Rear blow out

CarbonCopy

Well i`ve always run tubular wheels on my bike but since buying the Powertap rear clincher and front clincher for training the tubs have just been hanging off the wall.
On changing over i found the ride quality very harsh in comparison.
I run Vittoria cx Evotech tubs.
Clinchers are Conti Attack and Force coupled with conti supersonic tubes.Well they where until the Conti Supersonic blew a huge hole in it self ripping a gigantic six inch slash down the seem of the tube and blew the tyre off the rim.
I think i blew a big hole in the gusset of my bibtights the bang was that loud.
After inspecting the tyre and tube things clearly pointed to tube failure along the seem.
I lost faith in those Supersonic tubes and ordered me some Michelin latex jobies.
After a nice hilly bumpy 50 miler this fine day i can honestly say these are very supple to ride.
Not quite tubs but a very comfortable ride indeed.
I know they loose a bit of air pressure from day to day but the ride quality is worth the trade of getting the track pump out.

blackhands

Get yourself some decent tyres as well and you'll find the difference with tubs even less. How about :

Vittoria Pave or similar from Challenge?

northpole

Pave's aren't my favourite at the moment - I got thrown off my bike following two friends through a corner. They were running Contis 4 season and gp4000 and made it through without incident.

I hope that was a complete one off - fortunately no bones broken but 'interesting' twinges developing. Apart from that incident, pave's are lovely to ride on - just not sure if they are an all season tyre or more summer oriented.

Peter

sungod

to explode, the tube has to be outside the tyre

some possible causes...

tube trapped between rim and bead

bead not seated

not inflated fully, or got a puncture, pressure dropped allowing tyre to roll off rim

tyre damage/worn

rim damaged/worn

if the wheels are new, most likely is you trapped the tube or didn't seat the tyre correctly

Lillywhite

sungod wrote:

if the wheels are new, most likely is you trapped the tube or didn't seat the tyre correctly

I agree. The tube must have been trapped for that to happen. :oops:

CarbonCopy

Tube was`nt trapped i always check these things when blowing them up.None of the above mentioned was the cause.It was clearly a bad tube.The day before it blew i did 47 hard miles on it no problems.I just checked pressure before going out and topped it up a tad.

rake

wider rims give a more tubular type ride. tightens the front end up no end. i cant see a tube splitting could blow the tyre off. there is just as much pressure weather its in the tybe or tyre. i know you checked but it must have been trapped slightly under the tyre bead. even if not trapped it can still be twisted up in the tyre.

sungod

CarbonCopy wrote:

Tube was`nt trapped i always check these things when blowing them up.None of the above mentioned was the cause.It was clearly a bad tube.The day before it blew i did 47 hard miles on it no problems.I just checked pressure before going out and topped it up a tad.

tbh i don't see how a "bad tube" can cause the effect - if the tube is holed, by the time the pressure falls enough to let the tyre come off, there won't be enough left to cause such a violent bang

an internal tube failure won't "blow the tyre off the rim", the tyre is already holding all the pressure, there's no extra force on the tyre if the tube is breached inside it

if the tyre appears to have blown off, it's because, for whatever reason, it came off the bead, allowing the, still fully pressurised, tube to expand violently and explode

might be the thin supersonic tube was forced into the rim-bead area before the bead was seated by the pressure, it is possible to do a lot of miles on a pinched tube

fwiw i don't like the supersonic tubes either, i find they puncture way too easily

CarbonCopy

The massive rip was central down the seem of the tube in a uniform line.?

Monty Dog

I agree that the tube must have been 'stressed' e.g. trapped under the bead or kinked and therefore it would 'blow' at the weakest point - along the moulding seam.

ADIHEAD

CarbonCopy wrote:

Tube was`nt trapped i always check these things when blowing them up.None of the above mentioned was the cause.It was clearly a bad tube.The day before it blew i did 47 hard miles on it no problems.I just checked pressure before going out and topped it up a tad.

Same thing happened to me a couple of years ago, new tyre, 35mile test ride all seemed great, second ride blew tyre off rim! I would guarantee I pinched the tube when fitting the tyre though, despite it being fine the first ride. Ultra thin tubes like Supersonics could easily pinch under the bead without you realising.

CarbonCopy

Right i think i had better wear my specs when fitting tyres and tubes from now on. :oops:

rake

a particularly prone area when i fit tubes is where the valve is fitted, and it moves about when the pump is attached. if you put the threaded nuts onto the valve wait untill the tyre is inflated, it can pull the tube down under the tyre bead when its deflated. i still manage to pinch the tube now and again when being carfull.

Lillywhite

CarbonCopy wrote:

I just checked pressure before going out and topped it up a tad.

Exactly what do you call a tad? I hope you weren't running pressures as high as you may have been doing with tubulars. :oops:
I weigh less than 75 kgs and will never run high pressures above 100psi..

Perhaps this tad of extra pressure you added was enough to blow a trapped inner tube? :oops:

owenlars

CarbonCopy

It wasn't you by any chance who had the blow out down Whitedown yesterday? I was behind someone who had one and it sounded like a gunshot with a big puff of blue smoke. I assumed the tyre had overheated with braking.

CarbonCopy

The puff of blue smoke came from my undies :shock:

Down the Road

Supersonic tubes are built with racing in mind. They are over half the thickness of "normal" tubes. When they blow they tend to BLOW. You can pinch them and not really see and finally they "wear" a bit and BANG. Wait until you get a flat in Latex and you'll be straight back to rubber tubes.

we all used latex tubes 15 years ago but with the weight of modern rubber tubes (50g) most of the older guys swapped to these as they tend not to EXPLODE when punctured