Originally Posted by hypersnazz
The torque on the chain doesn't change, since the gear ratios are the same. The forces applied to each individual tooth are greater, causing faster wear on *both* chain and gearing. However the advantages of micro gearing (increased impact durability and smaller drivetrain profile) far outweigh the wear issue, which is actually pretty minimal. Check your chain every couple months with a ruler, replace it on time and your drivetrain should last a good long time.
Yes it does, the amount of force on a chain running a 25/9 is nearly twice the force on one running 44/16, it's simple leverage.
To that you have to add the fact that there're less teeth to carry the load and you get worn sprockets, ****ed driver bearings and broken chains.