CuttersRidge

This is the derailleur-type, a fairly well known one I'd say. Last week, the lowest pulley wheel came loose and fell out while riding. It happened at night but I was able to retrieve it the next day. I was probably a half mile from home so was able to make it home that night.

Now, I've installed it all back on the vintage ride and the rear derailleur seems to flex too much and I'm wondering if I even need to use such a long cage rear derailleur. Would a short derailleur work for a triple crank? Did something go haywire with this vintage Shimano Deore rear derailleur?

I do have a front derailleur for a Triple and the FD doesn't really seem to be the problem. The bike was going good for awhile but now, I can't get it back to how it was working.

I'm using it on a typical 10-speed cog cluster in back, so meaning 5-6 cogs, I have both on wheels.

The chain may be the culprit and I did get a new chain but as of now, today I tested it with the old chain.

I think the Triple crank part is okay, the problems to me, seem to somehow originate with the back part of the drive train.

Thank you earnestly for any answers and happy holidays.

bikemig 

What exactly is the problem? Is the rear derailleur shifting properly through your cluster in the rear? If there's movement or "flex" in the RD, that may be caused by the shifter. Usually the shifter has a screw of some type; you can screw it down a bit and see if that helps.

Your RD may be buggered up. Losing a one of the rear derailleur pulleys is never a good thing.

Did you put the derailleur pulley back together properly? That is also a likely source of the problem.

CuttersRidge

I'd say it is too much flex in the rear derailleur is the problem. It flexes far forward.

Thank you for the response.

I had the suspicion that I did have a loose link in the old chain as well and I wonder if that contributed to the matter.

Next, I will try one of my other rear derailleurs on it even if it might be a short cage.

I really have been running experiments on this one bike keeping another 1 or 2 ready to ride but I'd like to have it running on the triple comfortably.

TimmyT 

That looks like an Shimano MT-60 Long cage RD: VeloBase.com - Component: Shimano RD-MT60, Deore
It has a max chain wrap of 38 and a max cog size of 32.

Chain wrap is calculated by (#of teeth on big front - #of teeth on little front) + (#of teeth on big rear - #of teeth on little rear)
For example, if you were running a 30-44-50 up front, and a 13-28 freewheel in the back, the chain wrap you would need is: (50-30) + (28-13) = 20+15 = 35.
Generally, for a triple crankset, you need a long cage rear derailleur.

My guess is that you don't clean your drivetrain, and that is the culprit. The build up of chain lube and dirt and grit can cause problems with the rear derailleur. I would make sure that everything is cleaned and lubed, and that your cage is not deformed.

Are you running a 6-speed indexed drivetrain? If that is true and you took off the rear derailleur, you will need to make sure the indexing is set up properly.

CuttersRidge

Thank you TimmyT; for the record, I'm running friction shifters. The bike has run this way for quite awhile, the LBS installed the Triple Crank maybe 3-5 years ago. The chain somehow may be dirty but the rest is actually fairly clean.

I will check your data too, despite being a triple, it crossed my mind that maybe I had too much chain.

One reason the bike had been running "okay" is because generally, I don't run through a wide variety of gears so I was curious to see what it would do and that seemed to snag it up some.

CuttersRidge

I'll add one more thing, once I did have a braking mishap, I didn't even fall off the bike or anything but I snapped the derailleur about 5 years ago, took it to the LBS and they said it, it is the bike frame, got slightly bent in the derailleur hanger area but they straightened that up for free actually, they said it wasn't a big deal and only slightly bent.

CuttersRidge

Yes, I should probably remove the RD and take it to the LBS and ask them if it looks okay. I can probably do that this week.

CuttersRidge

Thanks BiKeMig; when one says "the shifter"? Meaning the thumb friction shifter? Or maybe a part of the derailleur? In that sense, maybe something on the Deore needs to be tightened up.

plonz 

I've replaced newer derailleur cages and it is not uncommon to see blue Loctite on the pulley screws. Could be as simple as a little dab of this?

CuttersRidge

The freewheel froze up, I didn't even check it, I was so sure the derailleur was at fault. It was the cog cluster frozen up or however one would describe it.

The derailleur is working fine now.

Many thanks for all of the help!

TimmyT 

Glad you figured it out! Good luck with the maintenance.