A hitch in my morning commute

[forrestw]

http://www.youtube.com/embed/VwH3aLqWd-A

Tire was inflated to 120 psi, I think this rim is about 3 years old with about 9000 miles on it. I'm given to inflating on the high end, would have expected this rim to still be up to holding that pressure but I won't have time to go over the brake surface wear for a while.

Happily the wheel kept turning etc and pulling off safely wasn't a problem.

[Louis]

Tire was inflated to 120 psi

That is a lot of pressure. Why so much?

[keevon]

I hate that "starting gun" sound of a tire blowout...

Guessing that the brake track was worn thin. 9000 miles is a good run, especially if you commute in all weather. Worn-out rim + high pressure road tire = ka-blam.

Probably time to replace the other rim, too.

[MattTuck]

Well, it could have happened in more traffic, or going around a curve...


Guess that is a positive way to look at it.

[forrestw]

That is a lot of pressure. Why so much?
Because if I run much lower I get pinch flats or rim damage. It's ca 20psi lower than Sheldon recommends extrapolating from my 220# and sheldonbrown.com/tires.html.

I run my tubular tires higher.

[gearguywb]

Because if I run much lower I get pinch flats or rim damage. It's ca 20psi lower than Sheldon recommends extrapolating from my 220# and sheldonbrown.com/tires.html.

I run my tubular tires higher.

But why? Part of the deal with running tubies is to be able to run a lower pressure.

[palincss]

Because if I run much lower I get pinch flats or rim damage. It's ca 20psi lower than Sheldon recommends extrapolating from my 220# and sheldonbrown.com/tires.html.


Have you ever considered going to a wider tire?

[Louis]

Have you ever considered going to a wider tire?

+1

This is where I was heading when I asked about the high pressure.

[Johnny P]

have you ever considered going to a wider tire?

+1.

[coylifut]

congratulations. You put 10k on a rim, wore down the breaking track and blew the bead off. that thing had to be severely cupped before hand. don't do that again. it's dangerous. yes. a wider tire with less psi would have prolonged it, but not by much.

[Peter P.]

Sorry to laugh; that video was a riot!

I've blown rims before. While I can see how this would lead to an accident, I guess I've been fortunate in that it's never resulted in a crash.

I can understand why everyone is commenting on the high pressure but I'll have to be the contrarian. The high pressure wasn't really the failure-wait long enough and it would have happened no matter how low the pressure was. The rim gave out due to sidewall wear. True, if you ran lower pressure the rim would have lasted longer but eventually it would split.

Unfortunately, rims don't give a clear warning when the sidewalls are wearing thin. Usually if you're real in-tune to your equipment you'll notice a "blip" when you're applying the brakes, but you won't recall bottoming the rim on something, and the blip may go on for a couple months before the sidewall splits. Some rims used to come with minimum wear marks but I felt they were mostly useless or best ignored if I wanted maximum mileage out of my rims, cheapskate that I am!

For your weight and the commuting that you do, I'd say 9k miles is reasonable for a lightweight rim such as the Open Pro. If you're not satisfied, I'd recommend the Open Sport.

In fact, if you think your rim split was something, then I've got a pic for you! My buddy Bob split a rim on a ride and we were too far from any practical support. So we stopped at a drugstore and Bob bought a roll of medical tape. He replaced the tube, pumped the tire to shape, then wrapped the piss out of it with tape. Pumped it up to 50psi. or so (It was a 1.5" tire) and we rode 30 more miles at speed without incident!

[palincss]

A 25mm tire at 90-95 psi is a much more pleasant thing to ride on than a 23mm tire at 120 psi, regardless of rim wear.

[palincss]

Unfortunately, rims don't give a clear warning when the sidewalls are wearing thin. Usually if you're real in-tune to your equipment you'll notice a "blip" when you're applying the brakes, but you won't recall bottoming the rim on something, and the blip may go on for a couple months before the sidewall splits. Some rims used to come with minimum wear marks but I felt they were mostly useless or best ignored if I wanted maximum mileage out of my rims, cheapskate that I am!

For your weight and the commuting that you do, I'd say 9k miles is reasonable for a lightweight rim such as the Open Pro. If you're not satisfied, I'd recommend the Open Sport.


Actually, the Open Sport has a brake track wear indicator.

[Louis]

yes. a wider tire with less psi would have prolonged it, but not by much.

I'm thinking the pressure is more of a ride quality issue than a "help the rim last longer" thing.

I agree that grit + braking is going to chew up the rim whether you're at 90 or 120 psi, and that's probably the root cause of the failure, with tire pressure being a secondary factor.

[forrestw]

Well, it could have happened in more traffic, or going around a curve...

Guess that is a positive way to look at it.
Yep the moment I realized what had happened I was thinking I was very glad (lucky) I wasn't going around a corner at the time.

[forrestw]

Sorry to laugh; that video was a riot!

For your weight and the commuting that you do, I'd say 9k miles is reasonable for a lightweight rim such as the Open Pro. If you're not satisfied, I'd recommend the Open Sport.

In fact, if you think your rim split was something, then I've got a pic for you! My buddy Bob split a rim on a ride and we were too far from any practical support. So we stopped at a drugstore and Bob bought a roll of medical tape. He replaced the tube, pumped the tire to shape, then wrapped the piss out of it with tape. Pumped it up to 50psi. or so (It was a 1.5" tire) and we rode 30 more miles at speed without incident!
No I'm quite satisfied and I've found the open pro to be more durable than the open sport I've been well treated by Mavic's aluminum rims for a long time.

That's a pretty cool hack, had I not been an easy hop by bus from a bike shop I woulda done something along those lines.

[forrestw]

But why? Part of the deal with running tubies is to be able to run a lower pressure.
Avoiding pinch flats is only one part of it. Hand built Al rim wheels can handle a load of about 700 lbs before collapse, local rim damage will start at much lower loads if the rim is allowed to bottom out.

I ride 25 - 28mm tires in the winter, switching to 23s in summer is always a welcome pleasure.

[Fixed]

I would look for a beefier rim IMHO
Cheers

[Bob Loblaw]

Bummer! Glad it didn't end badly.

BL