what is and isn't pedal power, unless you're going 60mph up a 20% grade, so you have only speed limits to concern yourself with.

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Drunkskunk   100 GW

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Re: Critique this performance velomobile idea (calling zombi

Post by Drunkskunk » Feb 08 2015 5:47pm

The Toecutter wrote: Minimum Design Parameters(needs)

-Legality: must be street legal as an "electric bicycle" within the state of Texas and able to be legally pedalled without license or registration
-Minimum Range: must cover 300 miles a day, leaving time for the rider to eat, sleep, and rest
-Minimum Efficiency: able to be pedaled at 15+ mph on flat ground with only 150W of pedal effort and no electric assist.
-Minimum Performance: top speed of at least 35 mph, and the capability to continuously and safely maintain 30 mph on smooth pavement all day long with 150W of pedal effort plus the required electric assist.
-Minimum Protection: the rider's body needs to be isolated from the elements
-Minimum Utility: trail-able on an off-road bike trail at 15 mph safely while able to store small tent/sleeping bag/tools(5 cu ft of storage space in one compartment)
-Maximum Build Cost: cannot exceed $4,000 parts/materials cost
-Minimum Safety Features: gauges, front and rear lights, working turn and brake signals, front and rear suspension, front and rear disc brakes

Theoretically Possible Design Parameters(wants)

-Range: ability to be pedaled and maintain 50 mph for 1 hour with 0.8 to 1.2 kW of electric assist
-Speed: top speed of 70 mph is theoretically reachable
-Stability: I want it to be stable at 50 mph on smooth pavement
-Acceleration: possible tire-smoking acceleration with 0-20 mph in 4 seconds or less
-Power: peak electric-assist of no less than 7 kW, continuous electric assist of no less than 2 kW
-Extended autonomy: solar recharging while vehicle is in use of no less than 150W (this plus light 150W pedal input could potentially allow 30 mph continuous as long as sun is shining, without draining battery at all)
-Entertainment center: nothing fancy, maybe a portable mp3 player or portable radio with some small < 15W speaker system, with a way to keep it charged and operational from the traction pack

Welcome to the forum.

your design requirements have some problems.
In the state of Texas an Ebike can weigh no more than 100 pounds, not exceed 20mph, and have no more than 750 watts nominal power. I recently ran into issues with those laws my self.
So your first design consideration, Legality, either kills the bike, limits it severely, or has to be disregarded in favor of something that works.


Minimum range. At 20mph, for a normal bike we say you need around 36 watt hours of capacity per mile. a velo would need less but you would need to be laying flat in a fully enclosed tube before you could expect to cut that requirement in half, and from the rest of your needs, that doesn't sound like it would work. So lets go with the 36 watts for now. at that rate a 300 mile trip at 20 mph would take 15 hours, and need a battery sized for 10,800 watt hours. With Lipo, one of the lightest batteries available, you get around 1000 watts for every 15.5 pounds of battery. that's 167 pounds of battery capacity to make a 300 mile range possible at 20mph. faster speeds would need much more. you would also have exceeded the legal limit on weight by 1.67 times in just battery weight.

Efficiency and performance specs are easy enough. A normal bike can do >15mph with around 150w input. Not likely with the weight battery you need to carry, but as for the bike it's self, very doable. 30mph isn't that hard either, on a normal bike and around 1000 watts of motor.
Also understand that most "fit" people can't even maintain 150w output for very long. That's a pretty impressive output for an athlete to maintain. here's a chart that explains some: Image

Protection. now this one is both easy and tough. since weight is a factor, you're going to need to get creative. Velos can be built with body work of nylon, like tent material. if you're good, you could probably build a fully enclosed body under a couple pounds. the windscreen and someway to clear the rain and mud off it while riding would probably be the biggest weight factor.

Minimum Utility- storage. Consider a trailer. That will help you beat the legal limits placed on the bike.

As for your theoretically possible, most of it isn't reality.
With some wind tunnel testing and a design team backing you, I think you could build a stream liner that might hit 1.2kw at 50mph, but not without a major investment and plenty of exotic materials. If you could get the rest of your design requirements and hit 50mph at 4kw, that would be pretty amazing.
70mph is possible, but you'll need more than your 7kw peak motor to do it, and you so far outside of Texas legal here that you had better have this vehicle registered, licensed, and insured or expect to go to jail.
4 seconds to 20mph isn't too hard, but tire smoking with a rider on board is. especially with the weight this vehicle will end up being if you hit most of the rest of your design. much depends on the design.if the weight is properly shared between the wheels, I'd expect not to see tire smoke at anything less that 20,000w of power. with less power on the drive wheel, that number comes down. a few trikes with less than 1/3 of the weight on the drive wheel can get tire smoke at around 10,000 watts
Solar recharging on the move is a joke. forget it on a bicycle. 150w of useable power panels is a huge area. they need to face the sun to work, and doing so can leave them as a major aerodynamic drag, wiping out any benefit they would give.
Solar charging when parked is another matter. But 150w of panel is big enough that you'll want to fold them up and store them in a trailer.
Buy the ticket, take the ride.
Monster Bike:http://endless-sphere.com/forums/viewto ... =6&t=38667

