Spokes.

[NYEngineer]

I've been riding the same Cannondale mountain bike for about 15 years now. It's been completely overhauled twice. The last rebuild, it got Mavic 217 rims with 14 guage stainless spokes and brass nipples. I can't use aluminum nipples since I weigh about 260 pounds. Lately, the bike hasn't felt very good, I'm in the market for a new one, so I've sort of neglected Old Reliable. The other day, while riding, it felt very unstable. I get off and inspect the wheel when I notice about half the spoke nipples are down inside the rim. I tightened them up to finish the ride, got the wheel trued today for 15 bucks and the bike feels unbelievable. What a difference, like it's old self. My stepson better watch out. The old man's gonna give him a run for his money.

 

[oilboy123]

Kinda scary they loosened up by themselves?

 

[NYEngineer]

That wheel owes me nothing. I built it 12 years ago and this is the first time it acted up. It's all cinched up with purple Loctite now.

 

[wantin150]

Scary to think what could have happened if you kept riding!

 

[NYEngineer]

It coulda been ugly.

 

[rpn453]

Loose spokes are usually caused by a poorly-built wheel or a very flexible rim. Some high-end Mavics, including the 517 and possibly the older 217 as well, are prone to long cracks on the inside (where the tube contacts the rim). Those cracks would make the rim very flexible. Have a look for cracks next time you have the tire off. Of course, it's also possible that they just loosened up due to a high level of usage, or that the 217 is simply too light for 260 pounds!

 

[NYEngineer]

I checked the rim for cracks. It's fine. This wheel is about 12 years old, so it owes me nothing.