Weird exploding tires - Cycling Mob: Road Cycling, Mountain Biking and More

08-19-2004, 07:02 PM

Hello All

Hope it's alright to cross-post this to these two groups.

I have a very strange problem all a sudden on my old, trusty Fiorelli 10
speed (I have a 23 lb alternative machine, but this old, heavy bike just
feels right). I just repacked the hubs and replaced the tires and tubes.
Though I have old steel 27 1/4 rims, I have for decades used 27 1/8 100lb
tires for the higher pressure.

This has never been a problem until now. I mounted the front tire about a
week ago (set to 105 recommended pressure on Avenir Discovery Korean-made
tires). That went fine. Today, I mounted the rear tire and brought it up to
105. After about 5 minutes with the bike sitting by itself, the sidewall on
the rear one literally lifts out of the rim, blowing out the new tube. I
decide to try again. This time I take it up only to 90 lbs. About 10 minutes
later... the exact same thing! The tire lifts out of a section of the rim by
itself and the tube blows. I was down the block with a friend, and we could
hear it happen with the bike in my house and the door closed. Sounded like a
gun going off.

I can't figure out the cause. (I made extra sure that I did not catch any of
the tube under the sidewall when I mounted the tire). I'm 49 and have been
riding this bike since I was 17. I never saw a tire pop out of a rim like
this on its own. Tomorrow I'll mount an old tire and my last tube, just to
see what happens. But has anyone seen this before? The only possibilities I
can think of are:

1) Using narrower 1 1/8 tires in 1 1/4 rims? (Never been a problem before
.... plus the front holds fine)
2) Some kind of defect in that rear tire
3) These are cheap tires with weak sidewalls or something. They were
inexpensive ($13). I've not used this brand before. But the front one hasn't
blown at full 105 lbs
4) Something suddenly wrong with the rim? It looks ok.

Any thoughts appreciated, especially if you've seen this before. I hate
blowing out tubes and REALLY don't want to blow out one of my ear drums.
Fortunately, in both cases so far, I was well away from the bike.

Thx

--
Regards,
Anthony Giorgianni

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