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Thread: mach 5.7 size

  1. #1
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    mach 5.7 size

    I'm looking for some help deciding on frame size for a mach 5.7.
    I'm 6 feet tall with a 33" inseam.

    Currently, I'm riding a large 2006 specialized stumpjumper fsr with a top tube length of 24.1".
    I guess that I found this a little long, since I've shortened the stock stem by 20 mm and I now ride with a straight rather than the stock setback seatpost.

    The medium mach 5.7 top tube length is 23.2" and the large is 24.2". This is the same length for the mach 5. I was wondering what frame size mach 5/5.7 riders are riding that are similar in size to me.

    I also noted on the Pivot website there this statement in the FAQ:
    "...our medium frames are designed around an average 5'11" (180.34cm) rider with a 33-34" inseam."

    Unfortunately, I cannot try these different frame sizes before I buy. Any help/comments would be appreciated.

  2. #2
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    I think you're definitely a large with a 90mm straight stem.

  3. #3
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    Pivot bikes seem to run a little bigger than "typical" bikes, even Pivot seems to think this:

    "sometimes our medium may compare to another companies large."

    Plus, like you mentioned, they built their medium around 5' 11" riders which are taller than most companies.

    Others have commented that they actually feel that Pivots run a little small, so it is obviously a very personal experience.

    That being said, I think that you would be a Large. You can experiment with stem length and see what is the most comfortable for you. I think that it is hard to recommend a stem length without knowing what size bars you are using. Obviously, you will need a longer stem if you are using 635 mm wide bars versus 760 mm bars.

  4. #4
    Jamin, Applesause, No?
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    do you have long arms? I would think about getting a medium. One advantage to smaller frames is the ability to accomidate more seat post options. Meaning you can get a longer dropping seatpost under you then you can with a larger frame. The Medium will be easier to through around under you when the trail gets really tight and twisty. It might feel better in the air as well. I think the big thing will be playing around with the stem and handlebar sizes. I am 6 foot 32" inseam with long arms and the medium fits me perfect. I ride a Large Cannondale as well that fits pretty much the same but with less stand over height.

  5. #5
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    Thanks for your replies.

    I want to get a medium, but I don't want to 'make it fit' by having to run a longer stem. I'd like to run a 70 mm stem (I'm running 80mm on my trailbike now, but have a couple other bikes with 70mm stems. All bikes have 27" low risers).

    As for seatpost height, I'd like to try one of the new 5" adjustable height posts, but I'm currently use a 4" gravity dropper and I wouldn't be disappointed if I kept using it.

    Not sure if I have long arms...I'll ask my wife. Do you think long arms would be better for smaller or larger frame?

  6. #6
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    I'm 6 inch (182 cm) and ride a Large Mach 5. I don't really think I'd like to go to Medium. I run a 90 mm stem with 680 mm bars. Tried 80 mm stem with the same bars and it was fine but I went back to 90 mm stem in the end.

    With Mach 5 you have to take a slack 72 deg seat tube into account - you'd need to move the saddle forward in the rails to get the same position relative to the cranks, and actual ETT is shorter when matched to bikes with 73 deg seat tube angle. Mach 5.7 has a much more 'convenient' 72.7 deg seat tube so this won't apply any more. Though I still think Large would be the way to go.

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