Why won't my tyres seat?

[fair weather cyclist]

Whilst the grommit at the end of the valve stem certainly does most of the sealing, surely the O-ring also plays it's part in sealing? Air can't escape from the spoke holes because there is tape covering them, with the valve though, the tape will have been punctured to let the valve stem through. I'm genuinely curious on this point and not seeking to be argumentative.

I agree, I think the O-ring plays a part in sealing. At least, if it fits right and covers the valve hole, it should limit the amount of air coming out of the valve hole. So, in theory, even if it doesn't seal the valve, it definitely would help with the seating of the tyre because less air escapes. Then yeah, I assume most of the sealing is done by the rubber plug at the end of the valve stem and the sealant (when it is applied).

I've just noticed an early post where the OP mentions he has purchased some DT Swiss Assymetric valves, I suspect that this will indeed solve the problem and I hope it does for the OP's sake.

I'm very hopeful that the valves for asymmetric rims plus a better taping job will do the trick.

 

[Alex321]

Whilst the grommit at the end of the valve stem certainly does most of the sealing, surely the O-ring also plays it's part in sealing? Air can't escape from the spoke holes because there is tape covering them, with the valve though, the tape will have been punctured to let the valve stem through. I'm genuinely curious on this point and not seeking to be argumentative.

Any rim that is suitable for tubeless will have two "layers" - the inner layer has spoke holes, but the actual spoke nipple heads will only come through the outer layer. This means there is an air void between the layers, so air would just escape round the spokes if it were blocked around the valve by that O-ring. It is there pretty well entirely to hold the valve & grommet tight against the inside of the inner layer of the rim.

Certainly on my bike, there is a small blob of sealant around the O-ring, evidence that some air has escaped this way in the past, the base of the spokes, however, bear no such witness marks.

It will tend to escape through the closest hole to the point it gets into the void. So if it is escaping arounbd the valve from the inner layer, it will tend to then appear round the valve on the outer layer too.

I've just noticed an early post where the OP mentions he has purchased some DT Swiss Assymetric valves, I suspect that this will indeed solve the problem and I hope it does for the OP's sake.

Sounds likely. Hope it will too.

 

[JhnBssll]

Whilst the grommit at the end of the valve stem certainly does most of the sealing, surely the O-ring also plays it's part in sealing? Air can't escape from the spoke holes because there is tape covering them, with the valve though, the tape will have been punctured to let the valve stem through. I'm genuinely curious on this point and not seeking to be argumentative.

Certainly on my bike, there is a small blob of sealant around the O-ring, evidence that some air has escaped this way in the past, the base of the spokes, however, bear no such witness marks.

I've just noticed an early post where the OP mentions he has purchased some DT Swiss Assymetric valves, I suspect that this will indeed solve the problem and I hope it does for the OP's sake.

I found this image online, it shows whats going on quite well. You're only trying to pressurize the tyre, not the rim. The valve stem passes through the rim tape and then through the rim cavity before coming out the other side - if the o-ring had anything to do with sealing, you would be trying to pressurize the entire rim (which would be bad). As @Alex321 says above, the air would just escape around the spoke nipples if this were the case.

As you've rightly deduced, air coming out from around the valve generally means you've got an imperfect seal either between the rim tape and the rim or between the valve and the rim tape. Regarding the latter, I have a very small scredriver that I use to make a small (~3mm) hole in the rim tape before then enlarging the hole with the valve itself as I gently push and twist it through. The sealant will take care of any small imperfections, but if you've made a hole in the tape that's ragged or bigger than the valve itself this is unlikely to ever seal properly.

 

[Dogtrousers]

Just as an aside, a while ago I noticed that the knurled locknut and little bit of rubber on the valve on one of my (tubeless) wheelswas really loose. I did it up finger tight. Wheels and tyres were fine and didn't care about the loose locknut.

The fact that it was loose didn't really matter much. All the sealing is done at the base of the valve (where the arrow in @JhnBssll 's pic says "Tubeless rim strip or rim tape". The locknut prevents any shock from knocking the valve back and breaking that seal but it doesn't do any actual sealing itself, I don't think.`

 

[geocycle]

That’s interesting @Dogtrousers , I found that the locknut had to be quite tight on mind to keep the pressure on the valve as it pulled up against the rim from inside. That was during the installation so it might have got suitably gunged up by sealant now to reduce the pressure a bit.

 

[Mark pallister]

Problem with tubeless conversion here.

I'm looking for possible explanations and solutions before I bring the wheels to my lbs.

I am trying to convert a gravel wheelset to tubeless. The wheels are tubeless compatible, meaning the rims have hooks but you have to put tubeless tape.

Here's what I did, chronologically:
- removed the yellow tape
- cleaned the rims. I used a microfibre cloth and wee spray of wd-40, cleaned it nice and then dried it off completely with paper towel.
- installed muc-off tubeless rim tape (to be on the safe side I did 2 rounds of tape for each wheel)
- installed the tubeless valves (also muc-off)
- put the tires on
- sprayed a bit of soapy water to help with the seating

The tyres don't seat. I tried with a track pump, nothing. Then went ahead and bought a tubeless air tank, still nothing.

A lot of air seems to be coming out of the tubeless valve, then I had this thought: is it because I have asymmetric rims? The wee rubber ring that goes around the valve does not sit around the valve hole.

Can this be it? My thought is it shouldn't matter because there should still be the tape preventing air going out.

Can it be a combination of a dodgy taping job plus the asymmetric rims? Another suspect is the use of wd-40. Maybe not the best thing to use and it's making the tape not stick nicely? I don't know...

It's my first tubeless conversion so I'd be surprised if I didn't f**k up something at some point.

I can take photos if you wanna see it.

Have you put any sealant in ?

 

[Mark pallister]

If your losing air around the valve area ,I cut about 1in of a old inner tube
poke a small hole in it then push the valve through it then the valve through the rim
gives a very good seal

 

[fair weather cyclist]

Have you put any sealant in ?

No. The sealant goes in just after the tyres are seated

 

[fair weather cyclist]

If your losing air around the valve area ,I cut about 1in of a old inner tube
poke a small hole in it then push the valve through it then the valve through the rim
gives a very good seal

Tried it. Didn't make any difference.

 

[Sillyoldman]

I had the same issue. I found a video on you tube where it showed using a ratchet strap around the circumference of the tyre, pulling it very hard into the rim well. I used a roof box ratchet strap I had. Worked a treat. I had never had an issue with 25 mm tubeless but the 28s just would not seat until I did this. Can’t find the video now but will have another look and post a link if I find it. I used an air tank at 120 psi with valve core removed.

 

[Sillyoldman]

Video


View: https://youtu.be/mWhlq-ky74s

 

[fair weather cyclist]

Update: all sorted.

What was the cause of the problem?
I am now 100% sure the tyres would not seat on the bead because
- I cleaned the rims with wd-40
- muc-off tubeless tape is garbage and isn't sticky enough (although this probably was related to the use of wd-40)

I re-did everything properly and with good quality materials.
- I cleaned the rims just with water.
-I left them there overnight until they were completely dry.
- I used stans no tubes tape. The quality of stans tape is 10x better than the muc-off.

And that's it. The tyres seated at the first try using the beto air tank. Even with the tubeless valve that is not designed for asymmetric rims.

The air tank works like a dream.

 

[JhnBssll]

Great, well done once you've learnt the pitfalls tubeless setup isn't too bad. I still have the odd calamity though