Shimano rd-6500 gs

[hans jatzke]

Randonneurs,

Has any one used this with a max cog of 32 teeth? The tech doc says 27 teeth but I've read that it does more. Anyone have any first hand use? Does it work well? It's a medium cage so I imagined it would.

Best,

Hans

[hans jatzke]

I'm sorry for the double message but what I meant to say is "shimano rd-5600 gs"

Thanks,

Hans

[Eric Keller]

I am using the long cage Ultegra version of that rear derailleur with 32 teeth.  I think the geometry is the same between series.  I got the idea from other PA Randonneurs, some who use 34 teeth with those derailleurs. 

You have to adjust what is called the "b" screw in order to rotate the body of the derailleur back enough that the top pulley doesn't ride on the larger cassette sprockets.   It isn't the best shifting experience I've ever had, but it works well enough.  I have considered going to mountain bike derailleurs that are made for this application. 
Eric

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[Bruce...@gdc4s.com]

> Has any one used this with a max cog of 32 teeth? The tech
> doc says 27 teeth but I've read that it does more.

It'll depend a lot on the geometry of your rear dropout. Shimano has a
recommended geometry that I'd expect most manufacturers follow these
days, but the thickness can vary depending on the material, and older
dropouts (e.g. horizontal dropouts with adjusters) can easily be
adjusted outside the recommendations.

27 teeth for road derailleurs is the safe maximum that should work for
all conditions; I'd expect the actual maximum rear sprocket size to
increase with increased dropout thickness (e.g. aluminum instead of
steel), larger distances between the axle and derailleur mounting bolt,
and increased effectiveness of the B-screw tab (some are designed so the
B-screw will overrun the tab if turned in too much).

My fanciest bike is a y2k Trek 5900 USPS Superlight set up with 39/53 x
11-34 9sp; of all the road and mountain derailleurs I've tried, the
original Dura-Ace 9sp short cage that came with the bike works best.
The dropouts are aluminum.

In cases where the B-screw overruns the tab (usually on aluminum
dropouts), the easiest solution is to remove the screw and screw it in
from the opposite side so the head is against the tab.

- Bruce

[Mark Beaver]

Cannondale actually specc'ed from the factory an 11-32 10-speed
cassette working with Ultegra STI and an Ultegra RD-6600GS derailleur
a couple of years ago on its T2000 touring bike. It worked like a
charm, although the b-tension screw had to be adjusted pretty far in.

You can also take out the b-tension screw and reinstall it "backwards"
to give more adjustment. I know someone who's using a short-cage
DuraAce rear derailleur with an 11-32 block using this technique.

Mark Beaver
Randonneurs Nova Scotia