Originally Posted by shane45
Hmmm...I'm not sure I'm understanding this.
My chainline is fine using my big chainwheel and the highest (smallest) cogs. My chainline is also fine using my middle chainwheel and the highest (smallest) cogs.
Why is it bad if I am in big (up front) and small (out back) and decide to shift my chainwheel only from big to middle? Again, my chainline is still fine with this combination (using outboard XTR BB bearings).
Simple lever-arm length fact: The smaller your gears that you are in, the higher the tension in the chain (because the chain is running on a shorter "lever-arm"). Higher tension, higher wear. AVOID. get out of the back small cog way before shifting to middle ring. Always run the biggest cogs practical.