The Great "Gearing vs Hub Motor" Debate

[safe]

tried my mbike 100'....7 seconds
WITHOUT bypass
it's lots quicker on bypass, but i doubt it would beat 5 seconds.

What sized motor do you have? And is it a hub motor or is it geared in any way? (you don't need shifting for fast starts, but a lower gear ratio would help)

5 seconds is about my average of the three runs with some a little above and others slightly below. It's a "ballpark" figure to be sure...

 

[xyster]

Interesting Safe doesn't want to do a midrange test. For short, 100' runs he needn't shift, and for mile long runs he has to shift through the gears for a relatively short % of the whole run, then he can take and make use of aerodynamics which most of us can't do while simultaneously recording video.

I tell ya', Safe thinks he's going to lose a midrange 1/8th to 1/4mile acceleration test where he has to shift through the gears, which is going to slow his time considerably, but can't rely so much on aerodynamic positioning.

And then of course he says he's got no way for on-board video either.... makes me say "hmmmm..." :?

 

[safe]

Safe thinks he's going to lose a midrange 1/8th to 1/4mile acceleration.

Geez, I'll try to get a test at those distances. My meter measures in 1/10 increments... could we do it on something that is 1/10 of a mile like say 5/10 or 1/2 mile?

The problem is that I have to STOP the bike and then read it. The decelleration is going to get added to my meter so that's going to SUBTRACT from the totals.

Do you see how my measuring limitations make 1/4 mile hard to do?

Correction

My meter reads to hundreths not 10ths. I should be able to get a reading for this after all...

 

[xyster]

Geez, I'll try to get a test at those distances.

Even if I don't prefer 'em the way you do, I can also yank a chain or two.

Besides, if you're smart enough to put that bike together, you're smart enough to find a way to accurately test it's performance at ~1/4 mile distances.

But then there's the trust issue, since you say you have no video cam. What kind of techie doesn't have a video cam by now? Freakin' dinosaurs, that's who.

 

[safe]

Quarter Mile Results

Conditions today are simply "bad" it's 40 degrees and the road I laid out had a slight headwind and a 20 foot high "hill" in the middle, so it was not possible to get the full speed out of the bike. That being said I think I have a "rough" estimate of the times.

After five runs they all came in around 33-34 seconds for the quarter mile.

My guess is on a flat course with no winds and warmer temps (makes the battery stronger) that I could get the number down to near 30 seconds. The thing to do is to "pre ride" the road and get landmarks (for me it was racing between two lamp posts) and then you can focus on the time and ignore the distance because you already measured that.

What speed is that? I think it's a 27 mph average for the quarter mile... (which was what the meter was showing... around 30 mph for most of the second half of the run)

 

[safe]

I went to an online calculator and they produce this result:

"The quarter mile acceleration time of a car that weighs 325 pounds and has 1.35 horsepower (1012 Watts) is 36.236 seconds."

So I'm (somehow) exceeding what I'm "supposed" to be able to do. The start of my course had a slight downhill that may have given "better than expected" results for the first (most crucial) 1/8 of a mile before I then had to climb the next 20 foot high hill. But I only lost 1-2 mph on the hill so... anyway... it's a "ballpark" figure and I'll be interested to see what other people get.. (there are some really flat areas not too far away and I'll repeat the testing later)

Note: I ran the test in both directions and got pretty similiar results... about a second or two slower in the reverse direction. So all I can say is hmmmmmmm??????????

Okay, I get it... cars are big and have lots of wind resistance, so the online calculator would calculate based on a frontal area probably 5 times what my narrow little "Road Racer" produces. So, with less resistance you could realisitically beat the numbers because about three quarters of the run is up near 30 mph.

 

[xyster]

Good results for the power it sounds like.

