Originally Posted by
ThermionicScott
I don't often start threads to be "provocative", but I didn't see a thread for this one yet, and was curious of the C&V Brain Trust's take:
https://janheine.wordpress.com/2019/06/26/myth-18-wide-tires-need-wide-rims
It never would have occurred to me to think of narrow rims pinching tire beads close together as making it more tubular-like, and I'm still working through that concept.
It also seems to me that Keith Bontrager's intent when rolling MA2/MA40's into 26" rims wasn't necessarily to make
narrow MTB rims, just to make
lightweight ones. I'd welcome correction on that one.
I feel like the truth is somewhere in the middle on the rim width thing. Probably would have titled it "Do wide tires really need wide rims?"
I had some Schwalbe Pro CX Pro cyclo-cross tires mounted on narrow rims. All was well until I punctured the FRONT tire. Down I went. the entire tire stayed on the rim. This happened on two different occasions and I went down both times. Fortunately I was riding quite slowly each time. I figured that the risk of a crash in heavy traffic was too great to continue using that combination of 30mm tires on those narrow rims. I replaced those tires with 25mm tires and will put the Schwalbe CX Pro 30mm tires onto wider rims. I will NOT risk a front tire flat throwing me into heavy traffic. YMMV but it's definitely something to consider. What happens if a front tire flats and causes you to spill as you're sprinting through a left turn with oncoming traffic or you spill in some other traffic gap because your front tire flatted and then the front wheel immediately went out from under you? When my CX Pro front tire flatted I went down IMMEDIATELY with no warning at all.
I recommend that if you insist on riding a wide tire on a narrow rim that you take the bike and your pump to a school yard or a quiet parking lot and let most of the air out of the tire and see if you can maintain control on it. I know with the CX Pro tire on the narrow rims I had them on there was immediate loss of control if the front tire flatted or went very soft.
Cheers.