Cracked Rear Rim

[Alex Jackson]

Has anyone ever seen a rim fail like this:

 

[Alex Jackson]

It's about 4 years old 50 mile a week for 1/2 of the year so 5k miles max all round town: London UK.
Any thoughts?

 

[accountantpete]

That's one of the more usual failures - spokes over-tensioned or more likely sub-standard metal.

BTW that braking surface looks well gone - it's done you a favour!

 

[Alex Jackson]

How do you know when the breaking surface has gone (no wear line on this rim). I've had rims fail on the breaking surface before - expected wear and tear - but I've never seen a rim fail like this. It's a hybrid bike for round town so nothing too daunting. Previous 7 speed screw on rim went round Vietnam for a couple of weeks - killed a few spokes and the bearings / cones needed replacing but rim was still solid. As you say probably a defective / cheap rim. Again I would expect the hub/breaking surface to fail first...

 

[Rohloff_Brompton_Rider]

I had a Mavic xc717 fail like that.

 

[accountantpete]

The braking surface looks to be rather concave from here- I may be wrong.. Put the edge of a ruler against it - if you can squeeze the edge of a folded page of a glossy mag between the two then the surface is nearing the end of its life.

I too have seen quality mavic rims fracture like that and expect it's down to a poor batch.

 

[vernon]

I've just had a Mavic 719 rim fail within 1500 miles with similar problems. I spotted the telltale hairline cracks before the bulges started. Had the rim and spokes replaced under warrantee.

 

[I like Skol]

The original factory rear rim on my GT hybrid failed exactly like this after only 1800 miles of commuting. They were Alex rims which a lot of people suggest are made of cheese. I ended up hand building my own replacement set using 700c Mavic MTB rims and DT spokes, a formula that has worked well on my MTBs over the last 2 decades but these tales of failing mavic rims has unsettled me a little