Below is two frames from the 72V 35Amp acceleration test movie I'm preparing (don't like the online vid services, their quality stinks). The first frame shows the speedo/odo just before I blast off at 412.60 miles. The second frame is right at the end of this run, showing a top speed of 36.8mph at 412.75 miles (after 0.15 miles and 18 seconds from the first frame). You can also see the voltmeter and ammeter readings. This was also a very cold day, and before I replaced my sucky blade connectors, voltage sag was a full 10 volts and I was only pulling 33 amps That situation has been fixed.

I was in the full upright position during the entire acceleration test (else I couldn't have shot the video with the camera around my neck). And this is at 8 volts less than what I'm running now. Maybe I'll do some math and make a quarter mile estimate; a reasonable guestimate would be low 20's.

Maybe I'll try and figure out how to do a quarter mile vid with my upgraded 80 volt pack in a tucked position. See if I can get it less than 20 seconds.

 

[safe]

Quarter Mile Retest

I found a perfectly flat piece of road and marked off a quarter mile. This is roughly how the speeds went...

10 seconds - 20 mph

20 seconds - 35 mph

30 seconds - 40 mph

After three almost identical runs I ended up with 31 seconds at a final speed of 41 mph. (best top speed)

So my "best quarter mile" (which will not likely change much for this bike) is 41 mph top speed and 31 seconds elapsed time.

And I managed to find a tighter "tuck" position that is giving me a little more top end speed and on the downhill I managed to reach 51 mph for 2 seconds. (so all in all it was a "good day") Seems that a quarter mile is just about exactly how long it takes my bike to get up to full speed so all testing beyond this will favor top speed over acceleration. It will be interesting to see your "elapsed time" because on average the last third of the run is at high speed where my higher top end does well. But massive power should get you there quicker, so if you beat 30 seconds that's "good", but if you beat 20 seconds that's really smoking!

My "average speed" calculates to 29 mph.

 

[Lowell]

I was all ready to run a 1/4 mile tonight, except that it started snowing.

The bike feels very strong off the line though, but not quite enough torque to wheelie on it's own yet. With a slight pull on the bars while applying full throttle it will go all the way up though, and I had a few exciting trips across the garage/basement on the rear wheel :lol:

Exciting because throttle modulation is not very good at all. If you bring the front wheel up at full throttle, you have to let off a lot so that it doesn't go over, and letting off just a bit more brings the front end down too quickly. This setup needs a user programmable throttle curve or some other way to linearize the torque vs throttle angle.

 

[fechter]

I was all ready to run a 1/4 mile tonight, except that it started snowing.

That's no excuse. Knoxie rides in the snow.


The throttle response on most controllers really sucks. The current mode throttle adapter should take care of that.... if I would ever getting around to building one.

 

[safe]

The weather has gone bad here in Missouri too. I won't be able to ride again until next monday most likely... we had a very brief warmup yesterday and now it's cold and likely to snow a little.

My quarter mile times will likely not vary much from 31-34 seconds depending on the road and weather conditions. All I can say is that for a tiny little 750 watt (1012 peak) motor to be able to do that it's pretty impressive just in a technological sense. That's getting a lot of performance for very little energy.

But we need to remember also that the human powered land speed record is something like 80 mph! Imagine that... somehow they are able to reach a speed of 80 mph with only the power that a human can provide which is not going to be more than about 1500 watts AT BEST and probably less than that.

So the human powered bicycle (recumbent with full fairing) is STILL faster than any electric vehicle we are creating, so it's good to be mindful of that.

 

[Toorbough ULL-Zeveigh]

To get into these 'clubs' are you allowed to crank to help out the motor? If not, then I'm still looking to make it into the 20mph club! 8)

If you're planning on selling you're configuration ostensibly to comply with the law, do you not require pedals to be legal in your state?

 

[Lowell]

But what's the human powered speed record for a bike that doesn't need a support crew to start and stop?

 

[Lowell]

To get into these 'clubs' are you allowed to crank to help out the motor? If not, then I'm still looking to make it into the 20mph club! 8)

If you're planning on selling you're configuration ostensibly to comply with the law, do you not require pedals to be legal in your state?

