Thread: Gearing
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Old 08-29-19, 11:03 AM
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tomkcook
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Thanks for all the feedback. I'm still figuring out what to do here. Thinking seriously about a fairly major rebuild, involving a larger rear wheel and a few other adjustments. To respond to some points:

Originally Posted by BlazingPedals
Not being familiar with that trike, what size is the drive wheel, and is there a mid-drive?
It's a 20 inch drive wheel. I am seriously considering asking an engineering shop to cut the fork off and weld on a 700c fork, replacing the rear wheel completely.

Originally Posted by sch
Stub axle would be subject to considerable force, not likely to be durable unless over-engineered.
(My 2 wheel bent has a stub axle mid-drive and took a year or so to work out the kinks.)
I'm perfectly prepared to over-engineer this, but I'm also trying to be at least moderately practical.

Originally Posted by BlazingPedals
Also, won't changing the gearing affect the motor too?

My thought is that if you need a motor, you probably need the low gearing.
Well, it depends. The bike is used for commuting and my commute has a ~200ft climb over about 3/4 mile. If the electrics are not working then yes, this goes pretty slowly in places, though I'm still not nearly down to the bottom of the gearing. The lowest gear ratios on this thing are that ridiculous. In practice, once I've figured out the basics of not letting the battery go flat, I never do it without the electrics. The motor is not subject to the gear ratios and so its performance is not affected by changing them.

Originally Posted by Leisesturm
Without the power speeds would drop then a rider would understand why those particular gears were chosen. IF the rear wheel is 20" then, yes, those are lowish gears. A road triple wouldn't be a terrible idea but some idea of the o.p.'s cadence and/or expected cadence (in revolutions per minute) would be instructive. It's one thing to enjoy a slow hard push and very high road speed due to e-assist but battery life will not be high. A much higher cadence may take some practice but allows better performance from the human side of the hybrid power scheme.
I'll measure my preferred cadence next time I'm riding but my guess would be somewhere around 30-40RPM. The rear wheel is 20" and yes, this is a significant part of the problem. Yes, the battery life will be affected but then as I only use it for a 9 mile commute, battery life is not a big problem at present.
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