Ultegra Gear Shifting Issues

rider25
rider25 Posts: 72
edited May 2014 in Workshop
Hi there,

Firstly, I've an Ultegra 6700 compact groupset with the exception of a 105 cassette. It's really smooth when I change down (move upwards towards the biggest rear sprocket) but when I shift in the other direction it really snaps/slaps into gear.

Is it symptomatic of the wide range of a 10-speed 11-28 cassette or are there adjustments I can make to retain the responsiveness without the aggressive nature of the gear change?

Hope that makes sense. :?

Cheers!

Comments

  • jordan_217
    jordan_217 Posts: 2,580
    So you have a nice positive, snappy gear change and you're not happy? ;-)

    I use 11-28 cassettes on my bike and no steps between ratio's are big enough to cause anything but nice, progressive shifting.

    Can you upload a video of this? Why exactly leads you to believe there's a problem? Is there any hesitation in the gear changes does the chain move across straight away?
    “Training is like fighting with a gorilla. You don’t stop when you’re tired. You stop when the gorilla is tired.”
  • rider25
    rider25 Posts: 72
    ;o) Thanks for the response.

    Admittedly, there's a small chance that I'm being a perfectionist... but I don't think so. Shifting on my Sora equipped winter bike is smoother. Albeit with a 9-speed triple.

    I'd describe moving up the cassette as progressive. Moving down the cassette is extremely responsive (too responsive!?!?) - no delays whatsoever. It just seems very 'harsh'.

    I'm not sure that a video would help. Shifting while on a stand doesn't replicate the 'harshness' that occurs when I'm out and about.

    I could try incremental adjustments to the barrel adjuster to see whether that takes the edge of things. But being a relative newcomer I thought I'd check others' take on things.
  • arthur_scrimshaw
    arthur_scrimshaw Posts: 2,596
    Is it a different wheel/freehub? less pawls could lead to a snatchy engagement.
  • Semantik
    Semantik Posts: 537
    Could be worth fitting a new rear mech cable and lubing inside the outers.
  • plodder73
    plodder73 Posts: 326
    I have a 105 set on mine with a very wide range gearing of 11/32. I have exactly the same with mine, don't see it as a problem, would think that is how it is supposed to be.
  • rider25
    rider25 Posts: 72
    Thanks everyone - quite a range of things to consider.

    What do you mean by a different a wheel/freehub, Arthur? I'm running Fulcrum Quattos with their original freehub.
  • arlowood
    arlowood Posts: 2,561
    It's likely be down to the way the rear derailleur functions. The tension spring for the parallelogram that moves the chain is set to default to the smallest sprocket on the cassette. So the spring is always trying to pull the chain in the direction of the smallest sprocket.

    When you change to lower gears (moving from smaller to larger sprockets) you are effectively pushing against that spring tension so the changes appear/feel smoother. When you move to higher gears (larger to smaller sprockets) by operating the inner paddle, the shifter releases the cable which then reacts to the tension of the spring in the rear derailleur and "snaps" over onto the smaller cog.

    This is why changing to higher gears is usually more clunky than moving in the opposite direction.
  • arthur_scrimshaw
    arthur_scrimshaw Posts: 2,596
    rider25 wrote:
    Thanks everyone - quite a range of things to consider.

    What do you mean by a different a wheel/freehub, Arthur? I'm running Fulcrum Quattos with their original freehub.

    Freehubs have different engagement distances, i.e. the distance the freehub rotates before the pawl engages on the ratchet, if you back of the power when changing this can lead to a snatch as the freehub re engages.
  • rider25
    rider25 Posts: 72
    Thanks all. Will give it another run out over the weekend and update.
  • dennisn
    dennisn Posts: 10,601
    rider25 wrote:

    I could try incremental adjustments to the barrel adjuster to see whether that takes the edge of things.

    That would be my vote. Although you should research HOW to do "... incremental adjustments..." instead of trial and error.
  • plodder73
    plodder73 Posts: 326
    arlowood wrote:
    It's likely be down to the way the rear derailleur functions. The tension spring for the parallelogram that moves the chain is set to default to the smallest sprocket on the cassette. So the spring is always trying to pull the chain in the direction of the smallest sprocket.

    When you change to lower gears (moving from smaller to larger sprockets) you are effectively pushing against that spring tension so the changes appear/feel smoother. When you move to higher gears (larger to smaller sprockets) by operating the inner paddle, the shifter releases the cable which then reacts to the tension of the spring in the rear derailleur and "snaps" over onto the smaller cog.

    This is why changing to higher gears is usually more clunky than moving in the opposite direction.



    Absolutely what he said

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