Originally Posted by
Bill Kapaun
IF your knees don't bend as far as they used to or one as much as the other, you don't need a doctor to tell you. Your knee(s) will.
++++++
Now to the OP's question:
cranks:
https://www.amazon.com/Sunlite-Piece.../dp/B000WY5QTY pick the length you want.
worst case, you may need this as well:
https://www.amazon.com/Sunlite-Botto.../dp/B000AO9PBQ 24TPI to go with the cranksets above, 65mm or 68mm is the shell width of the BB housing on your trike. Scroll down to #2 on this page which shows how to measure:
https://www.nashbar.com/webapp/wcs/s...bikeSpot_Part1