The Shims in question don't reduce the travel of the brake lever, they bring the brake lever closer the the bar, but the travel is the same.
This is what is used on Terry bikes, a Female Only bike Co, check what they say about shims
Isis uses the Shimano Ultegra compact group, 50/34 chainrings paired with an 11/28 10-speed cassette. Twenty gears with enough high and low to accommodate a variety of terrain. The shimmed Shimano brake/shift levers give you an easy reach to the brake levers.
http://www.terrybicycles.com/Bicycle...mance/Isis-Pro