Broken nipples on Mavic X819

[MoreTrails]

Hey Mongoose dude, glad to hear the LBS got your wheel sorted! Have a lekker race...

[mongoose_dude]

YAY! Seems that the blokes at my LBS managed to fix the rim... Six new spokes and a lot of patience. Hope it's stable and lasts.

 

 

 

Thanks, MoreTrails... And thanks again for your offer with your wheelset. Good man!

 

 

 

Have a good weekend, peoples. And to those of you doing Karoo2Coast: Good luck and I'll see you there!

[Johan Bornman]

Hi guys

I have a pair of Mavic X819 rims' date=' and managed to land so hard on a rock that I literally ripped 6 of the nipples out of the rim. It seems that some of the nipples snapped, leaving their thread inside the rim. Others might actually have stripped the thread of the rim.

Any advice / ideas? I suppose one could get the broken nipple-threads out of the rim with a reverse-thread thingie... But if the actual threads in the rim are stripped, I suppose the thing is farkt! Ai - awesome timing.
cut cut cut

 

QUOTE']

 

A whole bunch of things here don't make sense:

 

1) The nipples broke upon landing. Nipples can and do break in tension (but mostly from fatigue), but landing hard only reduces tension in the bottom few spokes whilst the tension in the rest stay static. No nipples will break off from landing hard.

 

2) The nipples were ripped out of the rim. Then the rim is damaged. Especially if like you say, they stripped the thread out of the nipple collars that screw into the rim. In this case the rim is permanently damaged and cannot be fixed. Yet yours were fixed.

 

3) Some of the nipples broke off at their heads (your words: the nipples snapped, leaving the thread in the rim). If this is the case, then you simply unscrew the nipple collars, shake out the broken pieces and replace the nipples.

 

4) You say 6 spokes were replaced. Why? Only the nipples broke?

 

You don't say whether this was a front or back wheel, but doing a trick like this on a suspension bike will also break other components, even if just the bottom-out bumper inside the fork.

 

You also don't say if they were brass or aluminium nipples.

 

If I have to reconstruct what happened here from your description I'll guess thus:

 

1) The wheels were undertensioned by a large margin. Your landing exceeded all the available tension in the load affected spokes (the bottom 5 or so) and therefore the bottom spokes went completely slack and perhaps even started to bend in compression. At this point the wheel would have collapsed. Did this happen?

 

2) Once the wheel collapsed, the top spokes were suddenly jerked into higher tension and broke a few fatigued aluminium nipples.

 

3) None of the nipples were actually stripped. The heads broke off but the thread was intact.

 

It would have been an interesting case to examine and reconstruct, but I suppose all evidence is now lost?

 

 

 

[JPW#]

I love the Mavic rim's but their just too expensive these days, for half the price I bought a pair of DT's , not at the LBS though they want 1k for a DT rim...haha madness! CRC rocks!