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The Toecutter   10 kW

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 08 2015 5:55pm

xenodius wrote:I am really interested in how your project develops, as I'm trying to start building my own tilting delta velo with similar criteria (~300 mile range, ~1.5hr charges, 80+mph top speed, lots of cargo space).
I considered a delta trike, but figured that straight-line stability and drive traction(assuming FWD) would be an issue, and might require a differential for high speeds.
My first recommendation would be to consider building your own pack of 18650 cells. Better gravimetric and I believe volumetric energy density relative to lipo. But it sounds like the kind of ambition practical transpo needs. You could build a 10kwhr 18650 pack for a few thousand.
A 10 kWh pack would be much too large for my needs, and would bring me over budget. My design consideration weighted power density with regard to mass more important than energy density. Whatever motor I put in this thing, I want to be able to "max out" within the context of not making the controller's FETs go pop, for as little weight as possible. 10 kWh would allow a 300 mile range though...
I considered a solar-faired velo VERY seriously but after running a test with thin-film panels and an incidence meter I determined that it wouldn't be worth it. The efficiency is not based on simple geometric incidence, so performance is pretty poor. 150W would be possible but I'm not sure you'll be able to spec a module and paired MPPT that fits your fairing. At an incidence of 60 degrees from perpendicular, expect ~20% of rated power. Further subtract from that figure when you're not in full sun.
Maybe more could be fit?
Second, really think about what top-speed you need, and what performance you want. If you want to rocket up hills (I do) then the cromotor or another high-powered hubmotor is a great choice.
I need 35 mph, but I do want to rocket up hills.
The Cro's kV is a little low for 70+, IMO, but it depends on your wheel size obviously. Most velo's have under-20" wheels though 26" rears are around.
I've seen builds do 60+ mph top end on them, but is continuous rpm a factor to consider?
If, however, you want to sip 1kw all day long, consider a mid-drive or parallel drive! You can get a little better efficiency for those long trips and you'll see better range.
A small 1 kW battery pack would prevent that, but a large 10 kWh pack to allow it would grossly put it over budget and add way too much weight. I have to keep the pack small and bike under 100 lbs. The best commercially available 18650s are at 250 Wh/kg, and a 10 kWh pack would be close to 90 lbs, along with needing a BMS and a bunch of other things. Too heavy.

I need to keep the pack small. 1 kWh seems ideal, as with no solar, I could pedal with 150W, and the motor could provide 150W, letting me cover close to 200 miles per day without being exhausted.

I may even be more fit than that; I can do 20 mph without tiring for miles on end on a Raleigh road bike, so 225W may be closer to my real capabilities, but I want to be conservative in my continuous speed estimate.
Your Cd x A of .125 is reasonable, my goal is to stay around .15 but I want a bit more ground clearance and a bit more cargo space. The numbers are crazy.
Crazy as in unlikely, or crazy as in physics being an interesting mistress?
Have you used swbluto's calculator? Here's a link, my stats are in the "Hubmonster" file that's in the folder. It's a convenient tool.
Never used it, and am trying to figure out how.
Oh yeah, and regarding legality, that's another key draw of a velo for me personally. No way to prove what is and isn't pedal power, unless you're going 60mph up a 20% grade, so you have only speed limits to concern yourself with.
I kind of figured that, but really want to be on the safe side. The police here seem to be assholes and tyrants, so this thing needs to follow the letter of the law...

xenodius   1 kW

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Re: Critique this performance velomobile idea (calling zombi

Post by xenodius » Feb 08 2015 6:20pm

Drunkskunk, you can build packs lighter than that. em3ev's packs have about 30% better gravimetric density than those specs, and they are comparatively small so that would include the weight of 10-12 BMS'es. You can build a 10kwhr pack for around 100lbs. Still doesn't meet that weight limit though, I wasn't aware of that.

I also think you might underestimate the contribution of aerodynamics. Check out the calculator I posted. 1.08kw @ 46mph, and that's a conservative CdA. Commercial velos with CdA's half as high are available, although they're all very expensive. With the right chainring, you could go 50mph on the flat with a BBS02. Of course, hill climbing is where things become problematic...

Curious about what your legal encounter was like. I ride a very illegal ebike and local LE has been nothing but impressed. Small town though.

I definitely agree that solar is a compromise and not worth it, specifically due to the decrease in efficiency at any real-world incidence.

@Toecutter; Crazy as in underestimated. My lycra buddies don't appreciate how important aero is vs. weight or RR. If you get insanely aero, you can get insanely efficient.

I've had my cromotor over 70mph (!!) but it needs field weakening and a slight downgrade to do so, and is still highly inefficient. It also accelerates very slowly past about 33mph without field-weakening. All in a 21.3" Pirelli.

Also, regarding solar, I designed a fairing in Solidworks and measured its surface area. If I utilized every square inch of the top half of the fairing, I could barely fit 400w of panels on there. Don't forget the weight compromise involved... I'm not saying it's impossible, but it's a giant PITA and limited returns.

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The Toecutter   10 kW

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 08 2015 6:31pm

Drunkskunk wrote:
Welcome to the forum.

your design requirements have some problems.
In the state of Texas an Ebike can weigh no more than 100 pounds, not exceed 20mph, and have no more than 750 watts nominal power. I recently ran into issues with those laws my self.
So your first design consideration, Legality, either kills the bike, limits it severely, or has to be disregarded in favor of something that works.
Do you have a reference for the 750W figure? That would dramatically change my design constraints. It would go from trying to get as much power as possible to trying to go as fast as possible on 750W plus pedal input.
Minimum range. At 20mph, for a normal bike we say you need around 36 watt hours of capacity per mile. a velo would need less but you would need to be laying flat in a fully enclosed tube before you could expect to cut that requirement in half, and from the rest of your needs, that doesn't sound like it would work. So lets go with the 36 watts for now. at that rate a 300 mile trip at 20 mph would take 15 hours, and need a battery sized for 10,800 watt hours. With Lipo, one of the lightest batteries available, you get around 1000 watts for every 15.5 pounds of battery. that's 167 pounds of battery capacity to make a 300 mile range possible at 20mph. faster speeds would need much more. you would also have exceeded the legal limit on weight by 1.67 times in just battery weight.
I'm looking to keep the battery weight under 20 lbs, and this will impose its own set of limitations. 300 miles range on electric only certainly won't be possible with this, but how about a steady 150W rider input plus a steady 150W from the electric motor? A 1332 Wh pack with 80% max DoD would yield a run time of almost 6 hours, assuming 80% battery+motor+controller efficiency.
Efficiency and performance specs are easy enough. A normal bike can do >15mph with around 150w input. Not likely with the weight battery you need to carry, but as for the bike it's self, very doable. 30mph isn't that hard either, on a normal bike and around 1000 watts of motor.
Also understand that most "fit" people can't even maintain 150w output for very long. That's a pretty impressive output for an athlete to maintain. here's a chart that explains some: Image
Thanks. I can do 20 mph for at least an hour on end on a Raleigh Technium and top out at 32 mph for a few seconds, pedal only. I figured 150W continuous was a reasonable, conservative guess.

