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How much play in frame sizing? 55cm vs 57cm

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How much play in frame sizing? 55cm vs 57cm

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Old 10-09-15, 09:23 AM
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El Gato27
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How much play in frame sizing? 55cm vs 57cm

Seen several really nice road bikes on CL that are listed at 55cm. Im 510 and normally ride ~57-58cm with the saddle raised ~2-3 inches, have always been comfortable riding this way. Was wondering how much play there is in the sizing. Would it be as simple as raising the seat an extra inch or should I expect stem/crank mods?

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Old 10-09-15, 09:41 AM
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You'll have to try it yourself and see. There won't be any modifications to the crank, but possibly to the stem if you want the same riding position.

In my experience sellers ALWAYS get the size wrong. I don't know why. So take some measurements on a bike that fits you and bring a tape measure when looking at a bike. It could be closer than you think, or it could be way off.
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Old 10-09-15, 09:41 AM
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Depends.. Some frames the seat tube extends taller above the top tube.. some it does not.

" size " is roughly BB center axis to top of seat tube . a C to C measuring goes to centerline of the Top tube.

Bring a TAPE MEASURE .
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Old 10-09-15, 09:41 AM
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That depends on a lot of factors, mainly because "55cm" doesn't necessarily tell us anything. Different people measure frames differently, and at different times/places bicycles were designed to fit differently. There's a lot more play in seat tube height than there is in top tube length.

The smaller frame may fit better; or not. You may be able to make it fit better by changing the stem or something; or not. It's hard to predict!
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Old 10-09-15, 10:19 AM
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Agree with all the above. Also when trying out the bike consider the seat set back. A dimension not often mentioned but very important for how the body is balanced on the 3 contact points. Andy.
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Old 10-09-15, 10:29 AM
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For those that care (weight weenies) a smaller frame would be lighter. If it can be made to fit with a longer seatpost and or HB stems, it should be fine.
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Old 10-09-15, 10:57 AM
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Originally Posted by rhm View Post
That depends on a lot of factors, mainly because "55cm" doesn't necessarily tell us anything...
Exactly. Stack and reach are the relevant frame fit parameters. Those, along with components and setup determine fit irrespective of frame size.
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