Best 1st gear final ratio? +BCD64 + Bafang Ultra?

[taserface]

Hello eMTBers-

I got a a couple questions...

Is there any guidance for what people feel is a good target for the lowest final gear ratio on a Bafang Ultra (or similar)? I am a big rider (250lbs) and don't want to struggle with any steep hills. Should I aim for a 1.0 or lower final ratio in first?... or can I *easily* get way with a higher ratio (erring on side of caution)?

I am considering the revolute hub to pair with a bafang ultra (200nm controller), but the gear ratios on the revolute are a bit taller than I was expecting (.8-3.15) and the largest sprocket they offer is 16t. It looks like I'd have to stick to BCD 64 to run a chainring that would keep the ratios reasonable.

Does anyone know of a BCD64 that would work well with Bafang Ultra? (I will need to maintain a good chainline.)

Thanks

 

[Ford Prefect]

Ouch, that's annoyingly small... I believe the Nine from 3x3, uses a 28tooth sprocket by default?

I have found miniature 104mm BCD spiders for the m620, but I've yet to find an aftermarket 130mm BCD spider to replace the massive chunk of iron Bafang supplies. Haven't looked for smaller BCDs, because I wanted to move in the opposite direction! ;D

With a 40tooth chainring pulling an 11-speed 42tooth-to-11tooth cassette, the first few gear ratios are only needed for very steep ascents (>30°/60% grade) & I launch in 3rd even with the motor off.

Likewise, even with the motor off, I usually double shift; skipping past half the gear ratios because it's easy enough to go a few MPH faster or slower, rather than needing a gear ratio for an ideal cadence at every possible speed.

On steep, challenging, technical bike trails, I believe this 11-speed layout could be just right. Even so, I suspect 9 speeds with the same overall ratio range, would work just fine (or possibly better).

For mixed trail & commuting use, the 11-speed feels like overkill considering the limited top end. Cadence ramps up very quickly, pedaling like mad long before "top speed" is approached, meaning the rider puts no significant power into the pedals, beyond ~20 or 24 MPH. "Top speed" and efficiency would benefit, from a lower cadence allowing more pedal force to be input.

Far more shift range would be welcome, since a motor as powerful as the m620 can handle far taller steps between ratios.

(I'd love to get our 40tooth chainring & 42-to-11 cassette, swapped out for a 46tooth chainring & 48-to-11 cassette; just to stay off the 11tooth a bit & to gain pedal power at moderate\high speeds.)

Especially when rolling downhill, it feels weird to be unable to gain stability by sending power to the rear wheel. My 3×10 speed manual bike has dramatically lower cadence at 28+ MPH, allowing me to maintain steady pressure during descents, for a much more stable feel than the 1×11 allows. On the ebike, I can use the throttle to help stand the rear end up, but the pedals turn into freewheeling footpegs once the cadence gets too high for me to really push against them.

I think we need the 3x3 Nine hub... 554% ratio shift range!
If only someone will buy them for us?