S bulge in front tire

[li10up]

I have a Specialized Allez 05 road bike with total of about 1300 miles on it. My tires are those that came with the bike. They have Specialized Pro (I believe) on the sidewall. Anyhow, twice now I've had S-shaped bulges in the front tire. The first time the tire exploded. This time I knew enough to replace the tire. So why am I getting these? Is it a poor quality tire? It's my understanding that the s-budge is because of a weakness in the tire. The roads I ride are mostly smooth - a few chip and seal. I did hit some railroad tracks a bit hard the other day...could that cause a weakness in the tire. The LBS guy just shrugged his shoulders. At least they replaced the tire and tube for FREE. Just wondering if I'm doing something to cause this problem...twice. Shouldn't I be able to get a lot more than 700 miles out of a tire? No problem with the back tire so far.

[DebW]

Normally back tires wear out alot sooner than front tires. Often a front tire can last 2-3 times as long as a rear. So your problem is unusual. When you say the tire has a bulge, is the tire casing enlarging at some point, or is the tire lifting away from the rim? If the former and the bulge is a weakening in the casing, you either got a bad tire or it was somehow damaged. Hitting bumps or RR tracks when underinflated might do that kind of damage, or might cause a pinch flat. Also, check if your rim might have been damaged by the RR track. It might have a flat spot (not round if you look from the side) or the rim may be spread too wide at one spot. You would probably notice rim damage when braking. That type of rim damage could make the tire not seat properly and blow off the rim. Another bit of advice is to always get your butt off the saddle before hitting RR tracks, balance your weight between your arms and legs, and keep them bent to absorb the shock. Maybe you already do this, but occassionally we are all surprise by some road hazard and take a bump too hard.

[ridebikeme]

That's definitely good advice about riding across railroad tracks. It sounds to me as though you broke a cord in the tire. At any rate, it's great that the shop replaced it for you!!

[li10up]

That's definitely good advice about riding across railroad tracks. It sounds to me as though you broke a cord in the tire. At any rate, it's great that the shop replaced it for you!!

I do stand when crossing RR tracks or anything rough to try to absorb the shock. Do you really think hitting the tracks hard could damage the tire? I thought they should be able to take that kind of shock.

Rim seems to be true. Tire just kind of pushed off to the side in one area.

[ridebikeme]

It's hard to determine what exactly happened.... you would think that a tire could withstand that force. However, if it did indeed break a cord/bead, there could have been a weak spot there from the manufacturing process( doesn't happen very often)or simply the force of the tire hitting the railroad tracks and hitting the rim at the same time. I quess the most important thing is that the shop supported you and you are back riding at no additional costs! It generally doesn't happen that way when you buy mail order, and I 'm sure your LBS appreciates your support!!

[spokewench]

Hard to tell what is happening with your tires. I bought Specialized Pros last year and am still riding them. Tires last forever for me as i am only 125 pounds but I have seen s bulges in tires. Usually if it is premature, i.e. not too many miles on them, I really think it is a manufacturing defect. But, if you rode them 6 months, time to anty up for new tire. In any event, if there is an s bulge by all means replace the tire - it is not worth crashing!

[DebW]

I do stand when crossing RR tracks or anything rough to try to absorb the shock. Do you really think hitting the tracks hard could damage the tire? I thought they should be able to take that kind of shock.

Rim seems to be true. Tire just kind of pushed off to the side in one area.

Guess you'll never really know the answer to that. Your tire problems could be completely unrelated to the track, or a direct result. All you can do is be more cautious in the future. Keep your tires well inflated. Slow down more for the track. Unweight your front wheel just before it hits. And when you hit something and get that "I hit too hard" feeling, try to learn from it. Good luck, and may your future flats be few and far between.