There is no easy or precise answer to this question. Too many variables to say that a tri-bike will make you xmph faster. It kind of depends on your positions on both bikes and how you ride. Part of the tri-bike theory is that you will be able to run faster after the ride so it may be more useful to consider the combined bike and run time for each bike..

Are you using aerobars on your road bike?

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no aerobars on the roadbike...Like I said this is just a general question...I am interested in how your position makes a difference aerodynamically...I was just looking at the results of a tri and saw that the winner averaged about 22.5 on the bike (oly distance). I ride that same course and can average about 20.5 on my roadbike (I don't own a Tri bike). I was just wondering how big a part the bike and it's components play in this...granted his swim time is a good 8 mins faster and his run is a good 45" / mile faster so I am not trying to win...just interested in bike technology.

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"One thing I have found there are just two ways to go
It all comes down to livin' fast or dyin' slow"- Robert Earlk Keen Jr.

I am more than one mph faster on my tribike on level roads. Big hills would probably be an equalizer. Your milage may vary.

There was a link from this forum to a web site that allowed you to put in constants (power, distance...), then change the position that you're riding in order to find out the difference in speed. Maybe that person will read your post and show us the link again.

Adam

http://w3.iac.net/...locity/velocity.html

It predicts a 4 mph diff at the same power or 100 Watt difference to maintain the same speed from aerobars to hoods which is not very likely. I'd say more like 1-2 mph difference from my own experience switching between bikes. I think there's also a difference in the run depending on what position you rode. If you're looking for justification to buy a tri bike. It's a NEW bike. That is justification.

If you read some of the fit articles on this site, and other articles I get the distinct impression that aerobars on a tri bike immediately puts you in the same position as the best pros can acheive with the best possible fit in thier drops - in the drops, not on the hoods. Not only does a properly fitting tri bike give you the position it takes people years to achieve on a road bike, but it is done very comfortably. For instance, how many of us would want to ride a road bike solely in the drops for 6+ hours? Yet, as a relative newbie with my properly fitting P2k I can ride in the aerobars for 6 hours and the only thing that hurts is the saddle region.

Personally, going from riding on the bullhorns to aerobars at the same power output is good for 2-3 mph depending on the exact power output and wind.

There are 2 huge advantages, for me personally, to a tri bike. #1 a well fitting tri bike is extremely comfortable in the aero position. In my upcoming 1/2 IM I expect to get out of the aerobars at the turn around and at T2, other than that I won't get out of the bars. Second, with the tri bike I'm riding at 80* seat tube angle yet the bike handles and fits perfectly.

I did a pretty decent test where I had my roadbike with aero bars. I rode six laps of an 8 mile flat loop course, alternating drops and aerobars, while keeping the wattage the same (using a powertap). I got almost exactly a 1mph speed increase from the aerobars. Also, note that this position puts me higher than on my dedicated tri bike (the aerobars were slapped on, without any real adjustment).

Absolutly.

It does really depend on your positioning on both bikes.

I am not sure of the absolute numbers, but assuming optimal positioning you should see some measurable increases in speed using aero-bars.

However, many triathletes are very poorly positioned and ironically, the gains may be minimal. Many good road racers get better aerodynamic numbers while riding in the drops on their road bikes than many triathletes do while riding on aero-bars on their tri bikes.

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Steve Fleck @stevefleck | Blog

I think 1 -2 mph. I have been commuting with some clip-ons on my road bike and that is what I have seen.
One of the things aerobars let you do for a short distance is pull on them, something you can't do with drop bars. I am not sure of the exact biomechanics, but it does something like recruit the muscles in your back to keep your hips and lower back from squirming all over when you really apply some power with your legs. You are using more muscles than you would with drop bars, and that takes energy, but for shorter distances, you can really power and go fast.

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Andy Tetmeyer (I work at HED)

My experience is about 1-2 mph increased speed as well (probably closer to 1 than 2 though.)

I agree you can and do pull on drop bars - no question of that.
The difference with aero bars is that your forearms are sitting on the arm rests, and that gives you something to brace against. It is analogous to trying to loosen a really tight bolt (I was working on my car last night). If you just grab onto something and pull, you can exert a fair amount of force, but if you have to loosen a stubborn bolt, or generate more pulling power while remaining aero, you are going to exert more force if you can brace your elbow against something.

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Andy Tetmeyer (I work at HED)