NuVinci no thanks

[Miles]

A powerful hub motor with a 2-speed that was under 15lbs would make me switch to a hub.

If it was under 5lbs, it might make me switch....

I'm sure they're coming. eg. http://v3.espacenet.com/publicationDetails/originalDocument?CC=WO&NR=2008088169&KC=&locale=EN_ep&FT=E

 

[liveforphysics]

I could put up with 15lbs as long as it was 8kw or more. I've had a road bike that was 15lbs total weight and it nearly felt like it pedaled itself and was so free feeling to ride. A 15lbs hub would ruin the handleing of the bicycle, but with enough power it could still be made fun to ride. I agree that 5lbs would be much nicer though, and entirely possible.


This road bike is 7lbs total weight:
http://www.velonews.com/article/73034/the-7pound-road-bike-

Making a powerful hub motor with a 2-speed should weigh a lot less than an entire bike.

 

[Miles]

You'd need deep reduction gearing for both speeds, though......

 

[GGoodrum]

You'd need deep reduction gearing for both speeds, though......

Maybe not. With the existing "smaller" hub motors, like a 4-series Clyte, you can get a wind that either has pretty good low-end torque, but the top speed is not high enough, or a wind that gets you the desired top speed but it lacks low-end torque. If a high speed/low torque motor could be married with a two-speed drive that was 2:1 in "1st", and 1:1 in "2nd", this would work well, I think.

-- Gary

 

[Miles]

Sure, but lfp was talking about a powerful motor (several kW).....

 

[GGoodrum]

Yes, with something like a big 3220, or a version of David's new motor, you'd probably need at least a reduction of 5 or 6 to 1 in "high" gear, to get the top speed down to something reasonable, and that is with a kV of about 70-75. "Low" gear would then need to be about twice that, or 10-12:1.