2x9 ala PVD
From Pvdwiki
Narrow Range Front Gearing
Finding a crank that will run adequate gearing for a 2x trail bike is a bit difficult. One crank that is almost perfect from the box in terms of gearing is the Ultegra 10 Speed road triple crank. The smaller gears of the crank are 39 and 30. A very good spread.
The Cassette
The Front Derailure
Chainline
The Ultegra 10 speed Triple cranks configured as a twin gear as I have done produces a chainline of 43.5mm. This is pretty bad. It brings the front derailure very close to the rear tire. Adding an additional 2.5mm spacer brings the line out to 46mm. Any more than this is very difficult to acheive.
