lizardcobra

I screwed up yesterday; I measured the new chain against the old chain, but I forgot that the Master Link required two male ends, and I had cut it leaving two open ends. Second dumb mistake was that I decided to cut two additional links off and ride it. After a few miles of riding I shifted, and wrecked my rear derailleur.

I'm trying to figure out now if any of the derailleur is salvageable. Can I replace just part of it, or will I need to replace the entire thing? If I do need to replace it, what should I look for to make sure that I buy something that is compatible? I'd like to stick with Campy, if possible.

I have an 8 speed cassette. The derailleur is Campagnolo 9 Speed "Mirage." I'm not sure if it is the original. This is on a 1997 Bianchi Volpe. The piece that has the make make/model on it has snapped clean in half. It doesn't look like any other part has been snapped or sheared, but I'm not sure.

Does it matter if I get an 8 speed? Should I look for a replacement 9 speed, since that seems to be what was on it now? I don't know if this was the original rear derailleur, so I'm wondering if I would actually be better off replacing with one spec'd as 8 speed. I can't find any info on what would originally come with this bike. Should I look specifically for another vintage "Mirage," or would other models also be compatible? I'm seeing a few for sale that *look* similar, but I don't really know what I'm looking for.

I tried to attach pictures showing this, but apparently I'm not allowed since I haven't made 10 posts yet.

79pmooney

Ouch! I have a Mirage on my best bike. Sweet shifting derailleur!

I wonder if there is an exploded view of those derailleurs. That might tell you what is possible to replace. Now, finding that part might be a tougher challenge, I don't see a lot of those derailleurs

And now you know - you always check big-big before the bike hits the road. Doesn't work? Screw in the low gear limit screw until you cannot reach that cog (or cogs)..

cxwrench

Sounds like you need to start shopping for a new derailleur.

3alarmer 

....all of this is "generally speaking" info, so take it like that. I've never had a Mirage derailleur.
But in general, as long as you stay within a manufacturer's products within a given age range, the shifters are what determine the indexing pull rate (in combination with the rear derailleur).

So IME 8 and 9 rear derailleurs, if designed for indexing, and designed for that maker's rear cog spacing, are more or less interchangeable. I hope I used enough qualifiers.

Sometimes you can find someone else's broke down rear de and use the parts of it to fix yours, or yours to fix that one.. But you need to be in an environment that allows scrounging, like a co-op. There's a C+V sales section here and there's also an ISO thread you can try a post in...it doesn't hurt to try there.

Andrew R Stewart 

So I read two mistakes. The first is the chain cutting one. The second was shifting into the big/big combo.

I agree with finding a new rear der and also checking the hanger's alignment. Andy

70sSanO

At one time I was thinking of using Campagnolo Ergo levers with a Shimano rear derailleur. None of that will help you, but in 2000 Campagnolo changed their shift ratio from 1.4 to 1.5 for their 10 speed systems, and 9 speed systems a year later. I'm only bringing this up in case you are able go to a Campagnolo 9 speed rear derailleur with your 8 speed system, you will need the old Campagnolo ratio. Someone with some real Campagnolo background can give you better advice.

John

billridesbikes

For a Campagnolo drivetrain you always use the longest chain possible and determine the chain length needed in the big-big combo. This reduces the spring tension in the RD for optimized shifting.

cxwrench

In general or in this instance in particular?

Andrew R Stewart 

Three replies-

I run a few bikes with Campy ders, Ergo 9 speed levers and Shimano cassettes with Shiftmate adaptors. All work well. I also have one with Shimano rear der/Ergo levered again Shiftmated. Again works well. Yes which generation of Campy rear der needs to be heeded.

Generally I have tried to use the longest chain possible. Between the options of being able to remove a link if something bad happens and the dislike of running a system at it's limits as the default... Today's connecting links make this exploration far easier then when replacement pins were the only way to connect chains. Often it's a trade off between lowest gear pulley knock and too little chain length for the big/big combo. This is where paint by numbers only can bite one.

Today's indexed rear ders are far more insensitive to hanger misalignment. But My focus was more about when a too short chain is shifted onto the big/big the der sees serious stress. The chain wants to have the least lengthy wrap about the system and the rear der adds a bit of chain length need even when played out fully. Thus the der gets broken off in the extreme. Or the hanger gets bent many times. Andy

cxwrench

I agree 100% with running the longest chain possible.

AndreyT

For this drivetrain in particular of course.

Shifting into the big-big combo stopped being a mistake and instead became a critical skill about 15-20 years ago. The ability to shift into bib-big has always been the Holy Grail of bicycle drivetrain design. The whole derailleur R&D of the recent era has been wholeheartedly devoted to that single purpose alone. This is actually the primary rationale behind electronic drivetrain systems.

Andrew R Stewart 

What??? This is not at all what I and many others who do this stuff daily have learned about both drivetrain development and e shifting. But it's your belief so it's not my problem. Andy

Litespud

seems a little over dramatic to say that that big-big was some sort of previously unattainable “holy grail”. AFAIK, there’s never been any issue getting ones drivetrain into big-big, it was simply frowned upon as cross-chaining, which was considered bad for the drivetrain. Seems like I’ve always had this critical skill and the Holy Grail in my pocket this whole time....who knew?🤔

cyccommute 

Less a Holy Grail than a Lazy Grail or a “Don’t Understand Gearing” Grail. What possible reason is there for shifting into big-big combination? The big-big gear is a duplicate of some other gear and a shift should have been made to a lower range long before getting to that combination. It is also at the severe range of the system. There’s almost nowhere to go if you need lower gears. If you shift to the inner range you are at the limit of that range and would need to upshift to get some wiggle room.

