Titanium Frame Fails at Bottom Bracket

See other failures under 000.html.

Titanium Carl Strong frame failed at bottom bracket cluster.

From http://piaw.blogspot.com/2010/09/my-strong-frame-is-dead.html as of 2010/12/11.

The rider was on a small bridge and heard and felt a "snap!" and found the bicycle had shifted from the middle to small chainring and continued riding although the bike "felt a bit funny". On later examination, the chainstay was broken part-way around. On yet later examination, the bottom bracket was cracked across both the seat and down tubes. Note these are separate cracks, not one long crack.

The cause of failure is unknown; the frame was replaced under warranty, albeit with one using straight-gauge rater than butted tubing.

A similar-looking bottom bracket failure of a titanium frame from another maker was explained by the maker as due to frame tubes welded only where visible — but not welded in the "hidden" area between the seat tube and down tube. That frame was also replaced under warrantee by it's maker.

The bottom bracket crack is not connected to the chainstay crack. It is possible the bottom bracket failed and that caused additional flexing, and the spoke holder served as a stress concentrator for the added flexing.

The water bottle boss on the down tube is a Riv-Nut™ or similar insert, not a welded boss.

Rider weight approx. 65 kgf. Bicycle used approx 25,000 km including hilly light touring. Rider's typical riding style more "sit and spin" than "stand and grunt".