Rim and tire widths for CX

Especially for light weight issues concerning cyclocross / touring bikes & parts.

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the_marsbar
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by the_marsbar

For my next CX bike I'm going to go all in on tubeless (spent too much time glueing tubulars now). I'm wondering; what happens if I use rims with an inner width of, say, 24.5 mm? I know this will affect the actual tire width, but by how much?

In other words; what rim should I go with if I don't want to exceed the tire width allowed by the UCI? I assume the corresponding rim width would vary across tire manufacturers (and even within).

Maybe we could make this a thread where people post their findings, stating:
1) Rim manufacturer and model.
2) Which tire is mounted (and the tire pressure).
3) A picture of the measured max. tire width.

mattyNorm
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by mattyNorm

I use 24.5 internal width rims on my xc bike so that is probably overkill for cross. I'd say 20mm internal is the widest you need but hey each to their own

by Weenie


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the_marsbar
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by the_marsbar

The reason why I would use wide rims would be that I could use the wheels on my mountain bike during the summer. I can't justify buying expensive rims if they're only used for racing during the winter.

mattr
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by mattr

FWIW the three different tyres my wife uses come up almost bang on 33 on ZTR Crests (21mm internal IIRC)
Vittoria XG/XM 33
Some cheap Conti Cyclocross in 32s (that they don't make any more)
And Schwalbe Racing Ralph 33

mattr
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by mattr

the_marsbar wrote:I can't justify buying expensive rims if they're only used for racing during the winter.
Don't buy expensive rims for cross! Or buy slightly expensive wheels and use them as MTB training wheels during the summer.

(My wife uses the crests as both summer MTB race wheels and winter CX race wheels, for the little CX racing we actually get! But Crests are almost cheap enough to be disposable)

grouk
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by grouk

sorry to be using this topic, I'm in a similar doubts but for tubular.

I have a set of 50mm rims that i use in my road bike, I will buy new set for my road bike and liked to mont that in my cx bike, but I have great doubts, the external diameter is 20mm.

it's possible to ride it in cx bike? i dont do cx competition, so it is only for good rides.

mattr
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by mattr

If you aren't racing, and aren't racing the mega low pressures they do when racing, 20mm wide rims should be fine.

I mean, until recently, everyone ran rims that narrow!

andrewfelix
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by andrewfelix

I used to run 19mm CX specific rims and pinched flatted a lot. I now run 24mm race face MTB wheels with tubeless CX tyres. Night and day difference. Love them.


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andrewfelix
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by andrewfelix

Vitorria XG Pro 33. As you said rim will change the shape of the tire though, so even if you get 30, 32 some rims will make the tire run wider. Are you seriously worried by race officials measuring the width of your tires?


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the_marsbar
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by the_marsbar

They sometimes measure tire widths here, that's why I ask.

mattr
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by mattr

Erm, the last couple of dozen races we've been to they measured everyone in a UCI categories tyres.

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the_marsbar
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by the_marsbar

The point of this thread was to try to get an understanding of the maximum inner rim width one could get away with, while still passing the 33 mm check.

Maybe I will try to mount a CX tire on one of my Mcfk rims and see what happens.

andrewfelix
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by andrewfelix

Yeh fair enough sorry misread the point. Ok I just measured them. 33s came out at 34 on my 24mm MTB rims.


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by Weenie


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F45
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by F45

This confusion could be avoided if manufacturers would publish a simple bead to bead measurement.

Anyway.

WTB Nano 700x40
Rim: XR200
Inner Width: 13mm
Tire width: 35mm

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