Here’s a visual example.




The red circles show the duplicate gear. The green arrows show a good shift point to get the most out of both ranges. The shift point could be the 17, 20, 23, or even 26 but anyone of them would result in having more usable gears than downshifting to the big-big combination. If the rider shifts at the 20 tooth cog, there are 5 more usable gear combinations and 2 of them are lower than the bib-big combination.

Litespud

I also find a psychological advantage in an earlier shift to the "low range" during a climb. I feel a lot better knowing that I have 3-4 "low range" sprockets yet available to me, as opposed to being at the low limit of the "high range" - even if I end up not using those extra gears, it's good to know that they're right there.

cxwrench

Sorry guys, but big/big is very useful for many riders. Shimano Di2 allows big/big standard...it blocks small/small. Sure you can duplicate the ratio in the small ring but many times it's easier to stay in the big ring. The best example is racers needing a slightly easier gear to get over a small bump and not wanting to risk shifting a bunch of cogs and shifting at the front. Like it or not this has been a prime concern of drivetrain designers. You may think it's bad, not needed, whatever...the truth is you just haven't been in some situations where it helps so you don't have that experience.

himespau 

Do you know what part of your derailleur broke? I have a 9 speed mirage (I think) triple derailleur that had a bad return spring (I think that was all that was wrong with it - it may have also had a crack above the hanger bolt as those were common, but that may have been a different one in my parts bin), that I took apart because I wanted to transfer the cage to a short cage 10 speed centaur derailleur before I looked at it and reallized that they didn't have the same shapes and then never bothered to put back together. I wonder if it would be possible for you to cobble one functional derailleur together with the parts both of us have.

cyccommute 

Frankly, I don’t care what Di2 does or doesn’t allow. Di2 isn’t the be all/end all of bicycle shifting. I also don’t care what racers do or don’t do. They don’t usually buy their own stuff so it doesn’t matter if they screw something up or destroy something. The sponsor will pay for the new parts. And I’m not particularly impressed by drivetrain designers because they design drivetrains for racing, which is only a very small percentage of the bicycle market. Drivetrain designers, in my opinion, don’t understand the drivetrains they are designing when it comes to the bulk of the market. They certainly don’t understand low gearing and how low that gearing should be for mere mortals.

I haven’t been in a situation where big-big is needed because it is never really needed for the vast majority of cyclists. I don’t need “that experience” because it’s unnecessary. Racing...and racing techniques...is only a very small part of bicycle riding and for those of us who have to pay for our own parts, using racing techniques can get very costly, very quickly.

phughes

cxwrench

You must have missed the last 10 years where low gearing has gotten lower and lower...and lower. And shifting performance has improved for all riders, not just racers. People like you and your stuck-in-the-mud opinions don't help things.

Atlas Shrugged

WTF? You can purchase a Campagnolo Super Record EPS in a 50-34 Crankset and match it with a 11-32 cassette and you mention they don't make gearing for the average cyclists? This is lower gearing of triples from back in the day.

AndreyT

The matter of "cross-chaining" has stopped being perceived as an issue a long time ago. (With the exception, perhaps, of a bunch of armchair cyclists on the Internet.) "Cross-chaining" is simply a matter of increased wear and tear and nobody cares about that anymore, especially considering that in modern drivetrains the increase in wear is negligible and probability of immediate failure is zero.

The problem with big-big is not "cross-chaining", but rather mechanical interference between the chain and the FD cage, especially in extreme racing frames with short chainstays. The shorter is the chainstay - the bigger is the chain skew in big-big. Which is why the past decades were defined by a frantic race to implementing a usable "trim" feature for indexed drivetrains. Yes, they made it. And, obviously, the whole purpose of "trim" feature is to facilitate the divine big-big.

Of course, electronic shifters finally provided the ultimate solution to the problem.

Litespud

Or Campagnolo - where trimming the FD was never a problem

Litespud

I agree - there have been times where i've gone big-big because I had no choice - I remember one time where I signed up for a 60-mile fast rotating pace-line ride where I was pretty much hanging on by the skin of my teeth (not quite out my depth, but the water was right at nostril level ) - I wasn't about to start screwing about with simultaneous front/rear shifts to find the next gear in such close quarters and under those conditions (one of those "you're going to get yelled-at" rides), so I went big-big because I had to.
I guess I don't see that big-big is such "a prime concern of drivetrain designers" - is it really some sort of technological challenge? Whenever I run through the gears on the stand after an overhaul or service, I run through all the gears - even the ones I don't ordinarily use on the road - getting a "clean" big-big or small-small has never been an issue. Granted, I'm running relatively low-tech mechanical 10sp - this might be more an issue with more crowded drivetrains.

70sSanO

OP, from what I have read, a pre-2001 9 speed should work with your setup.

You should probably research, by pictures or model number what late 90’s models look like and go on eBay and get another derailleur.

As already mentioned you can ask in the Classic & Vintage subforum about replacement rear derailleurs or about rebuilding yours. Unfortunately you need 10 posts to be able to post pictures.

If you are able to rebuild, you might want to still pickup a used derailleur and then wait for suitable parts only one to pop up.

Good luck.

John