Road Nazi Hunter
Join Date: Jul 2007
Location: Slow! But Ahead of You.
Bikes: Kuota Kredo, Litespeed Vortex, Aegis Victory, Burley Tandem, Cannondale Rush
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BB Width and Cross-Chaining
I am finding a problem with the newer-styled outboard bearing bottom brackets. On my newest road bike, a Kuota Kredo, the extreme width of the bottom bracket coupled with the outboard bearings creates a cross chaining when in the lowest two to three gears. The chainline is fairly extreme to anything but the outside half of the cassette. This situation is aggravated on the big chainring. I am comparing it to another carbon frame, my Aegis Victory with a Campy Record, old style bottom bracket. The chain seems to have fewer obtuse angles. The chain lines up better on the Victory than the newer Kuota. Since cross-chaining creates an energy loss, is this affecting performance? Will all new frames with wide bottom brackets face this challenge? I really noticed the cross-chain with a new chain whose links are still fairly stiff and straight. They hit the front rings at an angle and cause a good bit of noise which would make you believe you were out of adjustment. The carbon frame resonates the sound and it multiplies the volume.
When I pulled the old chain off, I could feel how loose it was side to side, it had stretched in all directions.