Tires Blew , One Tube is Good, Why?
10-28-20, 09:39 AM
#1
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Tires Blew , One Tube is Good, Why?
I have searched for similar threads and not found quite the same situation. On Sunday I headed out on a 40km ride, only about 2 km from home I hit a nasty pothole (long, narrow, deep inline with travel, not paying attention) I instantly knew my back tire was flat. I had one spare tube and replaced the rear tube, as soon as I stood the bike up I realized the front tire was flat too; so I shrugged and started walking the bike home. The next morning the rear tire was flat again. Yesterday afternoon I took the bike out to my shop to get it mobile again. The replaced rear tube was flat because it was a faulty patch job. the front tube obviously had a pinch puncture. The real mystery was to rear tube I replaced on the road ( 700C Presta) It did not have any hole in it! I fully immersed it in a pail of water to check. for leaks. My only explanation is that the air suddenly blew out the valve, on examination the Presta stem was turned out, I had either forgotten to tighten it the last time I added air, or it had worked loose. My question is, could the inertia of a sudden speed reduction have cause the valve to move in and release air? This really doesn't make sense because any sort of impact should have increased pressure. Is it possible that ultra high pressure from an impact could blow past the valve? I blew up the tube as much as I thought was reasonable ,been sitting on my workbench ever since still inflated. Could there be a leak at higher pressures ? I find this hard to believe given how quickly my tire went flat.
10-28-20, 09:55 AM
#2
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I recently had something similar with a presta valve.
Tire went flat, couldn't find a leak, so I just replaced it. Being an engineer, I wanted to find the source of the leak, though, so it wasn't until I submerged the stem that I saw air coming out the top of the valve. Not a lot of air, but enough that it would deflate after about 3 hours.
I took the valve out completely, cleaned it, and re-installed it, and it seems to be hold air again. I'm not sure what caused it, but it could be anything.
Tire went flat, couldn't find a leak, so I just replaced it. Being an engineer, I wanted to find the source of the leak, though, so it wasn't until I submerged the stem that I saw air coming out the top of the valve. Not a lot of air, but enough that it would deflate after about 3 hours.
I took the valve out completely, cleaned it, and re-installed it, and it seems to be hold air again. I'm not sure what caused it, but it could be anything.
