On Thu, 18 May 2017 13:10:48 -0500, Tim Wescott
wrote:

I use "thingie" in the title to not give anyone a false impression of
what I do or don't know.

EE, huh? g


I'm working with a client who's using one of these in his specialized
bike:

https://www.amazon.com/dp/B01KYKEP2Y...xx_P1400_1000?
tag=dradisplay-20&ascsubtag=c73ee0e485a804ac76001596b2b029f4_S

Did he use the mid-drive style because the bike doesn't use standard
wheels/tires? I paid $209 for the 800w front hub motor style,
complete with brake levers, thumb throttle, controller, pedal assist
ring/sensor, bag, and rear package tray. They run as low as $159 now.

Here's a 1kw rear for $185. http://tinyurl.com/ly2tdl8


He's currently using the 250W version, but we're having problems of
insufficient torque -- this is partially due to re-purposing a board, and
we're on top of that part, but I'm thinking ahead (well, borrowing
trouble, in proper engineering fashion). So we thought -- hey! We'll
use the 350W version (that's the one in the link).

The problem is that the 350W version actually has a lower current-to-
torque constant -- it gets its higher power through pulling more current
for the torque, and delivering more speed.

I believe that the lower wattage motors are designed for assist, not
to provide full power/torque, especially for long term use like hill
climbing.


So -- any thoughts on an easy way to gear the thing down?

It already has a reduction unit built in, Tim. There's not much you
can do with a small motor like that.


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.

I hope he isn't driving the pedals. Sprag clutches (cassette or
freewheel, in bike terms) are cheap.

--
In today’s academia and mainstream media,
we’re all guilty of hate until proven leftist.

--Robert Knight, senior fellow, American Civil Rights Union