Shimano RSX STI shifters are a combination brake/shift lever that allows the rider to control both a single brake and a single derailleur with a single lever. This functionality comes at a price however, as these shifters have very complicated internals that lend themselves to going out of adjustment, causing missed shifts, soft brakes and a myriad of issues. Learn how to repair your out-of-adjustment RSX STI levers and keep your bike working smoothly through every ride.
Pull the lever of the shifter you are having trouble with toward the handlebars to reveal its internal parts. Spray a liberal amount of bicycle part lubricant such as T-9 inside. Work the shifter back and forth to allow the lubricant to settle over all of the internal parts, then take your bike for a test ride. Sometimes this is all you need.
Locate the brake cable stop by following the brake cable from the shifter to the brake that it controls. Loosen the brake cable stop using a 5-mm hex wrench to release the cable and open the brake caliper.
Squeeze the brake caliper closed by hand until the brake pads sit about 5mm away from the brake surface of the rim. If either pad is misaligned with the rim, loosen the brake pad mounting bolt using a 5-mm hex wrench. Realign the pad by squeezing it against the rim, then retighten the mounting bolt. When both pads are aligned correctly, pull the cable tight in the brake cable stop and tighten the cable stop using a 5-mm hex wrench.
Locate the derailleur cable stop bolt by following the cable from the shifter to the derailleur that it controls. Loosen this bolt with a 5-mm wrench to release the cable. Press the black downshift lever of the shifter until it stops clicking, then spin the cranks of the bike forward until the chain and derailleur settle to the smallest cog.
Pull the derailleur cable taught underneath the cable stop bolt and tighten the cable stop bolt using a 5-mm hex wrench. Take the bike for a test ride. Shift through each of the gears and test the brakes thoroughly to be sure everything is working properly.