Rear Derailleur Bunched?

irishmotorist

I think I'm having a problem with my rear derailleur (Shimano 105 5600, approx 12,000 km). I broke a chain a few weeks ago and I think it's related and obviously don't want that happening again.

The problem is the hinge/joint at the mounting bolt. This is very stiff and doesn't rotate easily. I sprayed a bunch of WD40 on it and it freed it up a good bit, but it still requires a good bit of finger power to pull it either way. If I recall, it should spring back itself, but it's too stiff to do this so I don't think my chain is tensioning properly.

So, my questions (to anybody who doesn't TLDR) are:
1. Does it sound like it's misbehaving?

2. If it is misbehaving, what do you think are the chances of me fixing it myself? Zinn's book told me that to go into there is a pretty difficult area, even with 2 pairs of hands because of the springs.

3. I'm expecting it to not work out well, so I'm ready to replace it if needs be. A very brief perusal of a couple of my regular shops show (105 - 5700) short cages in stock, however it's a long cage that I have as I'm running a triple. I've got a 27 on the back, but would obviously never crossover anywhere near that. CCS (http://www.cyclesuperstore.ie/shop/pc/viewPrd.asp?idcategory=0&idproduct=46435) have it and mention "max front difference - 22t" Is my 50-30 <22, therefore OK? It also mentions "total capacity - 39t". I'm not sure what this means.

4. I usually get a chain with a quicklink but my last one was a Shimano (Ultegra, I think) that had a pin to be pushed in. Is this pin re-push-inable or do I remember from somewhere that I need a new link or new pin or something? I just want to check this in advance of doing 3, above!

Any thoughts appreciated.

doozerie

1: Yes.

2: Fixing it might be impossible but you may be able to live with it for a while longer having freed it up a little. It should really swing easily and if it jams in one position it'll make for rougher gear changes and possibly a greater risk of dislodging the chain in higher gears. It might even jam in a position that means you can't change into lower gears. But, on the other hand, you might find that it doesn't cause you problems. If you typically move across the full width of your cassette during a rider then it'll be more likely to cause problems.

My wife's 105 rear derailleur is in the very same state and has been for months now without causing any significant problems, but she wouldn't use the lowest gears much, if at all.

3. Yes you should be fine regarding max front difference as it is measuring what you suggest. Total capacity is calculated as
(biggest chainring - smallest chainring) + (biggest rear cog - smallest rear cog)
so in your case:
(50 - 30) + (27 - whatever your smallest cog is)
...so long as this works out as no more than 39 then you should be fine.

4. I believe that Shimano joining pins are not re-usable. Shimano sell new joining pins in packs of 5. Or you could just buy a quicklink for it, but beware that certain types of quicklink are re-usable and some are not.

Keep_Her_Lit

irishmotorist wrote: »

1. Does it sound like it's misbehaving?

Yes.

2. If it is misbehaving, what do you think are the chances of me fixing it myself? Zinn's book told me that to go into there is a pretty difficult area, even with 2 pairs of hands because of the springs.

I haven't disassembled that part of a rear mech before. I'd expect that it would indeed be difficult with your hands alone. But maybe if (carefully) clamped in a vice it would be manageable. I've had exactly the same problem with rear mechs and TBH I've found that they still work pretty well if that stiff pivot point is turned approx midway through its range.

3. I'm expecting it to not work out well, so I'm ready to replace it if needs be. A very brief perusal of a couple of my regular shops show (105 - 5700) short cages in stock, however it's a long cage that I have as I'm running a triple. I've got a 27 on the back, but would obviously never crossover anywhere near that. CCS (http://www.cyclesuperstore.ie/shop/pc/viewPrd.asp?idcategory=0&idproduct=46435) have it and mention "max front difference - 22t" Is my 50-30 <22, therefore OK?

Yes.

It also mentions "total capacity - 39t". I'm not sure what this means.

This indicates the maximum amount of chain slack that the derailleur is capable of taking up. Just add your max front difference, as above, to your max rear difference. If you have a 12-27 rear cassette you should be fine, i.e. (50-30) + (27-12) = 35 < 39. So this means you can use both the highest and lowest gears that you have without fouling up the rear mech. Edit: So this means you can get away with worst case cross chaining without fouling up the rear mech [too late for this carry on!]

4. I usually get a chain with a quicklink but my last one was a Shimano (Ultegra, I think) that had a pin to be pushed in. Is this pin re-push-inable or do I remember from somewhere that I need a new link or new pin or something? I just want to check this in advance of doing 3, above!

The pin which is used to join the chain must remain untouched. If it is pushed out again, the hole left behind is larger than the diameter of a standard joining pin, so the chain cannot be re-used. However, any other pin in the chain can be pushed out and replaced with one of these:
http://www.chainreactioncycles.com/Models.aspx?ModelID=186

irishmotorist

doozerie wrote: »

But, on the other hand, you might find that it doesn't cause you problems. If you typically move across the full width of your cassette during a rider then it'll be more likely to cause problems.

....

Total capacity is calculated as
(biggest chainring - smallest chainring) + (biggest rear cog - smallest rear cog)
so in your case:
(50 - 30) + (27 - whatever your smallest cog is)
...so long as this works out as no more than 39 then you should be fine.

....

I believe that Shimano joining pins are not re-usable. Shimano sell new joining pins in packs of 5. Or you could just buy a quicklink for it, but beware that certain types of quicklink are re-usable and some are not.

Perfect - thanks. Kind of as I was expecting, but good to get the confirmation. I do use a good range of gears (that's what they're there for!) so I think I'd be best replacing it while the going is still good.

Keep_Her_Lit wrote: »

....
This indicates the maximum amount of chain slack that the derailleur is capable of taking up. Just add your max front difference, as above, to your max rear difference. If you have a 12-27 rear cassette you should be fine, i.e. (50-30) + (27-12) = 35 < 39. So this means you can use both the highest and lowest gears that you have without fouling up the rear mech. Edit: So this means you can get away with worst case cross chaining without fouling up the rear mech [too late for this carry on!]

The pin which is used to join the chain must remain untouched. If it is pushed out again, the hole left behind is larger than the diameter of a standard joining pin, so the chain cannot be re-used. However, any other pin in the chain can be pushed out and replaced with one of these:
http://www.chainreactioncycles.com/Models.aspx?ModelID=186

Cool - thank you for this. I would have gone and tried to replace the pin.

BTW, good meeting you yesterday evening. I had thought I was getting back towards some fitness but the state of me when I got home set me straight on that!! Hopefully in another month or two I'll be in a position to converse properly at speed