Bicycle Mechanics - How Do I Adjust My Ultegra 6500 RD to work with a 12x30 Cassette?

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tandemnh
04-07-11, 05:15 PM
Ok this is an off shoot from another thread.

I have a 2004 C"dale R2000 Triple. I changed out the rear cassette to a 12x30. The drive tain is all Ultegra 6500.

When I switch the 27 or 30 tooth rings on the cassette I hear a clicking. After looking at itI can see the top rear whell on the RD is the place where the clicking is coming from. It appears as the chain rolls from the RD to the cassette 27 or 30 sprocket the hand off is no real smooth.

What I can see is that the wheel and sprocket are not in parallel with one another and because of their close proximity to one another the chain does not have the space to twist to fit cleanly to the rear cassette at the 27 or 30 sprockets.

Now if a move the RD by pulling down on the bottom wheel it moves the top wheel slightly away form the cassette and the noice goes away.

So, how do I adjust the Ultegra 6500 so that it is off the cassette when shifted in to the 27 and 30 sprockets? Sheldon Brown has said it will work... but how?


desertdork
04-07-11, 05:29 PM
You referenced Sheldon Brown; did you read this?
http://www.sheldonbrown.com/deakins/lowgears.html

FastJake
04-07-11, 05:43 PM
Turn your b-tension screw all the way in. Get a longer one if necessary. It might not be possible to run a 30T with your RD, but I've done 32T with an Ultegra short cage RD and the original b-tension turned in all the way.


tandemnh
04-07-11, 05:48 PM
No I had seen that page from Sheldon Brown. I'm rading now. Thanks

tandemnh
04-07-11, 05:59 PM
based on flipping the screw instructions, i'll need a longer screw or a long cage. I'll see if I pick up a longer screw tomorrow.

JiveTurkey
04-08-11, 01:28 PM
based on flipping the screw instructions, i'll need a longer screw or a long cage. I'll see if I pick up a longer screw tomorrow.

WAIT. Cage length has nothing to do with the max cog capacity. Cage length dictates how much slack the RD can take up between the bib/big combo (which needs a long chain) and the small/small combo (which needs a shorter chain). As a general guide, the longer cage version of the RD is for a triple chainring setup, and the shorter cage version is for a double (though some doubles may still require a long cage).

The upper parallelogram of the RD dictates the max cog it can handle. Shimano essentially has two classes: road (officially up to 27 or 28T) and MTB (up to 34 or 36T).

tandemnh
04-09-11, 06:53 AM
Great news, the fix is in!
I replaced the "b" screw from an old MTB Deore LX RD and a 10T sproket. That's all it took with a listtle adjustment and I am as good as gold. No click run through the gears great.
Thanks to all for the input. Great that I had the parts around the garage and did not have to drop a c note to replace the RD.
Now to go by that new computer with the money saved!

motobecane69
04-09-11, 06:33 PM
gglad it all worked out for you! I told you it would! go ride!