# Rule of Thumb on TT bike sizing?



## litespeedchick (Sep 9, 2003)

I'm tossing around the idea of buying a cheap TT bike on Ebay. I'm totally not serious about this stuff, i do 3-4 TTs and about 1 tri per year. I'm just so curious about how an aero set up would affect my times. I'm afraid of clip ons.

Anyhow, which direction would one want to err...too small or too large...when it comes to a TT bike? I'm currently riding a 51 Ghisallo road bike w/ a 52.5 top tube. I am slightly too stretched out, i made it fit w/ a short stem, girl-specific handlebar. 

So for a tt bike, would conventional wisdom say go smaller or bigger if not this precise size? I'm 5'2" , long legged but short torso. Thanks!


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## muscleendurance (Jan 11, 2009)

*If your afraid of clip ons, a TT frame isnt going to be any use to you!*

yeah thats all I got. says it all really


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## MR_GRUMPY (Aug 21, 2002)

You don't need to think of buying a TT bike until you can average 23-24mph in a 20K.

Unless you spend a lot of time in the forward position that a TT bike has, you might even be slower on the new bike ( you'll be using different muscles)


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## Mtn2RoadConvert (Aug 28, 2006)

litespeedchick said:


> I'm tossing around the idea of buying a cheap TT bike on Ebay. I'm totally not serious about this stuff, i do 3-4 TTs and about 1 tri per year. I'm just so curious about how an aero set up would affect my times. I'm afraid of clip ons.
> 
> Anyhow, which direction would one want to err...too small or too large...when it comes to a TT bike? I'm currently riding a 51 Ghisallo road bike w/ a 52.5 top tube. I am slightly too stretched out, i made it fit w/ a short stem, girl-specific handlebar.
> 
> So for a tt bike, would conventional wisdom say go smaller or bigger if not this precise size? I'm 5'2" , long legged but short torso. Thanks!


Most of the cheaper TT/Tri bikes come with clip-on aero bars from what I've seen, and you need to spend some money on the integrated TT bars. I don't have a TT bike, but see most people going with something slightly smaller than their road bike.


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## woodys737 (Dec 31, 2005)

Maybe this article will help you gain insight about angles, etc...While it doesn't directly answer your question, it may help illuminate the direction you need to go. 

http://www.slowtwitch.com/mainheadings/techctr/bikefit.html


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## kbiker3111 (Nov 7, 2006)

To actually answer your question: the time trial bike will be smaller than your road bike. It varies, but expect a cm shorter TT and at least 1-2 cm shorter headtube.


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## litespeedchick (Sep 9, 2003)

Mtn2RoadConvert said:


> Most of the cheaper TT/Tri bikes come with clip-on aero bars .


maybe I'm confused by the terminology. What I want is a bar with shifters where my hands will be. Isn't that integrated? What I don't want is something that has to be bolted on to my handlebar, and thus subject to moving around while I'm riding if I screw up the installation.


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## stevesbike (Jun 3, 2002)

yes, you're right re terminology - I say get a TT rig. They are fun and fast. As for sizing, most people go down in size. Some pros go radically smaller. Dave Zabriske rides a 58 road frame and a 54 TT frame, mainly to get as low as possible. Since it sounds like your road bike is a bit long, your sound like you should go smaller as well (a 1-2 cm shorter top tube). The slowtwitch links are good re sizing and fit. A frame people have been buying (including me) is at this link. Frame for about $500 plus shipping. It's pretty inexpensive to build up a TT by scouring ebay for parts (new or used). 

http://www.alibaba.com/product-gs/281967534/carbon_TT_frame.html


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