High speed blow outs

TheDrunkMonk

I managed to get out yesterday in some absolutely fantastic weather. While travelling down a long steep hill at 40 mph, my rear tyre exploded. Bit of a bummer, but no real damage done.
My question is: What would have happened if that had happened to my front tyre?
I'm kind of thinking it would be bad, but do you immediately face-butt the tarmac, or is that just a worst case? Can you slow down from high speeds on a flat like that?

cougie

I blew my front descending Alpe D'huez in traffic - the day after the tour.

(memo to self - just 'cos the tyres say 140 psi max - doesnt mean you SHOULD pump them that high)

Dont think I was doing 40 = but certainly over 30. Couldnt steer the bike and was coming into a hairpin - so braking quite hard on the rear and a bit on the front.

Luckily for me - it was a left hand hairpin and there was a bit of a run off.

If it had been the day before - I was descending the other side of the Alpe - unguarded drops and everything.....

Blowouts are pretty rare though - so no need to be too worried.

robmanic1

EJECT! EJECT! EJECT!

crankycrank

It's survivable. Best thing to do is stay in as straight a line as possible, stay as upright as possble (no leaning) and use only the rear brake if possible. Turning and leaning can roll the tyre off the rim not to mention there already is not much traction left on a flat tyre. Braking on a flat will be eratic at best.

chuckcork

Having had a fast flat on the front while going downhill at a more sedate 25mph, on the minimal hard shoulder next to a 100kph highway, I can only say its not that you'll neccesarily crash but you'll be scared witless. Very hard to brake on the front especially when the tyre runs off the rim!

toontra

I had my first front blow-out on a steep hill last week. Bloody terrifying! I braked hard on the rear and gradually increased the brake on the front and concentrated on keeping as vertical as possible. I managed to slow down to about 20mph until the bottom of the hill (250-300 yards) where I could gently run off onto a grass verge. Scary stuff :shock:

STEFANOS4784

:shock: Crikey, scary stuff. What causes a blow out then? It's enough to put me off riding.........well no it's not but still :shock:

El Gordo

Scary stuff indeed. I'm impressed that everyone who's replied here had managed to control it, which must take considerable presense of mind.

Never happened to me though (at anything over 20mph anyway) but not letting tyres get too thin, not over-pressurising and checking brakes are correctly lined up so they aren't cutting into the sidewall are be good things to check quite often.

markos1963

One advantage that wired tyres still have over folders is in this situation, I had a rear folder blow out and it came streight off the rim. As some have said if you keep streight and brake gently you stand a chance.

dennisn

markos1963 wrote:

One advantage that wired tyres still have over folders is in this situation, I had a rear folder blow out and it came streight off the rim. As some have said if you keep streight and brake gently you stand a chance.

On this same vein, tubular tires and tubular clinchers tend to stay on the rims, after
flats, better than regular clinchers.

Dennis Noward

Tootler

I had one doing 79kph (I happened to be wearing a polar 720i HRM so I have the graphs) down a country lane.
I remember nothing about it - and then I regained consciousness and was surrounded by some 'passers-by' and then the ambulance arrived.
I did a full on left sided face plant. Nasty.
In one of the cycling mags around the same time there is a photo of Marco Velo having a very similar crash.
That was 2 years ago and I still have the knee scars and a lump on my shoulder. No broken bones though because I am a double-hard bastard!

Quite a costly affair too; new forks & new wheels for the bike. All my clothes got shredded and so did a pair of Oakleys. About a thousand quids worth all in.

I wasnt even enjoying the ride either.

toontra

STEFANOS4784 wrote:

:shock: Crikey, scary stuff. What causes a blow out then? It's enough to put me off riding.........well no it's not but still :shock:

In my case it was a combination of things. I'm pretty sure I'd picked up a slow/medium puncture somewhere along the ride. That on its own would have been OK, giving me time to realise what was happning. But, the tyre must have been getting soft as I started the descent, and I then hit a pot-hole, which caused a massive snake-bite puncture having the effect of a blow-out (i.e. very rapid total deflation).

