Tyre deflating

General cycling advice ( NOT technical ! )
AlastairS
Posts: 510
Joined: 15 Aug 2011, 3:24pm
Location: Aberdeen

Tyre deflating

Postby AlastairS » 16 Feb 2015, 1:26pm

Hi I have 37mm Vittoria Voyager Hyper tyres on my bike.
I think I have Vittoria lightweight tubes.
I usually inflate the front to 40 psi and the rear to 60.
But if I inflate the front more to about 45psi, the next morning the tyre is flat!
The front tyre will keep its pressure for days if I inflate to 40.
Do you know what's likely to be causing this ? Thanks, Al

andrewjoseph
Posts: 1420
Joined: 17 Nov 2009, 10:48am
Location: near Afan

Re: Tyre deflating

Postby andrewjoseph » 16 Feb 2015, 1:34pm

I think you may have a puncture that the extra pressure is forcing open.
--
Burls Ti Tourer for tarmac
Saracen aluminium full suss for trails.

AlastairS
Posts: 510
Joined: 15 Aug 2011, 3:24pm
Location: Aberdeen

Re: Tyre deflating

Postby AlastairS » 16 Feb 2015, 1:46pm

Thank you andrew, pretty obvious really, but not for me.

User avatar
CJ
Posts: 3093
Joined: 15 Jan 2007, 9:55pm

Re: Tyre deflating

Postby CJ » 16 Feb 2015, 1:57pm

andrewjoseph wrote:I think you may have a puncture that the extra pressure is forcing open.

Almost certainly.

Could be a displaced rim tape (so a bubble of innertube extrudes into nipple socket and pops) or improperly seated valve (so little bubbles of innertube extrude under it from either side and occasionally burst), or suchlike.

I used not to bother with those valve securing rings, taking my cue from Michelin when (for a while in the '90s) they ceased to provide them - or even any threads on their valves, relying on inflation pressure to snug the valve down into the rim well. But since damaging a couple of tubes in the latter manner, I now use them again - and I note that Michelin valves now have threads again.
Chris Juden
One lady owner, never raced or jumped.

User avatar
cycleruk
Posts: 5532
Joined: 17 Jan 2009, 9:30pm
Location: Lancashire

Re: Tyre deflating

Postby cycleruk » 16 Feb 2015, 3:29pm

Take the tube out, but before you do make a note of the tyre to tube orientation.
Make sure you know which way round the tube is so that when you locate the puncture you can find the same spot on the tyre. That way you can check the area on the tyre for whatever caused the puncture.

Pump up the tube and put it in a tub of water (basin bucket or sink) and look for tell tale bubbles. If it is a thorn then the hole may be very fine and will take some finding. Now match up the hole position to the tyre and check for the cause.
You'll never know if you don't try it.

Brucey
Posts: 42162
Joined: 4 Jan 2012, 6:25pm

Re: Tyre deflating

Postby Brucey » 16 Feb 2015, 3:49pm

I have experienced the same kind of deflation syndrome with patches that lift, allow the tyre to deflate, then seal again (for a while).

If you have any patch on the inside of the tube, and/or the tube is at all stretched when the tyre is inflated, then patches are apt to lift in this way.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

AlastairS
Posts: 510
Joined: 15 Aug 2011, 3:24pm
Location: Aberdeen

Re: Tyre deflating

Postby AlastairS » 16 Feb 2015, 7:34pm

Thanks for help, will try at weekend with water in basin - no patches on tube at moment.

fatboy
Posts: 3456
Joined: 5 Jan 2007, 1:32pm
Location: North Hertfordshire

Re: Tyre deflating

Postby fatboy » 16 Feb 2015, 8:01pm

I'd chuck the tube and start again!
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly

Vinko
Posts: 180
Joined: 27 Feb 2014, 7:11pm

Re: Tyre deflating

Postby Vinko » 16 Feb 2015, 8:58pm

Yesterday I fitted an brand new inner tube. It stayed up all night, checked pressure again this morning and today I went out for a ride.

Did about eight miles and.....



........"B A N G " ....(was quite a bang too!)



inner tube.JPG




I am glad I have just read this thread though as I was a bit puzzled - so thanks to CJ for his suggestion above.
Now I think about it, it didn't feel right when I fitted the tyre/tube and I so guess (in fact am fairly sure) the valve didn't seat correctly and some of the tube got trapped.

Lesson learnt !

(Fortunately I had a spare tube and pump with me and able to get home!).

