Electric Bicycle VS Electric Motorcycle?

[staticGenerator]

Hello All,

New to this forum, thanks for making this available.

I had considered constructing an electric vehicle many years back. Realizing I didn't have the time or the funds to complete the project I later noticed a video on YouTube a few months ago of an electric bicycle with a claimed top speed of 75mph (120km/h)! I'm sure you've seen them.

I began considering the possibility of using such a bicycle as means of transportation to and from work where I would need to sustain speeds of 45mph (72km/h) for a distance of about 10 miles (8km). I thought I would now meet my desire to go electric without having to build an electric vehicle...or so I thought.

Since visiting forums here I am hearing remarks such as "my electric bike hit 28 mph!". It doesn't sound as if my goal of 45mph is a common one. I hope you can get me started with some advice on whether such an attempt would be practical.

Here are some facts:

• I weigh 155 lb
  I plan on working with the state of Colorado where I live to make the bike 'street legal' so am not concerned about bicycle law limitations
  No real limit on Budget if the cost is justified
  Distance to go on one charge is 10 miles
  Speed to sustain is 45mph

Here are some questions:

- 36, 48, 75, 100 or 120 volt system?
- Controller recommendations?
- Hub motor versus chain driven motor and why?
- Would the weight of the motor, batteries, and controller be practical on a bicycle at these speeds?
- For reaching these speeds would a hub motor on the front and a hub motor on the rear be helpful?

Bottom line, I'd like to keep this as simple and cost effective as possible. I'd prefer NOT to go with a motorcycle conversion if possible.

 

[LI-ghtcycle]

Talk to JohninCR he has such a bike that he rides even faster as his daily driver.

 

[patrickza]

Well it's possible but not very practical. To hit 40+ with off the shelf parts you need the following:
A powerful motor, either an X5 for a 9C
72v+
High powered cells. You'll need to have 2kw at your disposal so 3C continuous is a must.
A big enough battery pack.

My bike has all those and tops out just over 40, but there's no way I'd do that for 10 miles, feels much too scary. On my 200cc motorbike it felt slow though! Oh and btw 8 km is 5 miles, 16km is 10 miles.

If you plan on keeping up those speeds in traffic you might want to consider an e-motorcycle, but my gut feel is a 30mph commute will be enough fun for you.

 

[MadRhino]

If you want to be street legal with your targeted speed, you don't build E-bike. You are going motorcycle, and you'll have to meet all the requirements for mortorcycle approval. The best would be to start with a gas motorcycle, strip and build it EV.

If you don't care about being legal, many of us can do this speed with E-bikes. Read the building threads, this will give you some ideas.

 

[auraslip]

You'll need:

Upgraded tires, brakes, and suspension fork. That's $500 if you do it cheap right there.

For the electronics:
9c from methods $200
76v 60 amp controller from lyen $200
24s2p 10ah headway cells from bmsbattery.com @ $16 a cell shipped.
Charger and bms or have them build the pack for you $200

Should be a 72v20ah 4c-5c battery capable of putting out 7.2kw (although you'd melt even a cylte 5x motor with that much power)

That's basically my current bike if you replace the headways with a ping(but I'm upgrading to headways soon)

Then you need a bike, and a place for the batteries. Since you are asking about chain drives, I assume you are handy with the DIY so building a battery box won't be that hard for you. Also you'll need a good strong torque arm.

Rear motor is needed because a front one would just burn out with that sort of power.

If you really want a good resource look up the ebook "greasypants" sells. He is very thorough in documenting his build. It has similar goals as yours, and is actually faster and goes farther.

 

[RallySTX]

What he said, but, I gotta say, I don't think a bike doing 45 would handle very well with a 20 pound front hubbie. Think full suspension, disk brakes, downhill style steel frame for stability at speed, LIPO batteries, 26 inch wheels with top shelf tires, and always keep in your mind, that bicycles are generally not designed for such high speed. An eyes open aproach is mandated here, as the potential for catastrophy increases with every bulge of the envelope. The trouble with this hobbie is that it's all to easy to go faster. The question is, do you have the skills to deal with the issues that will arise? The rewards are great, and so is the price of failure. Good luck, and I hope to read a success story soon! Welcome to the forum!
Brian L.

