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Aero Savings from Road Frame to TT Frame
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 2010-07-26 6:02 PM |
Member  33  Milwaukee |  Subject: Aero Savings from Road Frame to TT FrameI had a question for the forum- How much aero advantage is there when comparing strictly a Road Bike frame to a TT bike frame (particularly in an Iron distance race)? I ask because I right now ride an all carbon Lemond road bike with a fully integrated tt bar setup, and am highly considering trading it out for an all carbon 2006 Cervelo P2C (of course with fully integrated tt bar setup). The weight difference is negligible (carbon bars and frames on both), and assuming my fit on my current road bike / tt bike hybrid is optimal and will be mirrored on a new bike, how much time is expected to be saved over an Ironman distance ride when I'm basically just switching out the frame? For what its worth, I went to my LBS ( a tri store at that) last weekend, and the owner and experienced biker was praising his new line of Trek Speed Concepts, boasting that when compared to a Cervelo P4, one could save 5 minutes over an Ironman distance race. Whether or not thats due to the storage box/airfoil on the back or not, if 5 minutes can saved from switching out TT frames, how much aero benefit is there when going from a road bike frame to a TT frame? |
| 2010-07-26 6:08 PM in reply to: #3005888 |
Master 2404  Redlands, CA | Subject: RE: Aero Savings from Road Frame to TT Frame For the frame, I think its negligable, like 10 seconds over 40k. The bars, wheels, and helmet count for alot more. |
| 2010-07-26 6:24 PM in reply to: #3005888 |
Master 1770  Bedford, MA | Subject: RE: Aero Savings from Road Frame to TT Frame A tri fram puts the rider in a more aero position, which saves the most time over a more upright position on a road bike. I know you are talking iron distance, but I can speak to shorter distances. I occasionally ride in a local 10 mile TT. On my road bike with clip-on bars I averaged around 23 mph. On my new tri bike I can average 25-26 mph. I think I'm a little fitter now, but there's definitely speed gain from being in a more aero position. |
| 2010-07-26 6:26 PM in reply to: #3005888 |
Elite 4235 Spring, TX | Subject: RE: Aero Savings from Road Frame to TT Frame 10 seconds here, 10 seconds there....it all adds up eventually.
The real advantage to a TT bike is the body position, which is the biggest component to reducing drag. The frame itself may not save you much, but being in a good aero position can result in big time savings. |
| 2010-07-26 6:28 PM in reply to: #3005888 |
Expert 1053 Culpeper, VA | Subject: RE: Aero Savings from Road Frame to TT Frame Tagging along... my road bike is somewhat aero but when I look at Cervelos @ races, head on they almost disappear. |
| 2010-07-26 7:49 PM in reply to: #3005920 |
Master 2855 Kailua, Hawaii | Subject: RE: Aero Savings from Road Frame to TT Frame AndrewMT - 2010-07-27 1:26 PM 10 seconds here, 10 seconds there....it all adds up eventually.
The real advantage to a TT bike is the body position, which is the biggest component to reducing drag. The frame itself may not save you much, but being in a good aero position can result in big time savings. and toss in an aero helmet, gives you the most advantage. more aero frames might help shave off seconds more, but it gets to be less effect for the $ invested. |
| 2010-07-26 8:31 PM in reply to: #3005888 |
Expert 2852 Pfafftown, NC | Subject: RE: Aero Savings from Road Frame to TT Frame 10mi. TT @ 23mph is 26:5.21. |
| 2010-07-26 10:08 PM in reply to: #3005888 |
Master 2372 | Subject: RE: Aero Savings from Road Frame to TT Frame t.petermann - 2010-07-26 6:02 PM how much aero benefit is there when going from a road bike frame to a TT frame? Just get a Kestrel Talon and then you don't have to worry about it.  |
| 2010-07-26 10:09 PM in reply to: #3006110 |
Master 2372 | Subject: RE: Aero Savings from Road Frame to TT Frame metafizx - 2010-07-26 7:49 PM AndrewMT - 2010-07-27 1:26 PM 10 seconds here, 10 seconds there....it all adds up eventually.
