Best Rim Inner Width for XC

[Mikej]

There are plenty of aluminum offset rims.

[tellyho]

I have 22ish internals on my XC bike, running 29x2.35. Works fine. I'm not sold on the necessity of width, especially as wider = heavier. I have 30 internals with my 650x48s on the gravel bike and they're nice but portly.

[Likes2ridefar]

Originally Posted by tellyho

I have 22ish internals on my XC bike, running 29x2.35. Works fine. I'm not sold on the necessity of width, especially as wider = heavier. I have 30 internals with my 650x48s on the gravel bike and they're nice but portly.

My 30mm internal width mtb wheels weigh about the same as my 25mm internal all road wheels. Both are below 1500 grams.

I prefer the wider 30mm on the mtb. When I upgraded to them from 25mm with the same tires they rolled smoother, quieter and had better traction.

[irideti]

Question before I make my decision. Would 2.25 tire be wider when mounted on 30mm inner comparing to 25mm? If so how much. I just want make sure there is enough clearance.

[dddd]

Originally Posted by irideti

Question before I make my decision. Would 2.25 tire be wider when mounted on 30mm inner comparing to 25mm? If so how much. I just want make sure there is enough clearance.

As has been mentioned, the tire width increases with any rim width increase.

Expect just a bit less than half of any rim width increase to be the mounted-tire width increase, perhaps less of an increase at the tread, though depending on the tread cap shape.
The mounted tire will also become very slightly larger in outside diameter (tire height).

[nspace]

It's so hard to say but I suspect the differences is like a couple mm at most, with a slightly rounder profile on the narrower rim.

I remember seeing this from Rene Here's for Humptulips Ridge 2.3" tires:

• Actual width on 20 mm rim (internal): approx. 52 mm
• Actual width on 23 mm rim (internal): approx. 53 mm

[November Dave]

Originally Posted by irideti

Question before I make my decision. Would 2.25 tire be wider when mounted on 30mm inner comparing to 25mm? If so how much. I just want make sure there is enough clearance.

Yes, by somewhere around 2mm. It's about 1mm of extra width and 1/2mm of extra height per 2mm of increased interior rim width.

There's no universal "best." For whatever reason, a ton of world cup xc pros still use 25mm. Most riders using 2.25" to 2.4" tires choose somewhere between 27 and 30mm interior rims. 30mm seems to be the reference standard. I notice no difference at all in going from 28 to 30mm.

Keep in mind that any particular tire in any particular size will be defined by its tread and width (for example, Maxxis Rekon Race 2.25) but will have 2 or 3 compound variants (on a "most grippy" to "fastest" scale) and 2 or 3 casing variants (on a "hardcore downhill" to "supple xc race") with potentially some protection layer variants as well. So your Maxxis Rekon Race 2.25 could be a very very different tire than mine.

Getting somewhere from 28 to 30 will put you in good shape with most tires you'll use in anything broadly defined as xc.

[mickey.d]

2.4 or wider- 30mm rim
It you really like 2.2 -2.3 xc tires(I do), you also like the 25mm rims they sre mounted to. 30mm wide rims and 2.2-2.3” tires is… not
optimal. You will need to change your tire pressure and your riding style, significantly.
Running the same tread, like an Aspen on 25mm id v 30mm ID, to have similar ride characteristics across the tire sizes you need to also change your rim width.

YMMV

[pwgoode]

Anything between 25 - 30 mm should work fine. All of my riding is XC and/or Trail oriented. I currently have rims with 26mm (NOx Teocalli), 27mm (We Are One Factions) and 30mm (WTB i30 alloy). IMO the benefit of rim width has more to do with the specifics of the tire (width, shape, height) than just the width of the tire alone.

[Likes2ridefar]

This btlos configuration with their new 30mm rim is appealing(to me anyways ):

[irideti]

I just placed order for a pair of Light Bicycle AM927. That's 33-27 outter-inner width. I think that's going be a good spec for my current riding style and bike setup. And I can use them for wider tires if I decide to go with different route for my next built. Thanks everyone for the help.

[eippo1]

If you ever think you might run an insert, go with 30mm. It's a struggle still, but just a little bit less of one because you have a little bit more to work with.

[mickey.d]

Originally Posted by eippo1

If you ever think you might run an insert, go with 30mm. It's a struggle still, but just a little bit less of one because you have a little bit more to work with.

This is a great point. The near universal adoption of 2.4” tires on the world cup circuit correlates a lot with why inserts have become near universal at that level as well. A big baloon at optimal pressure for rolling resistance is pretty easy to punch a hole in.

[bigbill]

I have two alloy offset MTB wheel sets, one with WTB I-29s and the other with Astral Serpentine with 32mm ID. I like the wider rim for tire profile which is less lightbulb-like.

[rothwem]

Originally Posted by mickey.d

This is a great point. The near universal adoption of 2.4” tires on the world cup circuit correlates a lot with why inserts have become near universal at that level as well. A big baloon at optimal pressure for rolling resistance is pretty easy to punch a hole in.

I didn't realize inserts were that common in XC racing, I know the downhill scene has pretty much given up on them, but I guess they can run heavier casings that have similar benefits.