sd5782 

I don’t really know much about the index compatible mid length cage Shimano rear derailleurs. I searched a bit and haven’t found much. I ride in the flatlands so don’t need the wide gear ranges of hillier areas. I’m a big fan of the Suntour VXs, although chain wrap is only about 28 teeth and no indexing. I recently put together a 7 speed cog set on a uniglide hub, and may try index on it in the future. I am generally a friction only guy and mostly Suntour, but a winter project might be fun.
I am not a fan of the looks of the long cages that wrap 40 links when it isn’t needed. Searching did show some nice looking Deore and XTR mid cage Shimano rear derailleurs. They seem like a very nice item for a compact double. Any experiences here?

mpetry912 

well it's hard to answer your question with precision but I'd say if you pay careful attention to chain length a mid cage should be able to handle a 13-28 rear and a 48-38-28

The extreme small / small and large / large combos should be avoided and those ratios can be approximated by other ring / cog combos with less extreme chain angles

/markp

sd5782 

The stuff I have read recommends these for trouble free wide ranging doubles ideally. As the 46-30 compact doubles seem to be popular with some here, I would have thought I would have seen more of these represented on builds. The XTR M900/910 GS seem quite beautiful and seemingly versatile. Looks like something to search for at swap meets.

nlerner

Ultegra 6500 comes in a medium cage. From Velobase: "The medium cage version (RD-6500-GS) has a max chain wrap of 29 teeth. Interestingly, the max cog size advertised by Shimano for the short cage version is 28 teeth while its value is 27 for the medium cage."

Piff 

Wasn't there a mid-ish cage dura ace derailleur from 7700 or 7800?

sd5782 

And the Shimano mid cage pulley to pulley spacing is very close to the same as the various Suntour GTs. The Shimano is index ready though and the upper pulley sits closer to the cogs for possibly better shifting.

rccardr 

Have lots of experience using a number of different Shimano short cage RD’s with 48/34 cranksets and 12-30 cassettes of both the UG and HG persuasions, both indexed and friction.
Not hard to get them to shift well at both ends with appropriate fettling.
However, moving to an inner ring smaller than 34 or a cassette cog larger than 30 (or perhaps 32 in some rare cases) really does require the longer cage version.
There were longer cage versions of pretty much all of the Shimano road going RD’s starting with 1055, but IIRC the body size and upper geometry was identical to the shorter cage versions which helps with chain wrap for a granny on a triple but not so much with larger cassette cogs. Important to remember that Shimano roadgoing triples were mostly of the 53/39/30 flavor. For larger (32-34-36) rear cogs a Deore RD works best, as the upper body geometry is designed to accommodate both the larger cog and the ring difference of a subcompact or triple.

sd5782 

The ones I am talking about list a pulley to pulley distance of about 66 mm vs the long cage mtn versions being around 87 mm. I think these are more of a shorter cage version on a mtn derailleur and still not nearly as short cage as the common 105 style road derailleur. The XTR for example is rated for a 32t big sprocket and 33 link chain wrap. Those numbers got me interested.

bwilli88 

I have a 7700GS on my Pro-tour and it shifts a 11-36 cassette quite well with a half step + granny up front.

mstateglfr 

A midcage RD is good for a compact crank. Shimano also call these 'GS' rear derailleurs.
They are well established in years of use and range within the product line.

Kontact 

In the early '90s Shimano made short cage MTB derailleurs. I used them or road short cages on MTBs with triples, by sizing to the big/big and avoiding the small/small when in the granny because there is some slack. This has worked very well for me, because shifting into the granny is not something that happens often or accidentally.

Old MTB gearing was essentially a low-ish road cassette/freewheel paired with a triple whose granny gear was sufficient to make the low/low combination low enough. But then triples went out of favor and the work producing low gear ratios went to the cassette, which then required that derailleurs have larger and larger max cog size.

If you have a triple, you can use practically any rear derailleur you want and get a very wide range of gearing. As soon as you shift to a double you need a much more specialized rear derailleur to maintain low gearing.

delbiker1 

I have a 1X set up using a 6500 short cage and 11-34 cassette with a 44 tooth front. Shifting is with a 6400 bar lever in friction mode. Works great. I have had an 11-36 and that is also fine. An 11-40 requires a longer caged derailleur.

sd5782 

Thanks for the GS info and experiences offered here. I will keep an eye out for one of these along with the Deore and XTR versions. I may even revisit the 105 as mentioned also. I have a 105 on a 1X now doing a 28 gear and think I had a 30 on there before too. Max chain wrap I need may only be around 28-30 anyhow, so the more common 105 may just be fine. Some of those GS ones mentioned are sure pretty.

Pompiere

If you already have a Sun Tour GT derailleur and Shimano index levers, you could try them together. A lot of people have been successful in getting Shimano levers to index with older Sun Tour derailleurs. I used that combination on a bike in the past and it worked great. I had Shimano 7 speed levers, a Sun Tour Seven derailleur, and a Sram 8 speed cassette. I set the high limit screw to lock out the 11 tooth cog.

sd5782 

I believe I tried a couple Suntour RDs with an indexed thumb shifter in 6 speed without success, but not 7 speed. My education pretty much ended at 6 speed. Indeed, the Uniglide freehub I am playing with was a six speed, but with time on my hand, I thought why not try to make it into a seven. Plan for now is to continue with the nice ratchet downtube Suntour power shifters. It seems to shift the uniglide gears nicely. I do have the parts to put together a clamp-on indexed shimano downtube shifter in 7 speed I think, so if I get bored I may try that.

