Triathlon - Why do TT bikes have track ends instead of vertical drop outs?

Can anyone tell me why TT bikes have track ends instead of vertical drop outs?

I've always wondered about this.

Thanks in advance.

You mean horizontal dropouts, no track dropouts.

Horizontal dropouts look like this:

http://www.machinehead-software.co.uk/bike/chain_length/horizdropout.jpg

track dropouts look like this:

http://www.singlespeed.net/articles/tension/horizontal.jpg

the major advantage of horizontal dropouts vs the more common these days vertical dropouts (pictured below) is that one can adjust the chain tension by moving the wheel slightly forward or backward if necessary. You cannot do that with the vertical dropouts

http://www.machinehead-software.co.uk/bike/chain_length/vertdropout.jpg

I'm familiar with the different styles of dropouts.

They are track ends with a derailleur hanger:

http://www.specialized.com/OA_MEDIA/2010/bikes/9704-02_l.jpg

Click for huge image of the bike below. (http://www.feltbicycles.com/Resources/ProductPhotos/Bikes/10_FELT_DA(5).jpg)

http://www.feltbicycles.com/Resources/ProductPhotos/Bikes/10_FELT_DA(5).jpg

The main reason they started putting in track style dropouts is because of the seattube cutaway. If they did not switch to track style, there would be no way to get the wheel in or out.

Thanks!

Can anyone tell me why TT bikes have track ends instead of vertical drop outs?

Cervelo use horizontal dropouts so the spacing between the wheel and seat tube can be made as small as possible (or legal) for different size tires. They're not necessary to get the wheels in and out on the P2 or P3 series.

Cervelo use horizontal dropouts so the spacing between the wheel and seat tube can be made as small as possible (or legal) for different size tires. They're not necessary to get the wheels in and out on the P2 or P3 series.

That's interesting. Makes sense.

Cervelo use horizontal dropouts so the spacing between the wheel and seat tube can be made as small as possible (or legal) for different size tires. They're not necessary to get the wheels in and out on the P2 or P3 series.

THIS. Ironman referees are hardasses. Sometimes they will go around the transition with a "gauge" (credit card or such :D ) and check the spacing between the frame cutout and the tire.

Don't get me started on their drafting calls, man. :mad:

Really? you think they make bad drafting calls? I think their only problem is not making enough of them.

But yeah, dropouts are so that you can get the wheel in close to the cutout.

Its so you can turn your p3 into a fixie!!

Its so you can turn your p3 into a fixie!!

Like this?

http://cdn.mos.bikeradar.com/images/news/2009/09/02/1251912938929-nocjioncc266-798-75.jpg

Or this:

http://velospace.org/files/Cervelo-P3-Fixie.jpg

I cry when I see bikes like that.

Of course I'm jealous and hat'in, but those always look like a lil boy got a hold of daddy's credit card and went to town. At least HTFU and get a real crank size or a lower rear.