 

[SamTexas]

I began considering the possibility of using such a bicycle as means of transportation to and from work where I would need to sustain speeds of 45mph (72km/h)...

I plan on working with the state of Colorado where I live to make the bike 'street legal' so am not concerned about bicycle law limitations...

Bottom line, I'd like to keep this as simple and cost effective as possible. I'd prefer NOT to go with a motorcycle conversion if possible.

You shouldn't have any problem finding the necessary motor, controller and battery pack to achieve your desired 45mph sustained speed. But I think you will have a hard time finding a bicycle frame with adequate suspension and stopping power without spending a fortune on it.

Any motorcycle with an engine size of 200cc or larger will have the properly required suspension and brakes. Plus you would benefit from the existing lights, signals, horn and mirrors.

I don't quite see the reason for having pedals when one is traveling at 45mph. Good luck and have fun with your build.

 

[AussieJester]

Sams hit the nail on the head, totally possible but will cost you
i would suggest reading the build logs from others on the forum
and then decide which way you wish to go with components.
All you will get with this thread is people telling you what you
should get based on their opinion, might suit your needs
might not, do the research and make your own deciosn is my best
advice. Whatever you do though, to be safe it is going
to be very expensive.

Best of luck

KiM

 

[FMB42]

I too would go with a motorcycle in this case (that is, unless your interest lies in the novelty of building 45mph e-bike).

Buying a street legal ICE motorcycle (or converting one to electric) would save you much time and trouble imo.


Quote:
"I plan on working with the state of Colorado where I live to make the bike 'street legal' so am not concerned about bicycle law limitations"

What are you going to do if this "street legalization" process doesn't go as planned?



The bottom line here, imo, is that a 45mph street legal bicycle is still a bicycle...

 

[dogman dan]

The real issue is going to be registering it as a motorcycle. To do that in most US states you HAVE to start with a frame with a vin number for it to be a tolerable process. I'm not sure what custom chopper builders do, but they have experience with the process, and may use frames that have done the paperwork, and then can be produced with vin numbers.

So In my opinion, you are building a motorcycle conversion. Look at 125- 250 enduro frames for stuff with headlights etc on it.

Or go renegade, and ride 45 mph on a solid build based on a 5304 or 5303 motor and a serious mountain bike frame. Eventually the cops will get you, aren't they a bit more strict than the NM state chotas? Here you could likely go forever as long as you didn't speed, run lights, hit something.

You must have suspension. My 50 mph racing bike doesn't have it, and by 50 mph on fairly decent street paving it's front wheel is a hopping like mad. On the track, it's Ok, much smoother pavement in Tucson, and you can't get so fast with all the tight corners.

 

[MadRhino]

Whatever you do though, to be safe it is going
to be very expensive.

Exactly. When you build for that kind of performance with a bicycle, you are really building a very lightweight motorcycle. To make it a safe ride with the required quality of components, is more expansive than building on a motorcycle from the start, and not likely to be approved as such, no matter how good you make it.

 

[Lock]

At target speeds costs of components and energy costs will be greatly reduced if ya go fully enclosed recumbent. G'Luck.
LocK

 

[staticGenerator]

Thank you for the replies. Here were the reasons I was looking at an e-bike as opposed to a motorcycle:

- build a bike capable of necessary speed
- minimalist design for build effort and maintenance
- more distance for less charge (plan to charge as much as possible with solar panels)
- make a visible statement about the ability of electric power

I thought with a decent downhill bike it might be possible to hit those speeds no problem with the proper setup. But I'd much rather be sure of being able to get the bike street legal.

I may settle for a more reasonable e-bike setup that will get me where I want to go in the bike lane, because what I'm really talking about here is turning a bike into a motorcycle.

Now that I have a little perspective, I will continue researching the forums to help me make my decision.

 

[staticGenerator]

Rear motor is needed because a front one would just burn out with that sort of power.

If you really want a good resource look up the ebook "greasypants" sells. He is very thorough in documenting his build. It has similar goals as yours, and is actually faster and goes farther.

