Tube problem

[Matt2matt2002]

Noticed a flat back wheel on daughters bike
Off with the tire
Inspected inside of tire - nothing sharp coming through
Inflated tube and held it under water section by section slowly turning tube.
No bubbles!
Tried again in a bigger pond of water Slowly turning.
Still no bubbles
Pumped up higher and left over night
This morning - flat tube

Any ideas folks - apart from buying a new tube
 

[JimK]

I had a strange slow leak a couple months back. It was a Schwalbe tube with a Presta value. I didn't realize that the Schwalbe valve core sits on top of the valve stem. I think of valve cores as sitting more inside the valve stem. In turning the little nut that seals the Presta valve, I had inadvertently been loosening the valve core! Once I snugged that valve core back down tight, with a pair of pliers, the slow leak went away.

I hear that a proper wrench is available for those Schwalbe valve cores. One of these days I will have to add one of those to some big order. Otherwise it could be $15 shipping for a $3 item!

[Matt2matt2002]

Thanks Dan - same valve here.
But the bubble factor still defeats me!

[Danneaux]

Thanks Dan - same valve here.

Er, credit goes to Jim for that, but I may be able to offer some suggestions as well.

Matt, when I've had no obvious bubbles...I increase the pressure in the tube. Sometimes, it has required me to inflate the tube to the diameter of my forearm for any small bubbles to appear, but those tiny leaks can be enough to flatten a tube overnight on the bike.

When the tube is under water, be sure to gently wiggle the valve as well and look for bubbles at the base. Sometimes, the valve stem will have broken vulcanization where it meets the tube or can have a tiny split.

Hope this helps.

Best,

Dan. (...who thinks it's sometimes worth blowing the tube waaaaaaay up BIG to find a hidden teeny-tiny leak)

[Relayer]

I had a strange slow leak a couple months back. It was a Schwalbe tube with a Presta value. I didn't realize that the Schwalbe valve core sits on top of the valve stem. I think of valve cores as sitting more inside the valve stem. In turning the little nut that seals the Presta valve, I had inadvertently been loosening the valve core! Once I snugged that valve core back down tight, with a pair of pliers, the slow leak went away.

I hear that a proper wrench is available for those Schwalbe valve cores. One of these days I will have to add one of those to some big order. Otherwise it could be $15 shipping for a $3 item!

I have had these removeable cores come out when unscrewing the dust cap!

However, today I got a puncture, a nail through the rear tyre. I have a Lezyne micro floor pump which screws onto the valve ...

well after putting in a brand new inner tube I pumped the darn thing up to 4 Bar (which took a long long time) and unscrewed the pump hose and whoosh! it was flat again ...

so I tightened the inner core and pumped it up again to 4 Bar, and the inner core came out again. By that time I was beginning to worry I wouldn't be able to inflate the tyre at all  ...

third time I tightened the inner core as much as I could and fastened the pump hose a bit looser; I got some air in then the tyre wouldn't get any harder, so rather than tighten the hose any more I decided to nurse the bike home on a very soft and wallowing rear tyre.

Tomorrow I'll need to research the wrench you refer to Jim and get one; I might also try the Lezyne on a Conti [skinny tyre] inner tube and see how it behaves, could be some mini pump swapping going on tomorrow.

I do like Schwalbe stuff, but if these remoeveable cores won't behave out in the wild with mini pumps then they'll be binned.

Jim

[Relayer]

Quick update: I have just ordered one of these  http://www.parktool.com/product/valve-core-tool-vc-1

This forum is amazingly informative, before I found JimK's post above I never knew such a thing existed.

You guys are great!

Jim

[mickeg]

I also learned that some of my Presta valve cores were removable when I bought the Lezyne pump.  I just use a crescent (adjustable) wrench to tighten them.