I think pedaling should be fine, after all it's an e-bike.

 

[safe]

If you're planning on selling you're configuration ostensibly to comply with the law, do you not require pedals to be legal in your state?

The law in Missouri covers all vehicles below a certain power level. They allow a variety of configurations (like gas powered small scooters) but the only "weird" thing they don't allow is a "clutch" because they figure that a child might have trouble using it safely.

The national law says that you need pedals to comply with it's rules. (if you want it to sell everywhere you do this)

State Laws "trump" National Laws so in the end it's all local, but there are other states that carry the higher limits that Missouri does. So it might turn out that what I might create would still be illegal in some states and legal in others.

Missouri Law:

"Any two-wheeled or three-wheeled device having an automatic transmission and a motor with a cylinder capacity of not more than fifty (50) cubic centimeters, which produces less than three (3) gross brake horsepower, and is capable of propelling the device at a maximum speed of not more than thirty (30) miles per hour on level ground."

California Law:

406(a) A "motorized bicycle" or "moped" is any two-wheeled or three-wheeled device having fully operative pedals for propulsion by human power, or having no pedals if powered solely by electrical energy, and an automatic transmission and a motor which produces less than 2 gross brake horsepower and is capable of propelling the device at a maximum speed of not more than 30 miles per hour on level ground.

National Law:

The National US law states that electric bicycles with fully functioning pedals, no more than 750 watts of motor power output, and a top speed of 20 mph on motor power only, are to be treated as "bicycles", and are not subject to motorized vehicle laws.

The Bottom Line:

In some states a bike that does not pedal is classified as a "moped" and then those rules would apply. So in a "worst case scenario" you can always own a "moped"... it adds some registration issues, but it can be done as a "last resort". Then you need all the mirrors and turn signals and all the other crap... with that extra crap many people would not by a vehicle like mine... and that's fine... you can't please everyone... especially in this weird legal environement we live in today.

Here's a case in point:

In the "politically correct" city of Boulder Colorado they have a special law that "trumps" the national law AND even the state law:

“Electric assisted bicycleâ€￾ means a bicycle with a battery powered electric motor with a capacity of no more than four hundred watts continuous input power rating which assists the person pedaling and which is not capable of propelling the bicycle and rider at more than twenty miles per hour on level pavement.

If you live there then you simply don't bother with a bike like mine at all because their rules are so restrictive that it would be useless.

 

[Lowell]

More important than the laws themselves, are how they are enforced. I don't know very many car drivers that travel the speed limit when there are no highway tax collectors on patrol.

 

[safe]

This does make me pause a little.

Maybe this is a "good idea" to think about?

I'm reaching "respectable speeds" with 86 lbs of Lead Acid batteries and only 750 Watts of power. What if I did focus on a "Road Racer" style but kept the 750 Watt limit and kept the pedals. What if my goal should be the "best possible" given the most "generic" National Law and then worry about gearing as the "afterthought" when the bike is sold. After all, you can gear a bike to comply with any speed restriction and the user can simply add an 8-speed hub and all of a sudden you have a performance machine again.

So it makes me think... this "reminder" might have me divide my next projects along two separate paths:

1. Path One - Top speed, 2 hp limit, no pedals.

2. Path Two - 1 hp limit, working pedals.

...all other things should "ideally" fit together, so things like fiberglass should work on both "platforms" and the overall frame geometry should be the same on both.

Hmmmmm....

 

[xyster]

Safe-
You're running three SLA in series, right?
What's the amp rating on the controller you're using?
Unless it's 20amps or less you're already above the legal 750 watt limit.

 

[Mathurin]

Also a non automatic transmission...
Shimano offers a 3 speed automatic w/186% ratio.

 

[knightmb]

Safe-
You're running three SLA in series, right?
What's the amp rating on the controller you're using?
Unless it's 20amps or less you're already above the legal 750 watt limit.

