i have a 20t freewheel...is it ok to use a 17t fixed on the other side? I thought someone said 3t difference is ok on the chain

wouldn't you want your fixed side to be larger...? I don't understand, someone 'splain.

1 tooth moves the axle ~1/8 inch. If you have the dropout, go for it.

i want the bigger freewheel so i can climb and just commute...i will use the smaller (harder) 17t fixed for goin around town and just long flatter stretches

ok, i get it, you'll just have to move the axle farther back when you switch to fixed - i had an idiot moment and forgot you could do that. i was picturing a bunch of slack in the chain from going down in size.