User avatar
NATURAL ANKLING
Posts: 12421
Joined: 24 Oct 2012, 10:43pm
Location: English Riviera

Re: Tyre deflating

Postby NATURAL ANKLING » 16 Feb 2015, 10:16pm

Hi,
Vinko wrote:Yesterday I fitted an brand new inner tube. It stayed up all night, checked pressure again this morning and today I went out for a ride.
Did about eight miles and.....
........"B A N G " ....(was quite a bang too!)
inner tube.JPG

I am glad I have just read this thread though as I was a bit puzzled - so thanks to CJ for his suggestion above.
Now I think about it, it didn't feel right when I fitted the tyre/tube and I so guess (in fact am fairly sure) the valve didn't seat correctly and some of the tube got trapped.
Lesson learnt !
(Fortunately I had a spare tube and pump with me and able to get home!).

That also looks like some I have had, one after the other on inflation............... :? ........very small burrs on the largest diameter of the rim, so small I missed them even with my fingers, take a good look.
NA Thinks Just End 2 End Return + Bivvy
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.

reohn2
Posts: 40642
Joined: 26 Jun 2009, 8:21pm

Re: Tyre deflating

Postby reohn2 » 17 Feb 2015, 9:09am

fatboy wrote:I'd chuck the tube and start again!


I never understand this reasoning.
A patched tube is every bit as good as new one,I have some tubes with quite a few patches on them and at the rate I puncture(about twice a year on average)they're quite old tubes,but they still stay up and keep trundling on.
I can count on one hand the number of patches I've had fail or lift and invariably they've been the C cure ones.TipTop patches(the ones with the orange zig zag edges) are,well,err, tip top,if applied correctly.
-----------------------------------------------------------

beardy
Posts: 3382
Joined: 23 Feb 2010, 4:10pm

Re: Tyre deflating

Postby beardy » 17 Feb 2015, 9:58am

Yet that particular tube is deflating itself and we dont know why so his reasoning is perfectly sound.

My personal suspicion is that the valve stem is partly separated, this can be tested by holding the tube and wiggling the valve and then you see the gap open, yet it can still hold air when in the correct position.

I have had mystery deflations before, I go through the puncture routine and find nothing, so you return the tube and think "what a mystery". It has happened while I am cycling, ruling out pranksters.
I am not blessed with a good enough memory to recall how those particular tubes got on after that, yet they performed well enough at the time.

I can understand that if you dont want to do additional puncture stops you would just throw away any such suspect tubes.

User avatar
mjr
Posts: 16585
Joined: 20 Jun 2011, 7:06pm
Location: Norfolk or Somerset, mostly
Contact:

Re: Tyre deflating

Postby mjr » 17 Feb 2015, 11:03am

reohn2 wrote:A patched tube is every bit as good as new one,I have some tubes with quite a few patches on them and at the rate I puncture(about twice a year on average)they're quite old tubes,but they still stay up and keep trundling on.

Indeed. Keep the spare tube in reserve to deal with punctures like Vinko's!
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.

karlt
Posts: 2244
Joined: 15 Jul 2011, 2:07pm

Re: Tyre deflating

Postby karlt » 17 Feb 2015, 1:09pm

Vinko wrote:Yesterday I fitted an brand new inner tube. It stayed up all night, checked pressure again this morning and today I went out for a ride.

Did about eight miles and.....



........"B A N G " ....(was quite a bang too!)



inner tube.JPG




I am glad I have just read this thread though as I was a bit puzzled - so thanks to CJ for his suggestion above.
Now I think about it, it didn't feel right when I fitted the tyre/tube and I so guess (in fact am fairly sure) the valve didn't seat correctly and some of the tube got trapped.

Lesson learnt !

(Fortunately I had a spare tube and pump with me and able to get home!).


Looking at that I can virtually guarantee that some of the tube was trapped. I did it once fitting some new tyres; colossal bang as I hit 80psi.

User avatar
NATURAL ANKLING
Posts: 12421
Joined: 24 Oct 2012, 10:43pm
Location: English Riviera

Re: Tyre deflating

Postby NATURAL ANKLING » 17 Feb 2015, 2:52pm

Hi,
Do you inflate the tube to form the inner tube to shape then place it in the tyre :?:
Splits like that can be trapped tube.
But mystery deflations where even pumping inner tube right up bigger than the tyre and immersion in water with no bubbles mean you have to bin it.
NA Thinks Just End 2 End Return + Bivvy
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.