I've just acquired a bike fitted with UST Nobby Nics on a tubeless wheelset (Crank Bros Iodine).

The tyres inflate really easily, but seem to be losing ~80% of their air every 24 hours. Also, when they're almost flat and I press the sidewall of the tyre just above the rim, I can hear air hissing out (and some sealant). I assume the tyre shouldn't do this and should be sealed onto the rim?

So I'm looking for some advice on how to sort it out, other than reverting to tubes (which will be my last resort – I want to give tubless a proper shot). Do I just add more sealant, or to I need to try to reseat the entire tyre?

first up, remove the tyre and get rid of the sealant – replace with some new latex, re-inflate to 40/50psi, ride it for a short while before putting the bike away.

it could be the sealant is crap.

if this doesnt work, its something else HTH.

are you pumping the tyre up to a high (55psi) pressure first?

You should hear the bead "pop" as you pump it up.

I only pumped it up to 35psi and certainly didn't hear a pop. I'll give that a try before getting the house covered in latex 🙂 Ta.

I've used ust tyres for years and generally speaking they hold air well over weeks (when new) dropping to days (when they get a bit older) with a bit of latex. If they're deflating over a day just sat in the shed then I'd be wary of taking them out on a proper ride because there's something awry with the seal – could lead to problems if you're smashing the bike down the trail. As others have said, though, it could just be that the tyre's not seated right and it will be fine once this is done.

Crank Bros are sort of a byword for total sh_ite IME, so it could be that you have a more fundamental problem. I've not used that wheelset myself, though, so it's certainly possible that they've managed to get one thing right. Be a first, mind.

Why not put the tire on the rim in a large bucket of water and then you can see exactly where the air is escaping from? But as previously stated some new sealant should do the trick as most recommend adding new sealant every three months. You don't have to take the tire off the rim BTW.Just remove the valve core (using the special tool that comes with tubeless repair kits) and pour the sealant through that and re-inflate. This negates the need to use a compressor pump as the tires generally stay seated and you can use a track pump or even a mini-pump if you want.

http://www.schwalbe.co.uk/pdf/techinfo.pdf

sounds like you've not sealed it properly to me. after adding correct amount of sealant and inflating to ~50psi:

1 – hold wheel at 3 and 9 (as in on a clock face)
2 – shake vigorously
3 – move hands to 2 and 8
4 – shake vigorously
5 – repeat until you have gone full circle
6 – lie wheel on ground drive side down
7 – have a brew
8 – repeat steps 1-5
9 – lie wheel on ground non-drive down

should do the trick.

Well pumping it up to 55psi helped. It didn't pop, but it let me see (well, hear) that the air was escaping from a 2cm long stretch of the tyre. Some random tugging and pulling of the tyre at that spot seems to have stopped the hissing. I'll probably add some more sealant too, didn't seem to be much in there.

Thanks for the excellent tips guys – I'll follow them all once the sealant arrives in the post

Macavity – Member

http://www.schwalbe.co.uk/pdf/techinfo.pdf

What an excellent read. Thanks for the link.