I'm thinking... dodgy valve

Ben6899

Finished my ride the other day with both tyres intact. Came to get on the bike last night, checked the tyres and they were still okay. As I got to the end of the street, I noticed A LOT (not all, but a lot) of air had left the rear tube.

So I went back to the garage, swapped bikes to save time messing about with tubes etc and headed on my way. However, before I set off I refilled the flat tyre as a bit of an experiment... it's still rock hard this morning.

I'm thinking I change out the tube for a new one in case it's a dodgy valve - I'd kick myself if it caught me out on a ride... any views from the learned forum masses?

:-)

fnegroni

Ben6899 wrote:

Finished my ride the other day with both tyres intact. Came to get on the bike last night, checked the tyres and they were still okay. As I got to the end of the street, I noticed A LOT (not all, but a lot) of air had left the rear tube.

So I went back to the garage, swapped bikes to save time messing about with tubes etc and headed on my way. However, before I set off I refilled the flat tyre as a bit of an experiment... it's still rock hard this morning.

I'm thinking I change out the tube for a new one in case it's a dodgy valve - I'd kick myself if it caught me out on a ride... any views from the learned forum masses?

:-)

I assume you are talking about a tube with a presta valve here.

If the valve has a removable core, there are two seals: one is where you inflate from, the other is inside the valve, where the core is screwed on the outer shell.

I had exactly the same problem as yours and I traced it back to the valve core not being seated properly, and letting air out while riding. Sorted it by re-tightening the core with just my fingers.

Ben6899

Hi mate, yes it's a presta valve. I'm gonna swap tubes out, but if you could link to a decent diagram of what you fixed then I'll be able to use it as a spare.

Cheers!

fnegroni

This is a presta valve with a removable core:



The outer shell is in yellow.

The core is the silver bit on top, from the valve outer nut to inside the outer shell.

Both the nut and the core can be unscrewed.

If you accidentally unscrewed the core when unscrewing the outer nut, prior to inflating the tube, that's when the air leak might be coming from.

Just ensure that when you tighten the nut after inflating, you tighten the core too.

Ben6899

Much appreciated. Never looked at a Presta valve in so much detail before!