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I'm one of those odd balls that falls between a 54 and a 56 and not many people make a 55. My biggest concern is getting the right set up for me to race, I'm stuck in the decision making process of if I should get a 56 with a short stem and cranks or a 54 with a longer stem and cranks.

any info would be absolutley awesome

thanks

marshall
 

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you're unlikely to be in between...

This seems to be a common complaint that's rarely accurate. There's usually no more than 1cm difference in the REACH of two frames that are 2cm apart in size.

To avoid confusion, reach is the TT length minus the setback and setback is the c-c frame size times the cosine of the seat tube angle. The difference in reach will accurately predict the stem length difference needed to make both bikes fit the same. A reach comprison is only guaranteed to be accurate when both frames are the same size. When comparing frames of different sizes, a reach comparison may not be entirely accurate due to differences in the both the head tube angle and seat tube angle. It's still possible to calculate the difference in reach, but it's more involved. With most stems only available in 10mm increments, there will nearly always be some minor compromise in the reach to the handlebars or the saddle setback.

Just as important as the probable 1cm or less difference in the reach, is the 2cm difference in the head tube length and standover height. To make the decision between the two sizes, you need to figure out the spacer and stem angle combination that each requires to get the desired handlebar height. The standover clearance should also be given at least some consideration.

To get any accurate answer, you should post more specifics.
 

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To add to that, the difference in the way manufacturers measure seat tube length (center to center, center to top, center to top of seat post collar) makes the numbers "54" and "56" kinda a ballpark deal anyway.
 

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the brand and model...

Assuming you're looking at new models, they all have geometry charts to review. I would also need the total stack height of your current setup (head tube with the headset and spacers) plus the stem angle. The TT length and seat tube angle of your current ride would also be needed. With that info, it's pretty easy to figure out the setup on a new bike.
 
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