1. Road 10 speed dérailleurs and shifters are completely incompatible with mountain (dyna sys) 10 speed dérailleurs and shifters. The cable pull by the shifters is different for both front and rear.
2. Nine speed rear dérailleurs will not work with 10 speed mountain rear shifters. They will however work with road “flat bar” 10 speed rear shifters. Dyna speed shifters pull twice as much cable per shift as 9 speed shifters, so if you use a 9 speed dérailleur it shifts two gears for every one push.
3. Dyna sys 10 speed rear dérailleurs cannot be used with 9 speed shifters. Road 10 speed dérailleurs can be used with 9 speed shifters.
4. Nine speed front dérailleurs can be used with 10 speed front shifters, but do not work optimally if used with a 10 speed crankset. Nine speed front dérailleurs and cranksets can be used with 10 speed chains and front shifters. A nine speed shifter can be used to shift a 10 speed dyna sys front dérailleur.
5. 10 speed road chains are different from 10 speed mountain (dyna sys) chains. The dyna sys chain is a directional chain that is made to shift better with 10 speed mountain drivetrains.
6. 10 speed road cassettes and 10 speed mountain cassette use the same sprocket spacing