Question for those using a road derailleur on an MTB:- Mtbr.com
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  1. #1
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    Question for those using a road derailleur on an MTB:

    Which type do you use, double or triple?

    I'm currently getting sloppy shifting on my current setup: I am running an LX crankset with 3 chainrings up front with an LX rear derailleur and ultegra 9 speed 11-23 casette.

    If it shifts up perfect it shifts down like crap about 1/5 of the time. It it shifts down perfect, then upshifts are crap 1/5 of the time. There is absolutely no middle ground where shifting is good both ways.

    I do have a bum LX shifter; the ratcheting mech doesn't grab the teeth sometimes. It has gotten progressively worse over the past year, but I'm pretty sure that isn't the problem.

    I am going to replace the shifter, just wondering if the mountain derailleur is the culprit(would like to order everything at once for shipping purposes).

    I was hoping if anyone has been through the same situation and what any possible solution could be.


    Thanks,

    beer

  2. #2

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    maybe this

    perhaps the derailleur spring that causes the cage to move to smaller cogs is weak? Or there's too much cable friction, causing sticky upshifts?
    Usually, when you can dial in shifting in one direction, but it's balky going the other way, it's one of the above. You get the downshifts to larger cogs working, but the derailleur doesn't have enough oomph to shift back to the small ones. So you back off the barrel adjuster so the derailleur snaps the chain to the smaller cogs, but then you have to overshift to get it to go onto the larger ones.
    Assuming you cable and casing are in good shape, adding one of dem SRAM bassworm thingees ( I don't know if they still sell them and if they do what they currently call them, but you probably know what I mean) is a cure. I scored a bunch at a local shop's annual "garage" sale, for a buck a pop, and have put them on all my mtbs and now enjoy snappy instant upshifts and dialed in downshifts.
    Your problem is likely not because you choose to use a road derailleur, especially not with such a tight road gear cluster, which road derailleurs can easily handle, of course.
    Also, if you got your B tension screw cranked all the way in, crank it back out all the way so the upper pulley tracks closer to the cogs, and there's fewer chain links in between, so there's less side deflection on said links when the pulley says "shift." Less deflection = snappier shifts. If you have the B tension cranked in because the upper pulley rubs the chain against the "large" 23t cog when in the granny chainring, then your chain is definitely too long. shorten it until the upper pulley no longer does that.

  3. #3
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    I agree that your shifter ratchet is unlikely to be the problem; mine did the same thing until I pumped it full of teflon spay a few months ago, but even before this the shifting was fine when it engaged. At first it would only do it in sub 0 degree C temps but gradually got worse.

    Sheldon Brown suggests that over 95% of shifting problems are cable related and that has always been my experience.

    Wombat

  4. #4
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    Upon further review...

    I think its the pulleys on the derailleur. My cables are set up right, just got anal with the sloppy shifting and decided to give it the "pimp my ride" high dollar treatment. I Remember someone writing something in this forum about Shimano pulleys being either designed to have a little slop, or just having slop. I was watching the top pulley angle to the side when it wouldn't shift right, so there, I believe, is my culprit.

    I think a road derailleur should fix the problem, I don't think mtn derailleurs are really designed for smaller cogs with tighter gear ratios.


    Thanks for the replies,

    beer

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