It’s easy to get into a muddle when trying to sort your gears. The main pitfall seems to be a lack of understanding as to what the adjustments actually do. On all rear mechs there are three main adjustments - the limit screws, cable tension and something called B-tension adjustment.
The two limit screws are actually mechanical stops that control the mech’s range of movement across the cassette. These can be adjusted at the high and low-limits of the cassette - hence the corresponding H and L written on the screws. Correct adjustment allows the mech to access all of the sprockets without overriding, which would cause the chain to derail, or worse, send it into the spokes. Once these limits are set they need no further adjustment, unless something becomes bent or you fit a different cassette or rear wheel.
Cable tension is used to set the indexing, which means that for every click at the shifter the mech moves one gear. This is set initially at the clamp on the rear mech when you install the cable, and fine-tuned with the barrel adjuster on the shifter (or derailleur if it has one).
B-tension adjusts the distance between the upper jockey wheel and the cassette sprockets. This distance is critical to optimum shifting performance, but it’s worth getting it right because is does vary across brands and types of rear mech.
You don’t need many tools for this job and, as long as nothing is worn or bent, it’s relatively straightforward.
Time taken: 5-40mins.
Skill level: Low
Money saved: £10 +
Is it worth it: Most definitely - poor shifting is infuriating!
Got into trouble? Go back to step 1 and try again. If that fails there’s always the good old LBS.
From the April 2015 issue of MBR magazine
23 фев 2015
