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Discussion Starter · #1 ·
well I got another pinch flat at a race yesterday. Always during races and never in training. At least it was only 1 and I could finish. Which leads me to this question.

I've had this rather large ding in my sidewall for a while. A little smaller than a thumbprint and about 2-3mm indented. Could this be all the pinch flat woes? I had the tire pumped to 48 and I weigh 170-175

braking is only affected when the bike is on the stand. When riding it's not noticable. But it does interact with the pad.
 

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stonethrow said:
well I got another pinch flat at a race yesterday. Always during races and never in training. At least it was only 1 and I could finish. Which leads me to this question.

I've had this rather large ding in my sidewall for a while. A little smaller than a thumbprint and about 2-3mm indented. Could this be all the pinch flat woes? I had the tire pumped to 48 and I weigh 170-175

braking is only affected when the bike is on the stand. When riding it's not noticable. But it does interact with the pad.
Maybe. But I think you just need to avoid hitting the big rocks. If you find your tires bouncing off of rocks in weird directions you may need to lower the air pressure so you are in more control and can avoid the big hits.
 

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Discussion Starter · #3 ·
nonono. I have fine control. It is the strangest thing I have ever encountered. I never use to pinch flat and now it's destroying my racing. Should I try and bend it back to original shape before my 10 hour trip to tanasi? How would I do this.... pliers and a cloth to cover them with? It's a mavic x517 rim. I REALLY don't want to have a rear pinch there. This pinch the other day was on a pretty smooth part of the trail.
 

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stonethrow said:
nonono. I have fine control. It is the strangest thing I have ever encountered. I never use to pinch flat and now it's destroying my racing. Should I try and bend it back to original shape before my 10 hour trip to tanasi? How would I do this.... pliers and a cloth to cover them with? It's a mavic x517 rim. I REALLY don't want to have a rear pinch there. This pinch the other day was on a pretty smooth part of the trail.
..a little late now, but may help you in the future. Always align your tire in the same manner with respect to the valve. That way, you'll know what part of the rim caused the pinch flat. It's easy with tubes, because they have a valve to line things up.

If you check things this way, you won't have to fix a rim that doesn't require fixing.
 

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Discussion Starter · #5 ·
yeah I should have but I always forget in the midst of racing. I lost my favorite tire lever too and I don't know where to get another one.

so pretty much a small 2 mm indentation shouldn't facilitate a pinch?
 

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What tires are you using? Are you using different tubes?

I weigh about the same as you and rarely use more than 38 psi and rarely pinch flat. The last time I ran 45 psi it was in a 1.55" tire. No problems in a fast muddy and rocky race.
 

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stonethrow said:
yeah I should have but I always forget in the midst of racing. I lost my favorite tire lever too and I don't know where to get another one.
You can still check the tube after the race.

What tire lever are you looking for?
 

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carpe mañana
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The best thing I found for repairing bent rims (317/717 in my case) has been a crescent wrench. A channel lock works alright as well. I would also suggest to give Stan's notubes a try. I had 5 pinchflats in a single week and said F**K tubes and got it and have been happy since.

_MK
 

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stonethrow said:
NBX lite 2.0

thinking about using pythons in dry weather due to this. I really like the NBX though.

looking at all this I really feel like it's the rim. yah, nay?
It depends how curious you are to know if the rim is causing the issues.

You could fix the rim now. If you don't get any more pinch flats....you won't know if it's do to the rim fix or something else that you didn't consider. If you just want the problem to go away....fix the rim and if you get another weird pinch flat....it was something else...maybe :rolleyes:
 

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The NBX Lite 2.0 is fairly low volume. You could switch to the 2.2 version.

Are you using lightweight tubes? Thicker tubes should help.

BTW Tubeless - UST or DIY - does not seal well with a dinged rim.
 

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carpe mañana
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shiggy said:
BTW Tubeless - UST or DIY - does not seal well with a dinged rim.
I don't know if this is universal, but my 717 disc rim had quite a few dings from hitting the curb really hard several times - in a span of a few months, I should add. I straigtened the rim, as well as I could, with a crescent wrench and converted to Stan's notubes. I did not have a single issue.

I will agree with Shiggy about UST rim, but only if you use rim and tire and no sealant. With sealant, whether it is home made or commercial, there is no issue, neither.

_MK
 
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