hybridbkrdr

How can you tell when your derailleur is officially done?

CbadRider

Moved from Long Distance to Bike Mechanics.

TallRider

are you asking a theoretical question or do you have specific symptoms to report? I don't want to lay out a general flow-chart to distinguish between poor adjustment and can't-be-fixed-wear unless I have to.

Retro Grouch 

I think that the rear derailleur might be the most reliable part of the whole bicycle.

Everything has a service life so, I suppose, the bushings in the parallelogram will eventually wear out and the derailleur will need to be replaced. If I was looking for such wear, I'd try to bend the parallelogram with my hands to see how much play I could feel. I'm thinking it would be a very long time before a replacement would be truly needed.

hybridbkrdr

Actually, I thought people who claim they replace parts often in the long distance forum may have been better to ask the question but anyway...
The point is, yes, it's a theoretical question.

What I'm trying to ask is say, if you have friction shifters, and don't need the indexing, how is it possible that it would stop working?

The reason for the question is I bought a touring frame and knowing that I wanted to start with local cities, I know eventually I may start going on longer and longer trips. (I mean with my personality, I know I'll hesitate a little at first then change my idea completely and go longer distances in the end.)

Of all comments I read though, some review on the Trek 520 touring bike where someone said they eventually wore out EVERYTHING excluding the front derailleur and frame.

cny-bikeman

Don't worry about it. I rode on a 5000 mile trip that included the Appalachians, Cascades and Rockies, with Huret Jubilee derailleurs, stretched to max capacity in the rear, and they had already gone thousands of miles before that. I did manage to wear out the original rear, but it took from 1972 to 1976 to do so and that derailleur was unusually subject to wearing out. I've never worn out a hub or bottom bracket because I keep them properly maintained, and have broken 3 spokes in the 40 some years I have been a bike enthusiast. One would have to log probably 100k to start wearing out significant amount of non-expendable parts.

FBinNY 

Derailleurs don't wear out per se, but some parts suffer the effects of wear.

The fastest to wear are the pulleys, where the diameter shrinks and the chain runs noisy. They also wear at the bearing to where you can wobble them.

The main place of actual derailleur wear is at the pivots. When severe, you can twist the pantograph sideways with a bit of hand pressure. The issue with pivot wear is that it takes overtravel to get the RD to shift, then it'll settle back to trim. Folks used to non-index get used to it and it's less of an issue, but it makes any index system sloppier.

Pivot wear takeas a long time, not in years or miles but in shifts, since that's the only time pivots move.

sreten

Hi, Not strictly true, there is a vibration element to it as well as the shifting, rgds, sreten.

FBinNY 

In the REAL world, fretting wear on RD pivots either doesn't happen or is such a slow process that movement wear overshadows it to the point that it isn't ever a factor.

Do you have any first or second experience that shows otherwise?

In any case I offered the Op a diagnostic for wear, and might remind him that the info provided by others is correct that derailleur wear is a v-e-r-y slow process, and other than mtb where abrasion from dirt accelerates wear in general. I have RDs with 10,s of thousands of road miles on them with little if any care, and all are going strong, though I have worn out some pulleys over the years. In my cycling career spanning 45 years and 100k miles, and I've yet to wear out a derailleur, ever.

fietsbob

When you crash on them and they go into the spokes and do in the wheel, as well .. then it's clearly done.

surreal

I wore out my first rear derailer rather quickly; rather, I wore the pulleys down pretty danged fast. In my early days on a bike, I rode in all conditions, and my idea of "bike maintenance" was long periods of neglect book-ended by putting copious amounts of wet lube on the chain, to shuch it up. Between the gunk, sand, road salt, and miles, those pulleys got round within a few years.

But, like cny mentioned above, it you maintain decent components properly, they'll last a good long time.

miamijim

...when you have to over shift a complete gear to shift 1. So when your in the 3rd cog and have to over shift to 5th to get into the 4th.....that's a worn out whipped RD.

surreal

Sure, but other problems could cause the same problem. Also, that's a moot point with friction set-ups.

miamijim

Oh really? I've worked on my fair share of friction bikes with biziillion mile RD's that wouldn't shift into high or low gear because there was enough over shift.

rm -rf

I wore out the paralleogram pivots in about 5 years and 16000 to 18000 miles. The symptoms were shifts that were noisy from rubbing the adjacent cog, and having to shift two cogs and then back one.

I took good care of the old derailleur, wiping it clean and lubing the pivots regularly. It still wore out.

I could move the cage holding the two pulleys by a fairly small amount of pressure from my fingers. The new one is still solid after a few years, barely moving at all.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The original 2006 Veloce had small pressed-in pins as pivot points.



The redesigned derailleur has much more substantial pivots, and they are set farther apart on the wraparound body, too. A much better design.

Looigi

FWIW: Wear on the P knuckle retaining pin and flange on a Red RD after ~12,000 miles resulting in ~2.5mm axial play:

hybridbkrdr

That's nice to know. At least I'll have a clue what to look for.

Kimmo

I've come across plenty of derailers that were too worn at the upper pivot (the mounting bolt) to be any good on 8s+ indexed systems, and maybe one or two with that much parallelogram wear.

But as for friction shifting, just about any sloppy old piece of crap will work, especially on Hyperglide (or equivalent) cogs. A RD has to be crazy-worn before you can't friction-shift it reliably.

RoadTire 

Using friction shifters, the RD is done when the upper pivot is so loose it dings the spokes. Mine isn't there yet, but pretty sloppy.

TiHabanero

Deraileurs do wear out. I have an old Sun Race from their introduction year that was used on my commute bike for 15 years. Winter took its toll on the thing and it was very sloppy in the pivots which made shifting to larger cogs difficult, even though it was a friction only system.

CalvinAL

My derailleur has play side to side at the rivet. The rivet can not be tightened. The High limit is all the way out. I still can't get into the highest gear. I think it is time to replace it and have ordered a new one. Perhaps the new one will have a bolt that can be tightened instead of a rivet.