172.5mm to 170mm crank arm - will I notice a difference?

Turnbull2000
Turnbull2000 Posts: 189
edited August 2009 in Road beginners
Looking to replace a broken 172.5mm with a second hand 170mm. Surely 2.5mm is too small to notice?

Comments

  • topdude
    topdude Posts: 1,557
    If you rode the bike and were not told the cranks were 2.5mm shorter you would never notice :D
    He is not the messiah, he is a very naughty boy !!
  • Shezzer
    Shezzer Posts: 229
    I don't notice the difference between my 170s and 172.5s ... you'll be fine but might just want to consider raising your saddle height slightly.
  • Takis61
    Takis61 Posts: 239
    No. I went for 170 on my new bike as it is supposed to be better for spinning fast, also went compact.
    Old bike has 53/39 chain & 172.5 mm cranks, I notice the gearing but not really the crank length.
    My knees hurt !
  • skyd0g
    skyd0g Posts: 2,540
    Turnbull2000 wrote:
    Looking to replace a broken 172.5mm with a second hand 170mm. Surely 2.5mm is too small to notice?

    I take it you're replacing both cranks? Right and left? :?
    Cycling weakly
  • ride_whenever
    ride_whenever Posts: 13,279
    Shezzer wrote:
    I don't notice the difference between my 170s and 172.5s ... you'll be fine but might just want to consider raising your saddle height slightly.

    You'll want to raise it 2.5mm!
    Neeermad
    Carbon 456
    456 lefty
    Pompino
    White Inbred
  • Takis61
    Takis61 Posts: 239
    Mmm, not necessarily, my 2 bikes are set around the same, but as I said the 1 with 170mm cranks is running a compact.
    Different geometries as well, they have different bar heights.
    My knees hurt !
  • juankerr
    juankerr Posts: 1,099
    skyd0g wrote:
    Turnbull2000 wrote:
    Looking to replace a broken 172.5mm with a second hand 170mm. Surely 2.5mm is too small to notice?

    I take it you're replacing both cranks? Right and left? :?

    That's what I was wondering too, on the other hand I've got one leg about 1cm shorter than the other and it took about 30 years to notice that so maybe it would be un-noticeable.
  • skyd0g
    skyd0g Posts: 2,540
    juankerr wrote:
    skyd0g wrote:
    Turnbull2000 wrote:
    Looking to replace a broken 172.5mm with a second hand 170mm. Surely 2.5mm is too small to notice?

    I take it you're replacing both cranks? Right and left? :?

    That's what I was wondering too, on the other hand I've got one leg about 1cm shorter than the other and it took about 30 years to notice that so maybe it would be un-noticeable.

    Riding with different crank lengths is not recommended. See:http://www.sheldonbrown.com/cranks.html#mixed
    Cycling weakly
  • juankerr
    juankerr Posts: 1,099
    Sheldon is talking about non-symmetrical freaks like me there.. he doesn't address the ably legged with unmatched cranks issue at all.

    But where has the OP gone? Was it one crank or two he was gonig to replace? Who knows? Who cares?
  • Smokin Joe
    Smokin Joe Posts: 2,706
    ride_whenever wrote:
    Shezzer wrote:
    I don't notice the difference between my 170s and 172.5s ... you'll be fine but might just want to consider raising your saddle height slightly.

    You'll want to raise it 2.5mm!
    Not that 2.5mm will make a sod of difference.

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