Technical FAQ: Pinch flats, non-tubeless road tires set up tubeless, wires in tires
From Velonews.com
By LENNARD ZINN
Pinch flats are ruining my ride aurora. What is causing them? (Besides the pothole I just rode thru.) Seems I’m getting more occurrences since I went to a wider rim (24mm) over the standard 17mm. I would greatly appreciate it if you would weigh in on this “Snake” Bitten ordeal. Could the inner tube fit/size have an effect on the situation? IE: Is a tube sized 17mm-25mm more or less prone to pinching opposed to say a tube sized 23mm-30mm fitted in a 25mm tire?? As it would seem that the smaller size would be more stretched out thus rendering the lining thinner and possibly more prone. Then again, I wonder about the larger size perhaps being more bunched up by not fully forming inside the tire casing rendering it to be more prone to getting that “snake bite”!! Second thought, do pinch flats only/ mostly occur over the spoke hole recess vs the rim bed?? I await your most revered wisdom response on this HORRIBLE ordeal. Thanks, signed waiting for my wife to bring me a 3rd tube…
– Doug
Dear Doug,
First, yes, the wider rim with the same tire will be more prone to pinch flats, because the tire is more flattened out. The top of the tire has less far to go to hit the rim edge on the wider rim than on the narrower rim. Furthermore, the rim wall is sitting under less of the sidewall on the wider rim, so less of the tire and tube comes down to the rim, requiring less force yet to cause the pinch.
Photo by Daniel Llorente on Unsplash
