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  1. #1
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    Who rides 170mm Cranks?

    Who rides 170mm cranks? I am 5'8" and have moved to 170 on my road bikes. My previous MTBs all came stock with 175's and I never changed them. I think 170 may be better for me on the climbs as I like to spin. Not sure if I would miss the leverage going over big stuff when you need 1 more pedal stroke to power over something.

  2. #2
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    I'm using 170 and I'm 5'11". My bike has a low bb so it helps me clear things. Leverage and power stroke I wouldn't be too worried about on a mountain bike.
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  3. #3
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    I'm 59 with 83cms inseam and use 170mm cranks. They came with my bike, I don't feel uncomfortable but I haven't tried longer cranks.

  4. #4
    West Chester, PA
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    I just switched to 170s after a lifetime on 175s. I can't tell any difference, but I have a little more pedal clearance.

  5. #5
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    I changed a few seasons ago and noticed things slightly easier. And then I didn't notice any more. Thin flats and the 170s get more clearance.

  6. #6
    Now, THAT'S gonna hurt!
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    Always been on 175's. Have always had a bit of an unexplained knee pain on my left knee. Not disabling but enough to seek an orthopedist and an MRI proving nothing structural. I read about measuring inseam for determining crank lengths and some issues people tend to have regarding crank length since the default on most mtb is 175. I bought a Race Face Turbine Cinch crankset in 170 to try. My regular pedal strikes were virtually all eliminated. My knee pain was eliminated...at least out to about 17 miles a ride where at about 9 it would always kick in. The one thing I gradually noticed was it felt like my fitness was waning. I was having trouble hitting the gnar on my climbs that I had always been able to hammer through. I was getting worried that I was loosing leg fitness gradually from my neck issue that I had previously experienced.

    I went along with it for a few weeks and actually had a sale for my carbon Sram 175 crankset but before I turned it loose, I put it on the bike for one last comparison run. That 5mm of leverage was absolutely key for me. I was back in the game overnight, albeit the knee pain and the pedal strikes were back. I'm quite astonished at the difference in my case. I sold the RF crankset instead. My new RS Monarch Debonair shock helped a bit with pedal strikes and I just deal with the knee.
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  7. #7
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    It's usually a function of height. At 5'6" my bikes all have 170s. Usually the small frame of a particular model will have 170s and everything else will be 175.

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  8. #8
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    5'10" here and switched to 170's with my Nomad because of the pedal strikes. I wouldn't say it was a huge change, other than the reduction in pedal strikes.

    I moved those same cranks over to my new Yeti and don't have complaints.

  9. #9
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    Like others here, I switched from 175 to 170 when I got a bike with a lower BB. That was in 2012. After the 2nd ride I didn't notice anything but fewer pedal strikes. I'm 6'3".
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  10. #10
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    I have 175 on my 29er and went 170 on my fat bike cause of pedal strikes. Don't notice a difference between the 2

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  11. #11
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    5'9"/29" inseam. I actually have MORE pedal strikes after switching because in my mind I should have more clearance so I pedal when I shouldn't...

    Seriously though, my knees feel better and I'm more comfortable at higher rpm.
    92.7% of statistics are made up on the spot.

  12. #12
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    I switched to 170s about 10 months ago due to lower back pain. Im 5'8" and have short legs. I also switched to 165mm cranks from 172.5mm cranks on my road bike.

    The geared MTB was easiest switch, I noticed that spinning was a lot easier, but i'd have to change gear more often. Some pinch climbs initially felt harder, but I'm used to this now. I feel like my riding has improved because of it.

    Switching my singlespeed, was a bit tougher, then in another thread, someone sugested to try sheldon browns 'gain ratio' calculator, which i used to recalculate my effective gear ratio (gain ratio) which takes into considertion wheel / tyre size and crank length, as well as sprocket size. I increased my rear sprocket by 1 tooth, and now the bike feels as it did with 175s
    What crank length are you running?

    On the road bike, flats and downhills feel great, but I've struggled on the climbs, even with changing down a gear or 2, but this is up steepish (>10%) climbs that I wouldn't have comfortablly spun on with my longer cranks (my gearing is probably too high). I've been experimenting with my cleat position (moved cleat back) and will see how this goes.

    With shorter cranks, you put your saddle up by the difference in crank length, so 5mm if going from 175 to 170, but your knee comes up 10mm less whilst pedalling. This is why you may reduce some knee of back pain, if you have flexibility issues or have short legs.
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