Shorter Top Tube For Tri/TT Bike?
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  1. #1
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    Shorter Top Tube For Tri/TT Bike?

    To date, I've always used clip-on aero bars for du's, tri's and the rare TT. I'm now looking to buy a dedicated tri/TT bike and common sense tells me I should be looking for something with a shorter top tube, since the seat tube angle will be about 78 degrees vs. the more typical road angle of 73-74 degrees.

    Am I correct? If so, about how much shorter should I be looking for?

    I know, I know....get fitted. I will, but I'm not quite ready to hit the LBS's yet, just trying to get some advice.

    FWIW, a 53.5 effective top tube with a 110mm stem seems to fit me about right in a road bike.

  2. #2
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    Typically, most people go a size down on their tri bikes vs. their road bikes. However, some companies (Cervelo comes to mind) adjust the top tubes on their tri bikes accordingly so you don't have to size down.

    Take a look at the geometry charts on bikes your are interested in and check their tob tube heights. Another thing to take in consideration is the the head tube length. Tri bikes usually have shorter head tubes than road bikes so you want to avoid ones that are too tall (can't get low and aero) or too short (having a bunch of spacers and/or a stem that points to the sky).

    If you decide to get fitted, I recommend going to someone who has experience with fitting tri bikes and not just a traditional LBS.
    Last edited by Tri Slow Poke; 11-27-2009 at 05:35 AM.

  3. #3
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    Yes step 1-2cm down in TT length, and look for something with a shorter head tube. I disagree with TriSlowPoke a bit, depending on what he means. DO NOT go to a tri specific shop to get sized. Go to one that has experience in tri, but one that tri is not their sole focus. I have seen some horrible fits come out of these kids of shops. Stay away! I would recommend getting fitted at Walmart over a Tri-centric shop.
    Also, a tri fit and a TT fit are different.

  4. #4
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    Quote Originally Posted by mtbbmet
    Yes step 1-2cm down in TT length, and look for something with a shorter head tube. I disagree with TriSlowPoke a bit, depending on what he means. DO NOT go to a tri specific shop to get sized. Go to one that has experience in tri, but one that tri is not their sole focus. I have seen some horrible fits come out of these kids of shops. Stay away! I would recommend getting fitted at Walmart over a Tri-centric shop.
    Also, a tri fit and a TT fit are different.

    So....you would get fitted at Walmart over a bike shop?? Incredible. Go luck with that!

    To the OP, go to www.slowtwitch.com and do some resaerch on a fitter in your area. You will hear the good and the bad on each. Suprisingly, you won't find Walmart listed

  5. #5
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    Quote Originally Posted by mtbbmet
    Yes step 1-2cm down in TT length, and look for something with a shorter head tube. I disagree with TriSlowPoke a bit, depending on what he means. DO NOT go to a tri specific shop to get sized. Go to one that has experience in tri, but one that tri is not their sole focus. I have seen some horrible fits come out of these kids of shops. Stay away! I would recommend getting fitted at Walmart over a Tri-centric shop.
    Also, a tri fit and a TT fit are different.

    So....you would get fitted at Walmart over a bike shop?? Incredible. Go luck with that!

    To the OP, go to www.slowtwitch.com and do some resaerch on a fitter in your area. You will hear the good and the bad on each. Suprisingly, you won't find Walmart listed

  6. #6
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    Quote Originally Posted by mtbbmet
    Also, a tri fit and a TT fit are different.
    Damn, now I gotta get two bikes. The household CFO ain't gonna like that. I used to use a road bike with clip-ons for everything.....

    Talk to me...how do they differ?

  7. #7

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    Tri Vs TT fit

    Quote Originally Posted by redlizard
    Damn, now I gotta get two bikes. The household CFO ain't gonna like that. I used to use a road bike with clip-ons for everything.....

    Talk to me...how do they differ?
    Triathletes are not bound by stupid UCI rules regarding saddle position. Most triathletes are running very steep seat tube angles with the nos of their saddle sometimes even with or in front of their bottom bracket. This preserves a similar hip angle that you would have on a traditional road bike fit, rather than resulting in a really acute hip angel and the associated loss of power. UCI pros overcome this to some extent by sitting on the nose of the saddle, which is semi tollerable for a 40 K TT every now and then.

  8. #8
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    Long reply

    Quote Originally Posted by mprevost
    Triathletes are not bound by stupid UCI rules regarding saddle position. Most triathletes are running very steep seat tube angles with the nos of their saddle sometimes even with or in front of their bottom bracket. This preserves a similar hip angle that you would have on a traditional road bike fit, rather than resulting in a really acute hip angel and the associated loss of power. UCI pros overcome this to some extent by sitting on the nose of the saddle, which is semi tollerable for a 40 K TT every now and then.
    "Stupid UCI rules"?

    Triathletes often ride a higher, more upright, more 'tolerable' position than a full-on TT racer would ride. Tri bike courses are sometimes longer than a time trial, and the triathlete has to swim and run in the same competition as they ride the bike. A "tight" aggressive TT bike position isn't helpful for their performance in the other two disciplines.

    A common mistake when fitting a TT bike is to get the rider too 'stretched-out'. Your shorter top tube helps with this.

    A teammate of mine has a bike shop, a Ritchey Fit-bike, and is the current Masters 50+ TT World Champion. I was having lots of trouble getting a time trial set-up that felt "right" so I went to him for a fitting at the start of this season. A world of difference! I can now actually almost enjoy a long time trial and my results improved dramatically.

    A couple of considerations (in my order, not his) for the proper TT set-up that he advocates..and since he's the current W.C. he has credibility...

    Work first on your saddle position...height and fore and aft. There is a UCI rule as to the nose of the saddle as related to the BB. If you are considering Nationals or something, you should comply. Jeanne Longo, famous womens TT legend got penalized in a Northwest women's stage race this past season for an uncomplying set up on her TT bike..

    Your back should be as 'flat" as you can comfortably tolerate. "Flat" being parallel to the road surface.

    This is where I was way off...My saddle was too far back and my bars were way out front...putting me into a 'stretched-out' position. Looked Fast, yes...for about one mile until everything begins to hurt....That frame was actually too big for me..

    Your upper body should be supported on your bone structure, not your muscles..Your shoulders above your elbows, kind of, so that you are not using your core muscles to hold yourself in the Aero position.

    The bike should be reasonably easy to control, not all squirrely. You want to use your energy riding smoothly, not braking for corners or fighting in a cross-wind.

    A good TT fit is pretty 'sensitive'. Little adjustments can make all the difference once you get into the ballpark. A minor adjustment can "make" it work perfectly so that you can forget all about the bike once you start your TT race...That is what you are looking to achieve..My WC pal trains at least one day per week on his TT bike to keep his body familiar with the position.

  9. #9
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    Quote Originally Posted by Tri Slow Poke
    So....you would get fitted at Walmart over a bike shop?? Incredible. Go luck with that!

    To the OP, go to www.slowtwitch.com and do some resaerch on a fitter in your area. You will hear the good and the bad on each. Suprisingly, you won't find Walmart listed
    First of all, it's called sarcasm. Some people just don't understand it. You must be one of them.
    Second, I did not say to get fitted at Walmart over a bike shop. I said "DO NOT go to a tri specific shop to get sized. Go to one that has experience in tri, but one that tri is not their sole focus." Which is to say, go to a LBS, not a triathaloners store. If you have seen some of the fittings I have seen done by tri-centric shops passing themselves off as "experts in kenesiology", you would likely agree with me.

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