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  1. #1
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    confused about bike fitting 6'6" rider

    Hello,
    I'm about confused about bicycle fitting guidelines/suggestions that I've read from many different sources (Andy Pruitt's complete medical guide for cyclists, Sheldon Brown's website along with the MTBR.com forums). I'm 6'6" with a 36" inseam and trying to decide between two different bikes, specs are as follows:

    Bike A:
    • Top tube length = 25.3"
    • Seat tube angle = 71.5deg
    • Seat tube length = 20.5"

    Bike B:
    • Top tube Length = 25.3"
    • Seat tube Angle = 73"
    • Seat tube length = 23"


    Bike A is designed for riders 6'2"+ and taller and Bike B is designed for 6'4"+. The confusion is, what is the real difference in fit between the two bikes? Does the seat tube really matter? Can I just as comfortably fit Bike a with a little more seat-post showing? It seems like the reach for both bikes should be roughly the same with the same TTL once you get the seat position at the right spot.

    The other part of the confusion is, I've been riding a 21" frame for the last 10 years so it feels normal to me but everyone says it looks like I'm riding a BMX bike. So I'm not quite sure how to interpret that...

    Sorry for the long post!

  2. #2
    dru
    dru is offline
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    You've got to be careful about seat tube measurement. At our height you need an actual physical measurement. For instance many manufacturers will list a 23" frame but when you read the fine print the seat tube is actually 560 mm.

    I'm only 6'5" but my inseam is 38", so I ride bikes with 23 to 24" seat tubes. The bikes have about 8" of post showing.

    The reason your friends are giving you grief is because you have a bike with 26" wheels.

    Aesthetically, 29ers look better for us tall folks.

    If you are a heavy guy, how much seat post showing does matter since they do bend on occasion.

    Is 36" your true inseam or just your pants?

    There is a difference.

    Drew
    occasional cyclist

  3. #3
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    I measure the exact same as you, I find 21.5 inch frames with a medium length ett works perfect.

    Sent from my LG-P769 using Tapatalk

  4. #4
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    I am a big fan of 26" as well, just look for an xl model with 25" ett

    Sent from my LG-P769 using Tapatalk

  5. #5
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    Hey Drew,
    Yes, I measured my inseam according to the competetivecyclist.com method, 36" is what I read. I'm not overly heavy 200lb at 6'6".

    Do the few inches difference in seat post length matter (if indeed the numbers cited are correct)? Can delta be accommodated by the seat post length/setback and I'll "fit" just as comfortably on either bike? As long as the seat post isn't extended too far to make it a safety problem...

    Thanks for the posts!

  6. #6
    dru
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    What you really need to worry about with those two frames is the different seat tube angles.

    The slacker one will have you sitting further back. If you want your saddle moved forward to the same position it would be on the 73 deg. frame it will shorten the reach to the bars by comparison by a centimeter or maybe two.

    Those two bikes will not feel the same at all due to the difference in seat angle, if you are positioning the saddle in the same place on identical seat posts, and running the same stems.

    You can make them feel identical but that would require different seat posts and stems.

    Either frame's seat tube length is enough fro you.

    Drew
    occasional cyclist

  7. #7
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    Got it, thanks for the comments. It seems that the fit algorithms should be just used to get you in the ballpark and then just ride whatever is comfortable...
    Thanks

  8. #8
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    You need to figure out what you want by demo, as stated bikes are different, a 24" Trek was to long for me the way I want to ride in sit up mode so I went with a 22.5. I measured both bikes and the biggest difference I could find was the 24 inch was a longer bike but height was really about the same.

    Your riding style has alot to do with it as much as your size.

  9. #9
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    I recently went from a Large size hardtail, (too small for me by measurements) that felt a bit big. By the fact that I was putting too much weight on my bars. Just received my XL XC bike.

    I was quite worried that the XL bike would stretch me out even more. After setting bike up for my weight, it feels perfect. On the large bike, I had to have the seat post so high that I couldn't help but put more weight on bars. Felt like I was sitting on top of the bike. The XL bike feels like I am sitting in it.

    Those measurements are just that.

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