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Intuitively I think they would, as the rim exerts less force per unit area on the tyre. So could you run a 30mm rim at 2/3 the tyre pressure of a 20mm one?
While we're at it , why are tyre sidewalls - rather than tread thickness - considered so important for pinch protection? Surely it's the tread you land on not the sidewall?
While we're at it , why are tyre sidewalls - rather than tread thickness - considered so important for pinch protection? Surely it's the tread you land on not the sidewall?
this made me giggle. you get a pinch flat when you land and pressure in the tire is not enough to stop the tire pinching the tube between its self and the rim. a stronger side wall help you to run lower pressures as the tire will not depress as much. but just increase your tire pressures and you will be fine
I find running big thick tubes helps.
currently using 2.3-3.0" back and front, weighs a bit more but I'm not racing so I'm not arsed.
Ah watsontony, thought it must be something like that.
I know thicker tubes, no tubes, dual ply etc are meant to help. But what about the rim. Can anyone
comment on my physics above, have I got it all wrong?
Rim width increases volume and may increase contact patch by flattening off the tyre, so you should be able to run a bit less pressure for a similar feel. All things the same though, a wide rim will bottom out on the tyre under a hard landing pretty much the same as a narrower one. It'll suport the tyre better tho so should feel better everywhere apart from short sharp sprints (heavier).
I have tubeless 2.4s at about 20psi on 35mm wide rims and I've still got a few minor dings in them, but overall I like them more than skinny light rims for all-round trail use.
jameso is correct. I believe the OPs physics is flawed. A wider rim won't really "exerts less force per unit area on the tyre", because it is the walls of the rim that pinch the tube, and they wont be any wider on a wider rim, they will just be further apart.
Aah but for the walls to pinch the tube the tyre first had to be squashed flat, using a wider area of rim, didn't it?
Can't argue with experimental results though, that _would_ be bad physics.
I know what you mean, i should've said impact rather than hard landing for clarity. When you pinch flat it's the contact area of the tyre deforming against an edge or a point, the rim size doesn't really affect that, it's just the rigid part of an air chamber that's deforming inward. It's not like piston sizes varying pressure.
So with different rim widths it's only where the rim and the object on the ground that it pinches against actually are that vary, so it'll still flat at times. Maybe just in different places. Anyway, wider rims are great imo, try it out and if there's no change in pinches at least they'll feel better in corners etc )
Makes sense. The sharp bit of trail is far narrower than the rim, so the rim isn't that relevant. Cheers.
The BEST solution for pinch flats is more tyre pressure. Stop running them so soft. And this will really appeal to the ST Massif because its free.
Unfortunately I like to ride fast without being shaken to bits 🙂
If you think St forum is full of cheap stakes I don't know whet you usually hang out!