# TT vs Tri frame - difference?



## Samadhi (Nov 1, 2011)

What's the difference between a Time Trial and Triathalon bike.

I've been thinking about checking out TT competition and have been researching bikes. I see both types of bikes but couldn't tell you the difference if any.

Could someone explain, perhaps?


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## Kerry Irons (Feb 25, 2002)

Samadhi said:


> What's the difference between a Time Trial and Triathalon bike.
> 
> I've been thinking about checking out TT competition and have been researching bikes. I see both types of bikes but couldn't tell you the difference if any.
> 
> Could someone explain, perhaps?


Short answer: not much difference. It wouldn't surprise me if some tri-bikes don't meet UCI specifications but that really isn't an issue unless you're at the highest level of competition. Each manufacturer sets up their "go fast by yourself" bike a little differently and what one company might call their TT bike may have the same specifications as another company's tri bike.


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## MikeWMass (Oct 15, 2011)

TT less likely to have been peed on!


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## Wookiebiker (Sep 5, 2005)

With most manufacturers ... they are the same bike. 

However some have separate bikes like Specialized who makes the Shiv and the Shiv TT. The Shiv is a Tri specific bike (it's a little taller and the tube shapes don't adhere to the 3:1 ratio specified by the UCI) and not UCI legal, so if you plan on racing where they do bike checks (most places don't, but some do) they won't let you race with the Tri version.

Ultimately you need to find one that fits ... just as you do with a road bike. If it has a UCI "Approved" sticker on it, you will be able to use it in a race where they check (assuming you have it set up within their limits  ).

If you want to check out TT's and see if you like them ... see if you can find some races with an "Eddie" category which is a road bike specific race ... if you like that, then maybe invest in an older used bike to start with ... then if you get into it big time, spend some serious cash on a nice bike.


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## EmblemCraig (Jun 5, 2013)

Tri bikes have steeper seat tube angles(75-78 compared to TT 73-75), to optimize endurance for the run. These angles are sometimes not UCI legal. 

Tri bikes also have aerodynamic covers which are not UCI legal. Zinn says some time trial bikes have negative BB drop (i.e. bb rise), but i cannot find an example of it. It would make for much twitchier handling.


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## cxwrench (Nov 9, 2004)

^ this post pretty much nailed it ^ 
the only other thing i can think of is the 3:1 rule the UCI uses to keep frame tubes and other things (base bars, seat posts) from getting too aerodynamic and causing mass carnage. the main tubes on the frame and things like base bars that the extensions are mounted onto can only be 3 times as wide as they are deep. this is why specialized, for example, makes the Shiv and the ShivTT. 
as EmblemCraig posted the 'triathlon' Shiv has a 77* seat tube angle and the UCI legal ShivTT varies from around 74* on the xs to around 76 on the xl. the tube shapes on the Shiv are not UCI legal but are fine for triathlons as they don't have a bunch of stodgy old men hell bent against technology advancing any further than it had 15 years ago.


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## Wookiebiker (Sep 5, 2005)

EmblemCraig said:


> Tri bikes have steeper seat tube angles(75-78 compared to TT 73-75), to optimize endurance for the run. These angles are sometimes not UCI legal.


Actually ... The Shiv is about the only bike/company that offers up different bikes for Tri and TT ... and the Shiv TT has a 75 degree STA that goes up to around 76 in larger sizes. I think they can do this because they are a big enough company that they can sell two different bikes ... the Shiv doesn't comply with UCI's 3:1 rule when it comes to tube shapes and in Tri's they don't have any rules such as that. It also has an internal bladder for fluids which is against the UCI rules.

Trek does offer a "Bento" box add on for Tri's with their TT bike so you can carry food, tools, etc. behind the seat tube and a few other brands do something similar.

You would be fairly hard pressed to find STA's below 76 degrees on any TT bike and there isn't any illegal angles on the TT bikes, a rider just has to be able to meet the saddle set back of 5cm to be legal ... if they can do that with an 80 degree STA, they are fine.

Most TT bikes come with adjustable seat posts that allow angles to be adjusted from 76 - 78 degrees on average, but some allow more adjustment for Tri guys that have STA's up to 80 degrees.

A bike with a STA as shallow as 73 degrees would not be considered a TT bike ... that's regular road bike geometry ... though some riders do have special seat posts that move their saddle back to that basic angle because most pro cyclists have extremely long femurs compared to the average person. 

Tom Zirble actually won the National Championships this year on a road bike because it fits him better than Orbea's TT bikes with a longer top tube, taller head tube and with his leg length (he's 6'5") he easily gets away with a 73 degree STA. The slacker STA also allowed for a longer reach on the bike to help him comply with the 75 cm rule for the bar extensions (The UCI hates really small and really large riders apparently as the 5 cm rule hurts smaller riders and the 75 cm rule hurts big riders).

Some manufactures also sell separate seat posts for less or more STA ... such as the Specialized Transition and Blue's TT/Tri bike.

Overall though ... a companies TT bike is also their Tri bike.

BTW ... If you don't know what the 5 cm and 75 cm rules are they are basically this:

The 5 cm rule stipulates that the tip of the saddle nose must be 5 cm behind the center of the bottom bracket and the 75 cm rule states that the tips of the bar extensions can not be more than 75 cm forward of the center of the bottom bracket. With electronic shifters this is measured to the end of the shifter ... with mechanical (non RTR) they are measured to the pivot of the shifter.


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