pedalstrike won't be an issue for you on the rush with 170s, but toverlap might. I get some toverlap on my 58cm Rush with 170s and size 12s. It's much worse with toeclips than with spds, so if you use clipless pedals, and have small feet to overlap might not be that bad. Then again I'm sure it would be better with 165s which are probably the correct length for a 53 anyway.