Because I myself did my first IM on a road bike and have known others who have done that distance from poor positions on road bikes years ago to the latest (P3 for myself) example. For a 6.5 bike for 112 they could drop 40 minutes to a 5:50 with same power. Maybe I am an idiot, but I have never seen anyone drop anywhere close to that time soley on that, my self included…2 mph is freaking huge and my example is going from 17.5 mph. Now going from 21 to 23mph is even bigger… Again I have seen it touted on drag numbers that going from hoods to drops gets you 1mph,. I do not see a constant variance in speed by going from hoods to drops to hoods ect…
Now I see I am going to get flamed here. Thats ok. Guess many have seen 2mph changes with same power in field tests, if you have, I will not say your wrong but I have never seen it
Well I can see that many are disagreeing with me…So be it. …So no reason to argue the point. I do know this. On long course going from raod to P3, i did not come close and people I bike with did not see it either. +1mph sure…
There are any number of reasons one could either not realize the 2mph benefit, or think they didn’t.
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if you have a super super aero road bike position and you hold it the whole way, then the TT position will not be that much better.
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You don’t have a good position on your TT bike
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you don’t stay in the aerobars on your TT bike
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power output changed
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wind was different one year to the next.
It isn’t that often that someone will go from a road bike to a great TT position that they can hold for 112 miles. That usually takes time to develop. Ironman is a hell of a thing.
Because I myself did my first IM on a road bike and have known others who have done that distance from poor positions on road bikes years ago to the latest (P3 for myself) example. For a 6.5 bike for 112 they could drop 40 minutes to a 5:50 with same power. Maybe I am an idiot, but I have never seen anyone drop anywhere close to that time soley on that, my self included…2 mph is freaking huge and my example is going from 17.5 mph. Now going from 21 to 23mph is even bigger… Again I have seen it touted on drag numbers that going from hoods to drops gets you 1mph,. I do not see a constant variance in speed by going from hoods to drops to hoods ect…
Now I see I am going to get flamed here. Thats ok. Guess many have seen 2mph changes with same power in field tests, if you have, I will not say your wrong but I have never seen it
Thanks for the link. I have seen this stuff and it must be accurate in the perfect conditions they get. However when I worked in a shop and a guy came in and got a new bike I never saw anyone gain 2mph in there avg rides. As in a guys avg training rides were 20 then gets new bike, change of position and he suddenly average 2mph consistantly. Seen gains yes, but not 2mph+. Is it out there, probably. But as I posted I am going to get flamed on this one and thats ok…
So again, I do not see some one 40 minutes on an IM on soley bike change…though I know most on here are going to say I am an idiot…I am ok with that
Kenney, I don’t think you are an idiot =)
Thanks for the link. I have seen this stuff and it must be accurate in the perfect conditions they get. However when I worked in a shop and a guy came in and got a new bike I never saw anyone gain 2mph in there avg rides. As in a guys avg training rides were 20 then gets new bike, change of position and he suddenly average 2mph consistantly. Seen gains yes, but not 2mph+. Is it out there, probably. But as I posted I am going to get flamed on this one and thats ok…
So again, I do not see some one 40 minutes on an IM on soley bike change…though I know most on here are going to say I am an idiot…I am ok with that
Thanks Jack…I will say that I respect all things aero from you and if I had a position question or needed other aero data you would be the first I would ask
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Thanks Jack…I will say that I respect all things aero from you and if I had a position question or needed other aero data you would be the first I would ask
Don’t ask me first, maybe 10th
I can refer you though.
A friend of mine recently made the switch and the average gain over a test course with the same average power and same conditions was just slightly under 3kph at ~260watts. The course is a low degree climb to the mid point then a descent on exactly the slope.
Same training wheels, clothing, helmet and conditions (temp and wind). Only difference is the bike:
Interval 1:
Duration: 15:05
Distance: 5.674 mi
Min Max Avg
Power: 93 389 295 watts
Cadence: 68 113 87 rpm
Speed: 11.2 31.4 22.6 mph
Interval 1:
Duration: 13:19
Distance: 5.669 mi
Min Max Avg
Power: 145 373 288 watts
Cadence: 54 156 95 rpm
Speed: 13.4 34.1 25.6 mph
Actual power is about the same, since the TT bike is measured at the hub. I was doing out and back intervals, and the speed differential was the same each way, so wind conditions were very close. Over 40K that ends up being about 7 minutes. And keep in mind, I can’t even stay in the position for this entire interval due to turns and traffic. If you aren’t getting a huge difference due to switching to a TT bike, it’s probably because your TT position is pretty bad.
I’ll pile on:
There’s a 1.7 mile flatish loop that i regularly ride both roadie (Giant TCR Composite) and TT (Cervelo P2) on. I wear all the same stuff, etc…etc…etc… and I’ve done this loop on probably 60-70+ times in the last 3 years, if not more.
Today for example (60 degrees F), doing my typical 180-200w ride, I averaged 19.5 mph on the road bike. This # was in the 18’s over the winter and will get into the low 20’s on a hot day in the summer with the same watts.
The same ride on my TT bike, same watts, consistently produces just under 21 mph. Right around 20 mph in the winter, and sometimes tickling 22 in the summer heat.
I’ve seen it over and over and over again. The only reason why my difference is probably closer to 1.5 mph is probably due to my habit of doing my road bike rides in a more aggressive than “normal” position.
There’s one more thing to consider.
