A barrel adjuster will allow the fine adjustments to the tension of control cables. Screwing it out - anti-clockwise - extends the length of the outer-cable run while leaving the length of the inner-cable unaffected. Thus the inner-cable gets tighter.
Barrel adjusters are used in braking systems to compensate for brake-block wear. The adjusters are usually designed and positioned so the rider can turn them ‘on the fly’. Barrel adjusters on gear-cables allow fine tuning to make index systems work precisely.
Where To Find Barrel Adjusters?
Barrel adjusters usually have a locking mechanism. To stop them moving when they’re not being adjusted.
Lock-ring Or Lock-nut
The barrel may lock with a lock-ring – or lock-nut – that runs along the thread of the barrel and can be jammed against the end of the thread once the adjustment is in the right place. Unscrew the lock-nut to allow the barrel to move.
Gear adjusters may be self-locking, these have a plastic sleeve on the outside of the barrel. The sleeve has small teeth at one-end that engage with a matching key at the end of the barrel thread. A spring pushes these sets of teeth together. To adjust the barrel, slide the teeth apart then turn the sleeve. Once the sleeve is released the spring re-locks the adjuster automatically.