The recent post about road rims for 29″er tires and off roading brings up an interesting point. How wide a rim do we really need for offroading? Does it have to be at least 24-25mm wide, or can it be less than that, say 20mm wide? Some folks seem to be getting along just fine with narrow rims intended for road bikes. Some folks seem to be clamouring for a rim that’s at least 30mm wide or more.

I remember when the cross country racing rims for 26″ers were all in the neighborhood of 20-25mm wide. It didn’t seem to be a problem, but then again, you couldn’t run really low pressures either. The wider, free style type of rim tended to be a throwback, initially to when mtb rims were all about 28-30mm wide. Then they morphed into disc compatible only rims and got even wider. You certainly can get your big, beefy 26″er tires on a wide footing and run really low pressures with these rims without much risk of rolling a tire off, or pinch flatting.

Now with 29″ers, we seem to be headed towards the really wide end of the spectrum with our rim widths. Of course, heavier weights come along with that. There just doesn’t seem to be many choices for a racing rim yet. Something in the 22-25mm width that’s disc only, without doing the road rim thing. (It seems Salsa is going to be filling in this area soon with a 25mm rim.)

However it may be for your needs in terms of rim width, I’d say what we could really use is a bit larger rim diameter, or something that will make the tires fit a little bit tighter. It seems that most 29″er tire offerings slip onto 622mm bead diameter rims just fine if you only look at them! No effort to put on the tire at all makes me a little leary of running lower pressures in tires that might be blowing off a rim bead at any moment. It just seems like it could be better than it is.

So, you might be okay with narrow rims, or you might be waiting for that beefy, super wide rim to come along, but all of us could use a little help with the tire/rim interface in 29″er-land. It’s just not a good fit, or at least as good as it should be. What do you think?