I referenced the following chart:

http://www.avdweb.nl/cache/long-term-hu ... m250_0.jpg
Protection. now this one is both easy and tough. since weight is a factor, you're going to need to get creative. Velos can be built with body work of nylon, like tent material. if you're good, you could probably build a fully enclosed body under a couple pounds. the windscreen and someway to clear the rain and mud off it while riding would probably be the biggest weight factor.
5 lbs or less would be excellent for the body. A lexan or acrylic canopy to cover the rider's face from the elements(and reduce drag) is desired, but may be difficult to make or obtain.
Minimum Utility- storage. Consider a trailer. That will help you beat the legal limits placed on the bike.
That is a good idea, and I could fit a ridiculous amount of solar panels and/or batteries in one, plus anything I need to carry... and keep the bike under the weight limit while leaving more space for batteries.
As for your theoretically possible, most of it isn't reality.
With some wind tunnel testing and a design team backing you, I think you could build a stream liner that might hit 1.2kw at 50mph, but not without a major investment and plenty of exotic materials. If you could get the rest of your design requirements and hit 50mph at 4kw, that would be pretty amazing.
70mph is possible, but you'll need more than your 7kw peak motor to do it, and you so far outside of Texas legal here that you had better have this vehicle registered, licensed, and insured or expect to go to jail.
What examples of vehicles can you cite for this? These numbers seem pessimistic for covered vehicles, but in-line with open ones.
4 seconds to 20mph isn't too hard, but tire smoking with a rider on board is. especially with the weight this vehicle will end up being if you hit most of the rest of your design. much depends on the design.if the weight is properly shared between the wheels, I'd expect not to see tire smoke at anything less that 20,000w of power. with less power on the drive wheel, that number comes down. a few trikes with less than 1/3 of the weight on the drive wheel can get tire smoke at around 10,000 watts
Interesting. A HubMonster may be able to exceed 20 kW...
Solar recharging on the move is a joke. forget it on a bicycle. 150w of useable power panels is a huge area. they need to face the sun to work, and doing so can leave them as a major aerodynamic drag, wiping out any benefit they would give.
Solar charging when parked is another matter. But 150w of panel is big enough that you'll want to fold them up and store them in a trailer.
I was thinking of using thin-films, and making them contour to a complex/curved surface. I haven't seen a vehicle do this yet, and wonder why, when there are solar cars with more than 10 times my expected panel area and 3x the frontal area and 600+ lbs heavier that can do 20+ mph continuously in direct sunlight on just solar power alone:

https://www.youtube.com/watch?v=pYtWl0TtaKU
Last edited by The Toecutter on Feb 09 2015 9:36pm, edited 2 times in total.

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Re: Critique this performance velomobile idea (calling zombi

Post by cjh » Feb 08 2015 6:42pm

So, what if you build it with less battery onboard which is fine for the short trips and keeps the weight down to met your legal limit and have added battery capacity in a trailer for the longer trips and it can also haul your cargo?

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Re: Critique this performance velomobile idea (calling zombi

Post by xenodius » Feb 08 2015 6:45pm

The Toecutter wrote:I was thinking of using thin-films, and making them contour to a flat surface. I haven't seen a vehicle do this yet, and wonder why, when there are solar cars with more than 10 times my expected panel area and 3x the frontal area and 600+ lbs heavier that can do 20+ mph continuously in direct sunlight on just solar power alone:

https://www.youtube.com/watch?v=pYtWl0TtaKU
I've been there. It's not impossible but I don't think it's worth it. The problem is that when semi-flex panels are bent, you lose efficiency not simply as a result of geometric incidence....

That is, if you're at a 60-degree angle away from perpendicular, you'd expect a cos(60) = .5 = 50% efficiency. What you really get is about 17%. For 30 degrees it's not quite as bad but it's less than half. So if you can fit 400w on your fairing, expect no more than 50-100 watts. Also keep in mind this depends on the direction of travel and latitude. It's potentially useful for a commuter parked in a sunny area, but is it worth it? I used to think so. I don't anymore.

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 08 2015 6:48pm

cjh wrote:So, what if you build it with less battery onboard which is fine for the short trips and keeps the weight down to met your legal limit and have added battery capacity in a trailer for the longer trips and it can also haul your cargo?
I am considering that, but I need to know for a fact that there is a 750W motor power limit. That constraint will change the whole design. A trailer can hold as much batteries and/or panels as I could practically use, but also slow acceleration and reduce aerodynamic efficiency.

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 08 2015 6:50pm

xenodius wrote:I've been there. It's not impossible but I don't think it's worth it. The problem is that when semi-flex panels are bent, you lose efficiency not simply as a result of geometric incidence....

That is, if you're at a 60-degree angle away from perpendicular, you'd expect a cos(60) = .5 = 50% efficiency. What you really get is about 17%. For 30 degrees it's not quite as bad but it's less than half. So if you can fit 400w on your fairing, expect no more than 50-100 watts. Also keep in mind this depends on the direction of travel and latitude. It's potentially useful for a commuter parked in a sunny area, but is it worth it? I used to think so. I don't anymore.
50-100W from 400W would still be quite usable, if I can keep the weight in check.

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 08 2015 6:58pm

With regard to legality, here is the Texas state code:

http://www.statutes.legis.state.tx.us/D ... TN.541.htm

I can find no reference to a 750W limitation on electric bicycles. Maybe it also varies from municipality/county to another?

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 08 2015 11:32pm

If 750W limit does not apply, a MidMonster set up as a hub motor might work better than the CroMotor due to higher rpm per volt.

http://endless-sphere.com/forums/viewto ... 31&t=47607

If 750W is a limitation I need to abide by to be legal, then perhaps a high efficiency 750W motor, with the vehicle designed for maximum streamlining, might allow 50 mph on only 1 kW(motor 750W plus 250W pedal input). With the reduced weight, more battery could be fit, allowing greater range. This design variation wouldn't use solar panels at all unless they were being towed on a trailer.

