Cause of tubeless flat?

[super_claret]

Not very experienced with tubeless but the other day went out with the Wife and she had a flat running tubeless. I tried pumped up the tyre and it got her about a mile before it was flat again, so I decided to put a tube in but found nothing stuck in the tyre or damage to it. There was plenty of sealant in there. I noticed that the rim tape had come away at the end and I'm guessing this could have been the problem?

Any thoughts on what else it could have been or suggestions to stop this happening in future?

 

[OldBean]

could you see any sealant running along the rim??
I had mysterious leakage which turned out to be my "tubeless ready" wheels being "NOT tubeless ready " due to inadequate rim tape ...took ages to locate ...LBS did a fine job.

 

[super_claret]

Thanks. Don't recall any sealant along the rim but then again, I wasn't really looking for that.
I've since inspected the valve (Presta) and it was bent where the screw tightens. I'm mystified as to why it went flat. When I get chance, I'm going to take the rim tape off and re-tape it, put a new valve in and see if this works.

 

[steve_sordy]

Remove the wheel and dip it into a waterbutt, a pond....your bath if necessary! That will show where the leak is coming from. My guess is that rim tape, pretty much anywhere else the sealant should fix it, or the problem is obvious.

Because of previous rim tape failures, on every new bike I get now I strip off the rim tape and replace it with Gorilla tape. You need at least two layers over the spoke holes, overlap the strips over the valve hole and then poke through it.

 

[Mikerb]

...or it could be your valve if you say it is bent. I assume you mean the valve insert is bent rather than the entire valve being at an angle to the rim. With Presta valves you have to be careful when inflating the tyre. Its best to use a pump with a flexi hose rather than the type that just pushes over the valve...dead easy to bend the insert with those...and it will not close off properly if it is bent.

 

[super_claret]

...or it could be your valve if you say it is bent. I assume you mean the valve insert is bent rather than the entire valve being at an angle to the rim. With Presta valves you have to be careful when inflating the tyre. Its best to use a pump with a flexi hose rather than the type that just pushes over the valve...dead easy to bend the insert with those...and it will not close off properly if it is bent.

Can't be sure whether it was bent before the flat or whether I bent it using the pump or when removing it to put the tube in. I'm going to replace the rim tape first and see if that solves the issue. Thanks for the suggestions though.

 

[steve_sordy]

Can't be sure whether it was bent before the flat or whether I bent it using the pump or when removing it to put the tube in. I'm going to replace the rim tape first and see if that solves the issue. Thanks for the suggestions though.

I'd do both, valve cores are very cheap to buy and quick and easy to replace. Buy half a dozen or so and put them in a jar in the shed, put one in your pack.

 

[Pukmeister]

I had a tubeless leak recently, I used an indicator solution called 'snoop' (a glorified weak fairy liquid solution) on the rim, valve, spokes and sidewalls. Turned out my almost new michelin e-wild was seeping air through the sidewalls, shown as dots and slits of froth at random places. LBS replaced the tyre and its been fine since so I suspect it was just a bad tyre from new.

 

[steve_sordy]

Amongst my first fruitless attempts at going tubeless, I had a tyre inflated and with soapy liquid all over it. I left it for a few mins to get a drink and when I got back the tyre wall was covered in hundred and hundreds of white mini-volcanoes. The porous tyre wall was leaking air and the jets were foaming the soapy liquid. If your tyre is not tubeless or tubeless ready, then use a latex based sealant. Latex sealants have their downsides, but they are unsurpassed at their ability to seal porous sidewalls. I haven't yet found a non-latex sealant that does that satisfactorily.

 

[mclydeg]

I had a stubborn issue, would go down overnight.
Ended up the tubeless valve stem had a bad o-ring seal.
Might swap the whole stem out.
Only way I found it was water test and pressed down hard on the tire with valve stem at the bottom, could see some air but also sealant leaking in small amounts.

 

[Pukmeister]

Thanks Steve Sordy for the latex info, my tubeless tyres did exactly that despite having the stock tyre goo from Giant in them. If these tyres do the same I will source a latex sealant and see if it cures it.

 

[steve_sordy]

Thanks Steve Sordy for the latex info, my tubeless tyres did exactly that despite having the stock tyre goo from Giant in them. If these tyres do the same I will source a latex sealant and see if it cures it.

Make sure that you clean out the Giant goo. It might not react with the latex, but many non-latex sealants do. I'm not talking explosions or anything like that, but the latex may go off much more quickly or even set into one lump when the bike is parked and the sealant collects at the bottom. I don't believe that you need to be too scrupulous (I'm not), but give it a good attempt. I drain off what I can, wipe out with some paper towels or rags and then wash in the water butt.

With any latex sealant, I always park the bike overnight with the valves at or close to the ground, so that any latex in the valves drains out rather than collects there. I find that this reduces the incidence of the sealant blocking the valve holes. This prevents the tyre from deflating when you want it to, does that ring a bell?