Dave Mayer

You need a 8 or early 9-speed Campy rear derailleur from 1992 to 2000. They have B-tension adjustment screws. Any model will do, from Mirage to Record, although the less expensive ones are heavier, and do not last as long. At any one time, there are dozens of these derailleurs for sale on Fleabay; I would not bother trying to hobble something together from parts.

Scavenge the old jockey wheels, and chuck your old Mirage unit. I have rebuilt many many rear derailleurs from parts, but about half the time you find some subtle problem (such as a slight bend in the parallelogram, or a crack in the casting) that renders them useless. Or worse.

himespau 

Which is why I have this derailleur in pieces I was offering him. Not a mess I want to deal with, but I hate throwing things away. There used to be a box of junk in the C&V list that people would put in their small bits and bobs that they couldn't use any more and ship off to the next willing victim to try to do something with them because none of us hoarders would willingly just throw things away.

cyccommute 

It hasn’t gotten “lower and lower...and lower”. It has the possibilities of getting lower but the gear combinations offered stock have been in the same range. For example, in the days of 26” mountain bikes, a 22/34 combination was the lowest possible stock gear at 17”. When 29ers came out, they added a 36 tooth cog to the cassette which gave a slightly higher low gear at 18”. If a 10-52 1x is used, the low is still around 18” if a fairly good high gear is maintained. A lower gear is available with the 1x but at the expense of the high gear. I have a 44/34/20 with an 11-36 9 speed on a couple of mountain bikes that is wider than any 1x 10-52 system. The 1x can match the high or the low but not both.

As for shifting performance, that was was worked out long before 10 years ago. Shimano’s index shifting make shifting performance better for all riders back in the days of 7 speed cassettes. It also has nothing to do with the big-big combination and whether or not it’s a good idea to use it.

Finally, I’m a lot less “stuck in the mud” than many people. I have pushed gearing a lot lower than the drivetrain designers say that is possible while also maintaining a reasonable high gear.

Road triples, perhaps but nothing kept me from putting an 11-34 cassette on a bike with a 50/39/30 crank or replacing that 30 tooth inner on some road cranks with a 24 or even replacing the road crank with a mountain crank in a 48/36/22 or even a 48/34/20 to get a much lower gear than anything sold stock by anyone.

lizardcobra

How do I know that if I buy a full working derailleur it won't also have some subtle flaw? Is the reasoning that if a derailleur has one catastrophic break there is also a good chance that something else broke at the same time (as in my case)? And that if there is nothing at all noticeably wrong, it hopefully was never in an accident?

I do see the benefit of just paying more to avoid not having to mess around learning how to cannibalize and rebuild from multiple broken parts. At the same time, it may turn out to be a fun project (though I have more than enough of those already). Thanks for the advice!

lizardcobra

Now that I think about it, that's probably what I was doing when it broke. Another issue with this bike is that the front derailleur has issues, and often skips/over-shifts. It will often shift too far when I try to shift to a lower chainring, and I have to be careful not to throw the chain off the smallest ring by down shifting to fast. The Chainrings and front derailleur are Shimano, so I'm guessing they could potentially have been replaced at some point, and are not actually compatible with my Campy shifters? I haven't been able to find what this would have come with originally, but it seems strange that they would have used Shimano here.

At any rate, I bet that I shifted into big-bigger to get up the very small hill on the bridge, rather than downshift front and upshift rear, just to move back again a few meters later. I'm not positive, but I don't even think I was all the way cross chained when it broke. I think I may have been in the largest chainring (I have three) and a large-but-not-largeest rear cog.

DaveSSS 

For those of us who day dream or solve other problems while riding, shifting to the big/big by accident is entirely possible. Campy's recommendation has always been to use the little/little method that makes the chain as long as possible. If it's not long enough, then you have a big/big combo that exceeds factory recommendations. I have such a combnation, but I'm smart enough to add 1 inch of chain and know that the chain will hang a bit loose in one or two of the smallest sprockets and the little ring, because my 42T wrap exceeds the normal 39T maximum (16 front, 23 rear).

With Campy's latest RDs the big/big plus 1 inch method does not work, due to an extended pivot mount. Campy has specific instructions for every crank and cassette combination and chainstay lengths from 405 to 415mm. They all insure that the big/big combination is safe.

Drew Eckhardt 

Nope.

With the move to 10 cogs Campagnolo changed the actuation ratio from 1.4 to 1.5 to get enough derailleur movement to fit the offset big cog which extends beyond the freehub splines, which are 1mm longer on 9-12 speed freehubs than 8.

To limit the number of parts they made, they switched the geometry on all derailleurs and used compatible index cams in their 9 speed shifters.

himespau 

That 1.5 actuation ratio is shared by both 10 and 11 speed RD's, right? I was recently looking for an RD as a replacement in a 10 speed triple setup and couldn't easily find 10 speed long cage derailleurs for what I considered to be a reasonable price but saw a number of more affordable 11 speeds in both medium cage and long (either should work for the chain wrap I require).

