Friday November 21st 2020 – One here for Bob’s big book of bizarre mechanical failures – specifically the ‘This is not my circus, and those are most definitely not my monkeys’ chapter.
This is not my bike. I was asked by an old family friend to change their tyres, as they didn’t feel comfortable to do so themselves. ‘No problem!’ I assured them as they wheeled the bike into the garage.
First step, remove rear wheel and let air out of the old tyre. Simple enough. Since the tubes would be too big for the new tyres, I removed the valve for a full deflation – and the telltale green ooze of tyre sealant – slime brand – bubbled out.
This would be no problem, usually, except the local bike shop who originally fitted these tyres made a mistake.
What I found was only half of the tyre went down – the other half opposite the valve state inflated. That I was astounded and somewhat bemused is an understatement.
Never, ever had seen that before, and it took me a few minutes to work out – with the help of a mate by text – to diagnose that the tube had been twisted when fitted, under inflation the pressure had compressed the two twists, and the sealant blocked them creating an effective seal.
Great. But how do you release the trapped air?
I didn’t want to try puncturing it. Friend suggested a sharp tap with a blunt, soft object on the inflated section, or bouncing it off the floor. I grabbed an offcut of 2×2 and rapped the tire sharply.
There was a loud bang, and a volcanic ejaculation of green sealant.
Everywhere.It went everywhere. It’s just possible there’s an object in the workshop that doesn’t have green slime on it somewhere, but as yet I’ve not found one. A total mess. I was dripping.
The areas where the tube had twisted had clearly worn tissue-thin against the tyre, and the tap with the wood was the straw that broke it’s back.There was no patching THAT tube.
I have never seen this before, and probably never will do again, but it was a messy, if perplexing adventure.
That was a blowout on the road waiting to happen, and the bike shop deserve a slap.
Fixing other people’s bikes is never as simple as you think…