On Thu, 18 May 2017 14:25:29 -0400, Ecnerwal wrote:

In article ,
Tim Wescott wrote:

So -- any thoughts on an easy way to gear the thing down? I just
recommended to the customer that they put two chain rings on the crank,
so that they can drive the pedals at one speed and the bike at another.

Depends what you mean by easy - planetary gears are a classic compact
method, since you didn't mention cost as an object. But it probably is.
If using chains, timing belts, or belts, a jackshaft is the classic
serious gear-down method.

Something that can easily be stuck onto an existing gizmo, preferably
while leaving the linked-to motor intact.

In a world of unlimited lead time and with no object to cost, "best"
would be to get a motor custom-made for the purpose. That's kind of the
opposite situation from what we have.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com