I bought H3s and rode them for the first time yesterday. There was such a significant difference from the velocity deep-vs I’ve been riding, that I started going wheel crazy. I was very skeptical in the past about wheels, because I didn’t see how it was possible that there could be such a difference, but there was. So I’m about to buy a disc. I’ve never ridden a disc, but I’ve been told that the fastest set-up for my bike would be a disc rear/h3 front.
I’m doing my first ironman distance race this fall, and it’s on a completely flat, fairly windy course. Is a disc rear/H3 front my fastest set-up, or should I stick with H3s on both front and rear? If it makes a difference, I’m 6’0", 170 pounds, riding a kestrel km40, and hoping to average 20mph over the ironman (which should be a lot easier with these wheels).
Any advice would be appreciated. How much time might I be saving over an ironman by using a disc instead of a H3 rear?
How much time might I be saving over an ironman by using a disc instead of a H3 rear?
I’m a fan of discs and of being aero. But I’ve gotta be honest – the difference is small. In calm conditions, there is likely no measurable difference. In windy conditions, the disc is a little better – maybe a minute over 112?
Now that you’ve got a quality set of wheels, you might have a better return on your money with an aero helmet.
Race wheels definitely make a difference. After my first season of tris I bought a set of H3s and a Renn disc. Besides one training ride to test it out, I’ve never ridden my H3 rear. I race with the H3/disc setup because it is the fastest setup I have. If you get a disc and anticipate riding on a windy course, practice riding with it in the wind. You definitely get blown around a little bit (as you probably do on your H3s), but it isn’t anything you can’t manage (I’m similar height and weight as you).
For my Cdn. customers it’s in my best interest for them to buy discs with a pair of H3C’s, but I believe in for most courses & conditions the H3 rear is a better choice than a disc.
Ultimately the customer buys what ever they want. Based on historical sales in Canada, my company sells many more H3 rears than discs.
I ride the H3/Renn combo as well - it has been good to me. I’ve thought about getting a H3 rear, but after talking with other people, I think I’m going to stick with just the disc. Yes it does weigh a little more, and might catch a little more cross wind (I can’t say that it would be a big difference) but for the majority of time, a disc will do just fine.
The use of a disc is really dependant on wind, more wind, the more advantage the disc offers. Here is a link to aero data from 2 years ago showing some wheels as well as the H3 (listed as dupont3, same wheel) and a disc. You see that at lower wind angles the differences are smaller, but at 15 degrees, the difference is 0.10 lbs of drag which equates to 6 watts energy savings, or about 15-18 seconds per 40k for a pretty average build 5’11" guy making 250 watts, with higher wind like 25 degrees, the difference is even more, but to get wind angles that high you either have to have extremely strong cross-winds, strong cross-winds exactly perpendicular to the rider, or be going very slowly. Real world testing shows that more than 85% of real world riding occurs at less than 20 degrees of yaw.
Now Josh, I love my 303s(only new Zipps I could afford). But I am skeptical that in the majority of wind conditions they are that aerodynamically comparable to a Hed trispoke. Most of the other tests I’ve seen put a H3 in the field of the 404/808.
The Tour tests from 05 and 06 had a 404 rimmed wheel as runner up to the 808 one year and a H3 winning the next, the numbers for the two wheels(Ritchey WCS Carbon and Hed3) on different years were very similar. I do believe they kept protocal as close as possible.
Do you feel your tests better represent the interaction of the H3 with fork blades, which would explain worse numbers?
Josh has the numbers basically correct when looking at non-Zipp data as well. The difference between a disc and an H3 is fairly minimal at 0-10 degrees, and at best about 0.1lb different at 30mph. This translates down to something like 110 seconds on a 20mph average IM bike.
If you were competing for the win in a race I would say yes, go for it. But averaging 20mph at IMFL won’t get you anywhere close to a win, so the 1.8 minutes of placement is not likely to be worth the investment. It comes out to something like $250 per minute saved…and that’s with a relatively cheap Renn 575!
