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Correct bike sizing - road to mtb

luketorroniluketorroni Posts: 73
edited November 2009 in MTB beginners
Hi all... I was wondering if anyone could help me size up correctly for a new mountain bike.

I am primarily a road rider but looking to hit some singletrack/trials for some additional off-road fun. What size frame or dimensions should I be looking for?

My road bikes are usually a top tube length of 53-54cm centre-centre and I'm 5'7"

Should I look for the same in a mountain bike or should it be longer?


  • supersonicsupersonic Posts: 82,708 Lives Here
    Try some out and see what feels right. MTBs vary a hell of a lot more than road bikes do - a typical medium frame maybe 66-72 head angle, 540mm-600mm effective top tube length, plus stem and bar set ups make a huge difference.

    Many beginners prefer a shorter top tube and more upright confidence inspiring stance. I am 6ft, 33" inside leg and my Zaskar has a 595mm top tube and 80mm stem. I think you are in the right ball park, maybe a touch longer but keep an eye on those angles - 69-71 degrees is normal for a 100mm forked XC bike, and 73 degrees in the seat angle.

    Also see the What Size thread in the buying forum.
  • nicklousenicklouse Posts: 50,675 Lives Here
    supersonic wrote:
    I am 6ft, 33" inside leg and my Zaskar has a 595mm top tube and 80mm stem.

    while I am 175cm and have an effective top tube of 570mm and a 100mm stem
    and riser bars.

    there is no real science like there is with road bikes it is so much more on how the bike fits
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Goto your local bike shop and try a few and see how they feel

    Both my road bike and MTB are a medium frame but stand them next to each and you wouldnt say so
    On One Inbred 456
    On One Inbred SS
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