The Bicycling Guide to Complete Bicycle Maintenance & Repair by Todd Downs

Author:Todd Downs
Language: eng
Format: epub
Publisher: Rodale
Published: 2010-01-25T16:00:00+00:00

SHIFT LEVER LOCATIONS

The most desirable road bike shifter is the combination brake-and-shift lever (commonly referred to as a brakeshifter) because it allows shifting while climbing and sprinting. In fact, anytime the hands are near the brake levers, it's possible to shift by pushing sideways on the levers, small built-in toggles, or thumb buttons. This ingenious design makes it so easy to shift that you actually shift more often, which helps keep your legs fresh on long rides. Manufactured by Shimano, Campagnolo, and SRAM, the dual-purpose levers are more complicated, more expensive, and heavier than those old downtube levers but provide a huge shifting advantage.

For a long time, the down tube was the standard position for the lever on dropped handlebar bikes. To shift, you reach down to the lever. To some degree, this would lower your center of gravity, maintaining stability while you have a hand off the bar. Also, the cable runs are short and direct, resulting in very fast shifts. Moreover, many down-tube shift levers are designed to mount on braze-on bosses. These fittings are actually part of the frame and can't slip or break like regular band clamps. The bosses give the frame a clean look.

Handlebar-end (also called bar-end) shifters are still found on some long-distance touring bikes. Their positioning at the ends of a drop handlebar is nearly as convenient as integrated brake-shifters. Their real draw, though, is that they retain the ability to switch between indexed mode and friction. In the case of a topple or other situation affecting the rear derailleur’s ability to accurately index from cog to cog, a simple twist of a knob puts the shifter into friction mode so the rider can make fine adjustments until a permanent repair can be made.

There are several types of mountain bike shifters available. Thumb-operated shift levers attach to the top of the handlebar (old style) or under it (modern style). There are also popular shifters that are twistedthrottle style.

The top-mounted shifters are simple, having only one lever on each side that moves forward and back to shift gears. Under-the-bar shifters use dual levers: one for upshifts and another for downshifts. Some designs take two-finger operation: You push one lever with your thumb to shift to a larger cog or chainring and the other lever with your forefinger to move the chain to a smaller cog or ring. Although below-bar levers are a little more complicated to repair and are heavier than above-bar levers, they're standard now because they shift more quickly than above-bar models and allow you to keep a better grip on the bar during shifts.

Shimano also makes integrated Dual Control brake-shift levers for mountain bikes. The lever moves in three directions: Pulling toward the handlebar pulls the brake cable, pushing the lever down with the fingertips pulls the gear cable, and flipping the lever up with the backs of your fingers releases cable. Shimano has mated this system with a rear derailleur with a reverse action called low-normal. The return spring pulls the derailleur toward the largest cog, rather than toward the smallest, as most derailleur’s do.

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