Hi,

I’ve tried to set my new carbon tubeless wheel up tubeless 3 times now.

3 times the air comes shooting out of this little hole in the carbon on the side of the rim.

Do I just need to try re taping it for the 4th time, or am I missing something?

The other identical tape, valve, tube and tyre combo went up no problem first time.

Bump for visibility!

Yes mate, you need to redo the tape! Make sure you warm it up first!

Do you have any sealant in it?

🙂 I’ve never warmed tubeless tape up before and didn’t on the other wheel. Is that a thing?

It had loads of sealant in on the first go and second. The sealant didn’t seem to end up in the hole in the rim.

Does the rim tape cover the full width of the rim bed?

Does the rim tape cover the full width of the rim bed?

It doesn’t on the other wheel, just over the spoke holes.

On the third attempt I’ve covered the whole internal width of the rim. Or at least I thought I had!

I stuck some sealant in and pumped it up this morning, still air straight out the hole. I have it a good shake and got sealant out the hole.

Is it worth mixing some glitter into the sealant to help it seal on the hole?

Are you using the same valve type on both? I’d put money on the leak being at the valve hole.

Pictures of the taping would be handy, but it’s highly likely that it’s the valve that isn’t sealing

I’ve never warmed tubeless tape up before and didn’t on the other wheel. Is that a thing?

Yes, I keep it in the house, not the garage, helps keep it pliable and as such works better. If I can be arsed, I’ll leave the wheel inside overnight too, just works better when both are warm and dry.

Is it worth mixing some glitter into the sealant to help it seal on the hole?

I assume that the hole is a breather hole for the hollow bit underneath the rim bed, in which case, you don’t want it to seal. Presumably it’s to let water out, and to avoid the hollow bit pressurising if your tape doesn’t seal properly. Can’t remember which brand it was, but there was a problem recently with carbon rims failing because the hollow section was pressurising.

As above, some pics of the taping and the valve base would probably help.

It sounds like you aren’t getting a good seal with your valve with the extra info. Have you got any different shaped rubbers to try?

To test the valve seal wrap plumbers PTFE tape around the base of the rubber bit, if it works then it’s 50p well spent.

Thanks for the suggestions!

@oldnick I tried PTFE tape, air still coming out of the hole in the rim. Tried it again, air still coming out of the hole and now it was also coming out the side of the valve

http://ep1.pinkbike.org/p5pb20610715/p5pb20610715.jpg

Next stop is finding the different valve rubber bungs that I’m sure I’ve seen somewhere…

Are you using the same valve type on both? I’d put money on the leak being at the valve hole

Yep. Exactly the same brand new valves, on the same brand new rims, with sub 100 mile tyres and brand new tape off the same roll.

I’ve tried taping it again with hot tape.

Still loads of air straight out of the wee hole.

I think I’m just going to stick a tube in and ride it for a while.

Bah!

I had that with an alu rim. There was a metal seem in the rim that i hadnet got tape on all the way round. The air was passing through that seem and out of the hole.
I bought some slightly wider tape to cover the seem and it was fine

What inner width is the rim and what width tape are you using?

I reckon to be safe you want the tape to go the whole width and a touch up the inside of the rim. For 30mm inner width Dt rims I’m using DT Swiss 32mm tape. On the 25mm inner DT rims I’m running 27mm tape.

Making sure the tape and rim are warm ish and really stretching it on. Generally been using DT Swiss valves on DT rims – but I’ve gone for light / lightly ish treaded tyres on both back wheels right now (Forekaster 2.6” tyre on one and 2.6” Slaughter on the other) so stuck in Rimpact inserts with Rimpact Valves. All good so far I think – just need to pop out and check the slaughter has stayed up I put in a few days ago.

I really like the Rimpact valves so far.

I hate it when this happens,I ve had a pair I swear I’ve spent more time taping and arsing about with than riding.

Finally sorted em out and what you want is something like this

Race one rubber band

it’s a nice tight thick rubber band Seals the rim really well.

and a valve with the square square type rubber instead of the round rubber on the valve. I’m liking the muc off ones if on offer.

I mate was ( socially distantly,) round.

I’ve got tape one and a half full wraps. He thought that the air was getting under where the tape overlapped and suggested more tape.

I forgot about trying the other sized gromits.

More tape and different shapes gromits next!
Or a tube

Success!

After adding several layers of tape it almost sealed.

Took the hump and put a couple of wraps of insulation tape on for a rim strip for a tube.

Then remembered to try a different shape gromit on the valve…. Success!

So despite the back rim being fine with the conical bung on the valves I bought the front needed a u shaped bit like the one on the right of this picture

The gromit I had lying about was much softer than the rubber on the valve.

I’m very happy!

Thanks for the advice 🙂