I don't ride brakeless. I'm at 46 x 18 - which is spinny most of the time except when I'm climbing. Hills here are not huge - just rollers. I start the bike with my body weight as well. Given all those things, is it likely that my knees will suffer? I'll go to 42 x 18 if anyone things that'd be better. I'd rather be spinny and safe than mashy and regretful.