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Re: Critique this performance velomobile idea (calling zombi

Post by xenodius » Feb 09 2015 12:50am

While you consider this legalese, I do sincerely hope you will have an "off road" mode for the real commute. I'm all on board with doing as much as you can with as little power as possible (though the 750w spec is not anywhere I can see, it's 1kw here in WA but has to shut off after you pedal over 20mph. All that said, if you find you need to run 800, 900, or 1200 watts instead of 750w, I'd encourage you to go ahead and do it, and have road-friendly mode as well. What's important is how you ride, and what's the safest way to do so. It takes a lot of power to maintain 50mph up a grade, and it would be safest if you used that power instead of grinding to a halt while everyone behind to is trying to get by. About 1.7% of passes w/ cyclists were too close in my hometown, and about one in 300 (!) was a collision. Fits with my thousands of miles riding in spokane.

It sounds awful but it's true; It's good to be legal, but you only need be believable, and sometimes the safest approach for everyone is surprising.

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Re: Critique this performance velomobile idea (calling zombi

Post by Drunkskunk » Feb 09 2015 10:04am

The Toecutter wrote:With regard to legality, here is the Texas state code:

http://www.statutes.legis.state.tx.us/D ... TN.541.htm

I can find no reference to a 750W limitation on electric bicycles. Maybe it also varies from municipality/county to another?

6 months ago when I got hit I had an investigator looking real closely at my bike. My bike is a monster capable of 10,000 watts, but I have a road legal switch that cuts the power down to be legal. He quizzed me on law and then showed me the statutes he was concerned about. At that point, 750 watt nominal limit was in the code, and by my finding it he decided I was aware of the law and trying to comply in good faith. He also quoted all the statutes and regulations back to me at the time, including the 750w limit, and his findings of weather I was in compliance.
But that was 6 months ago. Last night I went digging for it again, using my notes from after the accident. I can't currently find any reference to 750 watts. I think it was part of 541.201, but now that section only says 20mph and >100 pounds.
The only thing that would concern me is I can't find a reference to a revision in 2014 that would have removed it.
Buy the ticket, take the ride.
Monster Bike:http://endless-sphere.com/forums/viewto ... =6&t=38667

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 09 2015 11:53pm

Drunkskunk wrote:6 months ago when I got hit I had an investigator looking real closely at my bike. My bike is a monster capable of 10,000 watts, but I have a road legal switch that cuts the power down to be legal. He quizzed me on law and then showed me the statutes he was concerned about. At that point, 750 watt nominal limit was in the code, and by my finding it he decided I was aware of the law and trying to comply in good faith. He also quoted all the statutes and regulations back to me at the time, including the 750w limit, and his findings of weather I was in compliance.
But that was 6 months ago. Last night I went digging for it again, using my notes from after the accident. I can't currently find any reference to 750 watts. I think it was part of 541.201, but now that section only says 20mph and >100 pounds.
The only thing that would concern me is I can't find a reference to a revision in 2014 that would have removed it.
Thanks for sharing. I am guessing that they may have pulled up some municipal or county code, or might have been referencing a Federal law limiting commercial e-bikes to 750W. I checked that state statute more than a year ago and its present iteration that I linked to is unchanged from what I saw then. It is also possible that the statute has changed, but the website hasn't been updated to reflect that. I really need to know this though, as it limits just what my design can become.

I have a lot to think about.

I've been harassed by police in the state since I've been here in 2008, and I don't want them to have any legal "justification" for harassing me if they get too overzealous. A 750W limit isn't too bad. I know a bit about aerodynamics, and am an employed electrical engineer. I built a working electric sports car conversion designed with efficiency in mind, but haven't gotten to do much testing of it due to its location.

This bike vehicle is sort of going to be my "f*** you" to the Texas DPS. I want it to go as fast as possible, while being 100% legal to operate without a license. I realize that all traffic laws will apply, but if the speed limit is 50 mph, I damned well want a vehicle that can at least reach that for a brief period of time if desired. Regardless of whether I have 7.5 kW or 750W available, this speed capability would be a natural result of the aerodynamic efficiency needed for the efficiency that I require for long distance travel in the course of 1 day. If I can't get the efficiency to do the speed, then the range too will not be possible, even at lower speeds, simply due to the limited amount of hours in a day that can be used without rest and the increasingly overwhelming power requirements from air drag as speed goes up only slightly.

As a rider of a pedal bike, I notice about a 3 mph difference in top speed based on whether I tuck myself down a few inches or not. that is a small fraction of my frontal area lost, resulting in big gains, by itself. There are land speed HPV riders that can exceed 80 mph, on pedal power alone, with only like 1.5 kW of human power!

If I can match the drag coefficient of the average new car, and keep frontal area at 0.5 m^2 or less(average mid-tier consumer velomobile frontal area), I'll be in pretty good hands because a lot of possibilities open up!

1) The design for the high power 7+ kW version would be a tadpole trike whose main body structure consisting of the faring of roughly 1m high by roughly 0.6m wide by roughly 2.5m long(+/- 20% on each), with a monster hubmotor in the rear or an oversized mid-drive, moped/downhill bike/motorcycle rims and tires, and very thin wings extending from the sides of the main body structure spanning from the front of the front wheel wells to the rear of the vehicle whose sole purpose is holding solar panels and rear lights and signals, each wing sticking out another 0.1m or so(main body structure = the entire vehicle besides the wings). Imagine a narrower version of a Mango velomobile with motorcycle parts and a 5" ground clearance, that had wings jutting out on each side by a few inches, with as little frontal area imposed by them as possible, with the only interruption of a semi-flat surface for the solar panels being the bottom of the canopy area where the rider's head is located. The wings would have to be curved for as little drag and lift as possible, in such a way that the vertical space imposed by its cross section to the wind is no more than 3cm. They would be placed right at the height that the airstream is expected to experience flow separation(the bottom of the area for the rider's head), and would avoid breaking the laminar flow too early. Should give me roughly 1 m^2 of solar real-estate, wired in a manner to divide the power produced into sections that each closely match pack voltage, this way a tiny bit of shade doesn't kill the entire solar circuit.

