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Discussion Starter · #1 ·
I'm doing a short (9 mile) TT this weekend and winds are predicted at 22 mph. Interested in thoughts from those with more experience as to if these winds present a control problem The race is in a park (never been on the course before) and I'm guessing it will be somewhat protected by trees. Only been using a disc wheel for two years and have never raced it with more that about 8-10 mph winds. My other choice is a HED three spoke. For background I'm 58 and do about 10 TT's a year and have been for about the last 4 years. thanks for your thoughts.
 

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I did a TT recently with similar winds - brief crosswind, then headwind out and tailwind back. I don't think anyone used a disc for it, and keeping things under control in the crosswind wasn't the easiest for me on 606s (admittedly which I had never used before on the second time on a TT bike).

With the park though, it could cause the wind to come from different directions, and at least for me rolling along and then getting hit by a crosswind with a disc is not a pretty option.
 

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The HED website has some tools for this. Take a look at their yaw calculator and then read up what they say about their disc and tri spoke wheels.

Obviously, its a commercial website, so you need to take their advice with a grain of salt and the more important issue is going to be whether or not you can control the bike.
 

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Discussion Starter · #6 ·
Thanks. I thought that would be the general opinoin but wanted to hear it from others. Thanks again.
 

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ok

megmarc said:
I'm doing a short (9 mile) TT this weekend and winds are predicted at 22 mph. Interested in thoughts from those with more experience as to if these winds present a control problem The race is in a park (never been on the course before) and I'm guessing it will be somewhat protected by trees. Only been using a disc wheel for two years and have never raced it with more that about 8-10 mph winds. My other choice is a HED three spoke. For background I'm 58 and do about 10 TT's a year and have been for about the last 4 years. thanks for your thoughts.
I've ridden my Cervelo with 909 and 808 out in the Mojave desert with winds much worse than that, including 55 mph descents in cross winds. It can keep your attention, but it's managable. Just pay attention.
 

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I raced in similar winds, gusts to 25+ at the Ft. Desoto TT in Florida last month. I used my trispokes front and rear and didn't have any problems with the rear in the crosswinds, but the front can be a handful if a gust catches you the right way. I was in the minority, as most racers had a disk on the rear. In hindsight, I would probably have been more comfortable using the disk in the rear and something with a smaller profile, like a Zipp 303, on the front.
 

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The winder it is the deeper you should go and the more rim depth make a difference. I've said and will continue to say that anyone who uses the "crosswind" argument isn't used to crosswinds, doesn't own a deep set of wheels, or just parrots what they read on the internet.

I live in the 3rd windest city in america and own 1(one) set of wheels that are not aero/deep. Our monthly summer series started last mosth and we always have at least one TT for a series monthly. That day we had 25 sustained and 30+ gusts. I ran a 900 rear and 68mm deep front wheel. All of my teammates ran a disc as well and at least a 60mm front wheel. The 2 lightest guys ran a 1080 front and an 808 front. No one had handling problems. Our daily average windspeed in 2008 was 15.1 mph and we had less than 15 days without any measurable wind. It's stupid windy here.

The greater the yaw angle the more aerodynamics matters. Couple that with increased velocity and it becomes really important. Additionally, it's only 9 miles which, hopefully, is <20 min for you. Moreover, the shape of the rim matters much more than the depth as it relate to the effect of crosswinds on a wheel. My Ksyriums are way worse in cross winds (because of the spokes) than my edge or two zipp front wheels. It's shape and size, not just size. Aerodynamics is a game of frontal area and shape. A brick is aero at 0º yaw, ask an R3 :lol:. No frontal area + bad shape = high drag at high yaw. Ask an Orbea Ordu or the Transition.

Run as deep as you can afford.

Starnut
 

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I ran Zipp disk, HED tri spoke in a 16 mi TT in Boulder yesterday. When I did the ITT the cross wind had me using half my energy just to keep the bike upright and in a straight line. I agree that it is the fastest combo but I was just praying to not hit the deck at that speed. This is the first year I have used a disk so maybe it just takes getting used to. That and I'm only 140 lbs. Rode the TTT an hour or so later and the cross wind was not near as bad, felt very manageable
Perhaps it is the tri spoke and not he disk, that caused the problems?? Only othe aero spoke wheels are Edge 38's. Maybe I should look at getting some 66's.?
 

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Discussion Starter · #13 ·
A report back from my race. The winds were in fact 22 mph but did not seem to be too gusty. The course had numerous turns so we were constantly changing directions and encountered regular cross winds. The road was little traveled and incredibly flat and smooth. The last 1/4 distance was either directly into the wind or into a strong cross wind.

I chickened out and used the HED 3 on the front and back. Most people used a disk on the back and reportedly only had minor problems with control. Based on what I experienced and what I have read here, I would defintley go with the disk on the back next time, but might go with with a little smaller profile on the front as I (and everyone else in talking afterwards) really fought to keep it straight. Thanks for all your thoughts.
 

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Here in Kansas I gave up using deep dish wheels period.

Friday....30mph straight winds.
Saturday.....36mph straight winds
Sunday.......37mph straight winds with gusts to 50mph.

Bombing a hill at 45mph with deep dish in a crosswind at almost 40mph is sketchy at the least. Keep in mind this is Kansas we don't have trees, the farmers cut those all down. That wind is wicked coming off the feilds.

I'm not sure I agree with StarNut's assesment off deep rims.
 

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front/rear

heathb said:
Here in Kansas I gave up using deep dish wheels period.

Friday....30mph straight winds.
Saturday.....36mph straight winds
Sunday.......37mph straight winds with gusts to 50mph.

Bombing a hill at 45mph with deep dish in a crosswind at almost 40mph is sketchy at the least. Keep in mind this is Kansas we don't have trees, the farmers cut those all down. That wind is wicked coming off the feilds.

I'm not sure I agree with StarNut's assesment off deep rims.
My understanding, and experience, is that running a full disk in the rear causes very little problem. The front is far more important, because a cross wind hitting it actually steers and upsets the balance of the bike. The rear is more like a sail, and actually gives you thrust in a cross wind.

Also, I read somewhere, and sorry I can't find it, that running a rear disk actually helps in a cross wind, having something to do with the "center of pressure" of the wind on the bike.

Also, a little nit, not sure there is such a term as a "deep dish" wheel. There are "deep section" wheels. "Dish" is the relative offset of the rear spokes for drive line clearance. Of course, there is "deep dish pizza" ... ;-)
 

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heathb said:
Here in Kansas I gave up using deep dish wheels period.

Friday....30mph straight winds.
Saturday.....36mph straight winds
Sunday.......37mph straight winds with gusts to 50mph.

Bombing a hill at 45mph with deep dish in a crosswind at almost 40mph is sketchy at the least. Keep in mind this is Kansas we don't have trees, the farmers cut those all down. That wind is wicked coming off the feilds.

I'm not sure I agree with StarNut's assesment off deep rims.

3 hours south of you... same wind or more (oftern more, actually) that you guys get. I disagree with your disagreement.

I still say it's the rider not the wheels and wind that makes it sketch.


Starnut
 
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