Magical deflating tyres.

[LosingFocus]

So Ive been having flat/puncture issues with my bike (as related in other threads so I wont bore you all here). The latest was a completely flat front tyre discovered the morning after an evening ride with a friend round the local woodland, after 7 or so on the back over the last month. They were the cheap Kenda tyres that came on the bike, and the matching Kenda tubes, so I decided enough was enough and that any tyre would be a step up.

So yesterday, after my hols, I replaced the tyres with Conti Mountain King 2.0s and the tubes with standard 26x1.9-2.2 from my local Halfords (quiet at the back).

When each tyres was off, the rim was cleaned and checked for sharps, thorns, nicks, screws, nails... you name it. I was particularly interested on the front as once it was off, the tube seemed OK and to hold pressure. Clean and fresh, the new tubes and tyres were fitted and inflated to 60psi yesterday afternoon. A few times round the garden and drive to check alignment (all good) and bike placed in its usual place in the garage for the night.

Go to check it this evening to make sure all is fine for a ride tomorrow am, and I find both tyres and flat as pancakes.

That cant be right! I havent got time to get the wheels off and check 'em tonight, but I gave them a quick pump and they seem to hold air with no rushing out. I would have suspected a dodgy valve, but that would make 3 in the last week - unheard of.

Any ideas?

 

[screenman]

What type of valve?

 

[Zoiders]

The Halfords valves are shonky.

I picked up a few because I got a voucher as a gift and they won't hold pressure for more than a day.

 

[al-fresco]

Remove the tubes and put some air into them. Feed the tubes into a bowl or bucket of water to see where the punctures have occurred - it might be that they were pinched against the rims by the tyre beads or that they were ruptured by a rough spoke nipple. If it was a defective valve you would also see bubbles escaping there.

 

[LosingFocus]

What type of valve?

Schrader (spl?)

The Halfords valves are shonky.

I picked up a few because I got a voucher as a gift and they won't hold pressure for more than a day.

Ive had a Halfords tube on the back for 6 weeks with no issue with the valve. Also, the first tyre to mysteriously go flat was the Kenda.

Remove the tubes and put some air into them. Feed the tubes into a bowl or bucket of water to see where the punctures have occurred - it might be that they were pinched against the rims by the tyre beads or that they were ruptured by a rough spoke nipple. If it was a defective valve you would also see bubbles escaping there.

I'll do that tomorrow and see if I can see where the issue is. Still confused that this could happen to 3 different tyre and tube combinations over 3 days.

 

[Grizzly]

I had a problem with self deflating tyres on my road bike. Turned out that it was because I had a tiny gap between my rim tape and the hole for the spoke. I'm sure people would argue over the science but it would appear that about an hour after a ride, there would be some sort of movement of the tube, it would pinch in this gap and puncture. It was all very weird but it is worth checking the rim tape.
I've also had repaired punctures where the tube would deflate when in the tyre but when out and inflated the patch would re-seal.

 

[2Loose]

If you can't find any obvious cause, try leaving the valve cap OFF.

After replacing the tubes on my mum's bike she had a similiar problem. Pumped them up and they would stay inflated until the morning. After a few days of this I left the valve caps off and eureeka! A fortnight before pumping up was needed again. It seems that the valve cap was slightly depressing the valve stem.

 

[vorsprung]

Fit new rim tapes

 

[billy1561]

Brand spanking new bike for the missus. 1 ride and back tyre flat as a pancake. Turned out it was the rim tape had moved and was allowing the spokes to rub the tube. Left two very distinct marks.
LBS replaced tube gratis

 

[Midnight]

I've got into the habit of marking the tyre and innertube with chalk when looking for punctures. Then if you locate the puncture, it can tell you where abouts on the tyre/wheel that hidden problems can lie...

 

[LosingFocus]

Quick question... If one doesnt have any rim tape, and it does turn out to be that which is the issue, could I simply use some electrical tape until I can get to the shops?

 

[tyred]

Electrical tape will be fine. It's all I use on my bikes.

 

[LosingFocus]

Electrical tape will be fine. It's all I use on my bikes.

Sweet, as I have a LOAD of that, and stuff all chance of getting an LBS or even H-fords/Evans until the weekend.

 

[LosingFocus]

Small update. I whipped the front wheel off and took it inside for a check over tonight. Tyre of, tube out.

Checked over the wheel inside and out. No little bits of metal, not thorns, nothing.

Checked over the (still new ) tyre. Nothing, clean as a whistle.

Checked the tube. It had deflated to almost nothing since Saturday afternoon. Pumped it up to a reasonable level and put it in the sink. Squeezed it and moved it round. No leaks visible. Did the same with the valve -nothing. Put the valve cap on - still nothing.

So just to be safe I've added some thick electrical tape (2 layers) to the rim to make sure there are no spoke pokes (doubt there is as the the tube was fine).

Tube back in and tyre back on. Pumped it up to approx 40psi with the mini-pump (too lazy to get the track pump from the garage) and its sitting next to me to I can keep watch on it. If this stays OK, I'll tackle the back one tomrrow.

This is very odd.

 

[Nebulous]

I'd almost be beginning to wonder if someone is letting them down!
I had some serial punctures and came to the conclusion it was a tiny piece of flint in the tyre.

Some things I found;

Leaks in tubes can be incredibly difficult to find. I had to go very slowly and really squeeze to find one slow one.

Locating the point in the tyre is a pain, but is really worth. Mark both tyre and tube, as has been said.

It will get better once resolved. I haven't had a puncture in over 500 miles and the frustration has almost gone, or I wouldn't be able to write this.