I currently have a 19mm clincher rear wheel with a wheel cover. I run a 23mm tire (conti pro race3).
Any guesses what would be the time saving in moving to a 23mm wheel, over a 40K TT?
NOTE: I’m not asking if it’s worth the money. I’m just looking to guestimate the time savings. How much I’m willing to pay for those seconds is up to me!
It’s been 20 minutes and Jackmott hasn’t replied yet.
I doesn’t know the answer. I don’t recall if anyone has clear numbers on the drag difference. Perhaps Vince@HED can provide data on the old jets vs the new or something, with 23mm tires on each?
I doesn’t know the answer. I don’t recall if anyone has clear numbers on the drag difference. Perhaps Vince@HED can provide data on the old jets vs the new or something, with 23mm tires on each?
Cool thanks anyway.
What frame?
Oh right… Cervelo P2C. Although after doing some winter bike fits I might go to a P4 if I conclude the fit makes sense… (or this PX nonsense if it exists)
do you mean the time penalty?
you didn’t mention which wheel it is either.
On your rear wheel this is probably not worth worrying about. Put on the 23 and roll.
…it does depend on the frame
and i am not trying to be sarcastic, unfortunately that is true
.
do you mean the time penalty?
Yes.
you didn’t mention which wheel it is either.
It’s a Kinlin XR-300 rim with a wheelbuilder wheel cover.
On your rear wheel this is probably not worth worrying about. Put on the 23 and roll.
The current wheel is 19mm. 23 is where I’m considering moving to.
Hmmm…sorry, I know it’s not what you asked for but on a P2 I’d go the other way…keep what you have and find a narrower low crr rear tyre. Are you thinking of replacing the rear with another (wider) training wheel that’ll be covered, therefore keeping the same shaping of the disc surface area? Going to a wider rim may help slightly with a smoother transition from rim to tyre (ie, reducing the “bulge”), and of course there may be some other spin-offs like rolling resistance, comfort, etc, but from an aero perspective you’re still left with a wider rim/tyre combo on a frame with somewhat average rear wheel coverage.
And what’s a “conti pro race3”? 
Not what you asked again, but either way there are faster tyre options…
Are you thinking of replacing the rear with another (wider) training wheel that’ll be covered, therefore keeping the same shaping of the disc surface area?
Something like that. I’m looking for the fastest setup that would allow the cover to be removed so the wheel w/powertap can be used on my road bike.
And what’s a “conti pro race3”? Not what you asked again, but either way there are faster tyre options…
Doh, sorry. Michelin pro race 3. I thought it was decent? What are you recommending over it?
Doh, sorry. Michelin pro race 3. I thought it was decent? What are you recommending over it?
It’s decent, but there are faster options:
http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf
I have the same bike and wheel as you and have mainly used either a mich pr3 race 23mm or a Bontrager aero TT 19mm.
The PR3 bulges out a bit too much
The Bont. is a very low profile tyre that blends really well with the wheel and disc, but gives quite a jiggly ride on rough roads. I prefer to save it for my hed3 front as those tires are now hard to find and it is one of hte best for a hed3.
I have just got fitted a 23mm conti gp4000s and it seems a good compromise. It bulges less than the PR3, is less jiggly than the Bont. and gives a bit of a better ride with similar rolling resistance to both the other tyres. It also feels like it last longer.
I wouldn’t bother switching to a 23mm rim.
http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf
Hmmm… How much should we trust this data without it being replicated elsewhere?
For example, why sould the “Michelin Pro 3 Race (25)” (which I assume is 25c) test better than the “Michelin Pro 3 Race (23)”
For example, why sould the “Michelin Pro 3 Race (25)” (which I assume is 25c) test better than the “Michelin Pro 3 Race (23)”
!(…/…/images/clear_shim.gif) !(…/…/images/clear_shim.gif) !(…/…/images/clear_shim.gif) !(…/…/images/clear_shim.gif)
Because a wider tire has a lower Crr, all else being equal.
4mm.
Interesting chart, havent seen that before. Here’s a dumb question regarding that data…whats faster: a lower or higher crr? How about that watts per wheel data column? Better to have more watts per whee? Or is that how many watts required to run at a 100 rpm cadence? Thanks
it has been ‘spot checked’ a few times.
http://www.biketechreview.com/tires_old/images/AFM_tire_testing_rev9.pdf
Hmmm… How much should we trust this data without it being replicated elsewhere?
For example, why sould the “Michelin Pro 3 Race (25)” (which I assume is 25c) test better than the “Michelin Pro 3 Race (23)”
Bike tech review used to have a ‘pay-for’ report on “The Importance of Tire Selection”. It focused mainly on they aerodynamic difference between a 20c vs. 25c tire on a Zipp 404 and Hed 3 wheel.