Newbie questions: best single speed e-bike conversion?

Dear Alll,

I posted a week or so ago about possibly converting my current single speed commuter to an e-bike. I'm after something as low-maintenance as possible so would want to keep the single speed. Heavy rider (90kg when in shape, 95kg at the moment...) but happy to pedal hard. Usual cadence 70-100rpm when unassisted, can comfortably keep 110rpm for a few minutes if I'm in a hurry. I initially assumed that a rear hub drive would be best but have since read a bit and am not so sure any more! I'm still not keen on a front drive so this is a "mid drive vs rear drive" question. Seems to me that the issues are:

1. Torque. If I have to cycle slowly up a hill (e.g. setting off from lights, or in heavy traffic) I will be doing 30rpm but exerting lots of torque. Is this likely to be more of an issue for mid rive motors or for a hub drive?

2. Safety. I'm pretty risk averse. What's the safest way to run an e-bike so that you have control over speed and don't feel like the motor will push you along faster than you want to go?

3. I quite like the look of the Tongsheng mid drive kit that Woosh sells. Is the torque sensing likely to cause problems in traffic?

4. Gear ratio: I would probably want to run a slightly longer gear than the 44x17 that I have at the moment. This would again increase the torque issues. (EDIT: I could run 42 front, and fit either 14 or 16 at the back depending on how things go.)and then

5. Chainline....... really not sure what will happen there..... may take some fiddling and some swear words...!

Any comments and suggestions welcomewelcome!

Edited March 29, 20197 yr by closetleftie

the Tongsheng kit is low maintenance but may not be the best for single speed bikes because you can't change gear to climb hills.

The best choice is the 48V SWX02 kit. It has very high torque and will easily cope with your weight. Range is about 45 miles on a full charge.

http://wooshbikes.co.uk/cart/#/product/uid-188-swx02-48v12ah/bafang-swx02-48v-250w-rear-hub-kit-with-48v-12ah-battery

If you are interested, please send some pictures to support@wooshbikes.co.uk for us to check for possible issues.

1. Torque. If I have to cycle slowly up a hill (e.g. setting off from lights, or in heavy traffic) I will be doing 30rpm but exerting lots of torque. Is this likely to be more of an issue for mid rive motors or for a hub drive?

large geared hub drive for single speed.

2. Safety. I'm pretty risk averse. What's the safest way to run an e-bike so that you have control over speed and don't feel like the motor will push you along faster than you want to go?

in pedal assist mode, the amount of assist is set by the assist level and the bike does not go faster than you pedal.

4. Gear ratio: I would probably want to run a slightly longer gear than the 44x17 that I have at the moment. This would again increase the torque issues. (EDIT: I could run 42 front, and fit either 14 or 16 at the back depending on how things go.)

14T is OK with the 48V SWX02 for your weight but because you can spin quite fast, the best ratio for 26" (assuming you derestrict the bike for the purpose of this estimate) is 44T/16T and for 700C is 44T/17T.

5. Chainline....... really not sure what will happen there..... may take some fiddling and some swear words...!

should be same as you have now.