The fastest TT tire in the world

Triathlon Forum
1

I saw the link with claims about the bontrager winged tire:
http://reviews.roadbikereview.com/blog/say-hello-to-the-worlds-fastest-tire/

The relevant information is:

http://i42.tinypic.com/k3lvlf.jpghttp://i42.tinypic.com/2r5xqxh.jpg

http://i42.tinypic.com/314cmk9.jpg

Very interesting to see that at low windspeeds (15 mph), where Crr would be dominant - that the
bontrager tests so close to the veloflex record. (Care to comment on that Al? Tom?)
I find that interesting, to say the least.

I talked to HED, and they said that their aero charts for the H3 clincher were produced with the Bonty TT tire above. And that they observed about a 20 gram differential over the Mich 23. Bontrager seems to see more than double that from
the chart above.

I understand that a great tire can make a wheel great … but it is hard for me to believe at 30 mph, there is a 50
gram differential (or about 5 1/2 watts) due mostly to the “wing” (I guess - or some mysterious Cd shape problem) over the veloflex - which starts out about the same.

And with regards to the other tires - all the other non-winged tires seem to maintain a consistent gap at higher speeds (!!!)…which is strange, since you’d think the advantage of the wing would come into play. ( assuming rolling resistance is similar from 15 - 30 mph). But the veloflex loses out. What gives the velo the special property that it gets worst at higher speeds, relative to the bonty, but the others do not. That is curious.

So, what does this graph tell us?

It says that a winged tire vs non-veloflex non-winged tires stay relatively consistent in drags of gram differential.

It says that a winged tire vs a veloflex tire wins (e.g. something unique to the veloflex makes it’s drag rise much higher
as speed increases, unlike the other tires).

It says the veloflex Crr is about the same as the Bontrager.

It says - given that HED ran their tests with this tire with the H3 – that if you aren’t using a winged TT tire with that
wheel, you are going to lose BIG time watts… making an H3 + any other tire a pretty lousy choice.

And perhaps - one might think - that maybe if one smears some silicon in the groove between the tire/rim of a veloflex, one will get 5 1/2 W - if that is it’s issue.

I am just so confused.

Dave Linenberg

2

i’m also curious if these wings are optimized for the tordial wing shape of hed/zipp wheels as opposed to standard wheel shaped.

In any case it does not say if that Veloflex is a Record, Carbon, Servizio, critirum or even a tubuar at all.

3

If it is comparing clincher to clincher - Veloflex makes: the master, the corsa and the record in 20 mm.
(At least that is what google comes up for me with a fairly non-thorough search)
I had just assumed that the veloflex they are comparing was the record, since it is most often mentioned as a fast tire… specifically for race day time-trial like events*.*

Dave Linenberg

4

the fit (in the real world) isn’t EXACTLY like the little drawing:

http://farm4.static.flickr.com/3357/3333976260_01d9c50ee2_b.jpg

and a 50+post conversation re: this tire- http://wattagetraining.com/forum/viewtopic.php?f=2&t=115

g
.

5

wow, that is a bad fit. i think it is safe to say that the ‘wings’ are so small as to be ineffective and totally insignificant.

6

thats terrible, lol
.

7

What are you talking about!!! It looks just like the marketers…er I mean, the artist rendition of the tire! :wink:
M~

8

What rim is the Bonty tire on in your picture?

9

FWIW, the above photo is a 19mm tire on a campagnolo shamal (19mm rim).

I also have the 23mm on the rear (19mm rim).

g

10

for what its worth I run these tires on my training wheels and they have been great as far as durability and ride quality, have ridden them fast in the rain even and they seem to stick well. I can’t speak to the aero part cause I don’t really know…the skinny one I have (19) though was a bare to get on, shoul’dve run 21’s on both front and back…found out later that was actually more aero, but who cares for training purposes.

11

Can we see the whole label on the tire? Or a side profile?

12

shoul’dve run 21’s on both front and back…found out later that was actually more aero, but who cares for training purposes.

Really? Where was that info? Thanks!

13

Kinda hard to see, but this is the best I have:

http://farm4.static.flickr.com/3547/3333962388_e692e23621_b.jpg

g
.

14

“wow, that is a bad fit. i think it is safe to say that the ‘wings’ are so small as to be ineffective and totally insignificant.”

I can tell you the fit on my Hed Alps, which are designed around the same rim and structure as the H3s, looks MUCH better than that. I’ll try to photo and post later. That pic looks like the TTs did on my Mavic CXP-33 rim, which has a larger rim bead than the Heds. I think the rim edge radius is different from Heds too.

15

those photos are making me think that the tire’s <19mm width has a lot more to do with it’s aeroness than anything else.

Then again, maybe the 'B’s stamped into the tread are the ‘new dimples’?

That chart certainly asks more questions than it answers, that’s for sure. I do think the ‘in a 10 MPH headwind’ part certainly maximizes to the extreme any differences in ‘aeroness’, and is a pretty disingenuous way to present the data.

16

the Bontrager logos are probably “bimples”. wind tunnel test prove a “b” to be more aero than a “d”.

17

the fit (in the real world) isn’t EXACTLY like the little drawing:

http://farm4.static.flickr.com/3357/3333976260_01d9c50ee2_b.jpg

and a 50+post conversation re: this tire- http://wattagetraining.com/...ic.php?f=2&t=115

g

Something’s definitely “odd” about that interface on your rim…the ones I have mounted on both the Forte Titan rims and the Hed Jet90 rims (narrow) are MUCH more flush with the brake track. That above almost looks like you didn’t get the wings to “pop out” over the rim edge…but it looks like you can see the bottom of the wing edge, so that implies that the Campy bead section is a bit thick.

Now then, one other thing about that tire that catches my eye is that they fill in the rim/tire gap, but then create a “step” where the tread portion meets the sidewall…hmmmm…I wonder if that acts as a “boundary layer trip” of some sort…

18

Tom, how does this jive with the table you made a year ago where the rxls were faster until 35mph?

Thanks,
Dan
www.aiatriathlon.com

19

Tom, how does this jive with the table you made a year ago where the rxls were faster until 35mph?

Thanks,
Dan
www.aiatriathlon.com

Greg linked to the recent discussion on the wattagetraining.com forum where I updated that figure with the most recent Crr data on the “light” aero TTs…

And, I don’t recall the “crossover point” ever being quite that high…

20

I talked to HED, and they said that their aero charts for the H3 clincher were produced with the Bonty TT tire above. And that they observed about a 20 gram differential over the Mich 23.

I remember reading that somewhere as well. So, it seems interesting that Hed claims the H3 has the same drag in both tubular and clincher form. Hmmm…

I wonder if the data from the various Zipp clinchers on Hed’s site are with the Bonty aero tires?