Bicycle Mechanics - shifting problems

Hello everyone,

I'm new here and was hoping someone could help me out. I have an older (94) GT mountain bike that's having shifting problems. Basically I was riding it and the chain went into the smallest rear ring and pressing the shifter does nothing.

I replaced the cable thinking it may just be worn and this did nothing. If I mess with the small adjustment screws on the rear derailler the bike will shift to the larger rear rings and then shift down to the smaller rear rings but not up again. Which leaves me back in the smallest rear cog. I'm a real novice at working on bikes so any help is appreciated.

Thanks!

your problem doesn't have anything to do with the screws that set the upper and lower limit for your derailleur.

it sounds to me like your cable came loose from the rear derailleur, unless it was a broken cable or your shift lever is broken.

i think that,
if the problem was with the old cable breaking or coming loose, then the problem NOW would have to be that you didn't install the new cable correctly. (didn't get the cable set to the right length, or didn't attach the rear derailleur to it tightly enough.)

Sometimes, older shifters get sticky and the ratchets don't spring back. Jetting some carb cleaner in there and then working the shifter will often free it up. Then lube it with some light oil.
It can also be a broken spring, if the above trick does not work, this is probably what is wrong. The fix is a new shifter.

Cool, thanks guys. I looked at the cable, it seems to be ok. I can get it to shift if I fiddle with it. Feels like the shifter gains traction once in a while and it shifts. I think I'll replace the shifter and see what happens. Although it's a 7 speed, hopefully I can locate one. Looks like a lot of work to upgrade to a modern 8 or 9 speed rear.

I had a similar dilemma. And found that there is not much selection when looking for 7 spd MTB stuff.

However, I like twist shifters and was able to find a set of SRAM MRX shifters for cheap (about $20 for the set). They work fine, are compatible with my Alivio deraillers, and there are fewer moving parts. Its a matter of preference, but I like them and they work fine (albeit a bit loudly).

- Jeff

I think I'll replace the shifter and see what happens. Although it's a 7 speed, hopefully I can locate one.

What kind of shifters do you have currently? Are they integrated with the brake levers? If not, I just noticed that Bikeman has some old 7-sp STX shifter pods for cheap.

Right pod:
http://www.bikeman.com/miva/merchant.mv?Session_ID=3F810B4D000127780000560800000000&Screen=PROD&Product_Code=LD8752&Category_Code=COMPSHMTNINDVSH1

Left pod:
http://www.bikeman.com/miva/merchant.mv?Screen=PROD&Product_Code=LD8751&Category_Code=COMPSHMTNINDVSH1

If your shifters and brake levers are integrated, I also saw some Alivio integrated shifter/lever combos.

http://www.bikeman.com/miva/merchant.mv?Screen=PROD&Product_Code=LD8878&Category_Code=COMPSHMTNSETSH

Oh yeah. Forgot about that. If the shifters are integrated, new brake levers would also be in order with the grip shift option.

- Jeff