E-Bike acceleration vs traffic

speedyebikenoob · Feb 10, 2019

I have looked through many threads on this forum and I couldn't find a proper response to this. I was riding my e bike through traffic a couple days ago, and I was surprised to see that I could easily keep up with traffic and more. Granted that the cars at stoplights weren't stomping on their gas pedals, but again neither was I, and it seemed like I was considerably quicker off the line than them, although after 25-30 mph the cars would take off. I don't have an extremely powerful e bike from hell or anything, no I have a cyclone motor on my bike running 60 volts and 40 amps. Compared to all the cars I've driven though, my bike feels much quicker than them, other than my father's BMW M240i. I don't see how this is possible though with my motor making.. 3.5 hp? Maybe it just feels quicker because a bicycle is a two wheeler, but I've ridden a 125cc motorbike (4 stroke unfortunately) and frankly it was pathetic. So has anyone compared the acceleration of their e-scooter or e-bike to an actual car, like from 0-20 mph? I'm genuinely curious but unfortunately I don't have any friends who are enthusiastic about drag racing an electric bicycle. :lol: If someone has acceleration figures I would seriously like to see them.

flat tire · Feb 10, 2019

Few main factors at play here:

--traffic not trying to race you
--electric torque curve and low gears give good boost off the line
--your bike feels faster than it is

It takes 10 or 15kw to give lower end sports cars a run for their money in the 0-20 MPH range. Light weight and accessible torque make quick takeoffs from a stop very easy but power to weight will dominate once both parties are rolling, in the powerband and have traction.

ebike simulator (google) will be interesting for you. It's not hard to make a ebike that theoretically delivers >1G acceleration for a short time at low speed, if you have a way to keep the front wheel down.

speedyebikenoob · Feb 10, 2019

flat tire said:
Few main factors at play here:

--traffic not trying to race you
--electric torque curve and low gears give good boost off the line
--your bike feels faster than it is

It takes 10 or 15kw to give lower end sports cars a run for their money in the 0-20 MPH range. Light weight and accessible torque make quick takeoffs from a stop very easy but power to weight will dominate once both parties are rolling, in the powerband and have traction.

ebike simulator (google) will be interesting for you. It's not hard to make a ebike that theoretically delivers >1G acceleration for a short time at low speed, if you have a way to keep the front wheel down.

So it's the lower gearing on these e bikes that makes it quicker? Standard electric cars with only a single gear can keep up with normal ICE cars with the same power, and these e bikes in many cases have 6-7 or even 8 gears.

amberwolf · Feb 10, 2019

At the root, it's about power to weight ratio, *and* the power/torque curve of the motor itself.

BUT:

In 2WD(+), having different motors/windings can make it quicker, one with power band peaking at low RPM, the other at higher RPM where the first one's acceleration starts to fall off. (though if they ahd the same powerband, they'd reach that point even faster, so it might'n't matter).

If middrive, thru the bike's pedal gearing, then it's about starting out in the right gear, and changing up thru the gears as you accelerate to keep the motor in the ideal RPM.

THus, wheelsize also matters (as it is the "gearing" of a hubmotor to the road).

My 200lb-ish 2WD CrazyBike2, with me on it (when I weighed 130-150lbs) could do 0-20MPH in under 4 seconds with something like 2.5-3kW, just with a generic 9C 26" wheel on the front and a basic Crystalyte on the 20" rear.

My ~400lb SB Cruiser trike, with me on it now that I weigh more like 190, can do 0-20MPH in around 4 seconds with something just over 4kW...but it takes more massive MXUS 3k motors in 20" wheels to do it. (if I had the same motors and wheel configuration as CB2, I would guesstimate twice the acceleration time, or worse).

For me, acceleration from 0-20MPH (the max I can go anyway) being under 4 seconds, under 3 if possible, is more important than the max speed, because I ride in traffic most of the time, and frequently end up stuck at the front of the line at a red light. So when it goes green, either I get the heck out of their way by being quicker than they are to get across the intersection, or a significant number of drivers waiting behind me get impatient, even aggressive. Some still do...but not many compared to more typical "bicycle" accelerations.

speedyebikenoob · Feb 10, 2019

amberwolf said:
At the root, it's about power to weight ratio, *and* the power/torque curve of the motor itself.

BUT:

In 2WD(+), having different motors/windings can make it quicker, one with power band peaking at low RPM, the other at higher RPM where the first one's acceleration starts to fall off. (though if they ahd the same powerband, they'd reach that point even faster, so it might'n't matter).

If middrive, thru the bike's pedal gearing, then it's about starting out in the right gear, and changing up thru the gears as you accelerate to keep the motor in the ideal RPM.

THus, wheelsize also matters (as it is the "gearing" of a hubmotor to the road).

My 200lb-ish 2WD CrazyBike2, with me on it (when I weighed 130-150lbs) could do 0-20MPH in under 4 seconds with something like 2.5-3kW, just with a generic 9C 26" wheel on the front and a basic Crystalyte on the 20" rear.

My ~400lb SB Cruiser trike, with me on it now that I weigh more like 190, can do 0-20MPH in around 4 seconds with something just over 4kW...but it takes more massive MXUS 3k motors in 20" wheels to do it. (if I had the same motors and wheel configuration as CB2, I would guesstimate twice the acceleration time, or worse).

For me, acceleration from 0-20MPH (the max I can go anyway) being under 4 seconds, under 3 if possible, is more important than the max speed, because I ride in traffic most of the time, and frequently end up stuck at the front of the line at a red light. So when it goes green, either I get the heck out of their way by being quicker than they are to get across the intersection, or a significant number of drivers waiting behind me get impatient, even aggressive. Some still do...but not many compared to more typical "bicycle" accelerations.

That kind of acceleration isn't too off from a car actually. Your average four cylinder car can do it in about 2-3 seconds. Speaking of wheelsize and torque, I suspect that the torque to horsepower ratio is far larger on our bikes than it is on a car just because a car is geared to do 140+ mph where an e bike is geared for more like 30-35. I have no idea how many ft lbs or nm of torque the motor on my bike makes, but I'm sure the number is much greater than the 3.5 horsepower it has. Regardless I'll know soon enough how slow or how quick these bikes are compared to a car, I'll try to get outside and have a tiny drag race with one of my friends or something within the next couple weeks. I'll reply to this thread with what happened once I do that if anyone else is curious. That might not be for a while though because of all the dang rain down here.

amberwolf · Feb 10, 2019

Rain just makes it more interesting.

E-Bike acceleration vs traffic

speedyebikenoob

1 kW

flat tire

100 kW

speedyebikenoob

1 kW

amberwolf

Administrator

speedyebikenoob

1 kW

amberwolf

Administrator

Similar threads