OK, two not entirely unrelated questions for those of us who like to ponder such things, one for real and one theoretical:

1. I'm starting a build with a frame spaced to 130. I'd like to run in friction mode with bar end shifters. I'm also planning to run a nine speed cassette with low enough gearing to get some pretty low gear inches, right? What are my long cage dérailleur options? (remember that my world revolves around five, six, and seven speeds for the most part.)

2. The theoretical question: as I was digging through my boxes of gear I came across a nine speed Chorus RD that I'd forgotten I had. It came in a box of trade stuff, looks to be in good condition other than the broken cage. Can a long cage be retrofitted? I've heard of such things with more vintage components but I wondered if the more "precise" nature of modern gear precluded such shenanigans.

I realize these are both loaded questions, so let the opinions rage on!

1. First, I'd like to play devil's advocate and ask why you want to use friction shifting with 9 cogs. It will work well, sure. But 9 speed cassettes are designed for indexed shifting and you have the options of DT shifters, bar ends or integrated brake/shifters.

As you know, your gearing isn't just dependent on the rear cassette. It helps me to start with the highest gear I want and also the lowest. That makes it pretty easy to figure out your desired cassette and chain rings. Once you know that, you can choose a rear derailleur. That said, you probably will want a long cage mech and there are lots of options from Shimano and Campagnolo.

2. Don't know.

Justin, I probably shouldn't type these things before breakfast! The low gears are my priority here and I want to go with a 28 or 30 there, 12 or 13-ish on the other end. Why friction? Just thinking about ease of repair out on the road for worst case scenarios. I'm a little curious about experiences folks have had. Going with nine would be a relatively new experience for me in the first place.

AZORCH, Touring bikes and mountain bikes have long used mountain group long cage RDs for their 19-100 GI drivetrains. I've used a 105 long cage RD on my distance roadie. What is the range of gearing you're looking for? Which crankset and cassette are you considering?

IMHO friction shifting a 9S could be a little fiddly.

Brad

Just look for a used Deore XT RD. They are plentiful, relatively cheap, bulletproof, and will run 6-9 with no problem. With the right shifters, will work friction or indexing. Btw friction shifting 9 with barends is not bad.

I was really oversold on the "maintenance" and "reliability" concerns of index versus friction shifting, but I don't tour out in the middle of nowhere so it's really not a concern for me. And, so far, my limited index experience has been great.

In general, I believe the Shimano "road" long cage derailleurs shift 28t (maybe 30t if dialed in just right), Campagnolo long cage shift 29t and Shimano MTB derailleurs up to 34-36t.

I've found that if I'm not hauling much weight a 1:1 gear on 700c is plenty low. I think 9 is a sweet spot with lots of options including Shimergo.

Standard shortcage Shimano RDs such as 600 Tricolor will shift 28t without any problem.

It's interesting that you mention this, Colonel. I've never actually had a shifter go south on me ever - let alone, out on the road and far from help - but that is certainly what I was thinking about. Possibly (probably, in fact!) just overthinking things. I know you are really intrigued by the Shimergo concept and I look forward to hearing your opinion on how that works out for you. That's still in progress at the moment, isn't it?

I have a complete Tri Color (64xx - 8 speed) group on my Paramount, but I installed a 9 speed cassette and ordered Athena 11 Ergos from Ribble. When they arrive I'll install them and let you know. It's my understanding that it should be relatively plug and play. I'm also considering Veloce 10 Ergos for my Shimano 8 speed equipped touring bike that uses a 6 speed era Deore RD.

Hey, I over think these things for sure, but I typically end up with satisfactory results.

I was actually running a 9 speed with Campy NR deraillers. Feels good to me. I think I had a 28 for my biggest in back and a 32 42 52 in front. I found a nicer frame to put it on and haven't finished the swap yet. The shifters do take a light touch.

I'm a little puzzled by your line of inquiry - a long cage is needed for wrapping chain due to tooth differences between gears. The largest cog that a particular RD will fit is another matter.
When it comes to extending gear range, a triple front goes a long way, I've found. And with a single step or half step setup between the upper two chainrings, shifting, during cruise at least, is arguably more straight-forward than a typical double setup with a large difference between the two chainrings. By that I'm referring to the need, when shifting to the large chainring, for also shifting down several gears in the back, in order to access the next-highest gear when you're all done with the small chainring.
As a data point, my triple setups have gearing turn down up to 2.9:1 (e.g. 107-37), and all of them use short cage derailleurs. I actually don't need a gear that low with my current riding; I get by just fine with 50" or so. The big advantage of a triple for me, as alluded above, is enabling one or two tooth cog spacing in the cruising range (15-19), which in turn enables a single or half step setup on the two large chainrings. The result of course, is small steps between cruising gears, around 7%, which I find very desirable for maintaining a comfortable and efficient cadence.

