Hi, I'm rebuilding an old mid-80's Trek 400 road bike. Many moons ago, I replaced the original narrow-range 6-speed rear cluster with a wider-range (13-32) 7-speed. The original Shimano Light Action rear derailleur wouldn't work with the bigger rear cog and was marginal on capacity, so I put a cheap Shimano RSX long-cage (86mm) derailleur on the bike. It indexes nicely with the Shimano bar-end shifters I'm using.

As I'm rebuilding the bike now, the RSX has quite a bit of slop in the parallelogram bearings. In my spares, I notice I've got a somewhat rusty, but I think serviceable, Shimano Deore (just "Deore" not "Deore XT") long-cage derailleur that appears quite tight. It will take some work, but I think I can clean it up to be in nice shape. Since RSX was Shimano's low-end, I assume Deore is probably an upgrade from RSX, but I'm concerned if it will index properly, and I don't want to go to the trouble to get it cleaned up if it isn't going to work. Does anyone know if the cable pulls are the same for RSX and Deore long-cage rear derailleurs?

Thanks,

- Mark

IFAIK all the indexed Shimano rear ders (excepting the first gen DA and current 10 spd versions) share the same cable pull spec. What has changed is the stroke the rear der can go through. The ders speced to fewer speeds might not handle the larger number of cogs. But the indexing on the cogs that are able to be attained should be the same. Andy.

Thanks for your help. I'm just changing derailleurs, not clusters, so if the RSX and Deore cable pulls are unchanged, then the new Deore should index the 7-speed like the old RSX did.

- Mark

Just to follow-up with a conclusion, it ended up the Deore and RSX cable pulls WERE different - the Deore was moving further with each click of the shifter compared to the RSX. The Deore, when adjusted to index at one end of the cluster, would gradually get more and more overshifted as you went towards the other end. When I refitted the RSX, it indexed perfectly. Both the long-cage RSX and Ultegra seven-speed bar-end shifters are around 1990 vintage - the Deore is something that was in my spares when I bought the drivetrain off an old bike to get the crank, so I really don't know when/where it came from.

In any event, with all the combos and changes over the years, I think there is still some trial and error involved - some things work that aren't supposed to and vice versa.

- Mark

Are you sure you connected the cable on the correct side of the cable pinch bolt on the Deore RD?

I think the Deore should index properly too. It's counter intuitive to think that a derailleur with a sloppy parallelogram should work better than one that's tight.

Good thought as I've read about the alternative routing fix to cable pull problems. But I am reasonably sure I have it right - it makes the least bend and lines up with the little indent in the tab where the cable is supposed to lie. I'm pretty careful about this stuff to make sure the cables are in the spot where they are supposed to lie, not just pinched any old way. And if I did put it on the other side of the pinch bolt, I think that would actually further increase the movement of the RD with cable pull - my problem was the opposite.... I wanted less movement for a given amount of cable pull.

- Mark

I think I've figured it out - it's a five-speed derailleur. Here's a picture from Velobase.com of what it looks like....



There is a note at the bottom of Velobase entry that says it originally shipped with a 5-speed group. And I just noticed that I have a five-speed cluster in my spares - I suspect I got this with the used drivetrain I bought that included this RD.

- Mark

While I don't have the answer as to why the Deore der won't index well i will say that it's not limited to a 5 spd system. It looks to me like a late 1980's design, which would be at least a six speed system. Buy the early days of indexing are foggy in my mind. IIRC the 6 speed freewheels had the same cog C-C spacing as the 5 spd ones did. The give away that I picked up on is the cable adjuster style. Is the upper pulley the correct SIS guide design with a touch of free end play? Andy.

Sure, I got the tension pulley and the guide pulley right.

I always thought there was a narrowing of cluster spacing between five-speed and seven-speed with the intermediate six-speeds either using the five-speed spacing or the seven-speed spacing (ultra-six). I have the five-speed and seven-speed clusters in front of me and the spacing on the seven is about 0.4mm narrower between cogs.

