I’ve heard lots of talk lately about tri-spoke wheels being slower with some forks and faster with others. Just wondering if anyone could tell me which one of these wheels would work better with the TTX fork and explain why. Thanks. I already have both so it’s an easy switch.
the hed 90mm is a faster wheel to start with so it s a no brainer…
a lot of it depends on the conditions you are riding in. if it is really windy stay away from the tri-spoke. The tri spoke is perfect for little to no wind
well, you just got it wrong. The only case the he3 will outperform the 90mm is at high yaw angle… so until it pass 20 degres yaw, the 90mm is faster. In hurricain wind, the hed 3 become the fastest wheel on the market… so if you can handle it, it will pay big time! To use a hed 3 on calm day is simply not the best thing to do as the wheel dosnt do as well in the 0-15 degres yaw (low wind)
when it s call, or moderate wind day, 90mm is the choice to go with.
Thanks for the great reply jonnyo. could you explain how the whole fork/wheel mesh thing works?
Hed’s published data has the H3 outperforming the Jet 90 just barely at 0’ (a condition you never encounter really), the 90 beats it by a lot at 5 and 10’, but Hed’s data says that by 15’ the H3 is again faster (and it’s not really close). So assume the breakpoint is between 10 - 15’, and figure out what conditions you race in most.
So where are you getting the 20’ breakpoint number from? You have other data?
To compare with other Hed wheels, Hed says the H3 is the fastest non-disk wheel they make in 0’ yaw, and again at 15’ and over.
i was just keeping it simple so everyone understand. The point is mabe 17 degrees… from the graph but the main idea is, a 90mm is a safe choice over the hed 3 in about any condition. I never say the hed 3 at the same level as the hed 90mm at 0 yaw. I have many data, some i will keep for myself or my client but this graph here is pretty reliable. The hed 3 with a narrower tire will be a bit better than this graph but still, the hed 90mm is a wise choice.
I’ll defer to jonnyo on the aero details, but I will say, the fork on the TTX is about the best fork possible for the Hed 3.
The Hed 3 works best with certain forks (particularly the original CarbonAero labelled fork, I believe designed by QR but sold on almost all tri bikes around 2000.) It’s a heavy fork, but tests well with the Hed 3. Seeing how the Discovery Channel team was sponsored by both Hed and Trek, when the TTX was designed and built, consideration was given to the shape of the fork and it’s use with the Hed.3. If you look at your fork and any of the older QR CarbonAero forks, your fork looks very similar.
So the Jet 90 may be faster, I don’t know. But the Hed 3 will be faster on your bike than just about any other.
But it doesn’t LOOK as fast 
jaretj
.
I’m a bit skeptical about the 10º as the common yaw. If my memory doesn’t fail me, I think the common 10-15º of yaw is the average yaw angle measured from few TT courses, so is a bit arbitrary.
I quote John Cobb (http://www.johncobbresearch.com/?p=322)
“I’m very sure about one thing, the wind that you feel is nothing like you think it is and if you average 15-17mph (22-26km/h), you are likely to see 25 -40 degree crosswinds very often. This crosswind at lower speeds is to be expected but I was very suprised at the regularity and length of time of large angle gust."
I live in an ocean side city and very often I wonder: where are the 10º of yaw (almost head wind or tail wind)? Because I feel riding like in a sail position. (I’m a 28-32Km/h rider)