Chainset size 170mm to 175mm is there a big difference

woozie Posts: 7
edited November 2008 in Road beginners
Hi all
I am thinking of buying a 175 mm chainset off a friend,the one on my bike is 170 mm is this going to make a big difference,5mm does'nt seem like much but does it not work like that,thanks for any answers,steve


  • I thought 175mm was "full size" :shock:

    Someone correct me if i'm wrong. I've never really understood different crank lengths.
    "A cyclist has nothing to lose but his chain"

    PTP Runner Up 2015
  • topdude
    topdude Posts: 1,557
    I doubt you would notice much difference, in theory the longer crank will increase the leverage and make all gears feel slightly lower :)
    He is not the messiah, he is a very naughty boy !!
  • It depends how much adjustment capability you have in your existing bike. If your seat post was at its min for you to ride the bike now another 5 mm 'reach' could be impossible. If you have plenty of seat post leeway and you are not too short in the leg in relation to your body you should be ok.
  • It could just be psychological, but I notice a difference between my MTB 175 cranks and my road bikes 170 cranks. I ride both on the road (MTB with slicks for commuting) and feel that I spin much more quickly on the road bikes. Of course this could all be down to other factors (lighter road bike, less resistance from 23c tyres etc etc) but when I had new cranks put on the winter bike last week i made sure they were 170s.