Odd problem on almost new wheels

[CharlieB]

I recently upgraded the wheels on one of my commuter bikes to a pair of Mavic Crossrides for summer use. They weren't wildly expensive but riding home the other evening, suddenly the brakes on the rear wheel made a 'per-revolution' noise.
On closer investigation in daylight, the braking surface has developed a tiny nodule of metal that is obviously causing the problem. It's not on the outer edge of the rim, so I doubt it's pothole damage - it's right in the central area of the braking surface.
These wheels have done less than 250 miles in five weeks - do I just file the little nodule down, return the wheel under warranty, or just wait for it to wear down in its own time?

 

[MacB]

Weird, have you verified it's not something embedded that's giving the impression of being a protrusion? otherwise I'd return under warranty, I wouldn't want to file down and trust to luck.

 

[threebikesmcginty]

I recently upgraded the wheels on one of my commuter bikes to a pair of Mavic Crossrides for summer use.

For summer use???

MacB's right (curse, swear), if it's a fault on the rim you don't want the wheel falling apart under you - take it back.

 

[Fnaar]

I've had those on my back wheel... a friend (who knows far more than me about cycling and stuff) said they were little impurities in the metal... and just sandpaper them off lightly. Worked for me.

 

[fossyant]

Take it off with sand paper. Could be caused by anything, contaminated pads, dirt/grit.

 

[threebikesmcginty]

So is everyone going along with the MacB's wrong theory then?

 

[MacB]

So is everyone going along with the MacB's wrong theory then?

everyone but you Sweetie

 

[threebikesmcginty]

everyone but you Sweetie

A given - it's well known that I know feck all about anything.

 

[accountantpete]

I have always presumed that these were caused bits of debris working onto the brake pad and then kicking up a bit of the rim when the brakes are applied.

As above, I just get some very fine sandpaper and level the surface off.

I'd check the pads for embedded metal fragments as well.

 

[Fnaar]

I'd check the pads for embedded metal fragments as well.

In fact I checked Mrs F's pads only this morning, but they had no debris in them.

 

[threebikesmcginty]

In fact I checked Mrs F's pads only this morning, but they had no debris in them.

You've been busy with Mrs F this morning - if ever a woman suffered!

 

[Fnaar]

You've been busy with Mrs F this morning - if ever a woman suffered!

I found some impurities on her rims, however, but I buffed them up a bit, and now they're ready to roll!

 

[zexel]

I recently upgraded the wheels on one of my commuter bikes to a pair of Mavic Crossrides for summer use. They weren't wildly expensive but riding home the other evening, suddenly the brakes on the rear wheel made a 'per-revolution' noise.
On closer investigation in daylight, the braking surface has developed a tiny nodule of metal that is obviously causing the problem. It's not on the outer edge of the rim, so I doubt it's pothole damage - it's right in the central area of the braking surface.
These wheels have done less than 250 miles in five weeks - do I just file the little nodule down, return the wheel under warranty, or just wait for it to wear down in its own time?

Is it directly opposite to the valve hole?

 

[CharlieB]

Thank you all. Fnaar's post proved correct (sorry MacB). It was a tiny piece of metal had got lodged in the wear indicator groove, now removed.