BAFANG BBS01 OR BBS02? 30KM/H efficiency

[athletic91]

Would like to seek advice which one is more efficient at 30km/h on flat ground? I leaning more towards bbs02 as it costs just a little more and its not much bulkier/ heavier.
Also does anyone knows the stock chainring no. of teeth?

 

[Warren]

Typically, smaller motors of similar design, will have lower no-load wattage. For example the BBS01 may use 35 watts at no-load, while the BBS02 might use 55 watts. At 30 km/hr, on flat ground, especially if you pedal at all, you won't be close to design load on the BBS02, so you will be wasting a larger percentage of the motor's power.

The BBS01 typically comes with a 46T chainring, while the BBS02 typically has a 48T chainring.

 

[95gtlts]

I'm interested in the same question, but rather than the figures on flat would like to know how the BBS01 and BBS02 stack up on light gradients in the 25-30kph range. I have a pretty flat commute with most climbing in the 1 - 2.5% gradient with 2 very short (100m) 3-6% hills. I'm not interested in going fast, around 30kph would be a good speed and like athletic91, am keen to find out if I'd be better off with the 350watt motor running fast for efficiency?

 

[KINNINVIEKID]

Typically, smaller motors of similar design, will have lower no-load wattage. For example the BBS01 may use 35 watts at no-load, while the BBS02 might use 55 watts. At 30 km/hr, on flat ground, especially if you pedal at all, you won't be close to design load on the BBS02, so you will be wasting a larger percentage of the motor's power.

The BBS01 typically comes with a 46T chainring, while the BBS02 typically has a 48T chainring.

You keep the motor at its most efficient speed by simply being in the right gear at the right time so no difference in wasted power from either motor.
My BBS02 came with a 46T chainring.
You can always program the motor to peak at a lower amperage if you want.

 

[tahustvedt]

Depends on how aerodynamic you and the bike is. I have a BBS01 250 W. With lycra and my cyclo cross with 35mm tires, fenders and a rear rack I averaged 31.3 km/h with throttle only over varied terrain. No pedaling. Efficiency was 78%. I measured in power with a wattmeter and out power with a rear wheel power meter. http://www.strava.com/activities/160122860

It takes me to over 40 km/h on level ground when I tuck down in regular clothes, and is gear ratio limited at that speed (12-25 cassette). Speed accuracy is confirmed with a Garmin Edge 510.

 

[95gtlts]

Thanks tahustvedt that's the sort of thing I'm interested in.

I'm trying to understand if under running a 750w or running it at higher rpm but in a low gear to achieve that 30k/h I'm hoping for on my commute, is more or less efficient than running a 250/350w at capacity which seems to naturally fit the speed I want. From my experience with rc motors, many electric motors are most efficient at a given rpm, voltage and current. An 11-32 cassette may not quite give me that with the 750?

 

[tahustvedt]

If it was legal in Norway I would go for the 500 W unit. The 750 W unit seems to be too powerful for its own good.