Jagwire inline barrel adjusters are small, plastic mechanisms that are installed between the shifter on your bike and the derailleur that it controls. The inline barrel adjusters allow the tension of your shift cable to be changed and adjusted while you are riding, making it a simple affair to keep your bike running and shifting perfectly. Learn how to install a set of Jagwire inline barrel adjusters and never deal with errant shifting problems on your bike again.
Loosen the cable stop bolt of both the front and rear derailleurs with a 5mm hex wrench. Pull the cable free from the cable stop and, if necessary, snip the end cap off of the cable so that it will slide through the housing.
Slide each cable through the housing toward the shifters on the handlebars. Be sure to pull the cable out of each piece of housing on the bike so that the cables hang only from the shifters. Take note of which pieces of housing are used for which cable.
Slide a short piece of housing (usually packaged with the inline barrel adjusters) onto each cable and up against the shifter. Slide one of the inline barrel adjusters onto each cable and fit the ends of the short housing pieces into them.
Slide the end of each of the cables back through the housing you removed them from. The cable from the left shifter should run to the front derailleur, and the cable from the right shifter should run to the rear derailleur.
Pull the cables taut under the drailleur cable stops, then re-tighten the cable stop bolts to hold the cables in place. From this point on, you can adjust the tension of either cable by twisting the corresponding barrel adjuster either clockwise (tighter) or counterclockwise (looser).