Little local sprint tri? Do you care about your results in such a race? I know I wouldn’t. I would not take my tri superbike with race wheels, or my best wetsuit, to a little local tri. Not worth risking damaging or losing expensive bit of kit.
Use an old road bike / training bike.
2mph…bull…You are always posting things like that Jack and its just not true. Yeas you may find some really far extremes to compare but just not true. I know, I know you are going to pull drag numbers out and refer to analytical cycling. Funny though, in over 20 years in real world I have never seen anyone come close to 2mph by changing positions and bike…Hell just from going from hoods to drops I should go 1mph faster without pedaling.
I would like to see someone post a 7 minute change in a 40k just from position and same power.
I’ve fit about 300 folks to aerobars from road bikes and I always find between 1-3 mph. If anything, Jack was too conservative.
Thanks for the link. I have seen this stuff and it must be accurate in the perfect conditions they get. However when I worked in a shop and a guy came in and got a new bike I never saw anyone gain 2mph in there avg rides. As in a guys avg training rides were 20 then gets new bike, change of position and he suddenly average 2mph consistantly. Seen gains yes, but not 2mph+. Is it out there, probably. But as I posted I am going to get flamed on this one and thats ok…
So again, I do not see some one 40 minutes on an IM on soley bike change…though I know most on here are going to say I am an idiot…I am ok with that
Clarifying, mine was 17.3 to 19.9 but only a long sprint. Dif course too. I also trained a lot more but comparing my avg solo road rides to ths tri, it was a solid 1.5 faster. The only dif was position. Because I lost a tire, my times were screwy. I’m basing it on actual ride time.
FWIW
Dave,
I think you and Jack are right about this. My personal data isn’t an exact comparison, but on a rolling course on C59 with Reynolds Assaults, I’ll do about 21 mph on a good day for a 2 hour ride. On a flat TT, using a Transition, with skinsuit, pointy hat, 808s and a wheelcover, I’m in the 24.7 range for an hour.
Try using this calculator:
http://bikecalculator.com/veloUS.html
There is also a 6 section calculator on anouther page.
If you really want to get into the weeds about it:
I see I am getting hammered here. …Here is the thing. I have been around for awhile and worked at a shop. When guys have gotten a new bike there is always these power numbers and data that lines up with what you a and Jack said (remember I am only disagreeing from 2mph to 3mph). It always seems that from that data this is correct. However when they do their first race it just does not seem the case. Ironman distance would be 50 to 60 minute difference. Half 25-30 minute difference. I have not seen their times drop that much just by getting a road to tt.
Also the guy thats been showing up on the sat morn ride and barely keeping up just is not way ahead waiting for us.
I really do not know how to reconcile that, just in my experiance seems to be the case. Recently had a guy that rides with us who has been on a pretty upright road bike with a long headtube. He is now fit very well on a P3. He is not riding 3 miles per hr faster when out with a ride with us, though he claims his power number show a 3mph speed advantage.
Really do not know what to say for everyone seems to be proving that I am way off base. …Again the guys I see when getting a new bike are just not going out on the group rides and going from hanging on to us waiting for them.
This is my last on the subject for it seems I will just be pointed to analytical cycling for drag numbers ect…
Lets put some hard numbers to this.
List all the guys you can think of who you have seen do an ironman on a road bike, and then a TT bike and when they switched. Then we dig up which races and see how their times changed.
As for the guy in the group ride - you aren’t really
I see I am getting hammered here. …Here is the thing. I have been around for awhile and worked at a shop. When guys have gotten a new bike there is always these power numbers and data that lines up with what you a and Jack said (remember I am only disagreeing from 2mph to 3mph). It always seems that from that data this is correct. However when they do their first race it just does not seem the case. Ironman distance would be 50 to 60 minute difference. Half 25-30 minute difference. I have not seen their times drop that much just by getting a road to tt.
Also the guy thats been showing up on the sat morn ride and barely keeping up just is not way ahead waiting for us.
I really do not know how to reconcile that, just in my experiance seems to be the case. Recently had a guy that rides with us who has been on a pretty upright road bike with a long headtube. He is now fit very well on a P3. He is not riding 3 miles per hr faster when out with a ride with us, though he claims his power number show a 3mph speed advantage.
Really do not know what to say for everyone seems to be proving that I am way off base. …Again the guys I see when getting a new bike are just not going out on the group rides and going from hanging on to us waiting for them.
This is my last on the subject for it seems I will just be pointed to analytical cycling for drag numbers ect…
Dude the first person is me. I gained 15 minutes. Jack, I agree that there are good improvements to be gained. I disagree with the 2-3mph like its the average. Again, just recently the guy who went to a P3 when going out on a training ride is not suddenly waiting for us but he claims his power numbers prove a 3+ mph gain. I do not know how to explain that and I am not willing to call him a liar. …but he is not suddenly waiting for us on a 40 mile training ride
What you describe sounds to me like people with bad TT bike fits. I get plenty of folks coming to me dismayed that they bought a shiny new P3 and don’t go much, if any faster. Take them through the FIST process in a competent manner, and everything comes together.
Jack to legitmitly do that i will have to post pics of their before postion to their new one. Then would have to show comparable conditions. Do not know how to do that on the internet. You can believe me or not. But I have seen guys riding in the 17 mph range on road bikes (= to a 6:30 im) and got to a tt bike with a good postion and going out on training rides with them, the are not suddenly in the 20+mph range riding away from us(5:35im). …Don’t know what else to say
I will just fold it up here and let you guys show the data of how i am wrong…