Is it possible/worth it to replace just shifters and derailleurs on an older MTB?

Question

I have an aluminum frame bicycle (mountain bike, 21-speed) that I purchased some time in the late 90s, it's marked "Skykomish Eureka" (though I can't find any evidence that such a brand and model ever existed), and it is currently outfitted with Shimano 300LX components.

I believe that the rear shifter is giving up the ghost, as sometimes the lower (up) handle will go all the way back without "catching" whatever it's supposed to be catching in order to shift the gears.

I toyed with the idea some time ago of replacing the components with something more upscale (back then, it would've been Shimano EX, I guess...), but I never did it. Now, I'm wondering whether it's worth the effort. I put several hundred dollars into this bicycle back then, so I'm confident it's not merely a BSO, but technology has come quite a way since those days.

Beyond the basic components (hopefully just a couple derailleurs and shifters), would it also be possible to replace the existing short-arm cantilever brakes with the newer long-arm type (which I assume would increase braking power)?

Answer 1

The great thing about bikes is that almost anything is possible for the home mechanic. But only you can answer the question of whether it's worth it.

Deraillers almost never "wear out", at most they need new jockey wheels. They can get damaged or bent, often is is the hanger that is bent not the derailluer.

So likely all you need is a new shifter, fortunately 7spd is a lot less complicated than bikes with more speeds. $17 for a new shifter

http://www.jensonusa.com/!q!CCO3MwJWuenvYwhoKCsA!/Shimano-M310-Shift-Lever?utm_source=FRGL&utm_medium=organic&gclid=CPby-unl0sMCFRRgfgodc0YAoQ

Or you could put friction shifters on for a little more cash.

What does get worn out is the rear cogs or cassette. You might need a cassette and chain. That's about $50 more or less.

You can put new canti's on there without changing the levers, if you go to V-brakes you'll need new levers. Generally getting good performance out of canti's has more to do with how well you set them up rather than the exact model you use.

So for roughly $100-$200 in parts, you can have a functional bike again. However, if you can't do the work yourself, paying someone else to do it is a long ways towards the price of a new bike. This also assumes you already have the tools ( although these repairs don't require much in the way of specialized tools. )

For roughly 3x what you'd spend in parts, you can get a lightly used MTB hardtail that will be a much nicer bike. If however, you enjoy tinkering around with bikes, then you really aren't concerned about the cost of parts.

I've fixed up a fair number of older bikes and if you don't enjoy the process and satisfaction of making something old work again, it's almost never worth the effort.

Answer 2

I have been rejuvenating old shifters for years now. It is common for them to start acting up just as you describe. What I have found it that the grease the factory puts in get hard and hold some dirt and dust. Especially when the bike sits for months at a time, the spring loaded racket pawls fail to open and return. The solution is to pop the cover (usually a pair of small phillip head screws) and spray it good with WD40. With a probe (I use a piece of wheel spoke, sharpened on one end and twisted into a handle on the other) lift and work loose the pawls. A clean old tooth brush helps clean the compartment out. repeat until the shifter goes thru the stops easily. I usually repack some grease on the moving parts and work it in.

There is also a flat spring on some models that gets weak. It has 2 catch points for ends of the spring. Release the spring and unwind it from under its cover plate. Expand the diameter and replace it, using a small flat heat screw driver to push the second catch into the stop. The shifting will be much sharper.