Thanks, I thought having a front hub motor and rear hub motor would even out the torque so that wouldn't be as much of an issue. Maybe its been tried before. I'm not sure how a front hub would have a tendency to burn out over a rear one though based stricty based on the placement location. Unless I'm just not getting the physics involved. I was think more like twisted/bent/broken forks and frame.

I have seen the book offer and I'm checking into it.

Let me know if you've got pics of your ride posted somewhere.

 

[pdf]

My opinion: continuous speeds of 45 mph will wear bike parts. They aren't generally designed to go that fast for that long. I'd start with a small gas motorcycle and convert it. Those parts are designed to go that fast for that long. Loosing a front wheel or even a tire problem at 45 mph isn't much fun.

Not saying it can't be done, but in my opinion, a bike is too light for that service. But then again, I have gotten more pain-averse since I have dependents and older bones .

 

[jag]

Like many pointed out, the challenge is not the electrification, it is finding or building a bike which handles well both at speed and with the extra weight of ebike parts. DH and all-mountain bikes are promising. I have Cannondales (prohpet, jekyll and super-V). All are stable at speed. I have the Jekyll electrified and it handles comparably well, but I'll have to wait until spring and no snow to test at higher speeds. My previous Specialized Stumpjumper+9C motor was built to do 50km/h/32mph on the flats, but I regularly took it to about 40mph on downhills and it handled ok also, but does not feel as stable as the cannondales.
Latest Cannondale+BMC motor build thread:
http://endless-sphere.com/forums/viewtopic.php?f=4&t=23518
Previous 9C build thread:
http://endless-sphere.com/forums/viewtopic.php?f=4&t=9549

You'll need:

Upgraded tires, brakes, and suspension fork. That's $500 if you do it cheap right there.

For the electronics:
9c from methods $200
76v 60 amp controller from lyen $200
24s2p 10ah headway cells from bmsbattery.com @ $16 a cell shipped.
Charger and bms or have them build the pack for you $200

The following would give you about 40mph top speed on the flats, and is about the best you can do for an easy build. No wire mods needed, just bolt to bike. Takes a few hours work.

9C rear 6x10 wind. $200 The reason for the slow wind is to not have to upgrade the phase wires. 7x9 wind would give 5% more power and speed due to higher copper fill. I got one but these are hard to find now.
12FET Lyen controller @100V $129
100V batteries. Lipo from Hobbyking, or A123 from Cellman.
I'm strongly advocating batteries in the frame triangle for weight balance and handling. Cell-man can build the pack into a triangular shape.
Best is if you can charge in both ends of your commute. Then you can go with a relatively small pack, say 5Ah at 100V (500Wh) for a 10mile commute.

A good, used bike with triangle space for batteries: Large price range. Sometimes used high end bikes show up for $500, but perhaps expecting $1000 is more reasonable. I'd advocate mono-pivot for rear suspension. and a front shock where the damping can be set really high to account for the extra weight of the ebike components.

 

[John in CR]

Some people have opinions and others have proof. I built the bike below as an experiment in less than a week, and put it in service in early Dec '08. Someone gave me a steel MTB and I added some steel tubing and flat steel for the dropouts plus a motorcycle seat. The only repair of the bike itself in 26 months was due to my crap welding skills where a crack started to develop after a year and a half of daily use. My weld was bad where I re-welded the headset after hacking the original off to slacken head tube angle. I've put between 7500 and 10k miles on this bike in almost daily use.

I weigh 250lb and it will push me just past 60mph on a flat road with no wind if I tuck. Those conditions are rare, but I maintain 50mph into headwinds (in a tuck) and up slight grades every time I get on the highway, and on the return with the wind I often let off the throttle because the speed limit on that road is 90kph. My regen braking makes it so I use the mechanical brakes only for slow speeds or emergencies. Saturday I went on highway run 11 miles out and 11 miles back. The only time my speed dropped below 50mph was up a 7-8% grade where I only maintained 33mph through the steepest section into a pretty stiff headwind. At your weight I have no doubt my bike would maintain over 40mph up that hill, maybe even your target flat ground 45. I used about 70wh/mile on that ride due to the strong wind. It typically takes 60wh/mi on calmer days for that road.

