Who can solve this technical issue for me?

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Who can solve this technical issue for me?

Postby CCS » 24 Apr 2016 13:20

I will start with a simple statement of the facts:

- a month or so ago, I changed from winter to summer tyres on my road bike
- did a long-ish ride - no problems
- put bike in garage; noticed a few days later that front tyre was pancake flat.
- pumped up tyre; thought nothing of it; rode for a few hours with no issue
- noticed again the other day that tyre was pancake flat
- changed inner tube; rode for around 4 hrs on Wed - all OK
- as an investigation, inflated the old inner tube - it still hasn't gone down, so I suspect no puncture
- yesterday, noticed that front wheel (with new tube) was pancake flat again
- swapped wheel - but to investigate, inflated the old one fully.... still fine
- put spare wheel on (different tyre; inner tube etc); rode for a couple of hours - no issue
- left bike sitting in kitchen while I had a bath to relieve mild hypothermia
- just went to put bike away.... tyre on the new wheel is pancake flat (only an hour after it was fully inflated - and has done nothing but rest gently in the kitchen in between)!!!!!

Why, oh why, oh why?????

Series of unrelated coincidences?
Bike is somehow trying to eat its own front wheels?
Poltergeist?
Bike inhabited by evil spirit?
Something completely obvious that I haven't thought of?


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Re: Who can solve this technical issue for me?

Postby Jack Hughes » 24 Apr 2016 13:33

I have to admit I've not bothered to read your post, however, I am confident that the answer is to buy a new bike. Or house.
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Re: Who can solve this technical issue for me?

Postby ris » 24 Apr 2016 13:47

check the valves on the inners? i've had a few where the core of the valve is a bit loose and it slowly loses air. i can imagine this being (feasibly) repeatable across a number of tubes.
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Re: Who can solve this technical issue for me?

Postby Ewan » 24 Apr 2016 19:11

^ checking valve cores was my first thought too...

Also, it can be possible to bend the tip of the valve so that it doesn't sit quite right and can therefore let air escape if the valve top isn't tightened fully.

Also, latex or butyl tubes? Letter ones tend to deflate pretty quickly, but I'm not convinced it would be the explanation in this case.
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Re: Who can solve this technical issue for me?

Postby CCS » 24 Apr 2016 19:16

Jack Hughes wrote:I have to admit I've not bothered to read your post, however, I am confident that the answer is to buy a new bike. Or house.

New house it is then ... will throw in a homework refusing child to the new owner (big falling out today)

I am going with random coincidence/evil spirit as most likely cause. Did find a pointy bit of flint in today's wheel... which must have been picked up on the driveway when I got home. Back to knobbly commuting tyres for me


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Re: Who can solve this technical issue for me?

Postby md6 » 24 Apr 2016 20:44

New child is probably the answer tbh
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Re: Who can solve this technical issue for me?

Postby Kevy427 » 24 Apr 2016 20:48

With your investigation and inflating the inner tubes, did you inflate them to over 90psi whilst out of the tyre? It only takes a few pumps to inflate a non-contained inner tube and this will only contain a few psi which isn't enough to force air out of a (tiny) hole, and if you managed to inflate an inner tube to 90psi without being strangled by the thing as it grows uncontrollably then please post a photo

I had something similar and upon a (very) close inspection of the tyre, a piece of flint had embedded itself in it without actually piercing the inner later but creating a tiny dimple, so when inflated to 110psi, the inner tube was pushing against this dimple and puncturing...

And as others have also alluded to, check the valve core is sufficiently tight as (depending on your chosen method of inflation device) you can unscrew the the core whilst undoing the inflator adaptor. The Leyzene ones have a little black button on them to release pressure in the hose before unscrewing so this doesn't happen. Apparently. Not that it happened to me. Once or twice :oops:
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Re: Who can solve this technical issue for me?

Postby Bopomofo » 24 Apr 2016 23:16

I've had a five pack of tubes where the valve inners all needed nipping up to prevent them becoming mystery slow-punctures.

And only last week I had the front wheel off my Trek, diligently checking the tube in a bucket of soapy water and checking the inside of the tyre only to find no problems, only to think 'Sod it' and put it all back together and sticking 120psi into it. Tiny tell-tale hissing noise from the valve and 10 seconds of swearing and plier action and we're all good to go, holding pressure for a week so far.

Tbh, if spooky stuff is happening with multiple wheels / tubes I'd look at common factors.... so be careful about how you wiggle/twist the adaptor when inflating, and maybe get rid of some of the flint chippings off one's driveway (or have one of the below-stairs staff see to it).
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Re: Who can solve this technical issue for me?

Postby kfjatek » 25 Apr 2016 10:27

+1 for valves. Also - if your tubes are Contis, they typically have a removable valve end, so you may simply need to tighten it a bit.

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Re: Who can solve this technical issue for me?

Postby Seasider71 » 26 Apr 2016 17:16

+1 too for valves,

When you inflate your tyre and ride on it, it actually increases the pressure in the tyre due to heat build up - this is why there are lots of blow outs on hot days, because people inflate their tyre's to 110psi and then with the heat add another 20psi and blow them up.

I learned this from motorcycle racing, they generally only inflate their tyres to about 20psi, by the time they have finished they are running at around 60psi.

When the bike is stationary there is no rolling resistance to the air slowly seeping out of a faulty valve.
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