We're heading out to visit our Daughter in Montana, and she's having trouble with the derailleur on one of her bikes. It's an REI Mt Bike, probably at least 10 years old. Hopefully I'll get some more info, but here's a photo:



It's one of those new-fangled 'index' shifting types, If someone can shed some light on its quirks I'd be most grateful. The bike is a Novara Aspen, and she guesses it dates to ~ 2000.

Thank you!

That barrel adjuster is almost all the way out, loosen the cable and tighten the barrel adjuster back in, then retension the cable and adjust with the barrel adjuster.

Check the cable's free movement by tugging on the exposed inner wire alongside of the bike's top tube or down tube. You'll be looking for perfectly smooth derailer actuation and return action.

Old lubricant eventually becomes thickened.
Often some thin-bodied lubricant like Tri-Flow introduced slowly into the end of the cable housings will flow in and free up a sluggish cable movement.

And I'll second bwilli88's recommendation to correct the cable tensioning, such that the shifter can move the derailer all the way to each extreme of sprocket positions.
Often the shifter's clicks don't position the derailer centered accurately with each sprocket position, resulting in noise, which can be fine-tuned using the cable's barrel adjuster.

But also first verify that this "derailer" problem is not a case of a shifter that does not actuate (click) or won't hold gear position reliably.
And inspect each end of all cable housings, to check for having possibly pulled out of a ferrule (end cap) and then having not fully seated back in.

I have found that with index shifting, RD alignment is more critical and with Mtn bikes RD alignment gets wacked. I'd start by eye balling or even gauging the alignment. Then do the tension checks mentioned above. There are folks who are not too careful about the right side of their bikes - lay the bike down on the right, mount the bike on the trunk rack with the RD against the bumper, lean it against a fence, etc.

90% of the time it is the gripshift shifters, not the FD or RD. Buy a set of those below and have them shipped directly to your daughter's home. They come with the cables, so you just need some housing. FYI, don't order from Niagaracycle in the ad, they are slooooooowwwwww shippers. Bikewagon is quick and shipping is free, $17.

https://www.amazon.com/Shimano-Shifte.../dp/B001NVAI7U

That's a great deal on the shifters with cables(!), but my experience with GripShifters of every quality level is that they are relatively trouble-free, usually not the cause of a shifting problem.

Now if a previous owner tinkers with them, all bets are off. Getting the cable out of it's groove inside, or even (especially) using the wrong lube, renders them useless.

Fortunately, most people can't even figure out how to get into them, so unless the shifter has taken a blow hard enough to break the externals, I generally expect them to work fine.

Especially with respect to aged bikes such as this one, GripShifters do not gum up inside because their special lube is Sil-Tef based, is inert so does not evaporate, nor oxidize, nor permeate plastics, so does not thicken and become sticky with age!
Whereas any Shimano RapidFire type shifter has usually become unusable because of pawl pivot gumming.
Not that a GripShifter cannot have it's sliding cable ramp become contaminated with silt from extensive use, outdoor storage or by blasting with water, but it is a very simple device, comparatively. The very early GripShifters did use plastic indexing "leaf" springs, which lose much of their tension over time, but which continue to work for a very long time.

OK, I'm here in Montana. The problem is clearly in the handlebar shifter. The rear shifts up from smallest up three sprockets, then the lower shift lever clearly loses mechanical 'feel' and nothing hgappens.

If I pull the cable out from the frame the derailleur shifts all the way in to lowest gear. I've taken a photo of the handlebar unit, now to figure out how to put it up...

FWIW, when I built up an indexed system for my sweetie I found that getting the barrel adjuster just right was like adjusting a brace of SU carbs. It's a process of getting in the ballpark first then getting it better then getting right. Once right it worked like a charm but until then it seemed to be fussy.

I will bet it looks like this!
[IMG]REI Novara Aspen ,on Flickr[/IMG]

I would recommend you take the grip shifter apart, clean and lube it. My wife couldn't consistently shift and it would not always shift correctly. Once cleaned and lubed it was like new. I just did this a month or two ago. This bike was purchased in 1998, BTW.

Similar, but horizontal top tube.

I took it apart, the pawl thing was sticky. It's 'working' but seems a bit wiggly.