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Assorted Failures, One Rider

Various failures under one rider.

Frame failure unknown make and model. Vigorously used by previous owner, then ridden over 30,000 km.

Frame failed at water bottle boss. This is an aluminum frame with a crimp-in "Riv-Nut™"-style threaded boss. The frame is drilled and the boss installed; the hole slightly weakens the frame and the crimping creates some local stresses. A typical alternative is to weld in a boss. In some cases, the weakening and stress-riser effects of welding and of the boss section may weaken the frame more than drilling a hole and using a Riv-Nut.

Frame failure, KHS Flite 2000. Failed after about 300 km. An identical frame from the same lot broken by the same rider after about 450 km, and another after about 1000 km. Part of a lot of about 20 frames used by a college team; all failed similarly and all after short service. The "trigger" for failures seemed to be a rider power of about 1200 Watts.

The non-broken stay is cracked. It is unclear if this occured before the main failure or as a consequence.

Rim failure, Bontrager Race Lite with ceramic braking surface and off-center spoke bed. Failed in tube bed after about 6 months of vigorous riding. Cracked almost all the way around. Found due to noise while riding.

Rims with ceramic brake surfaces may be more prone to spoke bed failures because the rim is much less likely to be replaced due to brake track wear. However, that was not an issue here as the rim was only six months old and was ridden in a relatively dry climate (e.g., a non-coated rim would also last 6 months or more.

Rim failure, Mavic Crossmax 26-spoke wheel. Several failures in spoke bed.

The Crossmax has 26 spokes and thus relatively high spoke tension. The spoke bed is relatively flat, and thus relatively poor at resisting tension. Some Mavic rims use a socket to transfer load from the spoke bed to the tube bed.

Fork failure, Cannondale "system six". Both sides failed while riding, throwing rider to ground and causing significant abrasion injuries. Fork did not initially fail through, the dangling lower portions were torn off later. About six months use. Cannondale refused warranty on the basis the rider "must have" abused the bike. No other fork fit the frame, so rider was forced to purchase a replacement fork to keep using the frame.