Shimano's ST-EF50-7R shifters, also known as "Rapid-Fire" shifters, are a combination shifter/brake lever found on many new bicycles. The system is known for its ease of use, low maintenance design and excellent shifting accuracy. However, the system cannot work if the cables that control the front or rear shift are broken or otherwise in disrepair. Learn how to replace the cables in your Rapid-Fire shifters and get your bike back into adjustment and out on the road.
Clamp your bike by the seat post in a dedicated work stand. If one of these is not available, set your bike on its handlebars and seat so you can spin the rear wheel. You need this in order to complete the procedure.
Spin the cranks of the bicycle forward and shift both shifters all the way down by pulling the finger-levers until they stop clicking. The chain should fall onto the smallest cog in both the front and back of the drivetrain. If the cable that needs to be replaced runs to the left shifter, loosen the cable stop bolt of the front derailleur. If the cable that needs to be replaced runs to the right shifter, loosen the cable stop bolt of the rear derailleur. Snip the metal cable end off the cable using needle nose pliers.
Locate the cable stop cover of the shifter that needs its cable replaced. The cable stop cover is a small plastic Phillips head screw just behind the brake lever, near the handlebars. Loosen and remove this screw.
Push the cable through the cable housing backward toward the shifter. The cable will begin to stick out of the hole behind the brake lever on the shifter. Pull it all the way out and set it aside. Slide the end of the new cable through this hole until it appears at the other end of the cable housing. Pull the cable taut by hand and press the thumb lever of the shifter. You should feel a slight tug on the cable if you inserted it properly. Pull the finger lever of the shifter to reset it.
Using a pair of needle nose pliers, pull the cable taut in the derailleur cable stop. Tighten the derailleur cable stop bolt using a five millimetre hex wrench. Spin the bike's pedals forward and shift through the gears to make certain everything is working properly, then take your bike out for a test ride.