After I put on the 10 speed FD, I decided to get my stoker some shorter cranks, too. I had a 172.5 FSA Gossamer 10-sp. stoker set redrilled and shortened to make 151mm cranks. Stoker has a 27" inseam, so this length is about perfect. We did a 48 mile hilly ride on Sunday and Stoker loves the new cranks. It feels like we have more power on the flat and small rollers but maybe less on steep hills when our cadence drops off. Or maybe we're just not in shape yet. Time will tell, but the new cranks are definitely staying on.