You just bought a new bike, and it shifts like a dream, crisp and clean. But lately, there’s been a slight hesitation when you click the handle; sometimes you have to click it twice. Don’t get alarmed, it’s very common. You can fix it on the fly.
Bikes rely on cables for shifting — cables with just the right amount of tension. Even the best Dura-Ace derailleurs won’t shift clean without proper cable tension. The problem is a result of cable stretch, worn parts or a combination of factors causing your bike to shift sluggishly.
Barrel adjusters are built-in solutions to cable tension. They look like serrated knobs, specifically designed to be twisted using only your fingers.
They’re located where the bare cable exits the plastic housing on the downtube, the rear derailleur is the cable on the right side of the bike. If you’re not sure what to look for, or have questions about the difference between a brake cable and a shifter cable, trace the path of the cable from the derailleur up to the barrel adjuster.
You might have seen experienced riders reach down and tweak the barrel adjuster while riding in groups, and you can do it too. If your bike isn’t shifting clean, don’t get off your bike, keep riding.
Don’t Look Down
There’s no need to look back at your derailleur or gears, it’s not recommended anyway. Keep your eyes on the road. Looking back at your gears won’t tell you anything that will help the situation.
Adjust on the Fly
Continue riding at an even pace, and shift the bike to a larger gear in back. If it doesn’t shift immediately and hesitates, it probably means that the cable has slack in it. Reach down, grasp the barrel adjuster on the derailleur cable, and give it one or two clicks counterclockwise to back it out slightly. Repeat shifting down and back up again to test it. If it still hesitates, give it another click counterclockwise and repeat until the gear responds clean and crisp. You shouldn’t have to give the barrel adjuster more than a few clicks to get the bike shifting clean again.
Maybe Too Much
It’s common to overdo it. Twisting the barrel adjuster too many clicks is typical. If you notice that the bike hesitates when shifting to smaller gears — you may have twisted it too much. Give the knob one click clockwise to lessen the tension. Work the gears up and down to balance the tension, adjusting the barrel one click at a time until you get it just right.
Rear Barrel Adjuster
If your bike is still having shifting issues, there’s another barrel adjuster on the rear derailleur where it exits the housing. It does the same thing, but you need to put the bike on a stand, work the pedals by hand and adjust the tension that way.
If All Else Fails
If you’ve adjusted both barrels, top and bottom, but your bike is still having issues, it might be because of dirty cables, and that requires a thorough cleaning, or cable and housing replacement. Other, more technical issues might lie with the derailleur itself, and require attention from a bike mechanic. It’s not advisable to mess with the high and low indexing screws on the derailleur itself unless you’re experienced, they rarely get out of adjustment.