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Tubeless - loss of pressure


gerhardsnorbaard

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Posted

Hubbers

 

I am expwriencing loss of pressure in both wheels. Giant PXC1 rims with Giant's stock black rim strips and valves. Wheels are Onza Canis / Racing Ralph Snakeskin.

 

The pressure drops by about 0.2 to 0.4 bar per ride, unless i put sealant almost every 2-3 weeks. Bike us stored in my study, so does not heat up too much.

 

On a long ride Saturday the pressure dropped from 1.9 bar to a sketchy 1.1 bar, with no signs of burp

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Posted

Not sure what happened, heres the rest of the story. No signs of burping, no air escape when wheels are tested under water. I have removed at re-seated the wheels, there was no caked sealant inside.

 

So...what now? Do i need to replace the rim strips, or keep adding sealant? Other options like insulation tape over existing rim strips? Remove rim strips and get a good helping of stans yellow tape?

 

Advice, pleass

Posted

Hubbers

 

I am expwriencing loss of pressure in both wheels. Giant PXC1 rims with Giant's stock black rim strips and valves. Wheels are Onza Canis / Racing Ralph Snakeskin.

 

The pressure drops by about 0.2 to 0.4 bar per ride, unless i put sealant almost every 2-3 weeks. Bike us stored in my study, so does not heat up too much.

 

On a long ride Saturday the pressure dropped from 1.9 bar to a sketchy 1.1 bar, with no signs of burp

Hi,

 

Could be that your rim tape needs to be replaced, as they do "get older" and wears out. Valves are also cheap, I'd replace those as well and see how it goes.

Posted

Hi,

I agree with NotSoBigBen, only hold the wheels for a minute or two. If you are losing that amount of pressure in shch a short time.......

Sarge

Posted

Might be an irregularity on the bead where it loses the seat/seal when the tire flexes under the loads of riding. If you are going to remove the tire to replace valves and rim tape you might as well check the bead, not that I would know exactly what to look for.

Posted

I would suspect the problem is with the valves and the way they are seated in the rim tape. I was told by my LBS that you must be careful how you punch a hole in the rim tape to insert the valve. They recommended using a hot match to melt the rim tape a little, cause the least amount of damage, do not force it through.

 

I agree that if there is any kind of leak you would see small bubbles forming and growing when you place the tire under water. They won't necessarily form a stream of bubbles if the leak is very slow, but the bubbles will get bigger and pop off now and then.

Posted

On wheels like that I replace the Stans/Joe's with a sealant I get from my local motorbike shop . This stuff is a lot thicker and will even seal a nagging wife's trap . I only use the stuff once then at refills go back to using Stans .  

Posted

I agree with those that said you should look at replacing the rim tape and valves. IMHO I would go with the Stan's rim take and sealant.

Posted

Don't use that horrible yellow Stans tape - it's really not nice.  The new(ish) Ryder white 24mm tape is seriously the dogs danglies.  It's a compliant tape, so it fits everywhere without creasing, is wide enough to cover the whole rim and is just sticky enough to stick really well, but not stick to anything it touches (like Gorilla Tape) so you can re-position it if needed.

You should be able to get it from any bike shop.  Let me know if you can't get it and I can send you a roll.

 

PS - I agree, new tape and valves and your problem will go away.  Personally, I think that it's just the tape.

Posted

Do i remove the OEM rim strips or just slap new tape over it?

 

Thanks everyone, seems like im in for anither round of messy, sticky sealant wars..wheel faff is the biggest faff of all

Remove, clean properly and replace.

Posted

Had this problem with my PXC's recently. At first I thought it was the Valve with air escaping at the valve-hole (the rim itself, not the valve).

 

So I replaced the whole tubeless valve. Did not solve it.

 

LBS topped up sealant. Did not solve it.

 

LBS replaced rim tape. Problem solved.

Posted

Second the advice, remove everything of the rim tape, clean with paraffin or meths before putting new rim tape. You don't need to clean the inside of the tire too much, just pick away any balls of sealant.

Posted

Gerhard - Just go out and buy those new wheels you saw on the hub, tell your Mrs you got a 100 responses and 99% said "buy new wheels" the other 1% said buy a new bike.

 

If all else fails, replace your rim tape and valve.

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