Punctures and blowouts at speed - what really happens?

[ianrauk]

Had a front blow out earlier this year. Was doing about 20mph and was accelerating. Very loud bang and instant deflation. Just held my nerve and the handle bars and braked gently. Because the tyre deflated so quick it slowed the bike down very quickly anyway.

 

[Globalti]

Had a front tyre deflate quite fast in the Cape Argus - some local lads were scattering tacks on the road then pouncing on the stopped cyclists and taking the old inner tubes (not sure what for - catapaults?) I stopped OK though and was on my way a few minutes later.

Had a rear tyre go down fast at about 80 mph, two-up on my motorbike once. I had probably squeezed around an island and picked up a nail, we got onto the M11 and got up to speed then I heard a clang as the nail flew out and seconds later I felt the tyre go down. I concentrated on keeping the bike upright and drifted towards the hard shoulder using the front brake gently; my GF got off and asked "Why are we stopping?" then couldn't understand why I went and sat down on the grass to hide my shaking legs!

 

[vorsprung]

Rear wheel blow out - the bike rides very harsh but otherwise so what? I don't think I'd like to corner fast like this though

Front wheel - steering is difficult, braking is difficult, handling is a nightmare. You want to stop, you need to take that bend at the bottom but it's all a bit nasty. Only had one front wheel blow out that was near the bottom of a descent and I'd already scrubbed a lot of speed. There was a twisty bit and a car coming the other way. I managed to stay up right but had to use the grass verge.

This is one of the differences between the beginner rider and the experienced cyclist. The experienced cyclist doesn't mind a rear wheel puncture but the beginner bangs on about how difficult it is to get the wheel out etc.

 

[HLaB]

Touch wood my front failures haven't been too bad. Two weeks ago I was descending 35mph + and some slashed open the side wall of my front tyre, whoosh although noisy it wasn't too bad. Another time I was going dow the Lomond hills at 39mph and I snakebited it was pretty rapid but it was controlable. The worst I've had wasn't actually that bad either, although it freaked folk out, in a tightish pack at about 25mph some pleasant person had left a 1000+ tacks on the Etape Caledonia route one too out my front wheel

 

[badgerjockey]

Ok, so if I'm reading this right, the tube bursts, instantly deflates, the tyre stays on and you ride on the rim covered with sagging tyre?

Doesn't that ruin the rim? Surely you wont be able to just replace the tube and put the tyre back on, you'd have to rebuild the wheel?

I never want to experience this, sounds hellish.

H

 

[doog]

I had three blow outs on my recent tour. One as I left Girona airport another 27 miles later in the mountains and another in Northern France. Each one was like a shot gun going off. It has never happened to me before.

Luckily for me each one was at low speed going uphill, however the bike was an immediate floppy mess, down hill in the mountains would surely have thrown me off.

The rim ended up sitting in the tyre...I couldnt even push it.

The fault was that the Schwalbe Marathon 308's were too big for my rear rim (Mavic open pro) even though the rim said it could take 28mm's.

Before each blow out I heard the inner tube escape momentarily before it went bang...and I mean bang!!...

 

[dan_bo]

The lesson about electrical tape seems a complete non-sequitur to the tale that went before. What was the role of the electrical tape in the brake block coming loose or the front rim overheating under braking?

By the way I don't think the front tube did explode from the heat in an instant. It takes some time for the heat on the rim surface to conduct through the rim body and heat up the tyre to the point where it bursts. It takes a long time and is generally only a problem on long continuous descents needing lots of braking, not short sharp stops. I would look elsewhere for what caused the burst. I'm also impressed by your precognitive powers that allowed you to be screaming as it burst.

Check the smart arse!

The front tyre burst because the heat generated by the braking made the tape around the front rim soft, therefore allowing the 120psi or so in the front tube to push the inner into the spoke holes and causing a burst on a rough edge.


And I was screaming at the lack of back brake on a 35mph descent.

I'll make sure to ask you next time I shoot myself if it's OK to let people know about it.

 

[Dan B]

Electrical tape is pretty darn soft and stretchy in the first place, I doubt the temperature rise from a single sharp burst of braking made that much difference. But yes, get some proper rim tape.