2) The 750W version would have no wings, and have a height of only 0.7 m, but with a body structure about the same width. The name of the game would be fitting as much batteries as possible for the weight, so no motorcycle parts; the more sturdy variations of mountain bike parts will have to do for this, also freeing up money and weight. A front suspension may not even be needed for this, and a rear spring in the back might be sufficient, freeing up more money and more weight. The smaller motor and controller frees up more than 15 lbs weight for other things as well. All of this frees up lots of money and weight for more batteries. A pack that allows 2 kWh of energy to be used to 80% DoD gives a run time of 9 hours at 150W. Assuming a 0.25Cd and an area of 0.4 m^2, a Crr of 0.006, and a fully laden mass of 136 kg, 272W in theory would allow me to maintain a steady 30 mph on flat ground, no wind. 150W from the motor and 120W of me pedaling would do the trick to maintain 30 mph! This is theoretically 6.25 Wh/mile from the battery assuming losses of 20% for the combination of battery, motor and controller. This would be a vehicle with decent streamlining and very low area. A 2664 Wh pack allowed to go to 80% DoD(over 2100 Wh usable) would yield 330 miles range. Top speed on the flat with 500W pedal input and 750W from the motor could approach 55 mph. A more modest 750W from the motor and 250W pedaling would still allow 53 mph.

3) A possible solar version of the 750W version would be designed more like the high power version in shape but with the lower height of the low power version, but with wings that are wider by 0.3m in each direction, and possibly hinged depending on the weight penalty that imposes, so that the vehicle can be narrowed for doorways or when the sun is not shining instead narrowed for more efficient pedaling. Imagine having enough solar power to cover 30 mph for 8 hours a day, on a good day... and then still have a 1.332 kWh battery pack ready to be drained at the end of it for another 6 hours run time with some more 120W pedaling. 1 kW worth of solar panels would allow this, and quite a bit more than that could be fit on this concept except that budget would be an issue.

4) Another idea is to make a low-speed 48V 4-wheel kart that is 1.5m tall by 1m wide with 750W(and an offroad mode with at least 4 kW), and have it tow a trailer loaded with a 48V 100AH pack of CALB CA100FI batteries and 2m^2 of solar panels. Assuming the entire setup is 600 lbs, Cd of 0.6, frontal area of 1.2 m^2, set it up to top out at 20 mph, then we get 490W needed to maintain 20 mph. The solar panels on the trailer could keep it at 20 mph all day long(8 hours or more a day), and the batteries in the trailer would give an additional 3840 Wh(80% Dod) to use giving almost 8 hours of run-time with no solar, or 160 miles. That's 320 miles in 16 hours. Pedaling with 100W all day wouldn't even add 2 mph to that 20 mph, but if kept at 20, that amount of pedaling might extend the range 20%. But this would be much too slow for my liking, and hills are going to require big kW numbers for anything over 15 mph. This would also be expensive, due to the batteries and solar panels, when that money could have been spent on building a much more fun and exciting vehicle. But when it comes to hauling 100s of lbs of personal belongings for long distances without a car, this idea would indeed be difficult to beat.



That's 4 drawings I need to get finished up, and simulations to further refine.

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Re: Critique this performance velomobile idea (calling zombi

Post by xenodius » Feb 10 2015 1:12am

You seem committed. :D I would recommend going for the most aerodynamic vehicle possible and not compromising on the fairing design for solar. Add panels, if you're willing, but don't compromise on aero.

You might find this helpful; http://bikesmithdesign.com/Design/12steps.html

I look forward to seeing how you progress.

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 23 2015 9:08pm

I just found a potential donor about an hour's drive away from me for under $600. I need to take a good look at this thing.

What I've found out so far by speaking to the owner is that it is a tadpole recumbent trike with front disc brakes and rear suspension. The owner claims it weighs 40 to 50 lbs. There is no front suspension and no rear disc brake.

Given these limits, a rear wheel swap to motorcycle or moped parts could allow a disc brake. Beefier front wheels could be substituted from a motorcycle/moped as well, to allow excellent traction and cornering, not to mention ride cushion.

I don't see myself doing more than 50 mph without a front suspension, but perhaps I could go for a setup that reaches about 50 mph, from a stop, in under 4 seconds, without one...

...or maybe develop my own suspension and steering system, to allow higher speeds, which I would have had to do anyway if I designed a completely custom chassis.

I was originally thinking of using a honeycomb monocoque sandwich composite and folding a fuselage structure out of it for my trike design, but getting a working trike frame that can already be pedaled would be infinitely easier, far less expensive, and shorten the time between having just my current bicycle available, and having a viable car substitute.

You see, with a working chassis that can be pedaled, I can immediately jump into making a body, while still planning the electric drive subsystem. Using zote-foam, a body of around 10 lbs can be done, but that material would not be suitable for mounting solar panels. Getting a feel for a pedal velomobile would definitely be a wise choice before jumping into building something dangerous, anyway, and keep the cost of my first trike project down.

I estimate, best case scenario, about 40 lbs of batteries can be fit to this. If I had only 25 lbs of those Multistar High Capacity 6S 10AH batteries, it would be a 3S3P pack of 66.6V yielding 1600 Wh usable to 80% discharge. This is 160W of power for 10 hours straight. 66.6V with 3 Astroflight RC motors and a mid drive could give a very broad operating range.

Pictures are attached of this used trike. It seems like a good buy. I hope to get a chance to look at it this weekend.
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Re: Critique this performance velomobile idea (calling zombi

Post by dogman dan » Feb 24 2015 7:31am

8)

Man, that first sentence made the coffee spurt through my nose. :lol:

Dude, if you are hauling ass down the highway keeping up with traffic driving some kind of odd as hell looking vehicle with no plates,,,,,,
you REALLY think cops won't want to stop you and have a chat?

Furthermore, you sound exactly like my brother in law. He's clean and sober now, and after driving a breathalyzer car for about 7 years, actually is free and clear again. He could even get a CDL.

But back in the day, all it took was his face in the left hand side of a car to be an instant bust. Every cop in town knew him. Surely even in a big city, plenty of cops know you now.

WHAT YOU CAN DO, is build a legal ebike. Texas legal is 20 mph, yadda yadda. Build for 25 mph will very likely slide by. AND, if not too extreme, you can have lots more watts without it being super obvious.

Build yourself a 20 mph ish, 36v 40 amps bike. That's about 1600w, and plenty to get up the steepest hills, even if the bike weighs much more than normal( huge batteries). You won't get there fast, but you can build a legal bike with 60-100 miles of range that will get you there without the cops having a reason to bust you.

