Tire deflates after a few hours

[potatorage]

I recently installed my hub motor but when I inflated the tire, it was completely flat after a couple of hours. I taped the rim so that the inner tube wouldn't be punctured, and the inner tube does seem to be holding air. So, why did the tire deflate so suddenly? There was some mineral oil... kind of everywhere but that wouldn't cause the inner tube or valve to leak air right?

 

[biohazardman]

I bought a couple of the nice extra heavy tubes from performance bike and they did that same thing. The leak was hard to find as it only leaked enough to find when the stem was bent just right. Both tubes leaked at the base of the stem within a couple days of the install. Tear the tube out of the tire and pump it up and find the leak. You don't have to take the wheel off of the bike just pull one side of the tire off and pull out the tube.

 

[amberwolf]

Stem failures have been the bane of my bikes over the years, but it has become a big deal on my heavy ones.


Anotehr possibility is the valve core may not be fully screwed in, or might not be properly seated. Unscrewing it and reinstalling it could fix the leak.


A pinhole leak in the tube somewhere can also cause slow deflation once weight is on the bike or the tube is compressed inside the tire, when it does not appear to leak sitting outside the tire (it does leak, it's just less evident and may be slower).

 

[Ykick]

Inject some Slime and tighten the valve stem core when done. (you might even wanna check the core 1st)

If it still leaks down the slime will probably show you where. The Modern Electric Wheelman should always have spare tubes on hand and good knowledge of tubes, tires, rims, spokes, truing....

 

[dogman dan]

Slime will generally find leaks and plug them, But a new tube that leaks, that I didn't jab a hole in it with a screwdriver, I'd be leery of trusting.

The stem rip can leave you walking for sure. Do check the valve first, just put a blob of spit on the tip and see if it bubbles there. If not there, then mabye put the tube underwater. slime won't work well if the hole is not on the tread side of the wheel. So you want to replace the tube, or put a good patch on it if the hole is on the spoke side of the tube.

 

[itchynackers]

Pull the tube out, inflate it partially. Fill your kitchen sink with water. Put the tube under water. The leak will become apparent. Dry and patch the tube.

 

[electr0n]

This just happened to me yesterday as well. I suggest you try wiggling the valve and reposition it and pump it up again to see what happens before pulling the tube out, this worked for me. I'm not sure why it happens but an otherwise good tube can leak air from the valve if it's not sitting just right in the rim.

 

[Kingfish]

Pull the tube out, inflate it partially. Fill your kitchen sink with water. Put the tube under water. The leak will become apparent. Dry and patch the tube.

I like this method. Don't forget to add a little bit of dish soap :wink:

+1 on the Slime; after my flat tire incident last summer, my spare had a rim flat that I had to fix before installation, and it was a slow leaker. At the next town, I pumped 16 oz. of Slime into and that was that. Tire still holding firm.

~KF

 

[amberwolf]

I'm not sure why it happens but an otherwise good tube can leak air from the valve if it's not sitting just right in the rim.

If that is happening, either the valve core is not seated or you have a leak at the stem taht will eventually rupture under pressure, and it is usually unpatchable, so if you have no spare tube when it does you'll be walking. It might never fail before something else makes you repalce the tube, but it probably will. You cant' get a leak from a good tube (short of a valve core problem), so there *is* something wrong and it is not a good tube.