# Crosswind effect on 30-45-52mm rims



## one80 (Feb 22, 2006)

I'm just trying to get an idea on how differently crosswinds would effect 30, 45 and 52mm rims.

I know it's quite subjective, depending on rider skills, weight, wind speed etc, but to give you an idea I'm about 75 kgs (~165 lbs) 171 cm (~5' 7") and we usually get average winds between 19 kph (11 mph) - 35 kph (21 mph). A lot of my riding is through the city, so it gets quite gusty, and the traffic is quite close so you don't have a lot of room to manoeuvre if you're getting blown around which is why I'm a little hesitant about deeper section rims (though they do still appeal).

I'd be using these wheels everyday too - I'd love to get two sets, but unfortunately that's not an option.


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## mimason (Oct 7, 2006)

Deep dish and gusty winds are not a good combo. I've seen a woman get blown off her TT bike from a crosswind gust. If I were you and these were the daily conditions I'd opt for safety and stay low.


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## spade2you (May 12, 2009)

At 175lbs, I wouldn't see you having as many problems as a really light cyclist, but I see minimal point in making most deep dish wheels your every day wheel, especially since you note that you'll be riding with gusts in traffic.


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## MCF (Oct 12, 2006)

I ride 46mm Reynolds Assault wheels everyday and don't notice any issues with crosswind, but that may be due to the fact I am ~200lbs.


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## tom_h (May 6, 2008)

30-35 mm deep rims will not have any significant effect, IME. Bladed vs round spokes will also register a slight cross wind effect.

My riding partners in the 150-170 lb range do not report any ill effects on rims up to 45-50 mm depth.

In any case, you may notice a difference at first, but you will quickly adapt and it will feel "normal" after 2-3 rides.

BTW, if "_a lot of my riding is through the city_,", do you really need deep aero rims that mainly matter at speeds of 25+ MPH? ;-)


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## RussellS (Feb 1, 2010)

I have 41mm deep Shamal and 38mm deep Vento wheelsets. I'm 180 pounds. Every great once in awhile I will feel some affect from strong wind. Just a little. But winds rarely give me any concern with these wheels.


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## one80 (Feb 22, 2006)

tom_h said:


> BTW, if "_a lot of my riding is through the city_,", do you really need deep aero rims that mainly matter at speeds of 25+ MPH? ;-)


If I'm being honest, I'm probably getting my needs and wants mixed up 

When I saw most, I really mean most frequent as I go through the city everyday for work. The bulk of my riding, distance wise, is on the weekend.


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## jmess (Aug 24, 2006)

When I went from 34MM to 46MM I noticed the 46s would get kicked around more with crosswinds. After 10 months and 2500+ miles I have grown use to how they react to wind. My most exciting moment was when I crossed paths with a small dust devil and it knocked me about 3ft off course. I now appreciate how much wind pressure one of these micro tornadoes can generate.


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## KMan (Feb 3, 2004)

My training/winter wheels are Mavic K's with the large bladed spokes.
I also have 50mm carbon wheels and 58mm wheels - both with sapim bladed spokes. I really do not notice any issues with cross winds much if at all. I won't ride these wheels sitting up with no hands on a windy day, but other than that - really can't say I notice much difference. Sure on a really windy/gusty day the front may grab a bit now and again, but as a general statement - no real difference.

Now I gave a new 82mm front wheel I got for using in TT and I expectt that wheel will be a bit more difficult to hanld on windy days....so on a windy day, I will probably just trhow on a 58mm instead.

Michael


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## one80 (Feb 22, 2006)

How much of the wind impact is actually on the wheels ? Would most of it come from my body and the rest of the bike, unless I was running very deep profile rims or discs?


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## spade2you (May 12, 2009)

one80 said:


> How much of the wind impact is actually on the wheels ? Would most of it come from my body and the rest of the bike, unless I was running very deep profile rims or discs?


Depends on rim depth, if the spokes are bladed, wind/gust speed, bike+rider weight.


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## tom_h (May 6, 2008)

one80 said:


> How much of the wind impact is actually on the wheels ? Would most of it come from my body and the rest of the bike, unless I was running very deep profile rims or discs?


Yes, body & bike dominate aerodynamic drag force.

For lab tests of over 50 wheels, read:
http://www.rouesartisanales.com/article-15505311.html

Note the power losses were tested at 50 kph (31 mph). Majority of front wheel losses ranged 19 to 33 watts.

Power losses scale as the 3rd power of speed. 
At 20 mph, the power losses would be only 27% of the losses at 31 mph. 
At 25 mph, losses are 52% of the 31 mph value.


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