Perfect starting point, that bent tadpole trike. Keep it kiss, and put a 25 mph motor kit on it.

Make it haul ass, and cops will look at you like this. :shock: It could be an option to make it do 35 mph, but 99% of the time use a speed limiter to keep it slow enough to slide under the cops notice. Then you could ride fast, if in the middle of nowhere.

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Re: Critique this performance velomobile idea (calling zombi

Post by dogman dan » Feb 24 2015 7:40am

Re the definition of electric bicycle in TX. I see NO mention of wattage. Just speed.

FWIW, If your motor winding is low rpm enough, a hubmotor could run on 48v, 2000w, and easily still be close enough to 20 mph max to pass. Mac 12t motor for example. Or a slow wind direct drive of the kind I've been a huge fan of for years.

No limit on motor size, but the big boy motors tend to be wound fast, for the 50 mph crowd. You could do a pretty powerful mid drive, then just gear it to a close enough to be legal top speed.

But in general, 400w will get you going 20 mph. So for most stock ebike kits, a 750w motor on 36v is about right, when used with saggy slow lead batteries. Generally they perk up to 23-25 mph on lithium. Many states put that 750w in the law.

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Re: Critique this performance velomobile idea (calling zombi

Post by dogman dan » Feb 24 2015 7:52am

A thing to know, this,

http://www.ebikes.ca/shop/conversion-ki ... ottle.html

is all you need. Upgrade to the 40 amps controller, and add the Cycleanalyst.

While the cop is getting out of the car, you have time to reprogram the speed limiter in the CA to 20 mph. 8)

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 24 2015 9:15pm

dogman dan wrote:8)

Man, that first sentence made the coffee spurt through my nose. :lol:

Dude, if you are hauling ass down the highway keeping up with traffic driving some kind of odd as hell looking vehicle with no plates,,,,,,
you REALLY think cops won't want to stop you and have a chat?
I expect that they will react to my vehicle in some manner, which is why I insist on it being legal to the letter of the law(but not the spirit, of course).
Furthermore, you sound exactly like my brother in law. He's clean and sober now, and after driving a breathalyzer car for about 7 years, actually is free and clear again. He could even get a CDL.

But back in the day, all it took was his face in the left hand side of a car to be an instant bust. Every cop in town knew him. Surely even in a big city, plenty of cops know you now.
I've never been arrested, and the reason for my inability to obtain a license is probably due to something much different than your brother-in-law's circumstances.
WHAT YOU CAN DO, is build a legal ebike. Texas legal is 20 mph, yadda yadda. Build for 25 mph will very likely slide by. AND, if not too extreme, you can have lots more watts without it being super obvious.
Here's the part I don't think is being clarified properly on this forum from the Texas state code:

(24) "Electric bicycle" means a bicycle that:
(A) is designed to be propelled by an electric motor, exclusively or in combination with the application of human power;
(B) cannot attain a speed of more than 20 miles per hour without the application of human power; and
(C) does not exceed a weight of 100 pounds.


Correct me if I'm reading this incorrectly, but isn't the speed limitation 20 mph without the application of human power(pedaling)?

If I'm applying an amount of power that's still used towards propelling the bike, and do 30 mph, is it correct to think that I would be within the confines of the law? After all, if my bike can't do more than 20 mph without the application of human power, then wouldn't it be legal with the application of human power at say, 30 mph?

Does 40 mph fall under a different category than 30 mph? 50 mph? 60 mph?

Also, the law gives no specifics on how much power the human needs to apply while doing any speed above 20 mph. What if I set it up to need 100W of pedal to get 200W of motor, 200W of pedal to get 2 kW of motor, and 1 kW of pedal to get 20 kW of motor? Would this not quantify as being an "application of human power" for attaining "a speed over 20 miles per hour", at any speed that the amount of wattage applied would carry me to?

I think that as long as I am applying human power, the bike can legally go as fast as it is capable, as long as I am following the laws governing bicycles.

That's what I get out of reading that code.

I'm not a lawyer, mind you.
Build yourself a 20 mph ish, 36v 40 amps bike. That's about 1600w, and plenty to get up the steepest hills, even if the bike weighs much more than normal( huge batteries). You won't get there fast, but you can build a legal bike with 60-100 miles of range that will get you there without the cops having a reason to bust you.

Perfect starting point, that bent tadpole trike. Keep it kiss, and put a 25 mph motor kit on it.
Sounds tempting, just to have a working velo on the road. But if I have a drag area of 0.125 m^2(average commercial velomobile), it would only need about 200W to do 25 mph, of which some will be pedal input due to the design constrains I set forth(I want pedal assist, not a thumb switch. The bike will only move when pedaled, period. This makes all of the difference in the world surrounding that legal code). 1600W would get an average velomobile to well over 50 mph... and I am aiming to be more streamlined than the average. WITHOUT ANY electric power, an average, unfit American could probably get an average velomobile to reach 35+ mph, at least for a few seconds, as it would only take 400W or so.

But if I can legally make use of more power, I want to do just that. As much power as is safe to use on that chassis, as a good starting point. I suspect 25 mph is probably well below the maximum safe speed for such a trike, because I've seen pedal-only ones fly down hills at 40+ mph.

From your experience, what do you think the maximum safe speed would be?
Make it haul ass, and cops will look at you like this. :shock: It could be an option to make it do 35 mph, but 99% of the time use a speed limiter to keep it slow enough to slide under the cops notice. Then you could ride fast, if in the middle of nowhere.
I've considered this very much, hence the need for it to be legal. I do want to ride fast out in the country, too.
dogman dan wrote:Re the definition of electric bicycle in TX. I see NO mention of wattage. Just speed.
Speed is mentioned in the context of "without the application of human power" though. Technically, doesn't that mean I can do more than 20 mph as long as I am applying power?
FWIW, If your motor winding is low rpm enough, a hubmotor could run on 48v, 2000w, and easily still be close enough to 20 mph max to pass. Mac 12t motor for example. Or a slow wind direct drive of the kind I've been a huge fan of for years.

