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  1. #1
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    New Crankset! What size should I get

    Hey guys, I'm a 5'7" rider with a 30" inseam. I'm thinking of upgrading my crankset.I currently have 175mm cranks on my bike and I'm thinking of going to 170mm? Not a huge drop in size but I'm curious if it'll throw things off. Anybody out there running 170mm from 175?

  2. #2
    thecentralscrutinizer
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    175mm
    2014 Giant Anthem 27.5
    2013 DeVinci Leo SL
    2009 SE Racing SoCal Flyer
    2008 SE Racing lil Ripper
    2003 TiSport Gman

  3. #3
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    Depends on your style, if you like to mash then go 175, if you're a spinner go 170. I'm 5'5" with a 30" inseam and am happy with 170's on all my bikes.

  4. #4
    Mantis, Paramount, Campy
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    Amen

    Quote Originally Posted by Kris
    Depends on your style
    I'm 6'1" and only have 1 pair of 175mm cranks in the stable. I have a few 172.5mm and a few 170mm.

    If at all possible find a friend who has 170mm cranks and ride them a few times. Some people (like me) can feel a huge difference in a 2.5mm change in crank lenght. Other people can't really feel the difference.
    *** --- *** --- ***

  5. #5
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    I had a 175mm for a year and a half. There was a manufacturing defect and the crankset was replaced with a 170mm (the 175mm were backordered and would be shipped as soon as they were available). I waited a month and the LBS agreed to replace the crankset with a Shimano XT crankset. I requested a 180mm crankarms.

    I am 6'2" with a 34.75" inseam
    My opinions of each:
    The 175's can be spun or hammered. I stalled out on very steep climbs but this size was a great compromise between the two styles of riding.
    The 170's felt cramped. Spinning was the only way to ride. Almost all the technical climbs required preselecting the gear and spinning as fast as I could. Stalling on a climb became much more frequent. For smooth fireroads they were great, but standing felt odd and tiring.
    The 180's are gravy. The big circles are easy for me and the extra arm length really allows me to power up anything. They have been installed for 2 weeks now and I haven't stalled yet. For me, the 180's spin like the 175's but have more power for hammering. I have actually found myself overcharging on uphill climbs and almost loosing it.

    The differences were less noticeable just riding around. Anything technical really brought out strengths and weaknesses. I could ride a 170mm crankarm and I wouldn't complain but the 180mm fits me soo much better. The 180's also killed my kness for the first few rides.

    Hope this helps

  6. #6
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    If you've been riding 175s you should stay with them. This is mtn biking, not road so the decision is easy. For road, I might suggets a 172.5 for your height, but then it would depend more on your style of riding (preferred cadence).

  7. #7
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    I'm a noob when it comes to this but please clarify for me...

    I ride Giant Boulder SE, its either an 05 or 06 and every time I try steep climbs I stall out. I was actually looking through this section to try to figure out why. I thought it might have something to do with gearing..

    so the bigger the crank the more leverage and easier to climb? and the smaller cranks like 170's more for street?

  8. #8
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    Quote Originally Posted by jyeager
    If you've been riding 175s you should stay with them. This is mtn biking, not road so the decision is easy. For road, I might suggets a 172.5 for your height, but then it would depend more on your style of riding (preferred cadence).
    Another overlooked factor is the terrain. Smooth flowing singletrack requires a nice smooth spin and very little hammer power. North Carolina singletrack requires lots of hammering for tight twisting ups and downs.

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