Rim failure last night

[anyuser]

After many years and miles my trusty Mavic X618 on SRAM 9.0 hubs (yes very old) rear wheel rim exploded last night on Wandsworth common waking up all the hibernating squirrels. The rim had finally worn though from braking. Cue a long walk home

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I am thinking of getting some non-disc custom built wheels from Merlin. Does anyone have any advice on the merits of Hope pro3 vs DT Swiss 240s hubs or anything else I should be considering?

 

[fossyant]

Nothing wrong with either hub, but out of preference, I'd get the Hopes - fantastic customer service, and made in Barnoldswick !

 

[661-Pete]

Can't help you with the hub choice sorry, but PLEASE don't let this come anywhere near happening again! Bust rims can be a killer, especially on the front going at speed.

I had this happen once to me, on a roundabout, going slowly. The only hurt was to my pride, fortunately.

Some rims incorporate a wear indicator, a groove or series of depressions. Or use a rim measurement tool. I have something concocted out of a bent coathanger, used with a vernier gauge.

I believe that 0.5mm is an absolute minimum thickness, though maybe others have different views.

 

[anyuser]

@fossyant
Thanks I think I will go for the Hopes, they also look a bit easier to service.

@661-pete
Thanks also. Luckily I felt something wrong with the brakes about 100 yds before it happened so I was going quite slowly. I don't think wear indicators were common when the X618s were made so I will be retiring the front rim too as it is the same age and mileage as the rear. I will measure it at the weekend to see. My new rims will definitely have wear indicators when I choose them.

 

[Trakentoo]

What do the brakes feel like when the rim is just about to go? Are there any obvious signs that I should look out for?

 

[anyuser]

The rear brake was grabbing (slowing the bike) as it went over the almost imperceptible bulge in the rim. So it felt like the brake was on/off as the wheel rotated. I have hydraulic brakes so that transmitted to the brake lever and I could feel the pulsing.

I should add this only happened about 100 yds before complete failure.

 

[661-Pete]

Sometimes you will get no warning at all - especially road wheels with tyres at high pressure.

For those who want to follow the measuring route, there are some helpful tips here on the CTC forum. Note particularly Chris Juden's picture which looks similar to what I made up.

 

[SlowerThanASluggishSloth]

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Have you any idea how many miles the rim had covered?

 

[anyuser]

About 6500 miles in all weathers.

 

[mgarl10024]

Wow - glad you're ok!

My wheels have a black rim-wear-indicator that is recessed into the wheel. Is the idea here that when the indicator is no longer recessed, that the wheel needs to be changed?

 

[the snail]

I believe that 0.5mm is an absolute minimum thickness, though maybe others have different views.

Do you mean 0.5mm wear? 0.5mm rim thickness sounds very thin.

 

[Mad at urage]

You're making me all nervous now!!!

Front wheel has a dish-like rim about 1.5mm off flat on the braking surface - and it has started to pulse on braking (can't see any wheel runout though). I'm getting to old to ride until it breaks!

 

[661-Pete]

Do you mean 0.5mm wear? 0.5mm rim thickness sounds very thin.

I meant thickness. Yes it sounds thin, but rim alloy is amazingly strong: it has to be! To be honest, I scrapped a rim when it was well above the 0.5mm theshold, about 1mm I think it was, but the hub was on its way out. I did say 'absolute minimum', I don't want a whole stack of litigation coming my way!

 

[anyuser]

@mgarl : Thanks I am fine.

I have managed to measure the one that split and it is 0.9mm and the front is at 1.2mm

 

[fossyant]

I've only had one rim crack through wear, but that was 10-15mm and it was retired.

My last rim to meet the 'knackers yard' was actually finished off by a pot hole - bent the outer edge. Was due to be replaced as the braking surface was well worn - just over a year in city traffic every day.