No limit on motor size, but the big boy motors tend to be wound fast, for the 50 mph crowd. You could do a pretty powerful mid drive, then just gear it to a close enough to be legal top speed.
I like the simplicity of a hub motor, but much greater peak power per pound can be had with a mid drive... and every pound available below 100 lbs is precious.
But in general, 400w will get you going 20 mph. So for most stock ebike kits, a 750w motor on 36v is about right, when used with saggy slow lead batteries. Generally they perk up to 23-25 mph on lithium. Many states put that 750w in the law.
What happens with those power figures when you cut the wind resistance at any speed by 75% by adding a very simple body? If 20 mph is the legal limit, then 750W in a velomobile would get me well above double that limit. Even a 100W system would be too overpowered if 20 mph is all I'm allowed to go because I would probably reach 40-45 mph peak in a velo on no electric assist at all... given that I can reach 30+ mph on a pedal road bike.
dogman dan wrote:A thing to know, this,

http://www.ebikes.ca/shop/conversion-ki ... ottle.html

is all you need. Upgrade to the 40 amps controller, and add the Cycleanalyst.

While the cop is getting out of the car, you have time to reprogram the speed limiter in the CA to 20 mph. 8)
Not a terrible idea.

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Re: Critique this performance velomobile idea (calling zombi

Post by xenodius » Feb 25 2015 3:08pm

The Toecutter wrote: Speed is mentioned in the context of "without the application of human power" though. Technically, doesn't that mean I can do more than 20 mph as long as I am applying power?
Aaaaand that is reason #2 I want a high-powered e-velomobile. "But officer, this is a very aerodynamic vehicle, and I was pedaling! :wink: You just couldn't see my legs. Some people are strong enough to take these bikes up to 88mph on human power alone! I only need the e-drive to get up hills." :roll:

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Re: Critique this performance velomobile idea (calling zombi

Post by Chalo » Feb 25 2015 3:50pm

The Toecutter wrote:This bike vehicle is sort of going to be my "f*** you" to the Texas DPS.
What did you do? This is Texas; it's not hard to have a driver's license here. Lots of people who shouldn't ever have one, do.
I want it to go as fast as possible, while being 100% legal to operate without a license. I realize that all traffic laws will apply, but if the speed limit is 50 mph, I damned well want a vehicle that can at least reach that for a brief period of time if desired.
You're not going to do it with a sub-100 pound vehicle, or else you're not going to do it with anything like the range you're suggesting. 300 miles in a day in a velomobile is more of an ordeal than you suspect, by the way. Why do you want that?

To fit lots of miles in a day without grossly violating the weight limit, I think you're better off looking at fast charging than onboard solar arrays. You'll want to get out of that economy class coffin pretty often anyway.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

xenodius   1 kW

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Re: Critique this performance velomobile idea (calling zombi

Post by xenodius » Feb 25 2015 7:56pm

Chalo wrote:
The Toecutter wrote:This bike vehicle is sort of going to be my "f*** you" to the Texas DPS.
What did you do? This is Texas; it's not hard to have a driver's license here. Lots of people who shouldn't ever have one, do.
I want it to go as fast as possible, while being 100% legal to operate without a license. I realize that all traffic laws will apply, but if the speed limit is 50 mph, I damned well want a vehicle that can at least reach that for a brief period of time if desired.
You're not going to do it with a sub-100 pound vehicle, or else you're not going to do it with anything like the range you're suggesting. 300 miles in a day in a velomobile is more of an ordeal than you suspect, by the way. Why do you want that?

To fit lots of miles in a day without grossly violating the weight limit, I think you're better off looking at fast charging than onboard solar arrays. You'll want to get out of that economy class coffin pretty often anyway.
I agree, re. weight and fast-charging. But hopefully it's not an economy class coffin :roll: If you're building your own velo it should be fitted to your proportions. It should be a rolling Lay-Z-Boy :D :lol:

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The Toecutter   10 kW

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Re: Critique this performance velomobile idea (calling zombi

Post by The Toecutter » Feb 26 2015 12:18am

Chalo wrote:What did you do? This is Texas; it's not hard to have a driver's license here. Lots of people who shouldn't ever have one, do.
...nothing that ever got me arrested, or a criminal record, or harmed anyone or their property, or even resulted in a ticket. I could PM you the details if you really want to know.
You're not going to do it with a sub-100 pound vehicle, or else you're not going to do it with anything like the range you're suggesting.
Understandable. I do see examples of very fine craftsmanship such as the following linked below:

https://www.electricbike.com/50mph-mons ... ric-trike/

...and want to replicate or improve the functionality of it, but with my own unique design choices. I want to push limits in all categories, but will compromise where needed. I intend to upgrade and/or reinforce the chain, the dropouts, the seat, the wheels and tires, the rear sprocket set, the brakes, the handles... and maybe even the suspension and chassis if it requires that, while keeping the budget in terms of weight and cost somewhat reasonable.

Judging by the 90 lb example linked above, 100 lbs is not impossible for an enclosed high performance electric trike. I realize that this vehicle has a ridiculous amount of custom work in it. But I cannot help but wonder while looking at this thing, what kind of "sturdy"(safely handle 50 mph) frame could be built, and for what weight, and what cost. Before electrifying anything, or adding any shell, I am trying to figure out the minimum safe weight such a vehicle would need to be to reliably and regularly handle 50 mph, or even to merely hold it for a minute or two. If the above linked insane trike can do 50 mph without a suspension of any sort, what do I need to do to make my proposed vehicle capable of handling it, and how much will that empty glider with wheels and pedals weigh?

That fully electrified trike linked above, being only 90 lbs, built off of a KMX typhoon(the one I am looking to purchase is a KMX Thunderbolt), and having no less than 25 lbs of electric-drive or related components in it, means that a glider weight of 65 lbs worst case scenario is possible in that thing, possibly less if I am under-estimating the weight of the custom components I see in it(versus the knowns that I can look up online, for the batteries, motors, ect). He's got a 44.4V 30AH pack in this, which is 15.8 lbs by itself and delivers 1 kWh to 80% discharge. At least 5 lbs of motor, 1 lb of controller, 1 lb of charger, an entire housing for a belt-drive that could be heavy, among other heavy things.

A zote-foam bodyshell with no enclosure of the rider's head is only about 10 lbs. Now we have 75 lbs for glider with shell.

