This headache has been plaguing me for a couple weeks.

First, the components: this bike has a triple chainring and a 6-speed Maillard hub (pretty sure it has 28T down to like 11 or 12). It has a deore LX long cage derailleur.

When I try to shift lower than the 3rd or so lowest gear, the chain will ka-chunk-ka-chunk along almost indefinitely. It is tough to observe directly while riding but it looks like the chain is still engaged with the upper portion of the cog I am shifting from, and it runs diagonally along the top of the teeth on the lower portion of the cog, but does not actually engage. Sometimes I can get it to skip a couple gears and shift into the lowest gear, then shift back up to the gear I wanted.

At first, it looked like the derailleur was rotated too far forward, such that when it moved inward, it just pushed the chain into the side of the next cog.

Things that I have tried:

- Initially, it did not have a long-cage derailleur. I got one from a friend and put it on. The info I found said that the current derailleur is good for up to 34 teeth, if I recall correctly.

- For both derailleurs, I tried adjusting the b screw to several positions: max in, max out, in the middle. Very little difference between the positions.

- I checked the chain length. It seems to be the proper length, according to Sheldon Brown's method of running it over the big gears, not through the derailleur, and then letting it overlap by a link. It actually overlaps by about 1.5 links, but that seems OK.

I'm at a bit of a loss. Is it possible that the length of housing is too short/too long, restricting the action of the derailleur? Is the hanger sliiiightly bent?



Any help would be greatly appreciated. I can take a video of what is happening if the description isn't clear.

Thanks!