Hi all,
I’ve found a good deal on a 29er wheelset, which I’m thinking of getting for my cross bike, the only issue is that it has wide ish (21mm internal) rims. I do quite a bit of tyre swapping, so I could be running anything between 28-45c tyres on them. Could running such narrow tyres cause any problems?
Thanks in advance 🙂

You’ll be fine. Currently running some 28c tyres on 27mm external (22mm internal) mtb rims. They’ve a more squared off rather than rounded profile but I can’t say I’ve noticed any difference on the commute.

Rims seem to be getting wider these days

Mavic say

THE RIGHT TYRE WIDTH ON THE RIGHT RIM WIDTH

28s should be fine on a 21mm internal width rim, I’ve not tried it yet but in theory I could go as low as 28c tyres on my 25mm internal width rims on my FatNotFat wheelset.

I’ve always reckoned on tyres 1.5 times the internal rim width as a minimum tyre size. The Mavic table roughly agrees with that I think. External rim width is a different issue.