Geoff, what chainrings and cogs are on your triple? I am trying to figure what dérailleur I will need for a triple I'm thinking of. I have 53/42/30 front and was planning 11-21 9-spd cassette. Idea being to have 42 ring a close-ratio for most riding, 53 for go-fast and/or intermediate steps, plus a bailout 30, which could even be changed to a 26 if needed? Is that similar to what you run with a short cage?

Sorry if I'm hijacking. BTW I think Chorus cages can only be replaced with Chorus or Record, at least in recent years, and I've not seen a source for replacement Chorus or Record cages that is much better than simply buying another derailleur. I'd love to hear of one.

I haven't tried mixing and matching cages, but have run into difficulties reinstalling cages when I may not have taken them off the right way. I'd tread lightly.

In addition to the Shimano long-cages that have been sugggested there's the Campy Racing T, not too dear used and designed to accommodate their 53/42/30 chainset combined with their 13-29 cassettes. There was an 8/9-speed version that I have used as an excellent friction derailleur. It has enough lateral range to easily accommodate the wide cassette of a 130 mm hub. You may need to try different shift levers. There's a real difference in how much cable they pull, and the sprockets are pretty closely packed together. You don't want the lever travel to be too sensitive - modern cogsets grab and release the chain quite readily if you don't have it feathered just right.

You might be able to order a repair part for your Campag 'nine speed Chorus RD'
as to precision, the extra length is about chain wrap up.
would not degrade the horizontal movement.
of the parallelogram of the body of the RD.

1. I don't see anything in the OP about a triple, so you seem to be focused on a wide-range double, running 9sp friction. There are plenty of modern Shimano RD's that will fit the bill, like Sora, Tiagra long cages, and any of the 9-sp long cage 105's, 600's and DA. I don't think the smooth 7-sp RSX long-cage will go 130mm. Above 30t rear, Shimano's MTB RD's are very good, the Deore lineup works well. Heck, even the Altus may work well. I don't see a lot of Campy long-cage RD's, so I don't know on that one. Suntour, I don't know.

2. If you could get a matching long-cage Chorus RD, it's probably a simple part switch, but I simply don't know.

I've used 9-sp cassettes on a 600EX system with the 6207 RD and the front shifters set to friction. Boy, did that require a light touch. I also have had good success using 9sp Sunrace DT shifters. They were something like $29.00 shipped, were new, and work very nicely with my 9sp 105 RD. That's something to consider.

I've run 9sp bar ends in friction mode and found myself shifting a lot, but the learning curve is much less steep than it was while running 9sp friction with DT shifters. With bar ends, I could stabilize my hand on the bar and focus on little shifts. The bumps in the road and pedaling didn't interfere near as much as when I tried to finesse my way through 9 speeds with friction DT shifters.

One thing, if you're used to 5,6,7 speeds, is that with a 9sp setup you may find yourself shifting what seems like constantly. I moved from 7-sp indexed on a bike to 10-sp DA indexed, and it seemed like I never stopped shifting. Sure, I had more available, more appropriate gears, but it seemed like my R arm needed to hang by the shifters almost constantly.

Quite right, but the OP did invite opinions, and appeared to be questing a wide gear range, so I gave my opinion.
jyl, my triples are all pretty old school (surprised?):

1. 52-49-36, 13-15-17-20-23-26
2. 52-49-36, 15-16-17-18-20-22
3. 52-48-36, 13-15-18-21-24

Quite right. I'm looking for opinions, which is why I left the questions annoyingly open ended. It's a bad habit, I know, but then sometimes you wind up getting some insights you wouldn't have otherwise gotten, or someone brings up a really valid point that might have been otherwise overlooked. Robbietunes, to clarify your point, I do plan to run a compact double. Old school, I run triples with half step six on a couple of bikes and your logic is pretty much infallible.

I'm looking at various configurations but will probably wind up going with a 48/34 up front with a 13-28 or possibly 13-30 in back. If I stick with eight instead of nine I pretty much have everything I need. The nine is really just me musing. The Colonel mentioned Shimergo to me and got me to pondering various configurations. I told him later that I have a tendency to overthinking things. But then that is one of the things I like about these forums: it lets you sort out your ideas (good and dumb) vicariously. Thanks for the input.