wider rims --> more sidewall flats?

Discuss light weight issues concerning road bikes & parts.
carpetrunner
Posts: 6
Joined: Sun Oct 02, 2011 2:45 am

by carpetrunner

This is only n=2... so probs not statistically significant but here goes anyway;

I'm noticing a few more sidewall failures with wider rims than I had with the old-school thin rims.

I'm thinking that maybe wider rims are exposing more of the sidewall to road debris than before?

Anyone else noticing this?

- Carpetrunner

by Weenie


bm0p700f
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by bm0p700f

no have not had that problem

tomycs
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Joined: Tue Mar 15, 2016 1:06 pm

by tomycs

no, not at all, granted I don't puncture often (one end of life tubular this year, no clincher punctures, but using 3 different wheel-sets, in 13k km).

Hexsense
Posts: 462
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

I would say: yes, kind of.

It's not actually the full sidewall but just some more area beside the dead center get more contact. Especially when you mount some radical size combination like 23c tire on 17c to 21c inner rim. Most tire wouldn't mind that but some tire like Michelin Power Competition with quite respectably thick enough center but get much thinner toward the sidewall might see some impact on durability. with the tire like that on wide rim, 25c (mount to be 28) might be a better idea than 23c (mounted as 25mm width) even with aerodynamic hit.

bungis
Posts: 134
Joined: Sun Oct 12, 2014 6:59 pm

by bungis

At the very least the contact patch of the tire will be wider thus will eat up a greater selection of road debris.

As far as sidewall exposure it will probably be closer to the road surface as well due to the rounder shape of the contact patch. I'm guessing you'll want to use wider tires to mitigate this.

boots2000
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by boots2000

I say it is possible.
I put a set of 700x28 Hutchinson Secteur tires on my fairly wide Specialized Roval tubeless rims.
I double flatted easily when I hit some gravel.
I think the reason is that the wider rim makes the tire less deep. I probably should have gone up to a 700x32.

PaulSD
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Joined: Wed Oct 19, 2016 2:38 am

by PaulSD

Possibly because of more contact patch with the road? Just a guess.

PaulSD
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Joined: Wed Oct 19, 2016 2:38 am

by PaulSD

Possibly because of more contact patch with the road? Just a guess.

cmcdonnell
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Joined: Sun Aug 02, 2015 7:50 pm

by cmcdonnell

May be true and very tyre dependent. I've been running 23mm Conti GP4000S2's on my 17C Campagnolo Bora 50C's since last autumn. Been through 2 sets with 2 punctures in total. Sidewalls have looked in worse condition than I'd expect and had several deepish cuts. Recently tried Michelin Power Competitions again in 23mm and I'v not had 2 rear punctures caused by sidewall cuts. All 3 obliterated the tyre with a cut from bead to tread. I'm not buying any more of them. I assumed it was just because they had thinner sidewalls than the GP4000S2's but there may be truth in the fact the side walls are more exposed on the wider rims because normally I get few cuts on my sidewalls on 15C rims using GP4000S2's. Another point is that the Michelin's were significantly narrower than the Conti's.
Bianchi Oltre XR2 + Campagnolo Super Record 11 + Campagnolo Bora 50C
Litespeed T1 + Campagnolo Chorus 11 + Campagnolo Shamal Ultra

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ms6073
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by ms6073

carpetrunner wrote:I'm noticing a few more sidewall failures with wider rims than I had with the old-school thin rims.

By chance were those flats experienced using Challenge open tubulars paired with latex tubes? I had an issue with those tires (700x28) and Michellin latex tubes mounted on Zipp 303 FC where the tire bead got blown off the rim, fortunately the blowouts (4 in a 3-week period) occurred after completing a ride and not during.
Michael - The Anaerobic Threshold is neither...

Fiery
Posts: 420
Joined: Sat Mar 16, 2013 9:21 am

by Fiery

boots2000 wrote:I say it is possible.
I put a set of 700x28 Hutchinson Secteur tires on my fairly wide Specialized Roval tubeless rims.
I double flatted easily when I hit some gravel.
I think the reason is that the wider rim makes the tire less deep. I probably should have gone up to a 700x32.

What is the inner width of those rims? Wider rims actually make the tire taller, as long as the inner width is not actually wider than the tire itself.

boots2000
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Joined: Mon Oct 15, 2007 9:28 pm

by boots2000

These wheels are 22mm internal-
How do you figure that a wider rim makes a tire taller?
I would say that the opposite is true in my practical experience.

Fiery wrote:
boots2000 wrote:I say it is possible.
I put a set of 700x28 Hutchinson Secteur tires on my fairly wide Specialized Roval tubeless rims.
I double flatted easily when I hit some gravel.
I think the reason is that the wider rim makes the tire less deep. I probably should have gone up to a 700x32.

What is the inner width of those rims? Wider rims actually make the tire taller, as long as the inner width is not actually wider than the tire itself.

Hexsense
Posts: 462
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

Fiery wrote:What is the inner width of those rims? Wider rims actually make the tire taller, as long as the inner width is not actually wider than the tire itself.

it may be taller by total height.
but as we consider sidewall from the center of the thread given that tire doesn't stretch more, just shaped with wider contact path. the sidewalls are then pulled down lower to the ground due to increased thread width. hope it make sense

Fiery
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Joined: Sat Mar 16, 2013 9:21 am

by Fiery

It's still taller when measured from the top edge of the rim, that's what's relevant when it comes to snakebite flats (as long as the pressure is about the same). It's not by a lot, not as obviously as it is wider, but still a little taller. It's not linear because the tire doesn't have a uniform thickness and shape in cross section, and it may look shorter as it gets wider and .ore stubby, but it doesn't really get shorter unless the rim inner width is wider than the tire. Here's a diagram, it makes it clearer:

Image

Hexsense
Posts: 462
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

Fiery wrote:It's still taller when measured from the top edge of the rim, that's what's relevant when it comes to snakebite flats

okay you are right, thank you. but
1.) we are talking about sidewall failure flats not snakebite.
2.) you have to flip the picture upside down then re-align all the tire to their highest point they contact the road, not align at the rim.

now compare sidewall again. isn't it clear that the tire are stretchout wider to the side on wider rim so the tire section off center are pulled lower to the ground?
like if we compare the point 1cm from the center. thread at 1cm from the center are going out wider but lower than 1cm from the center on narrower rim?

by Weenie


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