Gearing for Yamaha PW-SE


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2:22 PM
Aug 17, 2020
My Haibike SDURO, 27.5x2.2 tires came with single 38 tooth chainring and 11x42 cassette. This wasn’t ideal for climbing on steep grades over 10 percent, so I’ve switched to a 34 tooth RaceFace narrow-wide chainring which is about ideal for me - no need to go lower as I can now climb short sections of 20 percent grade. The trade-off is that to reach 20 mph on the ride home from the trail cadence is 80 rpm instead of 72.

Climbing isn’t as good as with the non-motorized bike, because I’m still using the stock tires (Schwalbe Smart Sam) and stock shock; also, lag in the motor controller makes torque less controller. But with the eBike climbing doesn’t make my SI joint hurt for the next two days.

The SDURO was sold as being suitable for “moderately rugged terrain” but I’m finding that it is a decent trail bike - the lower center of gravity compensates somewhat for the steepish 68 degree head angle. But it’s really best-suited for fire roads; I’m an experienced rider and haven’t taken the bike anywhere I haven’t also ridden my cyclocross bike.
If it's possible to mount a front derailleur, two chainrings might be the answer. My wife has a Giant full-e with a Yamaha motor. Chainrings are FSA brand 28-38. This setup works really well.
I will go test an haibike with 20 speeds 44/32, 11-36 and i plan to switch the cassette to 11-42 to avoid draining the battery on climbs. I might remove the front shifter and use the 32 only. I think many bikes and Ebikes are geared for speed but my fun is climbing. It is a Yamaha 250W, 500Amph. I enjoy 4 hrs rides so 26-28kmph will be my max.
Yes, it’s possible and probably easy because the bike has a direct mount for a front derailleur, which held a simple chain guide for the 38 ring. I’ll probably just ride to work at 17.5 mph instead of 19.5 and leave 2 minutes earlier, though.
Yes, high speed is a battery killer. I rode 10 miles to the bike shop in a strong head wind at 20mph and used more than half of my 400wH battery (which is theoretically good for 2000 feet of high-assist climbing). Conversely, I rode to the park and back with my dughter, 10 miles at low speed, and only used 6 percent battery. I think that your 4 hour ride will be possible with a low assist level or a with a spare battery if you want to loaf.