The Tour tests are very well done and are essentially very repeatable, and if you overlay the data (which according to Tour has been fully normalized to account for atmospheric differences, so generally we don’t compare multiple tests, but for sake of argument…) you see that the top two are the 808 and RitcheyWCS, followed by H3 and then Easton and Vuelta, also using prev. gen 404 rims, so you can see the difference that hubs and spokes make, but remember that this is the previous generation 404 rim, which you can see in the white paper posted earlier is a fair bit slower than the new version, which is essentially comparable to the H3. Also, the Tour test was done with 20mm tires, which favor the H3 over our rim shapes as we design for use with 21-22mm tires, so there is no penalty for using narrower tires, but with a wheel like the H3, you pretty much have to use a 19-20mm tire to get the real benefit as performance begins to decline rapidly with wider tires. While our testing is done with 21mm tires as we feel that is really an ideal real world tire size for most people, plus availability is good and they are reasonably puncture resistant, so with 21mm tires you see that the 2004 303 is very comparable to teh H3, and as soon as I have time to get the newer data posted you will see that the new 303 is about 10% better than the old and darn near as fast as the 2004 404. Basically the old 303 was very similar in performance to the H3 if both had 21mm tires, the new 303 is nearly equivalent to the H3 if the H3 has a 20mm tire and the 303 has 21mm, for low yaw angles of course, at the high yaw angles the H3 has so much surface area that it is hard to beat…but those are outlying conditions in the real world. And none of these tests were done with forks, so the boundary layer interference and pressure wave effects of a 3 or 4 spoke wheel in a fork show up in this data.
Here is a graph overlaying the two data sets which was posted on weightweenies:
Thanks Josh for the detailed andswer and the graph. I had seen the numbers from the two tests but that graph really helps visualize the difference, and non-difference(from Shimano Carbons to about Lightweight obermeyers seems to be a wash at 40km/hr) of all the aero wheels.
Considering the amount of Xentis that were on womens wheels at Worlds, they are quite low on the list.
One point here, independent data shows that wide vs narrow tires does NOT specifically favor the H3 vs 404. It shows both performing equally bad with a wide tire and the 404 actually performing better than the H3 with the 20mm tire. It’s within the measurement error, so it’s hard to make a specific claim one way or another.
Either way, it is clear that aerodynamically a 20mm is a far better choice for either wheel, but for a rear wheel the additional RR consumes a few more watts than the reduction in forward drag. Something like 2W of change for the narrower tire vs maybe 5W of higher RR. Not worth it for the heavily loaded rear tire, but probably a wash for the front. At higher speeds or wind speeds the 20mm is definitely an advantage in the front.
That’s because in my experience velocity dep v’s are the crappiest wheels outside Wal-mart. I couldn’t believe the improvement I felt when I went from those POSs to my Heds. I bought some Ksyriums to train on and I will never buy a velocity product ever again.
A disk won’t give you phenomenal changes like going fro mvelocity to Heds. If you have the money though, why not?
I agree about the velocity deep-vs. They are supposed to be semi-aero wheels, but I think I would have been faster all along with just an average training tire. I ordered a hed disc and it comes today. I’ll take every minute I can get. I may end up selling my H3 rear, but I’m not sure yet.
I forgot to add earlier that Tour magazine also had a Mavic Comete disc wheel in the testing which was not placed in the graph as it was only for reference and it baselined at 1 watt ~4 seconds per 40k faster than the 808. So pretty much like everybody was saying above it is faster, but by a relatively small amount when compared to the fastest non-discs.
I’m not sure what wind data points they are using to get the data in the graph above, or if they are using an average of a couple of yaw angles, but just using an average drag from 0-20 degrees, the 303’s would be in the top 6. Although I personally would always go for the 404’s over 303’s for Tri as they are more comforable, faster, and only about 100 grams heavier for the set, 303 depth wheels are really more for road racing where you are willing to give up a little aero performance for weight and acceleration purposes, but weight/acceleration are really only important strategically during maximum effort climbing or attacking.
Not to spoil the fun, but as an owner of a KM40 I was always under the impression that there is little (if any) benefit to a disc. Due to the lack of seat-tube the H3 will be just as fast.
Of course I could be wrong, but as my wife knows- not likely
It shows both performing equally bad with a wide tire and the 404 …
FWIW…my trials comparing a 404 with a narrow (20?) brand T tubular versus an 808 with a 23mm brand M clincher provided two results with a high degree of confidence: (1) The tubulars had a vastly higher rolling resistance. (2) The 404 with the narrow tire had better aerodynamics than the 808 with the wider tire, in calm conditions.
Net, net…the 808 w/clincher was very much faster. Still, I was a little surprised by the aero result.