Andrew R Stewart 

Maybe if you drank the Shimano Kool Aid after the early 1990s when their 30T ring and 27T cog set were considered the WAY and came on so many road bikes. But some of us older guys were running 24 or 26T grannies with a 34T cog for decades longer.
Sub 20" gears have been available for many decades and used by many tourists and tandems, let alone the early MtBs. And gearing is not just about how low can you go but also how many choices you have and how much gap between choices. A well designed triple gets you all this. Lowest gears, most number of close set choices. All are being lost because so many current riders are so lazy to not develop the skills to shift a ft der. Andy

Miele Man

In a few more years manufacturers will be touting 2x or 3x as the latest greatest thing. LOL

I see a lot of bicycles with double or triple chainrings where the rider picks one gear they like and seldom if ever shift out of it.

Cheers

Drew Eckhardt 

That's a question for gfk_velo .

When Campagnolo introduced 11 speed for the 2009 model year, people modified their 10 speed derailleurs by grinding down the cable fixing bolt diameter to get more travel suggesting it isn't.

OTOH, there could just be less float in the upper pulley (with low cable friction, 10 speed derailleurs perform great over a wide adjustment range). Web sources report the same ratio.

I wouldn't bank on it without confirmation.

Drew Eckhardt 

It will be 1X to reduce COGS thus increasing profit.

COGS reduction is the same reason all mass market road bikes come with compact cranks, although they may wear traditional 53x39 rings.

A lot of casual riders don't shift.

Some avid cyclists shift a lot - I wear out rear shift cables in 2000 miles when I'm in good shape, and not much over half that when I'm not. Longer cog life makes up for increased cable wear - I have 25,000 miles on my current cassette.

Dave Mayer

Good question. I've bought a lot of stuff on Ebay, and I'd estimate that about a quarter of the 20-year old derailleurs sold have some kind of major problem. Most you can see from the pics (with enough experience), and some you don't find out until it arrives.

I also volunteer at a high-volume bike Co-op, and we get lots of donations of 10+ year old gear, including really nice stuff. But, alas, most of the donated hardware has some kind of major problem, hence the donation. It is really frustrating installiing a set of shifters only to find that the composite bodies are cracked under the hoods - from some kind of collision. Or that a high-end rear derailleur looks fine, but is subtly bent, leading to all kinds of shifting misery.

Fortunately, I have enough spare parts that I can piece together good components from 2 or more broken ones. So good derailleur cage gets transplanted onto good derailleur body, and the broken parts discarded.

Not much else I can offer here, except buyer beware.

And, BTW, like most Bike Forums threads, it goes off the rails onto irrelevant tangents such as appropriate chain length or gearing range options. Ignore pretty much everything here, except my strongest recommendation that the next time you size a chain, it has to be long enough to fit your big-big gearing combo, regardless. I am particularly discouraged by the useless pedantic argument that you should size your chain to fit the small-small combo, and then if you tear your rear derailleur off, and it then gets carried into the frame and destroys that as well, then your drivetrain clearly does not follow Campagnolo specs, it is your own fault, and you should never do it again.

cxwrench

You've never really paid attention to this argument. The reason to size small/small is to end up w/ the longest chain possible and thus eliminate the exact thing you're talking about. As long as everything is in spec small/small is the safest method. It's also the hardest for people w/ minimal experience to screw up. If you're going to go past the capacity spec then you're correct...use big/big and make sure you have enough chain for that to work.

tomato coupe

I'm glad you settled that.

Dave Mayer

OK, now I've been drawn into this tedious peripheral debate. I volunteer at a high-volume bike Co-op as a mechanic. I've seen everything, including many drivetrains where our customers ride with a chain that is loose/droopy in the small-small cog combo. But their chains are also too short to prevent serious damage in the big-big combo! That is, the first time they attempt to shift into the big (pie plate) cog in the back, it will tear off the derailleur, the derailleur hanger, and carry the wreckage into the front derailleur and the crankset, probably wrecking these as well. I have seen the carnage that results from this.

Cutting the chain to fit the big-big combo prevents this catastrophe. It also allows you to have a reasonable discussion with the customer telling them they need a longer-cage rear derailleur.

Do not assume every rider buys complete gruppos, or adheres to 'manufacturer specs' or has bikes that contain compatible parts.

cxwrench

I specifically posted that there is a difference between 'in spec' and 'out of spec' in my reply. I'd be a fool to assume that every bike is 'in spec', but far more are than aren't. It's pretty easy to tell which you are dealing with. If you can't you shouldn't be working on bikes that don't belong to you. Even though you volunteer as a mechanic I'm still betting I see far more bikes and screw ups than you do. I've also been doing it for a living both in shops and with pro teams for 25 years.

Andrew R Stewart 

I think we all are getting splattered by our pissing into the wind here. Andy