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-   -   Frame Sizing Advice (https://www.bikeforums.net/33-road-bike-racing/702968-frame-sizing-advice.html)

rkwaki 12-24-10 09:44 AM

Frame Sizing Advice
 
Well as I trust you guys (well some of you anyway :)) I have to start getting a new build together for this year's team bike. I am torn between sizes and need a little input. I am currently riding a 55cm BMC. Top tube is 56cm and I use a 120mm stem with the seat in about the middle of the rails and one 4mm spacer at the base of the stem.
Where I am torn is at sizing on the new frame:
My choices are a 53cm and a 56cm.
The top tube on the 53 is 54cm and the top tube on the 56 is 56.5 cm. Head/Seat tube angles are about the same.
As many of you know I am a sprinter/crazy ass crit rider but also do road races (though they are not my focus).
As I have come off 53cm Colnagos I have traditionally preferred the more compact feel and have always found my BMC to feel a bit big.
My thoughts are to go with the 53cm and put either a 130mm or 140mm stem on. If I go with a 56 I will probably have to go to a 110mm stem for proper fit - not great as it will put more weight over the rear wheel.
I also prefer to ride on the hoods about 95% of the time - the smaller frame would get me even lower and more aerodynamic and leave the drops for sprints (which is what I normally do anyways).
The only other change I will make is going from a 172.5mm crank to a 170mm crank this time.

I'm hoping you guys can give me a little insight as to what I should do.

For other stats:
5'11" tall
32" inseam
Longer torso and long arms

Grumpy McTrumpy 12-24-10 10:03 AM

since you already ride a bike with a 56cm top tube and the saddle is in the middle I think it's a no-brainer. Get the bigger bike since the top tube is only 5mm longer.

Especially considering your body proportions. I am 4" shorter but my cycling inseam is pretty close to 32".

rkwaki 12-24-10 10:05 AM


Originally Posted by Grumpy McTrumpy (Post 11978005)
since you already ride a bike with a 56cm top tube and the saddle is in the middle I think it's a no-brainer. Get the bigger bike since the top tube is only 5mm longer.

Especially considering your body proportions. I am 4" shorter but my cycling inseam is pretty close to 32".

Thanks grumpy.

ZeCanon 12-24-10 10:11 AM


Originally Posted by Grumpy McTrumpy (Post 11978005)
since you already ride a bike with a 56cm top tube and the saddle is in the middle I think it's a no-brainer. Get the bigger bike since the top tube is only 5mm longer.

Especially considering your body proportions. I am 4" shorter but my cycling inseam is pretty close to 32".

Agreed.

carpediemracing 12-24-10 10:29 AM

Make sure the head tube isn't taller than your 55 BMC's. Other than that note I'd agree, the 56 sounds like the way to go.

cdr

rruff 12-24-10 11:47 AM

You need to look at the SA for all three frames in conjunction with the TT length to get a reach estimate. Also need the head tube lengths for stack/height comparison.

techlogik 12-29-10 11:24 AM

My measurements are real similar to yours. 32.5" inseem, 5'11" 184lbs. I have kind of long arms.

I ride a 56cm. I really measure out true at 55cm, but those frames are rare. I would rather ride a slightly larger frame, and you can easily accomodate and fix the issues to shorten it.

Like, I use a 90mm stem. And like my seat up forward more for comfort. I prefer a "competitive" fit, and since you are a crit/sprinter...that is a better fit setting than the Eddy or French, which put you stretched out, seat back etc...

You can fix the headset length, cut it down if able, and other stuff to make the bike "shorter". You can't make a shorter bike "longer/taller" though IMO. Well maybe, but not as easily and there might be limitations.

Really it is what is comfortable for you though, some people like a tighter setup, and the shorter wheel base of the smaller frame for Crit/Sprinter might be a better choice....everybody is different.

Good luck.


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