John Nolan 

I ditched my bike on some ice, and ended up breaking the spring on my Suntour Cyclone derailleur, so I purchased a Deore M59, but no matter how I fit it, and what I do to the B screw, the back of the derailleur hits against the rear of the sprockets; it's just too close! I tried an old deore I had in my spare parts, and it has the same problem.

Now, I know this sound like a bent hanger, but I put an old, very worn out suntour mountech on, and it fits, and the hanger doesn't look bent.

What am I missing?

FBinNY 

First of all determine whether it's possible for the RD to clear properly. Forget the B-screw for a moment, and manually swing the RD back and see if you can find a position where it works right.

If so, then then it's a matter of B-screw engagement against the stop on the hanger. A 1982 Bianchi should have a Campy style hanger, which is the defacto standard these days, but who knows. Remove the rear wheel and look at the back of the hanger and see how the B-screw engages the hanger or stop cam. If all you need is a few millimeters, then go and buy a longer screw that'll reach.

If you need more than a few millimeters it gets more complicated, and may (may, can't know without seeing) you to use body filler to bring the stop position of the hanger back, or modify the RD's stop cam.

John Nolan 

Thanks for those tips... I'll have a look, but I'm thinking if I can't get it to fit without altering anything, I'll try a different unit.

FBinNY 

If you're riding with a range suited to a short cage RD, I have a few NOS SunTour Sprint derailleurs which were one level above Cyclone (one below Superbe Pro). These should be 100% plug compatible with the Cyclone you removed. Email me using the link on the Chain-L site if interested.

John Nolan 

Sounds great, but I'm using a 50/40/30 triple, and something like a 12 to 30 on the back. (I don't recall exactly what's on the back.)

FBinNY 

I tried.

But I think that with a careful analysis of the hanger, and stop cam (if any) you should be able to work out a solution without great effort.

BTW- one thing I didn't mention... It's very common for people to mount RDs with the B-screw trapped between the RD and hanger, rather tha n behind the stop cut where it belongs. Take a look from the back, and if you have any doubt, loosen the mounting bolt slightly, pull the RD all th way back and down, and retighten. This may seem de rigeur, so don't take offense if you know how to mount an RD.

John Nolan 

Thanks, and certainly no offense... I'll have another look... I feel I must be doing something like that. I'll let you know.

Again, thanks for your continued efforts.

John Nolan 

It seems to be mounted correctly, but there's just no clearance. I tried to take some pictures, but they don't show much. The back arm of the mechanism (with the adjustment screws and cable anchor) runs afoul of the chain when one tries to advance up to the third sprocket.

I'll attach the pictures in case anyone can see any clue in them.

FBinNY 

Answering the original question ---Yes you're missing something.

That's a different model then the more common versions. It has the compound upper pivot like the Shadow derailleur. I'm not familiar enough with those to help you, but here's a link to Shimano's instructions for setting up Shadows, which should help you solve your problem.

John Nolan 

Thanks for that... it looks as if one needs to attach the cable in order to set the clearance, and the whole thing look.. finicky.

I'll think I'll try a different derailleur!

FBinNY 

I don't think it's any more finicky, or harder to set up, it's just that extra step of setting the hang angle on the upper pivot hinge. You already own this, you might as well use it. BTW- the design is common to many Shimano high capacity derailleurs so you might as well give it a shot.

If you need more encouragement (or maybe discouragement) you might start a new thread soliciting opinions on the "Shadow" design. If you do be sure to say you have a Deore XT of this type, because there are lots of low end versions.

John Nolan 

You're right of course, I'm just a little frustrated... a new thread seems like a good plan.

FBinNY 

I suspect it's actually very easy (otherwise there would have been a Greek chorus), but different. I suspect once you do your first, you'll have this as down pat as the RDs you're used to.

onespeedbiker

It appears that you have a very bent derailleur hanger; just one more photo would confirm. With the chain installed, stand your bike straight up and take a photo of the back of the derailleur from just right and behind the rear tire.

FBinNY 

No it's a brand new Deore, but with the "shadow" type articulated upper body. If you follow the thread you'll find my link to the instructions for this creature. Meanwhile, it's always possible he has a bent hanger, but that's not directly related to the immediate issue.

onespeedbiker

I have followed the thread, I just think your are overlooking the obvious. I know it is a Shadow style derailleur. The fact is he crashed his bike that ruined his previous derailleur and now a new Shadow derailleur doesn't work (nor does another standard derailleur). The issue with the Shadow derailleur is it does not rotate at the hanger bolt, but has an plate that moves the pivot to the left. It is here, most likely at the extended cable anchor arm, that the derailleur may be running up against the cogs. This arm runs along with the slant parallelogram just over to the top cogs. If the derailleur hanger is bent, it will rotate the entire derailleur inward and into the cogs.

Edit: BTW would you edit your previous and add a close bracket (]) after the final [QUOTE] in my statement; my OCD is screaming at you right now!!

FBinNY 

It could be a bent hanger, but it doesn't look very bent in the photo, though it's hard to tell either way because of the camera angle. I took the OPs statement that it looked OK at face value. He also said it worked with an older derailleur, though I understand that older designs can be more forgiving on bent hangers than some modern ones.

You may be more familiar with these RDs than I am (never had one in my hands), so you might know form experience whether a bent hanger would bring the upper body into the sprocket. But it would seem that only a very bent hanger should be able to do so.

onespeedbiker

That's where the Shadow and standard derailleurs differ. A shadow derailleur is very sensitive to a bent derailleur hanger because the pivot is attached to a plate 30mm or so to the left of the actual derailleur hanger. Because of this, any amount the derailleur hanger is off, is multiplied by the length of the plate. ie a hanger off 1mm could make the actual pivot (30mm away) off over 5mm.

frantik

I'm pretty sure the problem is that that RD is aesthetically totally wrong for a 1982 bianchi, so the bike gods are preventing it from working

John Nolan 

OP here:

Sorry about the crummy pictures: it's hard to get an angle that is informative... I'll try later today.

I'm thinking the bent hanger may be the answer: I can't confirm any bend eyeballing it, and my old worn Suntour does works, albeit sloppily, but nothing else makes sense. I'm not an expert, but I have been fixing my own bikes for thirty years, and I've never had any trouble fitting a derailleur before.

I guess I'll take it to the shop I bought the derailleur from; but I'll have to make sure they show me what they did; I can't stand the thought of not being able to fix my own bike!

Having said that, I agree the aesthetics are horrible, and if the shadow style isn that sensitive, I may go for some thing else.

Any suggestions?

cyccommute 

There may be more of a problem then you think. It looks like John Nolan has a Deore M593 Shadow. The Shadow derailers are meant to track very closely to the cassette to keep the derailer from being damaged by off-road hazards. But the problem with the M593 is that it is a Dynasys which is a 10 speed off-road system and isn't compatible with other systems.

John, you'd be better off with a Deore M591 for your bike. It's more conventional and should work better with your bike.

John Nolan 

Hmmm... says M592 on the box...
anyway, here's a couple of shots from the back:

frantik

do you have a straight edge you could use to check if it's bent? the RD cage definitely looks crooked in those pics

I would try to bend back the rd or look for a replacement that is like the one that you know works...

cyccommute 

Then it's not a Dynasys but it is still a Shadow which follows the gears more closely. Looking at your pictures, it looks like the hanger could stand a little straightening which, given the way that the Shadow works, could cause your problems. I'd still suggest the M591 which is more forgiving.

onespeedbiker

The derailleur cage should be parallel to the wheel, as you can see it toes in significantly at the bottom.