My bike was so cheap I won't even say, but the motors aren't available retail anyway. I bought 5 directly from the factory back in August of '08 The new Xlyte X5 with the 40mm stator is a comparable motor and easier to implement on a bike. For speed you want long and low. You want regen to greatly reduce brake maintenance. You also want your bike to have a top speed significantly higher than your target cruising speed, so you can still maintain the speed you want into headwinds and up slight grades, and gives you good passing power at cruise. The sacrifice in doing so will be essentially a steeped gearing, so it won't like really steep hills, especially at partial throttle, and low speed acceleration suffers. You can kick acceleration back up with higher current settings in the controller as long as you don't have to contend with much in the way of hills. These are the factors you must consider in selecting which wind count of motor you want and the voltage. A top of charge voltage somewhere between 80V and 100V is what you'll probably want, and definitely a programmable controller.

Doing it again, I would add rear suspension (at least for the seat), shorten the cranks (for better clearance and more comfortable leg position at cruise), and send the crank power to a jackshaft first to get multiple gears and get the speed up to be able to add effort at cruise without some kind of pizza size chainring. I can really only pedal assist right at take off now.

What started out as a "let's see how this works" experiment forever changed our family of 5's primary transportation. The van sits parked often for weeks at a time.

We call her Big Blue.

 

[John in CR]

If you have no access to metal working, the two easy options I can think of are:
1. Pick op an old steel tandem and hack it into a feet forward bike.
2. Pick up a moped and strip the gasser parts off.

I've been on the lookout down here for either tandem or a Motobecane moped to electrify. The moped will probably end up heavier, but they're made strong enough that the original stuff would be fine at 45mph. Plus it could be an easier route to being legal on the road.

This is what I'd love to a Motobecane:

 

[dogman dan]

Dial down your target to about 35 mph continuous, and it gets a LOT easier, and less likely to get the bust. The standard recipe is pretty simple. LOTS of us have this basic bike.

Good strong frame bike, many prefer a steel frame hardtail for use of a rear motor. Disk brakes if possible. Avoid any bike priced under $150 new, in general.
9 continent rear hubmotor. 2807 winding or the slightly faster 2806 if you have few hills. Ebikes-ca or Ebikekit
40 amp 72v controller, Lyens in the for sale section is one good source, along with others there.
20s lipo battery of 10 ah size or larger. Hobby king.
With the 2807 motor, yer just barely in the 40mph club, but only at the start of the ride. You'll have a solid 35 mph bike good for 9 miles full blast.

speed = voltage. Lyens sells 90-120v controllers too, mine almost got me into the 50 mph club. Running on 25s lipo.

 

[icecube57]

Id rather have a Clyte than a 9C at those speeds. 9C can do it and its 1/4th the cost of an X5 but i wouldnt subject the 9C to a continuous duty for extended periods unless the area was truly flat and you did some air cooling. The amount of watts involved to maintain 40+ is retarded and would fail very quickly. Id rather run a 5304 or 05. I just dont have the funds to throw money at one.

 

[auraslip]

how much power do think you need with a 9x7 9c to sustain 40mph?

with a 24" 9x7 9c I sustain 33mph at 48v using about 25amps or 1300watts. I'm aware air resistance grows exponentially, but 40mph can't cost that much more. I think a lot of people don't know the magic of the speed %120 setting.

Amen to the price difference though. A 30 mph bike is cheaaaaaaaaap.

 

[John in CR]

The OP said sustain 45mph, not 45mph max speed under perfect conditions. A 9C just isn't going to cut it. 2 could deliver enough power, but is there a winding of 9C that doesn't need a penny farthing size wheel to do 55mph on under 100V? That's not a typo, because if you want to sustain 45 you really should shoot for about 55mph as the top speed putting no load speed most likely above 70mph.