So the lesson is to avoid potholes on rapid descents like the plague.

LeighB

I had a tyre go like this whilst riding.
I was a few miles from home on my 25 mile training loop coming through a village at a steady pace when ‘bang’ the front tyre blew; I was pitched over the handlebars and landed on my head in the middle of the road. I picked myself up and a couple of people who were having a barbeque (can imagine the sausages going flying with the shock of the bang!) in their garden came out to help. My wife came out and picked me up in the car.
I had a sore head/neck, a very sore shoulder, a large bruise on my hip/leg and gravel rash on my arm/leg. The bike was ok apart from the tyre/tube.
Lessons learned;
Always wear a helmet, the impact of my landing broke my helmet; if I had not been wearing one it would/could have been a serious injury.
Don’t use ancient tyres as they don’t wear much on the front, the £20 cost of a new tyre is less painful than the potential injuries.
I was riding my fixed gear bike so my speed was limited, if this had happened down hill on my geared bike it could have been quite nasty, I’ve seen 50+ MPH on my computer.

TheDrunkMonk

Thanks for the posts. So, in summary, its definitely a bit dodgy, but not a guaranteed face plant.
As for tyres. It was a newish Continental Grand Prix 4 season indestructable bad boy. I think I'd done about 150 miles on it, and it looks like the tube popped out of the sidewalling. Not impressed.

ivancarlos

I had one last spring on a fast downhill. Managed to stay on but braked so hard there was a strong smell of burning rubber. When I stopped the back tyre was worn through to the canvas so ended up being quite costly :roll:

STEFANOS4784

ivancarlos wrote:

I had one last spring on a fast downhill. Managed to stay on but braked so hard there was a strong smell of burning rubber. When I stopped the back tyre was worn through to the canvas so ended up being quite costly :roll:

What the fnck!!!! These topics really should have warnings, please tell me your brake blocks caused it and not the generall going down a hill!!! :shock:

ivancarlos

STEFANOS4784 wrote:

ivancarlos wrote:

I had one last spring on a fast downhill. Managed to stay on but braked so hard there was a strong smell of burning rubber. When I stopped the back tyre was worn through to the canvas so ended up being quite costly :roll:

What the fnck!!!! These topics really should have warnings, please tell me your brake blocks caused it and not the generall going down a hill!!! :shock:

I don't know, front wheel went bang and I locked up the back wheel braking. No bodily harm done

iain_j

Can continual heavy braking on a descent cause a blowout, from the rims overheating? It's something that goes through my mind on steep, twisty descents.

dennisn

iain_j wrote:

Can continual heavy braking on a descent cause a blowout, from the rims overheating? It's something that goes through my mind on steep, twisty descents.

Maybe, but I'm not sure you could tell what caused the blowout / flat. If that makes any sense? I mean, how would you know the reason it let loose? Things may get a bit tore
up by the time you get stopped and, you might not have a clue as to why. I've done some pretty heavy braking in the mountains trying to slow my fat *ss down but have not had a bad thing happen, YET.

Dennis Noward

iain_j

What I meant was, when it's not a case of the brakes rubbing against the sidewalls, or braking so hard you skid and rip up the tyre... it's when I'm keeping the brakes on hard continually (eg. going down a long, twisty 20% hill), I start to wonder, this must be heating the rims up, will that cause the innertube at least to blow?

dennisn

iain_j wrote:

What I meant was, when it's not a case of the brakes rubbing against the sidewalls, or braking so hard you skid and rip up the tyre... it's when I'm keeping the brakes on hard continually (eg. going down a long, twisty 20% hill), I start to wonder, this must be heating the rims up, will that cause the innertube at least to blow?

I was trying to say "how will you know what happened?". Maybe heating of the rim caused the tube to go, maybe it just blew out on it's own, maybe it had a defect. Who can say, when you're standing there holding a blown out tube, what caused it?. Unless
you saw yourself hit something in the road.

