BBS02 RPM / Cadence at 34V

Backstory: I'm moving to Germany, where my current eBike setup is illegal. I want to get a BBS01 and fit it with the 500W BBS02 rotor and stator as others have done in order to bring the cadence to something more comfortable (>95 RPMs).
https://www.pedelecs.co.uk/forum/threads/bafang-bbs01-changing-rpm.34027/

For the cadence specs (below) for the 500W BBS02 at 36V and 48V, are those measurements taken at that actual voltage, or, for the 36V spec, are they taken with a "full battery" assuming something like 10S @ 4.2V = 42V or 10S @ 4.0V = 40V?


I'm looking at LiFePo4 packs that Tumich currently has for sale that run at 34V.

If "36V" is truly measured at 36.0VDC, the quoted 113rpm run at 34V, which is 113 * (34/36) = 107rpm is a completely fine cadence to me. But if "36V" is measured at 10S @ 4.2V = 42V, then running at 34V is 113 * (34/42) = 91rpm is on a the low side for a no-load motor speed.

Anybody have insight?

Or would somebody with a 36V 500W BBS02 measure their no-load speed at a specific voltage so that I know rpm/V for this motor?

Thanks in advance.

My 48V BBS02 had an extremely fast cadence, faster at its equilibrium speed than I could pedal along with. I decided to address it with shorter cranks, which allowed me to spin faster with less effort. I used 152mm steel unicycle cranks, which retailed for under $15. That doesn’t change your RPM situation, but it could fix your problem.

Balmorhea said:

My 48V BBS02 had an extremely fast cadence, faster at its equilibrium speed than I could pedal along with. I decided to address it with shorter cranks, which allowed me to spin faster with less effort. I used 152mm steel unicycle cranks, which retailed for under $15. That doesn’t change your RPM situation, but it could fix your problem.

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Are you running the 500W or 750W BBS02?

Any chance that you'd be willing to put your bike on a stand (or upside down) and run it full throttle with a voltmeter across the battery? You tell me the cadence if your controller shows that, or I could back it out from measured speed, wheel diameter (which tire size you run is close enough), along with number of teeth on both the front and rear sprockets. From the your battery voltage and cadence I think I could figure out if nominal "changed" voltages or actual voltages were used in the table.

mystryda said:

Are you running the 500W or 750W BBS02?

Any chance that you'd be willing to put your bike on a stand (or upside down) and run it full throttle with a voltmeter across the battery?

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It was a 750W, 48V unit, but it’s on someone else’s bike now. I only have hub motors at the moment. Otherwise, I’d be happy to oblige.

I use a metronome app to measure RPMs in that speed range. I attach a zip tie or flap of tape to the rotating apparatus so it goes tick-tick-tick, then find the metronome setting that matches.

Balmorhea said:

I use a metronome app to measure RPMs in that speed range. I attach a zip tie or flap of tape to the rotating apparatus so it goes tick-tick-tick, then find the metronome setting that matches.

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Smooth trick! I'll have to remember that one.

(As a lifelong musician, I've had all manner of different metronomes in my life, some of which cost pretty solid money. None of them hold a candle to the MetroTimer app on my iPhone; LOVE it.)

https://lunacycle.com/name-plate-for-clipped-wire-surron/

mystryda said:

Germany, where my current eBike setup is illegal.

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markz said:

https://lunacycle.com/name-plate-for-clipped-wire-surron/

mystryda said:

Germany, where my current eBike setup is illegal.

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I appreciate the thought, but my hub motor stalls out below ~23mph. And if I got caught the penalties over there for what would be considered an unregistered, uninsured motorcycle would be significant. I'm just not willing to take the risk.

mystryda said:

markz said:

https://lunacycle.com/name-plate-for-clipped-wire-surron/

mystryda said:

Germany, where my current eBike setup is illegal.

Click to expand...

Click to expand...

I appreciate the thought, but my hub motor stalls out below ~23mph. And if I got caught the penalties over there for what would be considered an unregistered, uninsured motorcycle would be significant. I'm just not willing to take the risk.

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Yeah I guess if your doing wheelies and whizzing by people on the pathways, no need to risk it.