20" crank 26" bike?

[Fahrrad]

Can you put a crank that fits a 20" bike on a 26" bike?
The reason I ask is that my mother has knee problems and she has a 3 wheeler she has been riding, but it only hurst on the upstroke while riding, not when pressing down. The three wheeler has standard lengh one piece crank. I was thinking a shorter throw (while harder to peddel) will give her some relief.

Will it work?

 

[Dee-Em]

AFAIK so long as the axle is the right diameter and length for the bearing shell you're good to go...

 

[Schwinnspastic]

Short crank .... didn't work for me and my bad knees,a smaller sprocket
helps .

 

[deven_science]

Re: 20" crank 26" bike?

It should work, as long as the bottom brackets are the same width.

 

[Fahrrad]

Short crank .... didn't work for me and my bad knees,a smaller sprocket
helps .

That is what I would think, but the fact it only hurts her on the up stoke. Might try the smaller sprocket too.
Thanks for the input.