February 24, 2010 3 Comments
In the search for more speed, the cycling community works on defeating the 3 main forces that try to slow riders down: wind, gravity, and friction. There are wheels, helmets, frames, and forks to beat the wind, components & parts to make bikes lighter, and smoother, more fluid parts to reduce friction.
To reduce friction, the industry has now turned to ceramic bearings. Modern external steel-bearing bottom brackets have tested drag of ~4% of power output. Ceramic bearings generate only ½%, helping to save 4 watts per 100 watts generated.
The friction and heat generated by ceramics is lower for a number of reasons:
- Ceramic bearings are rounder and less compressible (50% harder) than the highest quality steel bearing. This allows parts to be made to tighter tolerances giving a smoother motion with less vibration.
- Ceramics do not conduct electrical current and are chemically inert so they do not oxidize and rust like steel bearings.
- Ceramic balls are less porous than steel so they have less rolling friction.
- Ceramics handle heat better than steel (lower coefficient of thermal expansion). Ceramic bearings will expand and contract 35% less than steel bearings in like conditions. In tight tolerance conditions, added heat can cause bearings to expand and cause binding.
- Ceramic bearings are also 40% lighter than steel bearings creating less rotating mass, allowing for faster acceleration and deceleration.
In our new 2010 Scattante road bike line, ceramic bottom bracket bearings are included with the 2010 Scattante CFR Pro Shimano Dura-Ace Di2 Road Bike and the 2010 Scattante CFR Team Dura-Ace 7900 Road Bike.