ST measurements vs TT measurements?

[jasonification]

Hi all! Looking for some wisdom. I'm interested in getting a cyclo-cross bike and usually ride a 54-55cm square frame road bike..recently saw a 2002 cyclocross with a ST measurement of 51cm and a TT of 54cm. Was wondering if a 51cm ST would show too much post? Thanks all!

[Ken Robb]

Is it a compact/sloping frame?

[Lewis Moon]

You'll also need to pay attention to the HT length.

A lot of the time builders will basically "freeze" the TT length at some point as the seat tube length decreases. This is because they are still working with a 700c wheel but a smaller frame. You can only make a wheel base so short before ugliness happens.
Watch out for this on smaller frames. It still may have a 54 TT but the HT may be too short to be practical.

[kramnnim]

No, it won't show too much post.

[jasonification]

Thanks for info so far! It's a horizontal top tube..a early 2000 jamis Nova..

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[thwart]

Thanks for info so far! It's a horizontal top tube..a early 2000 jamis Nova..


Those are very good riding bikes.

I never worry too much about how much seatpost shows… as long as I've got an adequate amount still in the frame. But then again, I'm a relative lightweight.

[jasonification]

I'm just shy of 200..fingers crossed it's light enough! :-D

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[thwart]

I'm just shy of 200..fingers crossed it's light enough! :-D


Got it. Was actually referring to the cracked seatpost scenario… although come to think of it, with sloping/compact frames there's sometimes literally feet of post showing.

[jasonification]

Got it. Was actually referring to the cracked seatpost scenario… although come to think of it, with sloping/compact frames there's sometimes literally feet of post showing.

yeah i got what you mean...by "it" being light enough i was referring to the weight of my body.. haha:banana:

[Black Dog]

A part of the difference in the ST height is due to different HT heights and it may also be due to how the ST are measured. Sometimes it is C-T and sometimes C-C.

[Lewis Moon]

So, you'll be OK with what is probably a 3 cm shorter head tube? (given the horizontal TT) That's a lot.

[jasonification]

That is something I did not consider as well! Ah well. Someone ended up getting it before me anyway. Such is life! I shall live to buy another day.

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[kramnnim]

So, you'll be OK with what is probably a 3 cm shorter head tube? (given the horizontal TT) That's a lot.

Stack height might be taller since the axle-to-crown is longer...which may help some. The HT on my CX frame is 4cm shorter than my road frames.