Bizzare Tire Wear

On 16 Feb 2004 04:31:42 -0800, (Tony) may have
said:

Hello, have a question that is puzzling me and I hope someone can
help.

I have a 99 Specialized StumpJumper Comp. I commute to work in
Michigan, about 2.75 miles each way. It is cold out but the sidewalks
are usually clear, maybe ride a little ice and packed snow at
intersections.

My question is my rear tires are getting these weird diagonal lines on
the sidewalls where the tire just seems to be thinning out. This
first happened on a Hutchinson Alligator. I only noticed it when a
few of these wearing out bands got so bad that the tube was actually
bulging out. So, I switched it out for a Specialized Dirt Master comp
which is on a different rim. Now I am noticing the same wear pattern
on this second tire.

It is multiple diagonal lines that run almost the entire sidewall.
They are spaced less than an inch apart and it just looks like it is
wearing out. I thought at first it must be rubbing but I can't see
anywhere that the tire doesn't clear the frame and the brake pads
aren't far enough out to cause it. It is not abrasion from rocks or
whatever because I am riding only on the sidewalks and roads, and only
very occasionaly these aren't cleared of snow. Is it the cold?
Haven't had any problems with the front tire though, still has the
Hutchinson on it and no problems.

Any Ideas?

If you ride on the big rear cog or small front cog a lot, I'd look at
the possibility of lateral chain slap, possibly due to a stiff pivot
on the rear der. This is just a guess, but that's where I'd start.
Also, look for a front der cable end that might be rubbing on the
tire. beyond that, you've got a real puzzler...and I wouldn't give
better than one in 20 odds of my suggestions being the cause.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

Rick Onanian wrote in message . ..
On 16 Feb 2004 04:31:42 -0800, (Tony) wrote:
It is multiple diagonal lines that run almost the entire sidewall.
They are spaced less than an inch apart and it just looks like it is
wearing out. I thought at first it must be rubbing but I can't see
anywhere that the tire doesn't clear the frame and the brake pads
aren't far enough out to cause it. It is not abrasion from rocks or
whatever because I am riding only on the sidewalks and roads, and only
very occasionaly these aren't cleared of snow. Is it the cold?
Haven't had any problems with the front tire though, still has the
Hutchinson on it and no problems.

Any Ideas?

Are you keeping it inflated well, near or at it's maximum rated
pressure? Do you weigh a lot?

Sounds like what would happen to a terribly underinflated tire if
you rode on it for too long and were lucky enough not to have to
replace the tube daily.

Maybe terribly beat up bearings would allow the wheel to rub the
frame when weight is on it, but not when you spin it by hand. Try
looking down while you ride.

actually, one of my friend was riding his mountainbike always with
highly _overinflated_ tires (like 6 bars instead of 4 as in its specs)
when he was riding on paved roads. His tires started to produce such
lines on the sides (the pattern of the threads that form the base of
rubber compound) after a month or two. i believe underinflated tires
would have other, more eye-catching symptoms like excessive wear of
the tread.

but the problem definitely has to do something with inflation.

one hint: if you're inflating your tires at gas stations, beware that
usually gas station pressure meters are not at all correct! the
biggest difference I measured was 8 bar (shown at the gas station) vs
5 bar measured with a trusty piece of equipment.

Frank
www.plitkorn.com