TT Bike vs Road Bike Drafting

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2009-08-31 9:28 AM

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Subject: TT Bike vs Road Bike Drafting
Anybody out there have data indicating the difference in riding a time trial bike versus a road bike in a draft, assuming that the rider is producing the same amount of power?

I understand that there are likely too many variables, such as aerodynamics, pack size, bike fit, etc to produce an absolute number.  I'm inclined to believe that the roadie drafting would be faster, but I'm curious as to how much faster.

2009-08-31 10:15 AM
in reply to: #2380079

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Subject: RE: TT Bike vs Road Bike Drafting
i doubt the roadie would be faster.... otherwise we would see the TTT in the Tour de France using road bike and not the time trial bikes that they use...

BUt no, i dont have any data.  sorry.
2009-08-31 10:27 AM
in reply to: #2380079

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Subject: RE: TT Bike vs Road Bike Drafting
No hard data but from my experience drafting on a road bike is much easier. Just based on HR (I only have a pwr meter on my tri bike), I would be Z1-Z2 doing 24-27 mph on a road bike in a pack. Doing the same thing on my tri bike would put me in Z4 or Z5 if I was riding by myself.

ETA - are you talking about drafting on a TT bike or not drafting on a TT bike?

Edited by docswim24 2009-08-31 10:29 AM
2009-08-31 10:35 AM
in reply to: #2380079

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Subject: RE: TT Bike vs Road Bike Drafting
Correct.  This is under the assumption that the TT bike is not drafting, but the road bike is drafting.

Your situation sounds very comparable to mine.  My last crit, we averaged around 25-26, with my HR in high zone 2, low zone 3.  There's no way I could average that fast for that distance on a TT bike, unless I could stay in zone 5 for 45 minutes.
2009-08-31 10:54 AM
in reply to: #2380079

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Subject: RE: TT Bike vs Road Bike Drafting
Ballpark figures-

Road bike drafting drops power required at speed by 1/3rd or more on flat terrain.

Cycling power output produced during flat and mountain stages in the Giro d'Italia:a case study.  Journal of Sports Sciences, Oct,2007.

Road bike (std bars/helm/wheels) vs full TT bike set-up -up to 25% power savings at 40kph.

http://www.cyclingnews.com/features/how-aero-is-aero
2009-08-31 11:15 AM
in reply to: #2380079

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Subject: RE: TT Bike vs Road Bike Drafting
Nice reference.  Thanks.

So if I understand correctly and my math is good, it looks like to achieve 40kph:
* roadie w/o drafting = 290 watts
* roadie w/ drafting = 194 watts (assuming 33% savings from the draft)
* TT full setup = 220 watts

I actually would've thought the roadie drafting would've had a bit more of an advantage.

Edited by jcbolton 2009-08-31 11:16 AM

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