The real advantage to a TT bike is the body position, which is the biggest component to reducing drag. The frame itself may not save you much, but being in a good aero position can result in big time savings. and toss in an aero helmet, gives you the most advantage. more aero frames might help shave off seconds more, but it gets to be less effect for the $ invested. Bang for your buck in aero equipment. Just in case someone hadn't seen it. |
| 2010-07-26 10:13 PM in reply to: #3005888 |
Member 33 Milwaukee | Subject: RE: Aero Savings from Road Frame to TT Frame Hmm, I guess I was expecting to hear that the frame "upgrade" would account for a bigger aero advantage than what you guys are mentioning. When the wheels, helmet, handlebars (assuming an integrated cockpit on a road bike, not clipons) and body position stay constant, I thought I would be looking at ~10 minutes saved in a century ride with a fancy Cervelo frame. I already have a fast forward seatpost on which gives me about a 78 degree seat angle from the bottom bracket, and my handlebar stem flipped over and all the spacers moved to the top. I've noticed a lot of time savings from the beginning of the season to the end, as these moves were all done incrementally, and I'm talking above and beyond just getting more fit as the season progressed. I just can't help it, those frames look so darn thing when you see them head on! |
 2010-07-26 10:48 PM in reply to: #3006369 |
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| 2010-07-26 11:51 PM in reply to: #3005888 |
| Veteran 178 Eugene | Subject: RE: Aero Savings from Road Frame to TT Frame I'm kind of surprised that no one has mentioned the body positioning change switching muscle groups to help keep running muscles fresh. I've read of a couple tests where they compare 2 triathletes of similar fitness levels, one on a road geometry bike, and one on a triathlon geometry bike on trainers (no aero advantage when there's no wind). The riders spent equal time on the trainers and I believe went at the same intensity for the same amount of time, and then went for a run right after. The rider on the TT frame out performs the rider with the road frame on the run test every time. But I'd have to do some searching to get the details on the test. |
| 2010-07-27 12:26 AM in reply to: #3005888 |
| Master 2460 | Subject: RE: Aero Savings from Road Frame to TT Frame This article has very helpful info: http://www.bikeradar.com/news/article/how-aero-is-aero-19273 Costs per aero seconds are at the end of the article. I'm all about speed, but even after buying an awesome Cervelo P2C, I've concluded that the aero time benefits are definitely not worth it to me. And I'm usually contending for an AG spot in M30-35 in competitive CA. The guys who are beating me are not beating me because of aero. Edited by agarose2000 2010-07-27 12:28 AM |
| 2010-07-27 4:07 AM in reply to: #3006463 |
Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Aero Savings from Road Frame to TT Frame MaxPowers - 2010-07-27 1:51 AM I'm kind of surprised that no one has mentioned the body positioning change switching muscle groups to help keep running muscles fresh. I've read of a couple tests where they compare 2 triathletes of similar fitness levels, one on a road geometry bike, and one on a triathlon geometry bike on trainers (no aero advantage when there's no wind). The riders spent equal time on the trainers and I believe went at the same intensity for the same amount of time, and then went for a run right after. The rider on the TT frame out performs the rider with the road frame on the run test every time. But I'd have to do some searching to get the details on the test. Unfortunately the two studies that I have seen that compare road vs tri geometry have a few issues and concluding that tri geometry saves your legs for the run is suprious at best. It's hard to quantify the benefit of the frame without a wind tunnel, but assuming you setup a tribike to put you in a good aggressive position (the real benefit of the tribike) most athletes be more comfortable in this position than on a road bike. FWIW, the difference at similar power outputs for me between my road bike and tribike (both in training attire) is usually 3-4km/h. Add in race wheels, skinsuit, aerohelmet and the difference is usually 4-5km/h. Shane |
| 2010-07-27 6:31 AM in reply to: #3005888 |