Can its BMX tires really handle 50 mph though? They are sturdy, but not DOT approved. I don't exactly trust them, but I also don't want to doubt the opinion of the builder and cannot help but wonder what his experiences were. There are high speed moped/scooter rims and tires available though, that don't weigh much more than downhill or BMX bike parts, and are much more sturdy. The weight penalty for all 3 wheels and tires might only be 6 lbs for the set with proper selection.

We're up to 81 lbs for the glider with the shell. This is 19 lbs left over for wiring, batteries, motor, controller, ect.

Keeping it under 100 lbs probably means forgetting the solar panels, but a decent sized 500+ Wh storage 10+ kW peak power LiPoly pack isn't out of the question, is it? That's only 8 lbs of battery. Aren't there small enough setups where the motor, controller, charger, and their wiring and mounts put together only weigh about 10 lbs but can still exceed 1kW? We got 99 lbs.

He fit 1 kWh worth of batteries while self limiting to 80% DoD in a 90 lb trike! What would a 10 lb faring do to this build? It would be at exactly 100 lbs, with performance better than it was naked, possibly 4x the range with steady cruising.

Consider what 500 usable Wh would allow in my build, if I had to limit my pack size. That is 250W for 2 hours, 125W for 4 hours, and 62.5W for 8 hours. Stopping to charge three times during the trip would indeed allow one to do 210 miles in under 10 hours somewhere around 35 mph when not stopped charging in an average velo with 150W of pedaling combined with 250W of assist. 2 hour sessions each, 3 stops, 210 miles total, with 2 hours of rest.

The rub is finding charging along the way.

The above linked trike was sold for $7,500, but did it cost more or less than that in parts/labor to build? I've done some searches but haven't yet found the info I sought. I want to make something like it. It must be safe within reason(you are lying inches from the ground, after all).

I need to know what a safe glider weight would be to handle this vehicle. I could skip the large motor and go with a smaller 750W setup, and still theoretically reach 50 mph with a good enclosed shell and very heavy pedalling. That 750W would complicate things much less than going all out for power, but 50 mph is still 50 mph!

Every spare pound under 100 lbs allows a significant improvement in battery capacity, as well, whatever my empty glider happens to be.
300 miles in a day in a velomobile is more of an ordeal than you suspect, by the way. Why do you want that?
I have friends and associates in Austin that I require personal mobility with which to visit, but I want to avoid using a car or taking mass transit. Turning it into an 7-10 hour trip by foot+electric is the goal, so I could travel there and back during a 3-day weekend while having a full day to relax.

I have exceeded 50 miles around town in a 5 hour session(including a 2 hours rest, 3 hours riding) on a non-electric pedal-only steel-bodied Schwinn Traveler once, no suspension, upright, very skinny tires, crotch-buster seat. I figure a recumbent velomobile with suspension would be luxurious and far less taxing by comparison. That ride on the Schwinn was very taxing. What have been your experiences with velomobiles? I've never ridden one and want to hear your concerns and experiences. I badly want to build one out of a trike to see for myself, before any electrification.

I've also been up to 35 mph on the Schwinn on the flat with a light(< 7 mph) tailwind, before it got stolen 3 years ago. THAT was harrowing. So was doing similar with the Raleigh on the flat.

I want at least that amount of safety in this trike at 50 mph that the unsuspended Schwinn or Raleigh had at 35 mph. It's a rare event, but one I want to be able to do. Bonus points if I can safely do it regularly, but if my max "safe" speed ends up less, so be it.

I want to do 25-30 mph all day long when on the flat, but I want to be able to go faster where appropriate and when range is not an issue(such as around town).
To fit lots of miles in a day without grossly violating the weight limit, I think you're better off looking at fast charging than onboard solar arrays.
Makes sense. Perhaps the solar isn't worth it, unless the vehicle is built for a much lower speed, like 25 mph... Such a solar system including its mounting would add no less than 15 lbs for 150W usable in direct sunlight, and quite possibly much more if you go for cheap. Finding an MPPT controller would be a nightmare, but I suppose I could try to design one(NOT an endeavor I want to take right now).
You'll want to get out of that economy class coffin pretty often anyway.
I have a sports class coffin called a Triumph GT6. Steel-bodied, next to no crumple zones, very light weight(for a car); you're probably a goner if a Ford Ranger broadsides you in the drivers' seat at 25 mph. The car feels stable and corners very well, and can quickly get you out of(or into) trouble with correct driving procedures. While the ride is low and harsh, it goes safely at any speed limit(driven prior to EV conversion). I consider that a "reasonable" level of safety.

Being in a rolling coffin doesn't bother me, as long as I can safely and readily maneuver it away from danger to avoid collision, avoid going airborne or losing control unexpectedly, and avoid losing traction during corners. Even with safety during a wreck at the forefront of the design, a 35 mph(let alone 50 mph) collision in a velomobile could still prove deadly. Speed kills.

I don't have a death wish, mind you, and understand many of the risks. 20 kW and 250 lb-ft of torque, for instance, could potentially have my vehicle wheelie itself upside down and crush my head into the ground if I'm not careful, or a tire could blow at 50 mph causing me to careen into/under a truck, or my chain could come loose under aggressive pedaling and wreak all sorts of havoc if it hits the motor behind the drivers' set and becomes a spinning blade of death, or I hit a brick at 40 mph and go airborne, or a stiff gust throws me into a car coming in the opposite lane... and other scenarios I want to prevent and/or prematurely correct with my design considerations.

If I get this used trike and test it, I will have a basis with which to experiment. It's supposedly 35 lbs according to research, and is estimated to be "40-50 lbs" by the owner. That is a lot of spare pounds to work with.
xenodius wrote:I agree, re. weight and fast-charging. But hopefully it's not an economy class coffin :roll: If you're building your own velo it should be fitted to your proportions. It should be a rolling Lay-Z-Boy :D :lol:
I intend for it to be something like that, but with some compromise on comfort to keep weight down. I want it to feel sturdy like the Lay-Z-Boy, but not necessarily soft or comfortable unless it can be done without compromising the weight too much. The function of the suspension and disc brakes is for safety.

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