# 38mm or 50mm Carbon Rims?



## aplitt86 (Apr 6, 2009)

I made the jump to tubulars last year with a pair of Sun Vista Cruiser rims laced to king hubs I had lying around and am hooked. I'm about to build up a new wheelset for this coming season but cannot decide between 38mm or 50mm rims. These will be the chinese carbon rims that can be had for dirt cheap on ebay.

Thoughts?


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## rockdude (Apr 3, 2008)

38mm....


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## aplitt86 (Apr 6, 2009)

Why would you choose 38 over 50? Weight savings?


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## rockdude (Apr 3, 2008)

Weight savings is one reason. There is a great debate over if deep rims are better in sand, snow and muddy. I believe that 38s give you the profile to handle those condition without the extra mass. I guess the answer is I don't see any benefit of real deep dish rim, no aero advantage, but cross winds can be an issue. I have narrowed my wheels to 30-45mm. Keep in mind the trend in Belgium is heading to low profile rims....


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## BeerDrinkingDad (Oct 19, 2008)

personally doubt most would notice the weight diff between a 38 & 50 on a cross course. for my cross wheels, I put more emphasis on stiffness. Much of that can be addressed in the build but "generally speaking" a 50 will be stiffer than a 38 - but the tradeoff will be weight. How much depends on the rim.

also, if you're going to be using these for road racing/crits a 50 will generally have a bigger aero benefit.


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## aplitt86 (Apr 6, 2009)

Thanks for the info guys. Definitely won't be using these for road racing. Looking at some the big name manufacturer's, they are all using 42-46mm rims so I just wasn't sure which way to go, deep or shallow. I guess I could always build another set with alloy tubular for cheaper also.


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## pretender (Sep 18, 2007)

In cross, rotating weight trumps aerodynamics. There might be the occasional situation where a 50mm rim attracts less mud/vegetation, but I think 38mm is plenty deep.


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## TedH (Jan 1, 1970)

I went with the EDGE 2.25's when they existed and am very happy with the shallow depth. Spin up fast, not harsh, and very light. I can't quantify aero advantage/disadvantage, but I noticed sidewinds on the deeper section wheels, so depending on your size, you may or may not like that. I'm 6'4", 185lbs, so not small, but have a personal preference for the shallower wheel in CX.


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## wibly wobly (Apr 23, 2009)

I'm sort of in the same boat. One of the lbs has a pretty good deal on their own carbon wheels and I'm leaning towards a 38 up front and a 50 in the back. Or just getting both 50s. I want to use them on the road for most of the year and save them for dry weather conditions for cross in the fall. I'd like to go a bit deeper for road but, I'd like to stay a bit shallower for cross. Problems, problems.


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## way2go (Jun 10, 2011)

pretender said:


> In cross, rotating weight trumps aerodynamics. There might be the occasional situation where a 50mm rim attracts less mud/vegetation, but I think 38mm is plenty deep.


+1

And 38mm still allows you to go for aluminum rims. More durable I would say, especially for cross purposes...


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## aplitt86 (Apr 6, 2009)

I will probably go with 38mm. I just bought 38mm clinchers for my road bike and these will be race wheels only for cross. I'm only 150lbs so I'm not too worried about durability. Thanks all!


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