He's using a 20.83333333 amp controller

 

[TylerDurden]

In some states a bike that does not pedal is classified as a "moped" and then those rules would apply. So in a "worst case scenario" you can always own a "moped"... it adds some registration issues, but it can be done as a "last resort". Then you need all the mirrors and turn signals and all the other crap... with that extra crap many people would not by a vehicle like mine...

Rewind to an earlier post...

I'd rather be "safe" than "sorry". (that's why I chose my name as "safe" and not something else)

...and you ride yer rig on the street and want to sell similar rigs.

right.

 

[TylerDurden]

36 Volts 20 Amps
Lithium Pack of 60 cells 10 x 3 x 2 - (13.2 AH)
Weight is only about 8 lbs
Total Price only $282

At prices like that you could sell a lot of them because the battery doesn't scare people away. ($282 verses something like a $800 for a bigger machine)

Me confused...

off the shelf lipo, bms and charger?

where can *I* get that deal?

EDIT
Whoa... where'd his post go????

 

[knightmb]

EDIT
Whoa... where'd his post go????

I promise it wasn't me. I have his post preserved in my quote just in case someone hit the delete button by mistake

Just found it, was moved to new topic here:
http://endless-sphere.com/forums/viewtopic.php?t=416

 

[safe]

Moved to: "* * * Bike Designs and Theories * * *"

 

[Toorbough ULL-Zeveigh]

The law in Missouri covers all vehicles below a certain power level. They allow a variety of configurations (like gas powered small scooters) but the only "weird" thing they don't allow is a "clutch" because they figure that a child might have trouble using it safely.

I have to thank you for being the only one to ever offer an explanation for the 'clutch' prohibition. It's lifted a long standing, nagging weight off my mind. It was only ever to satisfy my own curiousity, but for the last 30 years I've axed cops, lawyers, legislators & nobody could tell me why it's there. How sure r u that's the real reason or is that your best guess?

Don't you find it 'weird' that Canada would have that same obscure provision? In fact, can you offer any speculation why the world over, the 'power bike' laws read pretty much the same. Supposedly separate sovereign regions, they all impose about the same limits. A few watts difference here or there is just splitting hairs. The 50cc limit looks to be a world standard. How does that happen? You yourself have remarked how overly onerus these laws are for something this insignificant & I find that quite conspicuous.

Here's a case in point:

In the "politically correct" city of Boulder Colorado they have a special law that "trumps" the national law AND even the state law:

“Electric assisted bicycle” means a bicycle with a battery powered electric motor with a capacity of no more than four hundred watts continuous input power rating which assists the person pedaling and which is not capable of propelling the bicycle and rider at more than twenty miles per hour on level pavement.

If you live there then you simply don't bother with a bike like mine at all because their rules are so restrictive that it would be useless.

Well that IS 'VER-R-RY Artie Johnson'! :?

If that's the case, then I fail to understand how Optibike with their HQ in Boulder is allowed to test drive their product & sell them to the locals. The 'electric only' speed must either be highly understated or else going thru the bikes gearing doesn't do a whole lot. My hub motor is capped at 500W & 20mph to comply with Canadian regs. So if gears only get you an additional 2mph & that's with an extra 100W, then you can see why I'm skeptical.


Optibike 600t Specs

Stock range:
38 miles - electric only
49 miles - moderate pedaling
52 miles - hard pedaling

Stock run time:
1.75 hours - sport mode
2.3 hours - economy mode

Top Speed:
22 mph - electric only
28 mph - cruising speed
30+ mph - with pedal assist

Overall weight:
71 lbs

Battery type:
36v 13ah NiMH + 36v 15ah Li-Poly

Motor:
High efficiency, brushless DC with Rare earth Neodymium Iron Boron Magnets

Motor Drive:
Patented Motorized Bottom Bracket® (MBB)

Controller:
Proprietary Derivative Power Control® (DPC)

Motor Power:
600w continuous

http://www.optibike.com/ index.php?option=com_content&task=view&id=44&Itemid=24