Dennis Noward

ivancarlos

I've heard anecdotes about tyres blowing out due to the heat from braking in the likes of the Fred Whitton because the descents are so steep.

nielsamd

On long steep twisty descents I'd usually alternate control braking between front and rear at least on the straight-ish bits.

markos1963

ivancarlos wrote:

I've heard anecdotes about tyres blowing out due to the heat from braking in the likes of the Fred Whitton because the descents are so steep.

Urban myth
There's not enough weight, speed, braking force or weakness in tyre design for this to happen. Tyre blowouts are caused by punctures in weakened areas of the tube or by collisions with very intrusive road debris.

DaveyL

I've heard of, and seen, tyres blowing on bikes that are parked in the transition area during an ironman event. The athletes turn up at 6 am, set their bike up in T1, pump the tyres up (OK in some cases to a ridiculously high pressure!) then go off for a bit of a swim. Then the sun comes up, it starts to warm up (this was in Tuscany....) and you hear the tyres start to go pop.

So, surely extensive braking during a long Alpine, or steep Lake District, descent could heat the rims up enough to make 'em go?

DomPro

I'm sure thats not an urban myth. It does actually happen if the tyre pressures are already quite high, hot tarmac and continuous braking.

markos1963

DomPro wrote:

I'm sure thats not an urban myth. It does actually happen if the tyre pressures are already quite high, hot tarmac and continuous braking.

Fair enough, name some pro racers that have had this happen on the TDF or Giro or Velta? My point is that if you follow the rules as per manufaturers tyre pressures they can't heat up enough to blow. In these liticious days do you really think that tyre manufacturers would put out products that exploded when they got a bit hot. I'm sure someone in here will know the melting point of vulcanised rubber but it will be far higher than any normal temperature.

alfablue

Not a high speed blowout, but it could have been.

On a descent down a 1200 metre high "hill" in the Pyrenees, my tyre became bonded to the plastic rim tape, punctured after I stopped, could have easily have happened on the descent. The rim tape was completely destroyed and needed chipping off the rim with a screwdriver where it had completely melted then hardened.

Only use cloth rim tape now!

DaveyL

markos1963 wrote:

DomPro wrote:

I'm sure thats not an urban myth. It does actually happen if the tyre pressures are already quite high, hot tarmac and continuous braking.

Fair enough, name some pro racers that have had this happen on the TDF or Giro or Velta? My point is that if you follow the rules as per manufaturers tyre pressures they can't heat up enough to blow. In these liticious days do you really think that tyre manufacturers would put out products that exploded when they got a bit hot. I'm sure someone in here will know the melting point of vulcanised rubber but it will be far higher than any normal temperature.

I'm not sure anyone suggests it's getting hot enough to melt the tyre, just that it's getting hot enough to increase the pressure in the tyre to the extent that it blows.

A quick calculation using the old PV = nRT suggests that the gas in a 120 psi tyre at 23 deg C would need to be heated to just under 100 deg C to take it up to 150 psi. Not sure if that is possible or not, or whether you don't need something so extreme, maybe after repeated braking, the heat dissipation is reduced to such an extent that you can get a localised hot spot and therefore very high pressure. Dunno, just speculating but would be interested to know more!

dennisn

There is always the possibility of poorly seated tire beads or poor tire beads working their
way looser and looser until....... I have had this happen while riding(years ago) and
actually watched the tire slip out of the bead, the tube bulge out into a sort of balloon,
and then BLOOEY. Didn't take long but it was weird to see. Happened to me 2 or 3 more times that same day(on a weekend tour), same tire. Ran out of tubes and patches, said
f*ck it, and hit the sag wagon for the rest of the ride. Haven't used clinchers since.
Thinking back it must have been a bad tire bead or poorly fitting one because the rims were a few years old and had not given me problems before. I sure was p*ssed off that day.

Dennis Noward