How do tubeless tyres work?

[simonineaston]

I'm reading about tubeless tyres. But I feel sure that the air I squeeze into the tyre in order to inflate it will escape through the holes in the rim where the spoke nipples are... or have I missed something?

[Paulatic]

You’ve missed putting a tubeless tape around the rim

[Jdsk]

https://en.wikipedia.org/wiki/Tubeless_tire

"A tubeless bicycle tire system requires a compatible tire, an airtight rim—capable of being sealed at the valve stem, spoke holes (if they go all the way through the rim) and the tire bead seat."

https://sheldonbrown.com/tubeless.html

"Motor-vehicle rims have large flanges and so it is easy to establish a seal. The much smaller flanges of a bicycle rim make that more difficult. Also, bicycle rims have traditionally had spoke holes that extend through to the well (deepest part of the space between the rim's flanges). Rim tape protects an inner tube from sinking into spoke holes, but has not traditionally been airtight."

https://www.parktool.com/blog/repair-he ... conversion

Jonathan

[Marcus Aurelius]

The holes are covered in a thick tape, some of the higher end tubeless rims have a fixed ‘tube gulley’ over the traditional holes as well. The valves have a thick rubber bed that prevents air from escaping the valve hole too. If you add a decent sealant ( high crystal concentration) you cover your bases even more. I used to dislike tubeless on road bikes, but they have raised their game of late, now I wouldn’t go back to tubes.

[Cowsham]

What's the procedure to fix a puncture and are they as prone to punctures or do they self seal.

[simonineaston]

You’ve missed putting a tubeless tape around the rim...

Genius!!

[mattsccm]

Same as a car or motorcycle. Only difference is that instead of the rim being sealed/holeless or what ever you call it you do it yourself with tape. There are high end wheels that don't have the spoke holes and these are exactly like a car/motorcycle.
Biggest difference is that cycle tyres carry liquid sealant which, unlike a car tyre, prevents most punctures as it seals the whole, mostly before you know it's there.
It can't fix huge holes but some can be plugged like a car tyre and this often can be done before all the air escapes.
So, mostly , a puncture isn't even noticed or it just means a slightly softer tyre.
A slashed tyre means a tube is needed but it would with a tubed tyre. Then you bung in a tube. Some people moan about it being really hard but thats often poor technique added to a tight tyre rim combination. Personally I have never used 2 levers evn over about 4 years of running tubeless. Maybe decades of bunging 5" wide knobblies on to 18" motorcross rims have given me decent technique. You can't blame the system for this .
A bit Marmite but so were free wheels, rear mechs and pneumatic tyres.

[Stevek76]

What's the procedure to fix a puncture and are they as prone to punctures or do they self seal.

You normally chuck some sealant in so they will self heal most small punctures (thorns, glass, flint etc). They're not really any less prone to actually getting those punctures of course. For offroad/mtb use where you're flirting with pressures that might be too low they do effectively eliminate snakebite/pinch punctures.

If the hole is larger then tubeless puncture kits consist of soft unvulcanised rubber 'worms' that you coat in the usual rubber vulcanising cement and use a some small prongs to stuff partway into the hole.

Worst case you can always just put an inner tube in but there's a good chance that if the hole/tear is large enough to not be fixable it may not contain an inflated inner tube either.

[mattsccm]

I would suggest that the last paragraph above over states things a bit. A 5mm rip as a fair chance of not sealing but that won 't hinder a tube.
One issue with bunging a tube in is that there may well be resident thorns etc that were un-noticed with sealant but punture the new tube.
A good feel finds them and you do that with tubed tyres anyway.

[simonineaston]

So, other than saving the weight of one inner tube - the other having to come along in case of a puncture that the sealant can't cope with... what am I missing out on, if I don't adopt The Tubeless Way?

[NATURAL ANKLING]

Hi,

The holes are covered in a thick tape, some of the higher end tubeless rims have a fixed ‘tube gulley’ over the traditional holes as well. The valves have a thick rubber bed that prevents air from escaping the valve hole too. If you add a decent sealant ( high crystal concentration) you cover your bases even more. I used to dislike tubeless on road bikes, but they have raised their game of late, now I wouldn’t go back to tubes.

Till you get a flat?
Worst job is inflating to seat the beads when the tyre is not new.
Two many motorcycle and car tyres fitted at home with a track pump

[Cowsham]

Hi,

The holes are covered in a thick tape, some of the higher end tubeless rims have a fixed ‘tube gulley’ over the traditional holes as well. The valves have a thick rubber bed that prevents air from escaping the valve hole too. If you add a decent sealant ( high crystal concentration) you cover your bases even more. I used to dislike tubeless on road bikes, but they have raised their game of late, now I wouldn’t go back to tubes.

Till you get a flat?
Worst job is inflating to seat the beads when the tyre is not new.
Two many motorcycle and car tyres fitted at home with a track pump

That's the bit that bothers me -- do you need a little co2 canister to blow the tyre up fast enough to make the seal against the rim or do you use sealant on the rims and if you do is it easy to get the tyre off clean the glue off and get the tyre back on again with new sealant or what's the deal with that ?

Would you not be better carrying a new foldable tubeless tyre?

[Grandad]

I've heard stories of major punctures that have resulted in the sealant being sprayed out over the bike and rider, creating a sticky mess

[mattsccm]

"Till you get a flat?
Worst job is inflating to seat the beads when the tyre is not new."
Pump the things up? Thats what I have done with other peoples tubeless sets ups that don't work and the one I have had in the woods. Used tubeless tyres are so much easier to seat any way.Or carry a CO2 cartridge if you are worried. I have one in every tool bag on every bike anyway.
Don't forget that, like almost everything in this world, you never hear of all the successful uses of something, only the moans. Like I said, I am a relative newcomer to tubeless, only converting on the road about 4 years ago. Most of my club mates have swapped, especially on their CX/gravel bikes and I have never heard of a situation that hasn't been an easy fix.
However this is a bit like helmets, 1x set ups or what ever. You like it or you don't knocking the other point of view isn't much use really

[Steve]

And are the valves entirely separate from tyre and tape? Now I'm curious too.