I just realized that my Shimano RD M-771 rear derailleur doesn’t have a cable barrel adjuster. This feature is standard on road and older mountain bike derailleurs but has been removed on mountain bikes over the past few years by Shimano. This is not a good idea in my opinion. While there is a rear derailleur cable adjuster on the bike frame for making fine adjustments while riding, I really can’t see any reason for not having one on the rear derailleur. I think most riders would prefer to adjust their rear derailleur at the back of the bike where they can see the derailleur, gear cluster and chain while they are making adjustments. Since I am waiting for parts anyway, this gives me the opportunity to modified my derailleur and add the missing cable adjuster. It may not be the most elegant solution but it should work just fine.
Just the thought of adjusting a bicycle derailleur strikes fear in the hearts of many riders. And the rear derailleur is perhaps the most feared. It is generally viewed as a task that can only be performed by a qualified bicycle mechanic at the local bicycle shop. In reality, it’s not all that difficult. Once you understand how derailleurs work it becomes a relatively easy task. In fact, I find that once I’ve set the limit screws on the derailleur the job is 95% complete. All that is left is attaching the cable and making fine adjustments as needed. As always, Park Tool’s website is a great place to find help on this subject.