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Warped rim sidewall?
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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

8/12/18 4:07 PM

Warped rim sidewall?

One of my wheels had a rough feel when braking. II kept thinking it's because the wheel is out of true. After a couple of halfhearted attempt to fix the out-of-true spots without improvement, I finally took it off the bike to give it a "proper truing". I immediately notice a section of the rim sidewall was warped. The side wall was twisted slightly inward, like a car had driven on the wheel! (no, no car had driven over the wheel)

It's an old enough wheel I'm not heart broken to toss it. Just I have never seen this. What might have been the cause? Just wear and tear from long time use? Improper maintenance? It's one of the "light" rims for its time, if that has any bearing. But it has served me quite well for quite many years prior to this.

Yes, the bike had been in one high speed spill. But that was 4 years prior. And it got looked over VERY carefully post crash. It was working fine since. I only noticed the rough braking last summer.

Anyway, just trying to satisfy my curiosity as to how this happened and to look out for it.

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dddd
Joined: 11 Jan 2004
Posts: 3221
Location: NorCal

8/12/18 6:14 PM

Sounds like the wheel may have been traumatized while inserted in some sort of bike rack(?).

I've used giant plumber's pliers over a rim wrapped in thick leather or nylon strap to remedy sidewalls flared out, but wedging them outward to restore braking smoothness seems more complicated.

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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

8/12/18 6:37 PM

Bike is rarely racked.

The usual transport is in the trunk with the back seat down. Occasionally, it goes on the roof rack.

Could it be from landing on rocks? Itís my gravel bike after all. Occasionally ventured into single track.

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ErikS
Joined: 19 May 2005
Posts: 8310
Location: Slowing boiling over in the steamy south, Global Warming is real

8/12/18 7:09 PM

Your last pinch flat did it. You can straighten it using an adjustable wrench. Just go slow. If it as coated rim you won't have any luck, the coating will crack but a machined and anodized rim can be easily fixed.

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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

8/12/18 8:14 PM

The section of warp is long. Like, 4-5Ē long.

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KerryIrons
Joined: 12 Jan 2004
Posts: 2927
Location: Midland, MI

8/13/18 4:47 PM

DIY

As noted, you can straighten with an adjustable wrench, but don't be surprised if you find this a frustrating challenge. Most people would bin that rim.

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dddd
Joined: 11 Jan 2004
Posts: 3221
Location: NorCal

8/14/18 4:19 PM

Just a tip that learned over the years when bending out rim side dings using an adjustable wrench:
Place a thin metal like the long edge of a cone wrench against the outside braking surface before applying the wrench. The wrench will still pull against the inside of the wall, but the tip of the wrench won't ding into the braking surface so the results will be better.
In a perfect world in this case an adjustable wrench would have one jaw longer than the other and the thin metal protection wouldn't much be needed.
I've saved very many "pretty bad" rims and wheels, just to see if I could do it in many cases, everything from dings to sharp bends and flat spots.
April's rim condition is one I have yet to see.

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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

8/14/18 5:59 PM

Iím not at home. So Iíll only get to try it on the weekend.

The braking surface also feels a bit rough. So Iím not sire of the result.

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daddy-o
Joined: 12 Apr 2004
Posts: 3201
Location: Springfield

8/14/18 8:37 PM

Are any of these the technique?

https://youtu.be/r6qXt0lsdUw?t=87

https://youtu.be/Zg4ZFruCfSg

https://youtu.be/uvjFuZ33vqQ?t=35

searches for dented worked better

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 4163
Location: Nashua, NH

8/15/18 5:30 AM

The fact that the braking surface is squeezed inward and is rough leads me to suspect that the rim is worn out, probably cracked and the damage is due to braking pressure, not some form of impact.

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Jesus Saves
Joined: 16 Jun 2005
Posts: 1131
Location: South of Heaven

8/15/18 1:32 PM

+1 Brian's comment -> worn out rim.

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Sparky
Joined: 08 Dec 2003
Posts: 16693
Location: Portland, OR

8/15/18 3:21 PM

Is the brake track flat, or is it concave?

Last edited by Sparky on 8/15/18 5:26 PM; edited 1 time in total

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dddd
Joined: 11 Jan 2004
Posts: 3221
Location: NorCal

8/15/18 3:32 PM

I remember certain Araya mtb rims with a welded joint, where the weld apparently softened the alloy, causing the rim to wear down severely near that one area. Barring any visible crack, if the rim's decal is at the same location, that is always where the weld is. A photo would clarify this.

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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

8/15/18 8:42 PM

brake track is still flat.

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Sparky
Joined: 08 Dec 2003
Posts: 16693
Location: Portland, OR

8/15/18 9:23 PM

Worn out usually means it ain't flat no more...

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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

8/16/18 7:47 AM

I know. Thatís why I checked that first thing.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 4163
Location: Nashua, NH

8/16/18 11:48 AM

You originally stated "I immediately notice a section of the rim sidewall was warped. The side wall was twisted slightly inward, like a car had driven on the wheel".

How can that be true and the brake track still be flat?

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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

8/16/18 12:13 PM

I believe Sparky was asking about the brake track on the rest of the rim. That's what I answered.

If the brake track on the rest of the rim were concave, "the rim" is definitely "done". If not, something else maybe the cause of the warped sidewall. (the rim may still be "done" nonetheless due to other factor)

That was the motivation when I opened the thread and asked the initial question.


Last edited by April on 8/16/18 12:23 PM; edited 8 times in total

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Sparky
Joined: 08 Dec 2003
Posts: 16693
Location: Portland, OR

8/16/18 12:14 PM

"How can that be true and the brake track still be flat"

Flat as in the braking surface plane, as opposed to having a worn concave braking surface is what I meant. The flat braking surface may well be bent in in that spot. As least what I have IMME from what I've read.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 4163
Location: Nashua, NH

8/16/18 2:19 PM

"IMME"?

The brake track doesn't necessarily need to be concave in order for the rim to be worn out. This is a case where a pic or two of the problem area would be extremely helpful.

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Sparky
Joined: 08 Dec 2003
Posts: 16693
Location: Portland, OR

8/16/18 3:22 PM

in my minds eye

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April
Joined: 13 Dec 2003
Posts: 6420
Location: Westchester/NYC

9/8/18 11:25 AM

Update:

(was busy kayaking the last few weeks, forgot about the bike and its rim issue)

Today in daylight, I took a closer look at the warped section. Looks like itís from trama: the braking surface has a bunch of small dimples! (the rest of the rim was clean and flat). I can only guess itís from contact with a rock, somehow.

I guess no point in straightening the warped section. The pitted braking surface will be grabby.

Thanks for you all for chiming in with suggestions. Now I know what to lookfor if the same ever happens again.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 4163
Location: Nashua, NH

9/8/18 11:45 AM

Sounds like time for a new rim.

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Jesus Saves
Joined: 16 Jun 2005
Posts: 1131
Location: South of Heaven

9/8/18 2:49 PM

It's a jungle out there

Snake bite tires, and now snake bite rims....

...either that or you are onto a new idea for areodynamic rims..like dippled golf balls.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 4163
Location: Nashua, NH

9/9/18 7:04 AM

Have you been living under a rock? Dimpled rim sidewalls have been common on aero rims for years.

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