Here's the data set again:

Here are some facts:
I weigh 155 lb
I plan on working with the state of Colorado where I live to make the bike 'street legal' so am not concerned about bicycle law limitations
No real limit on Budget if the cost is justified
Distance to go on one charge is 10 miles
Speed to sustain is 45mph

Here are some questions:
- 36, 48, 75, 100 or 120 volt system?
- Controller recommendations?
- Hub motor versus chain driven motor and why?
- Would the weight of the motor, batteries, and controller be practical on a bicycle at these speeds?
- For reaching these speeds would a hub motor on the front and a hub motor on the rear be helpful?

Bottom line, I'd like to keep this as simple and cost effective as possible. I'd prefer NOT to go with a motorcycle conversion if possible.

Here's another one I did that meets the OP's criteria. Red had the same motor as Blue, but in a 17" motorcycle rim instead of a 14". At only 155lbs, StaticGenerator would have no problems with the large wheel up to about 10% grades. Due to the more upright riding position the larger wheel diameter (23.5" vs 20") didn't make it any faster than Blue. With the between the swingarm battery in the pic it had right at a 10 mile range, though probably not at 45mph. It was a simple conversion of the cheapie 24" steel MTB. All I did was use a 1/4" thick steel to extend the swingarm, used a vice to flatten up the interior side of the swingarm for more battery space, welded in some supports for the battery which added lateral rigidity to the swingarm, made that L shaped seatpost to move the saddle lower and rearward, and swapped the straight MTB handlebar for a BMX type plus a cheapie 26" fork with disc brake. It wasn't good for off road, but a cushy street cruiser, and a better shock and fork would have made it quite nice.

A Clyte X5303 at 85V nominal using 23s of Lipo in a 20" rim with a 16" motorcycle tire would probably be a comparable performer. I'd go with Lyen's 24 fet controller, but at only 155lbs,. Something like that would make for an easy entry into high power ebiking that meets his criteria and would be a fun as hell street ride. Going off road requires a better base bike, and it's hard to find anything but aluminum which is more involved and risky to mod in this manner.

View attachment Red_.JPG

 

[John in CR]

Here's another one that meets the criteria. I built this one to try to come in below the 70lb weight limit for the Ebike Challenge racing. That's an 18.5" OD tire in a 14" motorcycle rim on the back and a 20" BMX tire on the front. The wheelbase is really too short and CG too high, so it's hard to keep the front wheel down if I set the controller current too aggressively. Big fat me is quite a sight on this little bike out mixing with traffic.

Stretching bike by moving the headset forward about 4", and extending the swingarm rearward 4" is what this bike needs. The geometry is okay, but as part of the stretch I'd want to get the BB an inch or 2 higher, because even those shortened cranks are too close to the ground. I'd also move the top battery forward so I can lower the seat. The bike is stable and nimble but a bit too thrilling for me in current form, which stretching would tame nicely.
View attachment Red Rocket race bike.JPG

 

[jag]

Some people have opinions and others have proof. I built the bike below as an experiment in less than a week
<snip>
What started out as a "let's see how this works" experiment forever changed our family of 5's primary transportation. The van sits parked often for weeks at a time.

We call her Big Blue.

Definitely plenty proof with the three pics of real-world conversions. How do the bikes compare? Do you still ride Big Blue mostly? How do the bikes compare?

One reason I looked into high performance MTB's for my ride was that bumps and holes in the road would almost throw me off the saddle when riding my first hardtail conversion. At night I would not spot the bumps in time (or at all) when going at about 50km/h. At the same time, a big bump hit at 50km/h makes me and the bike go flying way more than the same bump hit at more typical pedal speeds the bike was designed for.

With my more recent full suspension bikes, bumps are soaked up by the suspension up to its travel limit, but there is still a difference in handling between different FS bikes. Some suspensions can be well damped and keep the wheels on the roads, while others bob and sway.

 

[dogman dan]

With a 9c motor at 72v, full throttle continuous can overheat a motor in about 10 miles, or less if the weather is warm. You'd want holes in the motor cover for cooling for sure. Most of us have done that for high power.

I also agree, a 5304 crystalyte might be a better choice for long rides. Better able to dissipate the heat than a 9c. More mass means it can heat a bit longer before overheating.

My particular setup has a 40 amp controller on a 2807 9 continent, and running 72v it will pull 3400 watts breifly, but cruising at full throttle it will drop to 2000-2500 watts.