Rear derailleur rubbing on 34t cog

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A reader doesn’t enjoy the grind-grind-grind of his XTR derailleur on his 2003 Enduro’s cassette. What to do?

Lee,

I have a 2003 Enduro Expert and since your an Enduro enthusiast, I thought you might be able to answer my question.

The bike has an LX chain, LX cassette, and a 2002 XTR derailluer. I adjust the B-tension screw as much as I can and the derailleur seems fine when it’s in the granny gear in the back, but when I go to ride it in that gear, and I begin to put tension on the drivetrain (like in a climb), I begin to hear/feel the derailleur grind into the largest and second to largest cog (34 tooth).

Thanks for your time,

Brian Froeber

Hey Brian.

I got the scoop from the man himself, Brandon Sloan. He’s the product manager for Specialized Enduros.

Hey!

The hanger that is on the old Enduro (and our older Stumpjumper, Epic…) in combo with Shimano rear derailleurs and 34t cassettes can produce some chain bouncing in the 34. The hanger is within Shimano requirements, but the older Shimano rear derailleurs (non-rapid rise) were designed to work best with 32t cogsets. The 34 is at the limit of the derailleur’s comfort range.

Some ideas to help would be:

– Insert the B-tension screw backwards (basically extending the screw’s range).

– Run a rapid rise rear derailleur (bad).

– Rrun a 32 rear cog.

– Run SRAM. (This is what I do. – Lee)

– Play with the chain length (a longer chain might help?).

– Live with the noise.

Brandon

6 replies
  1. Brian Froeber says:

    Lee,

    Thanks for the help!! Brandon I did switch the derailer out to a 750 series XT which helped a little, but the problem is still there……

    Brian

  2. Patrick says:

    Another way to help with this problem is to slightly shorten the length of the piece of housing that goes to the derailleur. This pivots the derailleur up and forward, it generally works pretty well at fixing this problem. Good Luck.
    -Patrick

  3. Trevor says:

    wind the b-tension screw in, or run a more normal cassette, i never use the 32 or 34 on my xc bike, so i run a 12-27 road cassette, closer ratios so nicer gears and you can still use 22 27 which is a low enough ratio to get up most hills (in the uk anyways)

  4. jnormal says:

    Not much you can do, this is just a minor quirk of the Shimano design. With no solid B-pivot stop on the derailleur there’s nothing to prevent chain tension from pulling it forward until the chain gets sandwiched between the pulley and cog. It won’t hurt anything, just a minor annoyance in one or two gears and that’s about it.

    To me the noise has always been more prevalent in the workstand and less on the trail. Maybe because when the bike’s in the stand the derailleur tends to be right in my face so I hear it easier. Sitting on the bike riding with everything behind me I hardly notice.

  5. Peter S says:

    Wind the b-tension screw in all the way, then place a housing cap over the extended screw. This may give you enough tension on the pivot spring. One other trick is to put a 2mm spacer behind the derailleur pivot bolt. Because of the way the derailleur swings, this gives you a little more space between it and the cog. Try both and keep pedaling. Try whistling while climbing to reduce the noise and a softer saddle to reduce the vibration.
    Petey

  6. Morris M says:

    One way we found to reduce the contact between the cog and pulley is to use a smaller pulley. Older XT or XTR works well.

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