Bicycle Mechanics - Shimano 600 9 speed indexed compatibility

I have a Shimano 600 rear derailleur that was previously used with friction shifters. Will this be compatible with Dura Ace 9 speed indexed shifters, or do I need a 9 speed-specific rear derailleur?

Shimano's derailers from the pre-indexed-shifting era aren't compatible with indexed shifting, which requires a specific cable-pull ratio (amount of cable pulled per the horizontal distance traveled by the pulley wheel) such that the clicks in the shifts line up to the gears on the rear wheel.

If you're talking about the model pictured here (about 1984, at the end of friction-shifting era), then you're out of luck as far as using it with indexed shifting.

Shimano indexing compatibility: all Shimano rear derailers since the advent of indexed shifting have the same cable-pull ratio, except for 7- and 8-speed Dura-Ace. So theoretically, you could use a 6-speed-era 105 rear derailer with an 8-speed system, etc.
However, derailers originally designed for fewer speeds are generally less precise (because they didn't need to be), and so you generally want a rear derailer designed for the same number of speeds, or a greater number of speeds, than you are using.
So a 10-speed-era rear derailer will be fine on a 9-speed system, but an 8-speed-era rear derailer won't shift very crisply on a 9-speed system.

http://www.unc.edu/~cupery/pics/bikes/Centurion_Comp_TA/small/03_IMG_5823--600_rear_derailler.jpg (http://www.unc.edu/~cupery/pics/bikes/Centurion_Comp_TA/small/03_IMG_5823--600_rear_derailler.html)

So a 10-speed-era rear derailer will be fine on a 9-speed system, but an 8-speed-era rear derailer won't shift very crisply on a 9-speed system.
That may be correct in theory but I'm using an 8-speed 105 long cage rear derailleur on an otherwise all 9-speed 105/Ultegra mix bike and the shifting is very good. If there is a difference in precision, it's pretty small.

fair enough; I've done this to and been mostly okay with it, although shop mechanics I've talked to have sounded aghast about it :)

That may be correct in theory but I'm using an 8-speed 105 long cage rear derailleur on an otherwise all 9-speed 105/Ultegra mix bike and the shifting is very good. If there is a difference in precision, it's pretty small.

I think timcupery's point still stands. You should not expect excellent shift quality from a 6 speed derailer on a 10 speed cassette.

I upgraded a friend's triple from STI 7-speed to STI 9-speed and the shifting was perfect, front and rear.

I upgraded a friend's triple from STI 7-speed to STI 9-speed and the shifting was perfect, front and rear.
By this I assume you mean you used 9-speed STI shifters and cassette with the derailers that had originally come with the 7-speed drivetrain?

By this I assume you mean you used 9-speed STI shifters and cassette with the derailers that had originally come with the 7-speed drivetrain?

Yes, I probably should have offered more details. The new shifters were 105 9-speed. I rebuilt the old wheel with a new 105 9-speed hub (frame had 130mm spacing), one of my extra 9-speed Ultegra cassettes, and 9-speed Ultegra chain. The triple crank and both derailleurs remained original 7-speed RXS. The bike shifted perfectly, better than my wife's new, at the time, 9-speed Ultegra.

Al

Shimano's derailers from the pre-indexed-shifting era aren't compatible with indexed shifting, which requires a specific cable-pull ratio (amount of cable pulled per the horizontal distance traveled by the pulley wheel) such that the clicks in the shifts line up to the gears on the rear wheel.

I've never had this satisfactorily explained to me. I can't for the life of me figure out how a derailleur would know or care how much cable was pulled. I DO agree that a 6 spd. derailleur is not in all probability going to shift accurately or far enough for 9 or 10 speeds.

I've never had this satisfactorily explained to me. I can't for the life of me figure out how a derailleur would know or care how much cable was pulled. I DO agree that a 6 spd. derailleur is not in all probability going to shift accurately or far enough for 9 or 10 speeds.

The distance that the derailleur's pullies travel laterally is dependent on cable pull and derailleur geometry (throw ratio). We are lucky that Shimano has designed all of their modern rear derailleurs with the same throw ratio (with the exception of pre-9-speed Dura-Ace). Pre-indexed Shimano derailleurs may not have the same throw ratio as modern derailleurs. Campy's derailleurs have changed through time, their throw ratios changed as recently as 2001, and all modern Campy derailleurs are different from Shimano's. SRAM's road derailleurs are not compatible with Shimano's or Campy's.

Al

Hey, thanks! That's a great explanation.