| Expert 2852 Pfafftown, NC | Subject: RE: Aero Savings from Road Frame to TT Frame FWIW, the difference at similar power outputs for me between my road bike and tribike (both in training attire) is usually 3-4km/h. Add in race wheels, skinsuit, aerohelmet and the difference is usually 4-5km/h. Shane... I'm not disputing your finding, AT ALL. I'm just intrigued. That's over 8:30 in a 20K sprint bike leg! (diff. between 15mph and 18.1mph) These results are the strongest case for a TT bike I've seen posted. |
| 2010-07-27 9:30 AM in reply to: #3006531 |
| Master 2372 | Subject: RE: Aero Savings from Road Frame to TT Frame gsmacleod - 2010-07-27 4:07 AM FWIW, the difference at similar power outputs for me between my road bike and tribike (both in training attire) is usually 3-4km/h. Add in race wheels, skinsuit, aerohelmet and the difference is usually 4-5km/h. Shane Can you put out the same power numbers in both positions at the same effort level? I'm curious. |
| 2010-07-27 9:58 AM in reply to: #3005888 |
| Master 2158 | Subject: RE: Aero Savings from Road Frame to TT Frame My understanding of the benefit of a TT bike is that the body position, not the frame, is the source of the MAJORITY of aero savings. This also means that you can go faster with less of a power output. At lower power, you use less calories. Leaving more energy for the run. |
| 2010-07-27 1:36 PM in reply to: #3006972 |
| Champion 9407 Montague Gold Mines, Nova Scotia | Subject: RE: Aero Savings from Road Frame to TT Frame sand101 - 2010-07-27 11:30 AM Can you put out the same power numbers in both positions at the same effort level? I'm curious. I have tested power on both my tribike and road bike a few times and any differences have always been within the margins of error for the test (<5W) and I have not consistently had a higher test on one bike or the other. As another poster mentioned, obviously the position of the rider is the most important part of the equation and I have tried (and continue to refine) to get as aero as possible while still maintaining relative comfort and power. Further, part of the speed difference is taking great care in the setup of my tribike, the clothing that I wear while racing and holding my position for the duration of the event. Shane |
| 2010-07-27 1:57 PM in reply to: #3005888 |
| over a barrier | Subject: RE: Aero Savings from Road Frame to TT Frame The difference between a P2K and P3C is 2.5 secs per KM . That's two TRI frames, throw in a round tubed road bike and I'd say the gains would be much greater. That is 7.5 mins in an Ironman between two Tri Frames. http://forum.slowtwitch.com/gforum.cgi?do=post_view_flat;post=18021... |
| 2010-07-27 2:30 PM in reply to: #3005888 |
| 1072 | Subject: RE: Aero Savings from Road Frame to TT Frame If you keep the same position on the new TRI bike as you have on your road/TT hybrid as you say you are planning on doing, then the difference will be not be noticeable. Aero position of the rider has more impact then the frame will. A TT/TRI bike is designed to let the rider get into very effective aero position. If you are not comfortable in that position or can not develop as much or more sustainable power, then their will not be any time saved. It may even be negative. Aero helmet, clothing, and aero wheels will be a lower cost way to gain some time. Also improving the engine is the most cost effective way of gaining time. |
| 2010-07-27 8:37 PM in reply to: #3007910 |
| Master 2426 Central Indiana | Subject: RE: Aero Savings from Road Frame to TT Frame running2far - 2010-07-27 2:57 PM The difference between a P2K and P3C is 2.5 secs per KM . That's two TRI frames, throw in a round tubed road bike and I'd say the gains would be much greater. That is 7.5 mins in an Ironman between two Tri Frames. http://forum.slowtwitch.com/gforum.cgi?do=post_view_flat;post=18021... /> Interesting ST thread comparing the 2 Cervello TT (tri) frames. Don't doubt the P3 is more aero, but the 7.5 min advantage over IM bike leg is similar to the 7.3min difference calculated between Tarmac (road) and Transition (TT) in the Bike Radar wind tunnel testing. Those differences are so small it seems to me that they could be lost to minor changes in body position which could happen during an IM ride if rider comfort is sacrificed in the search for the "perfect" aero TT frame. Agree that it would be very interesting to see similar testing of old school round tubed roadie vs newer roadie & TT frames. If the difference was huge I suspect at least one of the major bike makers would have used such a test in their marketing much like wheelmakers (Zipp, others) have done in using the 32-spoke box rim wheel as their baseline. |
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