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Help finding slow leak in tubeless tyre

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Help finding slow leak in tubeless tyre

Old 10-07-20, 10:55 PM
  #1  
NoWhammies
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Help finding slow leak in tubeless tyre

The rear tyre on my road bike is a tubeless 25mm Veloflex EVO TLR. The tyre was a ***** to mount and when I did get the tyre on the rim, I used my pump, which has an 'air blast' cylinder, to seat the tyre. The air blast was done without the core in the valve.

I don't think the tyre ever properly seated. The tyre would inflate from the air blast, and then slowly deflate. I put some Orange Seal in the tyre, air blasted the tyre again, and again the tyre would slowly deflate. I then put the core in, pumped up the tyre and the tyre held air. I swished the sealant around, waited 24hrs, (the tyre was still inflated) and then deflated the tyre, took out the core, and added more sealant. That was September 1st and 1,500km ago.

Since then the tyre keeps deflating and I have added more sealant two or three times because when I checked the tyre, the tyre was dry. No sealant was present. Most recently I went for a 160k/100mi ride on Sunday. The tyre was firm for the whole ride. Tonight I checked on my rear tyre and the tyre was flat. Again.

Any ideas what's going on with the tyre? Any suggestions on how to stop the tyre from constantly going flat?

Thank you.
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Old 10-08-20, 07:57 AM
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Originally Posted by NoWhammies View Post
The rear tyre on my road bike is a tubeless 25mm Veloflex EVO TLR. The tyre was a ***** to mount and when I did get the tyre on the rim, I used my pump, which has an 'air blast' cylinder, to seat the tyre. The air blast was done without the core in the valve.

I don't think the tyre ever properly seated. The tyre would inflate from the air blast, and then slowly deflate. I put some Orange Seal in the tyre, air blasted the tyre again, and again the tyre would slowly deflate. I then put the core in, pumped up the tyre and the tyre held air. I swished the sealant around, waited 24hrs, (the tyre was still inflated) and then deflated the tyre, took out the core, and added more sealant. That was September 1st and 1,500km ago.

Since then the tyre keeps deflating and I have added more sealant two or three times because when I checked the tyre, the tyre was dry. No sealant was present. Most recently I went for a 160k/100mi ride on Sunday. The tyre was firm for the whole ride. Tonight I checked on my rear tyre and the tyre was flat. Again.

Any ideas what's going on with the tyre? Any suggestions on how to stop the tyre from constantly going flat?

Thank you.
Pull the tire and re-wrap your rims. Get some DT Swiss tape (it's the best IMO) and double wrap. Ensure you get the correct width for your internal rim diameter. Start the wrap on one side of the valve hole, wrap twice then finish the wrap on the opposite side of the valve hole. This keeps the wrap single where the valve goes (ensures better seal around the valve), and double wrapped everywhere else. I bet you are losing air through your spokes and/or around the valve.
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Old 10-08-20, 08:02 AM
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@jadocs Thank you for the feedback. The wrap on the rim is coming up to three years old now. Question. Do I remove the old wrap first? Thanks again.
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Old 10-08-20, 08:06 AM
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Originally Posted by NoWhammies View Post
@jadocs Thank you for the feedback. The wrap on the rim is coming up to three years old now. Question. Do I remove the old wrap first? Thanks again.
Yes absolutely, then get some alcohol and wipe down the rim and get rid of any residual residue.

You may find the old tape has become brittle and just lifts off. Wipe it down anyway.
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Old 10-08-20, 08:33 AM
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First I would dunk sections of the inflated tire in a tub of water to find where the leak is coming from which can make determining what is causing the loss of air much easier.
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Old 10-08-20, 10:33 AM
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Originally Posted by Crankycrank View Post
First I would dunk sections of the inflated tire in a tub of water to find where the leak is coming from which can make determining what is causing the loss of air much easier.
No need, the leak is not the result of a puncture, it just slowly deflates which means his tire is not sealing properly. Primary culprits is losing air around the spokes (which means poor tape job or tape is old and no longer doing the job) or around the valve (if the valve is not seating right it can be either operator error, or the tape is in such condition that it prevents it from seating properly).
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Old 10-08-20, 11:41 AM
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The real key with seating tubeless is to leave the tire/rim sitting flat over a trash can or waste basket so that the sealant runs toward the beads rather than pooling in the tire. Leave it there for 15-30 min, then wave it around a bunch, and put in on the other side.
Dish soap and water is the best way to detect leaks.
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Old 10-15-20, 10:15 PM
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Thank you everyone for the feedback. Very much appreciated. Looks like I have my winter project!
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Old 10-16-20, 01:56 AM
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i usually put the tire in water, and check the bubble position coming from the tire.
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Old 10-16-20, 02:47 AM
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Definitely remove the old tape and clean the rim with IPA or Acetone before installing some quality rim tape. I've tried a few of the off brands but always go back to DT Swiss as it has held up far better than the others I've tried.
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Old 10-16-20, 02:54 AM
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Originally Posted by jadocs View Post
No need, the leak is not the result of a puncture, it just slowly deflates which means his tire is not sealing properly. Primary culprits is losing air around the spokes (which means poor tape job or tape is old and no longer doing the job) or around the valve (if the valve is not seating right it can be either operator error, or the tape is in such condition that it prevents it from seating properly).
I would still put the wheel in a tub of water. It does not matter whether it is a sealing issue or a puncture, because there is always the outside chance that it is a different issue, such as a tire manufacturing error, a crack in the wheel and so forth. Once the tire is off, the problem often becomes invisible.

trev
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Old 10-16-20, 05:14 AM
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Another vote for retaping. Also, regarding @jadocs mention of losing air around the valve, I have found some rims require pressing the valve in very hard from inside the rim while tightening the valve nut to get it to seal. Valves in my HED rims seal up without much effort with the nut just finger tight, but I have a set of Hunt rims where I had to put a lot of force into pushing the valve into the rim to get it to seal. So after taping, when reinstalling valve, pay extra attention to seating the valve. Lastly tape — again @jadocs mention of width is spot on. The tape should be a couple of mm wider than the internal width of the rim. This allows it to cover the concave rim channel while sill covering the rim from bead to bead.
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