"Mike Jacoubowsky" wrote in message
...

The "trim" function on nearly all Shimano triple road groups (with the
exception of DuraAce and Sora) works the same way. On the smallest and
middle front chainring positions, you can move the front shift lever
slightly so that it's centered over the chain, eliminating chain rub on the
derailleur. This is really something that should be demonstrated to you, in
person, and if you come across a staff member who's confused by it, by all
means seek out someone else at the shop. Mountain bikes don't have this
feature, and somebody who's totally into mtn biking and nothing else may not
even be aware it's there.

Mountain bikes used to have this feature, with 7sp XT Rapidfire Plus shifters.
I was dismayed when it was discontinued with the 8sp drivetrains. But these
drivetrains can usually be set up so trimming isn't necessary -- as long as you
use all the parts that were designed to work together. Road bikes often have
shorter chainstays, which makes this more difficult.

Of course, Campy Ergo is infinitely trimmable...

Matt O.