echew said:
Interesting, I see recycles-ebike.com have dual 34/42 and 42/52 chainrings available:
http://recycles-ebike.com/home/80-dual-chainring-chain-ring-3442-for-tsdz2-tongsheng-motor-34t-42t-34-42.html
http://recycles-ebike.com/home/81-dual-chainring-chain-ring-3442-for-tsdz2-tongsheng-motor-34t-42t-34-42.html
Perhaps these would give more flexibility than a wide ratio rear cassette?
I think it depends on where and how you ride. For me less gears is better. 2 chainrings might be nice if climbing a lot of steep hills I guess. For my bike with a wide ratio (11-40 8spd) it will do 30mph @90 rpm in 8th and 8mph @90 rpm in 1st. That means to climb a steep hill I need to maintain at least 6mph (75% of max rpm), so the only reason I would need the dual chainring would be if I need to climb steep hills at a speed slower than 6mph. When you have a motor assist having a gear optimized for every 1-2mph doesn't seem necessary and at least for me it becomes very tedious shifting several gears at a time.
Here is my top motor speeds (90rpm) in 8 gears with a 42 front and 11-40 rear - 8, 9.5, 11.5, 15, 18, 21.5, 25, 29.5mph
now with a 34t front those speeds would change to - 6.5, 8, 9.5, 12, 14.5, 17.5, 20, 24mph
If you were pedaling those extra gears might be helpful, but with the motor assisting 1mph either way is nothing. The only thing you are really getting from the dual chainring is that 6.5mph @90 which will allow you to climb a hill at as low as 5mph.
Maybe the experienced bike riders feel differently, but for me I would prefer less gears. Ideally I would like a 6 speed that would go something like 6, 10, 14, 18, 22, and 26mph, and most of the time I would only be using the middle 4 gears.
The motor makes the close ratio gears obsolete, at least for me. I do not push up hills either so that probably influences my gearing choices, I like to let the motor do most of the work on inclines.
