# frame sizing - short seat tube length



## r_mutt (Aug 8, 2007)

i've bought a frame that has odd sizing. it's seat is 49cm and the top tube is 52cm (everything ctc). it's a bit short on the seat tube, but i'm only 5-7. my lbs seem to think it's an ok fit as i won't have too much drop (and this can be fixed with spacers), but i'm worried that it bought a frame that might be too small. 

the top tube seems ok but the seat tube is just so short. i was measured and ideally, i should have a 50-51 cm seat tube and a 52-53.5 cm top tube. in what manner will a short seat tube affect fit?


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## blackhat (Jan 2, 2003)

if you can acceptably raise the bars with spacers I don't see a problem.


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## Doggity (Mar 10, 2006)

Why is that when LBS's err in their fitting, it's always that they fit people on bikes too small for them? Anyway, to the OP: just make SURE they DONT cut off the steerer tube until you have your bars at the precise height you want them at. If you can stand a more than usual amount of seatpost and spacer tubes, it should be OK. But I'd question their
'fit'.


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## krisdrum (Oct 29, 2007)

Does the frame have a sloping top tube or horizontal? If it is sloping, and you are only measuring ctc, the virtual fit will be a bit different than the actual numbers you are getting. 

Incidentally, I was just professionally fit the other day, and am 5-6, and my ideals were a 52cm TT and 48cmST, with a 75 SA and 72 HA I believe.


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## cxwrench (Nov 9, 2004)

as krisdrum posted, your frame probably has a sloping top tube. a 49cm seat tube (and how is that measured?) doesn't seem at all out of line w/ a 52cm top tube. i'm very similar in fit to you and my road frame is even shorter, if measured center to center. it depends on the slope of the top tube, how much seat tube extends from the top tube...it should affect the fit at all. the important things to know are the effective top tube length and seat tube/heat tube angles you need.


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## r_mutt (Aug 8, 2007)

actually, the new frame has a traditional style top tube, so i was measuring actual ctc length (52cm). since the top tube is traditional, and the seat tube (ctc) is 49, i was thinking that the amount of seat post showing might be more than usual for a traditional style bike. my saddle to bb axle is 69cm on my present bike, which is sloping btw. 

just wondering what size you 2 (krisdrum +cxwrench)are and what are the measurements of the bikes you are riding? we seem to be somewhat similar. 

there is another frame available to me, but the seat tube is 53cm and the top tube is 54cm (also tradional). i prefer this frame, but i'm wondering if it might be too long a top tube for me at 5-7. 


:thumbsup:


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## krisdrum (Oct 29, 2007)

r_mutt said:


> actually, the new frame has a traditional style top tube, so i was measuring actual ctc length (52cm). since the top tube is traditional, and the seat tube (ctc) is 49, i was thinking that the amount of seat post showing might be more than usual for a traditional style bike. my saddle to bb axle is 69cm on my present bike, which is sloping btw.
> 
> just wondering what size you 2 (krisdrum +cxwrench)are and what are the measurements of the bikes you are riding? we seem to be somewhat similar.
> 
> ...


Personally, I've found 53 or so as the most I can go on a top tube and be comfy. And that creates a very aggressive position for me. My current ride has a way undersized frame compared to ideal. 50.5 TT, 48 ST (CTC) traditional frame. But I am running a 120mm stem, 25mm setback post and the saddle is pushed toward the back end of the rails. I got the frame second hand and was trying to get it to fit, which is does pretty well. The new bike I just got measured for is 52 TT, 48ST (CTC) as my ideal, with a 100mm stem. This provides a pretty neutral position for me, kind of a blank canvas to work with. Since the new frame is going to be sloping, that should be the virtual size I am expecting, not the actual measurements I receive.


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## r_mutt (Aug 8, 2007)

thanks krisdum. your answers have been a lot of help actually. 




a few more questions: i was wondering of you have your are or forearm measurements. what i'm most concerned with the 54 top tube measurement (my other frame) is if it is too long for me.

what width bars are you running? and what width are your shoulders (suit size)?


thanks!


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## cxwrench (Nov 9, 2004)

i'll throw my #'s in there too, just for the hell of it. 
i'm 5'7" w/ a ape index of 0 (wingspan is 67" as well...)
saddle ht 68.5 w/ 170 crank arm
setback 5.0 w/ arione
reach 53.0 tip of saddle to center of bar
bars are 5.0cm below saddle
42.0cm ritchey wcs logic bar
120mm ritchey wcs 4axis stem
frame
seat tube 50.0 c-top of seat tube
top tube 53.5 effective
top tube 53.0 actual
head tube 12.5
front center58.0


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## krisdrum (Oct 29, 2007)

r_mutt said:


> thanks krisdum. your answers have been a lot of help actually.
> 
> 
> 
> ...


My arm length (based on a dress shirt size) is 32 inches exactly. Although trying to measure it myself right now, I came out at about 30. I'm running 42 ctc bars at the moment, but my shoulders are 40 (suit size). So I could go down to a 40 if I want, but find the 42s pretty comfortable.


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## r_mutt (Aug 8, 2007)

thanks for your stats cx. i feel more confident that the frame i bought fits me after reading the posts here. 


here are my specs just for fun. the bike measurements were from my single speed. i was being measured for my present build- a road bike project that i'm working on atm.


HEIGHT (BAREFOOT): 170.5 CM.
WEIGHT (CLOTHED): 154 LBS.
INSEAM LENGTH: 75.5 - 78 CM.
TORSO HEIGHT: 61 CM.
ARMS REACH: RIGHT 60 CM., LEFT 60 CM.
SHOULDER WIDTH: 41 - 38
THIGHS LENGTH: RIGHT 58 CM., LEFT 58 CM.
SHOE: 9.5 US, 43 EURO

BIKE MEASURES

SEAT TUBE (BB CENTER TO SEAT CLAMP TOP): 47 CM.
TOP TUBE (CENTER TO CENTER): 51 CM.
TOP TUBE (THEORETICAL, LEVEL C-C): 52 CM.
TOP TUBE SLOPE: 10 CM.
CRANK LENGTH: 165 MM.
STEM LENGTH: 9.5 CM.
HANDLEBAR WIDTH: 42 CM.
HANDLEBAR DROP: TT BAR -1 CM.
HANDLEBAR REACH (SADDLE CENTER TO BAR CENTER): 65.5 CM.
SADDLE ANGLE: LEVEL
SADDLE TO BB AXLE: 69 CM
SADDLE TO PEDAL AXLE: 85.8 CM
SADDLE SETBACK (BB TO SADDLE NOSE): 5 CM.
SADDLE CENTER TO HANDLEBAR TOP: -3.9 CM.
SADDLE CENTER TO GROUND: 94.4 CM.


thanks for your help guys!


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