Tires blowing out
So - I'm in the middle of a spat out bad bike mechanical luck.
Yesterday, on what was supposed to be my 4 hr ride, I was about 2.5 hours into it when my rear tire blew out.. explosively. I had a spare tube with me, so I swapped it out and started up again. Quarter mile down the road - blowout. Same wheel. At that point, I was out of tubes, so I had to call for a ride home.
I noticed that the tire I was using (continental grand prix 4000s) had its bead on the sidewall blown out and separated from the rest of the tire. Ah ha! The culprit! Perhaps I swapped the tire out with the trainer tire one too many times, and it just wore out the sidewall with the tire levers.
This evening I stopped at the LBS and got another tire (and they will send back the old for warranty replacement - it's coming up on about a year old and only has probably 700 miles on it). Mounted it, pumped it up to my typical pressure, and let it sit on the bike stand.
Couple hours later, I hear it blow out again. Now I am concerned that there is something wrong with the wheel - and of course this is the wheel with my powertap on it (DT Swiss RR465). I spun it around and examined it to the best of my ability, but I don't see any warping or deformation.
I didn't think much of it before, but a couple months ago I had a bike session on the trainer interrupted by the trainer tire coming loose from the rim. It didn't pop, just that the bead came loose from the hook on the rim. Not sure how it didn't blow. At the time I figured I just didn't seat it properly and assumed it was a one time thing. But now I'm thinking maybe it is all related.
So I guess my question is - has anyone had any experience with this type of thing? If I can't see any obvious deformation, is it just that I've been really unlucky with my skills at putting a tire on and getting the tube pinched in between the bead and the hook prior to inflation? I can't imagine that the Grand Prix 4000S tire has a history for popping out, otherwise no ne would spend the kind of money it commands ($75!).
At the moment, I put an old tire on the wheel - a tire with a metal bead, as opposed to the collapsable bead material in the 4000s. With Quassy this weekend and IMLP coming up, I need to determine (quick!) whether that wheel is reliable or not. I plan on bringing the wheel to the bike shop tomorrow or Thursday to see if their more expert eyes see anything.
For what it's worth, I haven't been partially inflating the tube prior to putting the second half of the tire on.. so the process has been: (1) put one side of the tire on, (2) put deflated tube in tire, (3) put second half of tire on, (4) quickly look to make sure bead is 'hooked' and all looks ok. Before tonights blowout, as I was inflating the tire, I did actually stop @ ~20 psi and give a quick inspection to the rim to make sure it looked properly hooked.
Thanks!
Comments
... What if I had a blowout doing 43 mph on the decent into Keene?
Drive 1:15 to the only LBS I trust and talk to the owner. Tell him the ordeal and my panic 2 weeks before my first full Ironman. He figured my problem out - the Wheel Builder rim tape is slightly too wide for the Velocity rim and rides up under the bead lip (as the other side drops into the center spoke trough). Owner hand trims the tape (had to walk down the block to the hardware store for a pack of utility blades - he was all out) then re-assemble the tire/tube/wheel. Never charged me a cent. Must have spent almost an hour with me and my bike. Says "think of it as Corporate sponsorship". I'll be hard pressed to go to another LBS again.....
Pull your tire and look at the rim tape. See if it is riding up into the bead. It may be just enough to let the bead blow out. That was my problem but not any more.
I'll check out the rim tape when I dismount the wheel and tire tomorrow morning. I did glance at the tape before, but I can do so with a more critical eye. Thanks!
I also had the same issue and for me, like others, was the rim tape. This time the tape was too narrow and slide to the side exposing just enough of the hole(s) for the tube to force itself in under pressure. I switched to a proper width nylon rim tape and have had no issues since.
--Larry
Ultimately, the LBS guy says it was probably installation error. I'd love for that to have been the problem, because that just means I was being an idiot. Only problem is that I have to figure out how to NOT be one. He pointed out that there is an alignment marker on the tire, so once it is installed and partially inflated, one can check that marker to make sure there is an even space between it and the rim all the way around the wheel. I mean, I suppose I could have mucked up the installation of the tire 3x in a row, would just be kinda odd after never having an issue like that before.
The tire I had on it last night (the noncollapseable one, with the metal in the bead portion) held up through the night. I guess after I trim the tape a tad, I'll put the new tire in and be more meticulous about installation, and see if it holds. Even if it does, I'm not entirely sure I'll feel like I can trust it, at least until I get sufficient time on it to restore confidence - but that probably wont be until after Quassy this weekend.
I wouldn't mess with trimming the rim tape. Could cause more problems if you trim too much.
Just get the proper size and replace it.