Best Rim Inner Width for XC

[irideti]

I've been running 2.25 tires on my hardtail for decades but might try 2.40 in the future. What's the optimal inner width for these tires? I just had spokes cut off on my old wheelset since the rear Stans Crest Mk3 have crack around nipples. These rims have 23mm inner with. I'm planning to reuse those lovely CK hubs. My wheel builder told me to get a wider inner since wider 'pinches' tire less for more optimal shape. Should I go for 24, 25 or even wider inner?

I know this forum loves BTLOS but I'm still debating between BTLOS and Lightbicycle.

[Buzz Killington]

30mm

[dddd]

Are you regularly testing the limits of your current setup's pinching tendencies?

If not, then the width change might be little more than theoretical and debatable.

Do you ride in low-traction regions having hard-pack surfaces covered with loose soil? I do myself, and for my riding I prefer a wider rim to spread out the tread cap flatter, since I can't lean aggressively on the slippery surfaces.
At low pressure, the flatter tread cap gets pulled under the rim (in a favorable way) under cornering loads and off-camber surfaces anyway.

At some point, a much-wider rim will increase pinching tendencies (from my own limited experience using very wide rims with 2.3 and 2.4" tires), but you seem to be homing in on a narrower range of much narrower rim widths than I've used.

Carbon rims will allow you to increase rim width and depth at little cost in added weight, so some modest increase in rim width makes sense to me.

For XC racing, take note of what other XC riders are using in your geographical area.

[yarbsr02]

2nd vote for 30mm

[EB]

28 to 30mm.

[Jaybee]

My XC bike has a set of 25mm wide alloy rims and some 30mm carbons. Maybe placebo, but for the same tires in widths from 2.25 to 2.4, the sidewall support through corners and grip feels much more secure on the wider rims. The 25s are fine and I can't remember the last time I pinched, but the 30s are just more fun.

[catchourbreath]

29mm ID on 2.4s riding NYC area trails feels pretty supported and haven't had any problems

[irideti]

Is 2.25 tire going be much wider on 30mm inner? Or a non-issue for MTB since tire is already much wider than the rim. I'm concerning about clearance.

[Rev Bob Dobbs]

29-30mm. I write 29mm because Enve M5’s (which I ride and race) spec as 29mm. With that said, 30mm historically is my preferred width. However, I don’t think 1mm makes a difference.