Hypothetically, what kind of time difference would you expect when doing a 10 mile TT between riding your fancy TT bike and your standard road bike? Let say the course was rolling and a bit breezy. Same clothing/helmet. TT:wheel covered 60mm rear, 90mm front, latex tubes, bonty tt front rxl rear, internal cable routing(Felt DA) Road: road bars, easton vista wheels(29mm deep) butyl tubes, conti 4000 chili front, pro3 rear, no clip ons. TT bike ridden first, 25 inutes after finish, road bike ridden. TT 13cm drop, road 10cm drop
I was guessing, based upon being tired, that I was going to go 3-4 minutes slower.
What estimates do you have?? I’ll give the results later, all I will say now, is that I wasn’t happy.
Your saddle is too high. Well, using all of Zipp’s Propaganda data, a disc plus 808 is worth 80 seconds per 40k. So a little less than forty seconds there. A good tri position is worth four minutes over a really hood road position per 40k, so let’s say 1:40. But now, weight: slightly rolling, your disc alone weighs more than the vistas! That should slow you down.
Plus, you probably didn’t go balls-to-the-wall on the first one, because you knew you had another in 30 minutes.
I actually did go all out on the first one. I wasn’t expecting the second to be stellar and was just going to do it because it was only 10 miles and I wanted more of a workout. Power was lower than I wanted, but Ihave had a difficult time maintaining the power I want on rolling courses. Wanted 350(acheived once on a flat smooth course), got 330w which is in line with my individual efforts.
More info, I was on 170s on the TT(new, 2 days) and 172.5 on the road. TT 0cm ahead of bb, road 3cm behind bb
btw, you comepletely left out your rolling resistance calcs
I have been wonderng about a wheel cover however, lately. My annecdotal evidence says that if the headwind is on the non drive side, I am always slower that day compared to a day when it is on the drive side for the same course. Wheel covers are not lenticular, they are triangular, at least on my FP60. time for a wind tunnel test
If I ballparked out of that data, I’d get 7.5 minutes for 40k, conservatively which would be 3:03 for my course today. I guessed 3-4.
bars…3 richey 44 to vt base/clip/brake levers
wheels…2.5 29mm deep to 90 front, wheel cover rear
frame…1.5 litespeed siena to felt da
fork…0.5 reynold ouzo pro to felt bayonet
water bottles…1 round bottle/2 cages to arundel
of course you can’t add them all together like that, as the more you add the less impact it makes.
that link doesn’t count rolling resistance or use of aero tires I was guessing tube/tires alone might be 20 seconds
I haven’t noted any power diff between road and TT earlier inthe year, and since May, I have been on the TT at least 90% of the time.
Conditions might have become 1-2 degrees warmer, but wind was pretty consistent and no front passage.
I also know that anything is just a guess as I didn’t have a PM for the second run.
I think part of the difference was that on the road bike it was easier to take lines through the curves/turns and being jarred less due to pavement cracks. The road ride was noticeably more plush, and i didn’t notice the loose gravel as much.
Part of the problem of always playing with ones bike position, sometimes it works, sometimes, it doesn’t.
I was talking with a fellow afterwards, he coaches as well, he questioned why i make changes so often. What the heck can I say, never satisfied with the status quo.
I won’t be repeating the experiment very often, only a couple of events have both stock and normal categories here(not my naming convention).
Well the results are…
2nd and 7th overall. 94 seconds between them, take out tires and tubes diff, and…
Jack, the DA is apparently quite stiffer. The joint cracks in the first mile of downhill were quite apparent, so much so that I thought i was going to get tossed from the steed. Nust have been a bad line, didn’t notice it at all on teh litespeed.
2nd and 7th overall. 94 seconds between them, take out tires and tubes diff, and…
that's seriously surprising, which makes me think either you're having big power loss on your TT bike or your position on the TT bike is questionable. I've a few guys double up on the 10 milers, one old school and one in full aero, and the difference is almost always more--like in the 2-3 minute range depending, particularly if you did the old school one second.
That was my thought as well, however, I have done flat 10 mile TTs at over 29 mph(generally use 11-13 on cassette). Yesterday(rolling, used full range of cassette 11-23) was 28mph TT, 26.1 road, but I did have the aero lid and skinsuit for both.
This is also why I am questioning the wheel covers as fast as a disk. The wind was again in an unfavorable direction from my recent experience.
Power loss, not that I have noted. If I drop another 1 cm, power drop 20w, go up, nothing. On steep climbs, I generally favor being bent over even on the road bike, such that my forearms are about parallel with the ground
I have doubled up on the TT rig on 10-12 mile TTs, and they are always close zero.(one time faster the second time, one time slow by less than 5 seconds) so maybe it is just how I recover.
I did ride 15 miles warm up yesterday which was adequate for me, including a preride of the course.
Hypothetically, what kind of time difference would you expect when doing a 10 mile TT between riding your fancy TT bike and your standard road bike?
My CdA is 0.100 m^2 lower when comparing full aero mode to Merckx-style. All else being equal, that would equate to approximately a 2 min 41 s difference in a 10 mi TT.
ahem, it seems, in taking off the wheel cover for season, that i have grindy bearings on my PT(for lack of a better term). I also have a slightly high torque offset. It was about 515 when they replaced the torque tube last year, but now is 531(at start of ride it was, at end it was 529) I am taking it over to Saris tomorrow AM for the bearings and will have them check the offset while it is there.
Andy,
On your tests, did you have an aero lid on your head? Did you run same tires and tubes?
Can’t figure out if I have a somewhat less than ideal aero position, or a relatively really good road aero position.
