# Wheels with water drain holes?



## jmess (Aug 24, 2006)

I was checking out my new Shimano 9000 C24 clinchers and noticed a small hole in the side of the wheel. I assume this a drain hole between the carbon fiber shell and the alloy rim?

Click on the image to make it larger.


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## Merc (Oct 9, 2011)

I saw some holes on a set of my Mavic Cosmic Carbones and wondered why they were there. I think I read somewhere where it stated that those holes were to let the catch air to escape while the wheel was in motion.


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## cxwrench (Nov 9, 2004)

Merc said:


> I saw some holes on a set of my Mavic Cosmic Carbones and wondered why they were there. I think I read somewhere where it stated that those holes were to let the catch air to escape while the wheel was in motion.


Nope, they're to let water out. What the hell is 'catch air'? The things people come up with...:skep:


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## Merc (Oct 9, 2011)

cxwrench said:


> Nope, they're to let water out. What the hell is 'catch air'? The things people come up with...:skep:


Cxwrench, I agree with you for that is what I thought too. Common sense would tell you and then I read a review on Bike Radar where they talked about the holes in the rim. Who cares, they are there and I guess they serve a purpose.


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## cxwrench (Nov 9, 2004)

Merc said:


> Cxwrench, I agree with you for that is what I thought too. Common sense would tell you and then I read a review on Bike Radar where they talked about the holes in the rim. Who cares, they are there and I guess they serve a purpose.


Bike Radar actually wrote that? Wow, who's doing their technical writing?


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## coachboyd (Jan 13, 2008)

I could see that working, but there'd have to be a lot of air holes and they could work just like on an air hockey table. The air would glide over the wheels just like a puck on an air hockey table.

Science!!


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## changingleaf (Aug 20, 2009)

Let water out. Water gets in through the spoke holes and the valve hole. Even as tight as the spokes are water can still get in and out. Many rims don't come with drain holes and if you race cyclocross you may hear water splashing around in the rim after you're done washing the bike. A small hole drilled into the rim cavity will allow the water to drain.


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## Kerry Irons (Feb 25, 2002)

Merc said:


> I think I read somewhere where it stated that those holes were to let the catch air to escape while the wheel was in motion.


"Catch air" is a new term to me! Where do you go to catch air? Does it somehow not make sense that even if a wheel was somehow scooping air into the rim that it would be at equilibrium (backpressure) and not need to be "let out"? I'm with cxwrench: The things people come up with..


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## Enoch562 (May 13, 2010)

Letting "catch air" escape would be like "breaking wind"...


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