- Mark

No, that's a first-generation Deore, which was made to index on a six-speed cassette, but also worked fine on 7-speed. As Andrew said, all Shimano derailleurs have the same cable-pull-to-derailleur-movement ratio (except for early Dura-Ace and late Dyna-Sys systems).

Could you put up a photo of the Deore derailleur, showing how you hooked up the cable?

It's off the bike, but I know how to route a RD cable.

Let's just leave this as a mystery.

- Mark

There are no mysteries, only puzzles to be solved. You posted it, we're going to run this into the ground.

As Andrew and I said, swapping those two derailleurs should be inconsequential. The symptoms you describe indicate some sort of problem- we're just trying to figure it out.

I am absolutely, positively, completely 100% sure the RD cable was properly routed. It really will only go one way and there is a defined cable guide on the derailleur where it should go - you'd have to work to get it wrong. I'm not going to reinstall and post pictures to satisfy you on this point.

Frankly, I think the most plausible explanation is that Shimano, in the five-speed era prior to the advent of indexing, produced a Deore RD that had different cable pull spec than later indexed models; this was the era when it really didn't matter what the cable-pull spec was and I doubt the mfgs paid a whole lot of attention to it. If you want to come up with an alternative explanation that satisfies your presumption that "all Shimano RD's have identical cable pull spec except certain esoteric DA models ...", knock yourself out.

- Mark

The Deore derailleur you posted is an index derailleur- the cable adjuster (not to mention the logo) gives it away. Since the picture is from Velobase, why not show us exactly what you're playing with, instead of posting false leads?

"False leads"? Is it something I said, or are you so condescending to everyone?

My Deore RD:



My cable routing on this RD:



- Mark

Nope, just trying to get to the bottom of the issue. As Andrew and I said, Shimano's kept the same rear derailleur cable pull ratio throughout the index era (with noted exceptions). Your Deore and your RSX derailleurs should operate identically. Since they don't, there's something very weird going on. I'd like to figure it out, or it's going to keep me up at night.

FWIW: my experience with bicycles and bicycle parts started well before Shimano's indexing and includes the transitions to 6, 7, 8, and 9-speed indexing and the introduction of Hyperglide. I worked on those Deore and RSX derailleurs when new, and worked on them when well worn.

Is that the cable that was on the bike? I've had bad luck with the teflon-coated cables, but it sounds like you would have noticed the cable slipping in the pinch bolt. Also, the adjuster is screwed way, way, out... why?

A slipping cable would not explain mis-indexing where it aligns on one cog, gets progressively gets more and more out of alignment as you shift across the cluster, but then returns to original alignment on the starting cog.

Probably because I unscrewed it all the way at some point and just wanted to re-join it back before packing it away. In any event, indexing wouldn't change just because you're at one end or the other of the adjuster. And BTW, it's really not "way, way, out" - it's about at the 60% out point between fully seated and becoming unscrewed.

Afraid you're going to have some sleepless nights; I have all the explanation I need. Sorry, don't have any interest in pursuing this further.

- Mark

And if that explanation is wrong?
"Just to follow-up with a conclusion, it ended up the Deore and RSX cable pulls WERE different - the Deore was moving further with each click of the shifter compared to the RSX."

This is important. Many, like myself, are retrofitting mtb's with STI's and would like to have a handle on what works and what does not. This forum is kind of like a library, and we just want to be rigorous with our research. No need to take offense-- Jeff is just trying to make sure that we have rigorous information for posterity.

If I ask a question on here, it is fair enough for those offering help to ask questions back.

Yes, we have to go through the cognitive dissonance of a counter-example to the long-held maxim:

All Shimano indexing rear derailleurs have the same cable pull, except Dyna-sys and old Dura-Ace.

Just as politicians are reluctant to reverse their stand on, well, anything, in the face of overwhelming evidence to the contrary, we internet mechanics like to find root cause when our universes are being upset...