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  1. #1
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    Bike fit question

    I have a quick bike fit question.

    Generally speaking if your in between frame sizes is it better to take the smaller frame with better sand over and lengthen the cockpit...longer stem/ layback post etc. Or go with the larger with shorter stem etc?

    Any input would be great...thanks!

  2. #2
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    Quote Originally Posted by Bbruzzese View Post
    I have a quick bike fit question.

    Generally speaking if your in between frame sizes is it better to take the smaller frame with better sand over and lengthen the cockpit...longer stem/ layback post etc. Or go with the larger with shorter stem etc?

    Any input would be great...thanks!
    I would recommend the smaller frame. The riding style will be a bit more aggressive and you will potentially have more control.

  3. #3
    Plays with tools
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    It depends on what aspect of the geometry you are in between. For instance if your all legs you would want to go bigger primarily for the head tube length. That's assuming you can run a stem that's not to far outside 'normal'. On the other hand if your the opposite and have your heigh above the belt, like I do. Your pretty much screwed either way. But if the medium is just a tad to small and the large is just a wee bit big, go smaller. It's much easier to make a small bike bigger than a big bike smaller. Are there other bikes on the market that would fit you better? Might be worth a look. There is the custom route if your budget allows.

  4. #4
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    I like my frames a little on the small
    side if possible.

  5. #5
    Fat-tired Roadie
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    I think that it's rare for someone to truly be between sizes. Top tube lengths tend to run every 20 mm or so, although I think that it's effectively maybe even a little less. If a bike rides nicely for me with a 90 mm stem, I think it'll still be fine with a 110. By '80s standards, that would even be short! Substitute two short sizes that are 20 mm apart if you like short stems.

    Maybe this is colored by me being a little leggy, but I can't say I've ever had a bike that's required me to slam the stem. As in, a true slam - flat bars, -17 degree stem, no spacers. I don't know that I've run into one set up that way in the wild either. Pretty much only on slamthatstem.com.

    At the other end of the spectrum, following the guidelines on a lot of forks, one can have 30 mm of spacers above the headset, an up-angled stem, and some big honkin' risers to get the grips higher. It's quite a lot of vertical adjustability.

    Not that I deny the possibility that some people really have a tough decision between going smaller for a short enough head tube or larger for enough reach with a reasonable stem. (Or vice versa, maybe some people really need to go to a bigger head tube to get their bars high enough, even using +17 or +30 stems and riser bars) but I don't think it's very common.

    So, OP - rather than a general question, how about a specific question? What bike are you thinking about? How did the two sizes feel to you/what felt "off" about them or gave you pause as to being able to get them really dialed? What else have you tried?
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  6. #6
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    Fit philosphies and personal preferences,actually effective or not, are all over the lot. Andrews commen,t that being truly between sizes is unlikely, gets my support.

    You are best off working with someone who knows how to fit you on the bike. Doing it online is misguided.
    I don't rattle.

  7. #7
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    Finding a reputable LBS with the ability to give you a truly professional bike fitting is worth the coin IMO. I had never wanted to plunk down that much money for something I didn't get anything tangible for. I decided to do it recently though and the numbers and advice I got were worth every penny.

    I highly recommend you do this before spending any money on your next bike.
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  8. #8
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    Quote Originally Posted by Silentfoe View Post
    Finding a reputable LBS with the ability to give you a truly professional bike fitting is worth the coin IMO. I had never wanted to plunk down that much money for something I didn't get anything tangible for. I decided to do it recently though and the numbers and advice I got were worth every penny.

    I highly recommend you do this before spending any money on your next bike.
    + 1 million.

    Regardless of what frame size / bike you have or buy, GET A PRO BIKE FIT!!!
    I was a stubborn jackass for the past 10 years.... thought I knew enough about bikes from mtbr etc. Now in my mid 40's, my knees are shot from riding a correctly sized
    bike incorrectly. After getting a bike fit TODAY, adjustments were made to saddle fore/aft, saddle height/ stem and bars.

    I suspect that my knees could have been saved if I had done this a long time ago!!!!

  9. #9
    Monkey Junkie
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    My 2 cents...

    Bike fit is determined not only by body dimensions but also by flexibility and riding style. Your ideal position on the bike is static and can probably be achieved on either frame size with use of different stems and by having your seatpost more/less inserted into the frame. The way the bike will handle will depend on which frame size you ride. Achieving proper weight distribution and overall handling is probably the key difference, and comfort is a possible issue as well.

    A pro-fit is a good idea if it's someone qualified to do so, which some shops don't have obviously..

    I also agree that in many cases, people are not truly in between sizes. They just need to know which size to ride.

  10. #10
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    Thanks for the input. It's actually for my wife...for the record I'm definetly not trying to size a bike online more confirming my existing beliefs. She currently rides a small Rush with a 110mm stem and layback post pretty comfortably and would like to switch to a HT 29er. As i search online it seems smalls are a bit harder to come by than Medium so I was curious what others thoughts were about jumping a size. Thanks again...all good info.

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