As an aside, I just put an older Suntour Alpha 3040 rear derailleur on the back. My searches showed one from you getting that RD to index Shimano IIRC. I may just keep that on there, although it doesn’t have the visual appeal of some of the other units.

70sSanO

I’m running an XTR M910 on my road bike with a triple and a 14-36 8 speed cassette.

The RD-7700GS not withstanding, the M900/910 is probably one of the best RD for the era. With a rated 32t, which can be pushed depending on hanger, it is Dura Ace on steroids.

For an older medium cage, you would be hard pressed to find a better one. Biggest downside is cost.

John

dddd

Although not touted as Shimano SIS-compatible, the 3xxx (i.e. usually 3040) series Suntour Accushift derailers had different actuation, more in line with the later trend using longer cable travel for any given travel of the cage. As such, these tend to work better than other Suntour derailers with Shimano SIS shifters using a Shimano freewheel having the same # of cogs intended by the shifter.

I've used other Suntour derailers (both friction and Accushift types) with Shimano SIS levers, but all of these non-3040 Suntour derailers had actuation that seemed the same as all of the pre-9s Dura-Ace rear derailers, so would index an HG cassette having one fewer cogs than the shifter had clicks.

Even Shimano's friction-era rear derailers had seemingly the same actuation as those non-3040 Suntour darailers and pre-9s Dura-Ace SIS rear derailers, so are close to plug-'n-play with 7400 Dura-Ace if indexing-grade cogs are used (B-tension adjustment, cable smoothness and part-selection variables need to all be good though, for decent indexing to be realized).

A mid-cage R6500 mid-cage rear derailer can handle a 12-32t cassette and 42-52t double with still-good indexing crispness at both ends of the cassette (shown at bottom working with a 12-34t cassette on the Holdsworth, but which feels clunky going to/from the 34t).

This re-badged Deore's cage is longer than a short-cage road derailer, but not by much! Still will handle a 32t rear cog if the chainring range isn't too wide, so likely about what a mid-cage M900 can handle.

sd5782 

It is all kinda interesting as some Shimano versions are called long cage yet pulleys are listed at about 66mm apart while the usual long cage is more like 87. The 105 style and others may list long cage, but actually be in that mid cage area. Also interesting is that the 105 is pushing it with a 30-32t cog but can still wrap plenty of chain. That is why I commented about the XTR, and also the Deore 737/739 versions that are listed as that nice midrange without even pushing it for 32t and 33 wrap. Those are listed at about 66 mm pulley centers. Kinda strange Shimano uses the GS and long cage to mean different pulley center measurement distance depending on which model it comes from. When Suntour said mid/long, you pretty much knew what it was.

That Suntour Alpha 3040 seems similar to the Shimano 105 in initial dimensions, except it handles the 30t cog easily and probably wraps a bit more chain. It does however seem to be quite a bit more of a “bargain” unit, and there won’t be great pride of ownership with the composite inner pulley cage. It does look nice from the front though so will do for now. I’ll probably just keep the XTR and 737/739 in mind for a list for next years bike shows. They do look very versatile.

dddd

The composite inner plate looks modern, but unless it's a riveted design it's pretty solid.

The pullies on Suntour derailers have large-diameter bushings in them, which can cause a lot of drag if a viscous or age-thickened lubricant is present.
Some of the Suntour derailers use a special nut securing the cage and top pulley, so on those (just as with a riveted cage model) I simply flood the dust shield with 5W30 or even lighter oil to minimise the rotating drag in cool weather.

Erzulis Boat 

Yes. I have one!

The Golden Boy 

The Dura Ace 7703 and the 7803 were the DA triple derailleurs. The 7703 worked with a shorter cage, but with a larger pulley. The 7803 was a pretty standard GS cage.

620 Build Derailleurs by Dave The Golden Boy, on Flickr

1985 Trek 720 by Dave The Golden Boy, on Flickr




The XTR M900 derailleur is usually seen with a short cage. I don't think I ever saw a long cage until 2 years ago. This is as acquired:

XTR M900 SGS by Dave The Golden Boy, on Flickr




And I swapped cages with my relatively clean one:
M900 XTR Long Cage by Dave The Golden Boy, on Flickr




You can really tell the difference of the stock M900 cage compared to the M735 GS cage:

M735 XT and M900 XTR Rear Derailleurs by Dave The Golden Boy, on Flickr

sd5782 

The Deore XT 737/739 seem to have the attributes I am looking for along with the XTR 900/910. I can’t believe how expensive these are on eBay. As stated, it will be something to look for at a bike show. The 66-67mm pulley spacing looks very nice, but realistically, something around 57mm would be fine too. It just offends my tastes to see the long 87mm pulley cages used when it is not needed even though they surely would work fine. Indeed, I was running a classic long cage Superbe on this bike, but thought to perhaps try index sometime just for fun.