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Bontrager tubeless tyre issues

by allama699
Wed, May 20, 2020 13:14
7

Hi All,
I have tubeless tyres fitted to my Trek Domane. The rear has no issues, but the front continuously has deflation issues. I inflate them to about 75PSI, they are 32's. No issues with them going down over night. Over the last few weeks, I have had total deflation events when riding fast along slightly bumpy roads. This ends up with a total flat, with leaked sealant around the entire rim. I can re-inflate and get myself home, but it's clearly a problem.
Is it common for a front tubeless to get impact deflation due to potholes?
Thanks in advance.

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7 comments

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shufflingb | 4 years ago
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Not saying it doesn't happen, but in five years or so of gravel tubeless I've never had an experience with front tyres burping or otherwise leaking sealant. With the same rims and tyres both ends; it's always been the rear that gives a problem first because that's where most of the weight is most of the time. The problem sounds very much like there's something specifically 'wrong' with the way the front wheel and tyre are currently setup relative to the rear.

I would check the mating surfaces between the tyre and the front wheel rim carefully.  Dirt/grit, dents or cracks in the rim, tyre molding marks and similar are the most likely culprits.

Hopefully cleaning those up will fix it. Once done though, might want to have a look at the tyre pressures, they seem high - Gravel Cyclist's has got Enve's recommended pressures over here https://gravelcyclist.com/bicycle-tech/gravel-bike-tyre-tire-pressure-guidelines-by-enve-composites/ (the highest they recommend for gravel riding is less than 50psi for 32c's even for cart horses like me).

Good luck.

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allama699 replied to shufflingb | 4 years ago
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Thats great advice. I did wonder about the tyre preassure. I come from an old school high preassure world. So 50 psi seems low, but will reduce from tomorrow. I will also take the wheel apart and clean all components clean thourougly. I'll be an expert at re-taping, by the end of all this. Hopefully this will resolve the issues i've been having.

Thanks.

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Judge dreadful | 4 years ago
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It sounds like your front tyre is 'burping' on impact. It's not uncommon, how bad it is depends on exact tyre and rim combo. Trial and error with different combinations of tyre and rim is a good way to work out what works best.

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allama699 replied to Judge dreadful | 4 years ago
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Thanks.

I'm going to totally re-tape, and re-sealant this afternoon in the sun. If the problem persists, i will look at changing the make of tyre first. Probably won't be changing the wheel just yet though :-).

I do like the term 'burping', it pretty much sums up whats happening. Odd that the rear tyre hasn't had the same issue. Or maybe I've just tempted fate.

Thanks again.

 

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Judge dreadful replied to allama699 | 4 years ago
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allama699 wrote:

Thanks.

I'm going to totally re-tape, and re-sealant this afternoon in the sun. If the problem persists, i will look at changing the make of tyre first. Probably won't be changing the wheel just yet though :-).

I do like the term 'burping', it pretty much sums up whats happening. Odd that the rear tyre hasn't had the same issue. Or maybe I've just tempted fate.

Thanks again.

 

Front tyres are more prone to it, because you steer with the front, so it adds a bit of twist to the tyre, which tends to exacerbate any burping issues.

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allama699 replied to Judge dreadful | 4 years ago
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Looks like i'll have to start carrying spare sealant, and more than one CO2 canister. Or lose some weight 1

 

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Pilot Pete replied to allama699 | 4 years ago
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Just put a tube in.....dons helmet!

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