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How big is advantage of tri bike over high-end roadbike in 70.3?
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Hey all

I read a lot ST, and this is a my first post here. You guys are an amazing community!
I've just completed my first 70.3 in Santa Cruz, and I am really excited to continue the triathlon journey and keep doing more races (mostly, 70.3s). I am M, 32, and my times for 70.3 swim/bike/run were 0:49/3:07/1:45, total 5:54. I am a good runner, slow swimmer (and I am OK with that) and I am wondering how much I can improve my biking time from current by switching from good road bike to tri bike?


I used my road bike for the race (Cervelo R3, Dura-Ace 7900, no aerobars) and I am wondering how much of an advantage I would gain if I just switch from road bike to tri bike? If it's something like 5-10mins over 70.3 distance, then I am probably happy to continue doing 70.3 races with my road bike and avoid the hassle of having two bikes, but if it's something like 30-40 mins, then it's a whole different story. Basically I am debating whether I should just train more and improve my biking time on road bike, or I am doomed to no progress unless I switch to tri-bike.

I read articles saying that "it takes 20% less power to maintain same speed on tri-bike than on road-bike", but I am wondering how much of it applies to my level of cycling (3:07 bike leg for 70.3 distance).

Would appreciate your insights and thoughts on my dilemma.
thanks
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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You can do some simple calculated guessing here: http://bikecalculator.com/

Or go more in depth at bestbikesplit.com.

For example, with bikecalculator.com I just did 200 watts, 170 lb. rider, 20 lb. bike, clincher tires, 75 degree temp, and 0 feet elevation and for the different positions it was:

Hoods: 19.5 mph
Drops: 21.1 mph
Aerobars: 22.80 mph

Or to think of it another way, in order to average 22.8 mph given the same conditions you would have to ride 303 watts on the hoods or 244 watts in the drops, compared to 200 watts on the aerobars. Bikecalculator is certainly very basic and leaves out a lot of variables but it gives you a basic ballpark idea of how much more power it takes to generate a similar speed in those different type positions.

Bestbikesplit would be even better but requires a lot more info and time.

Favorite Gear: Dimond | Cadex | Desoto Sport | Hoka One One
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [GMAN19030] [ In reply to ]
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However, I have never in a ride switched from hoods to drops and suddenly pulled away from everyone at the same effort.
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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I'm no expert so discard this if you like.....but I think it really depends on the position you can keep on the bike. TT bikes are designed to support an aerodynamic position, road bikes can do this too but are designed generally for a broader purpose. Get some good advice on your position from a professional bike fitter. As some of the other replies have shown, position on the bike alters how much effort you need to maintain the same speed (all other things being equal).

You already have a nice race bike, maybe just get some advice on position and consider aerobars? Thats a relatively low-cost option. After that you could look at your wheels and then maybe a TT bike if you're committed. You can go other ways but thats what I'd do.
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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I’ve been thinking about this sort of thing lately too. I’ve just ordered an S3 as I plan on being more of a roadie for a while, but will still do some local standard course type races and maybe the odd half.
I’ve sold my Shiv so I figure that with the aeroness of the S3, assuming I get into a good position, and maybe swap out the drops for an aerobar, I won’t loose super amounts of time. It will be interesting to see how it works out.
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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well i compared hoods to an very aggressive tt position on bestbikesplit.com and it was a 2mph difference on the im maryland course at 175 watts went from 22.5mph to 20.5mph. i think you should get a very long/low stem, well fitting sleeved skinsuit, aero bars, aero helmet, well placed bottles, and a disc cover then call it a day that's like $300 and will give 99% of the gain. but it really depends 100% on your position how much time you'll save
Last edited by: eggplantOG: Oct 6, 15 20:12
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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Check out the video posted on specialized FB page on April 21. They to a wind tunnel test on shiv vs. Tarmac with clip ons. It might save you some $$$.

Sorry could not link.
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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get some clip ons and do something about your swimming.

Find out what it is in life that you don't do well, then don't
do that thing.
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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Redshift Switch moveable seat post and quick release aerobars are a nice option if you stick with the road bike and want to keep riding both positions.
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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You also won't produce as much power in the aero position. So it isn't as cut and dried as "you will go x amount faster at the same wattage" because you won't be doing the same wattage. You can try your times and comfort level with some clip-ons (they are relatively cheap) and see how it feels. But I'd wager that you won't see more than your estimated 5-10 minutes savings in a 70.3. If you were to gain 2mph on a new TT bike (typical case) with a 3 hour bike split, you're talking about 15 minutes savings in time. That is IF you can stay in the aero bars the entire 2.75 hours!
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Post deleted by gkartashov [ In reply to ]
Re: How big is advantage of tri bike over high-end roadbike in 70.3? [Grisham] [ In reply to ]
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Grisham wrote:
Check out the video posted on specialized FB page on April 21. They to a wind tunnel test on shiv vs. Tarmac with clip ons. It might save you some $$$.

Sorry could not link.

thanks a lot!
here are these videos - they have some great tests.
https://www.youtube.com/watch?v=LMLKcHyHPrc&list=PLcmaLnqmqDnmn_bCR0RJ-soSCDKCKR97t&index=8


basically,

  • roadbike with aerobars vs dropbars give ~5min advantage on 56mile distance
  • TT bike vs roadbike with aerobars gives 1-2mins advantage on 56mile distance

Bottom line: if total advantage of switching from high-end roadbike to TT bike is 6-7mins, then personally for me it's not worth purchasing TT
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [RZ] [ In reply to ]
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RZ wrote:
You also won't produce as much power in the aero position. So it isn't as cut and dried as "you will go x amount faster at the same wattage" because you won't be doing the same wattage. You can try your times and comfort level with some clip-ons (they are relatively cheap) and see how it feels. But I'd wager that you won't see more than your estimated 5-10 minutes savings in a 70.3. If you were to gain 2mph on a new TT bike (typical case) with a 3 hour bike split, you're talking about 15 minutes savings in time. That is IF you can stay in the aero bars the entire 2.75 hours!


interesting point re: "wont produce as much power in aero position" - I haven't thought about it. Do you know of any factual articles that estimate loss in power producing ability on aero position vs road bike position?
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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When you are riding sub-threshold (like during a 70.3) any difference will be minimal.

Also, there are some people that produce as much or more power in the aero position.

jaretj
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Re: How big is advantage of tri bike over high-end roadbike in 70.3? [gkartashov] [ In reply to ]
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Take a read of this, if you a haven't already.
A lot depends on your overall setup now (how low is stem, helmet, wheels, tires, etc) to what you could use as a TB setup. But say anywhere from 60 to 20 watts can be saved. If I figured that correctly ~4-12 minutes saved at your speeds/wattage. Probably can spend a lot less now getting that back, plus some, in the swim!!!

<We all know that light travels faster than sound. That's why certain people appear bright until you hear them speak>
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