Should I be able to access all cogs from second chainring?- Mtbr.com
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  1. #1
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    Should I be able to access all cogs from second chainring?

    I started out with a 3 x 9 set-up. I recently replaced the largest chainring with a bash guard. I did not change any of the components.

    Now I'm noticing that I cannot set up the front derailleur so that I can be in the 2nd chainring and access all of the cogs within the chain rubbing on the inside of the front derailleur.

    I can set up the front derailleur so that I can access 2-1 through 2-8 with no rubbing, but then have rubbing on 2-9, or I can go the other way and be able to get 2-2 through 2-9 with no rubbing, but then have rubbing on 2-1.

    I understand that, with a three chainring setup, you're not supposed to use all the cogs when in the first or third chainrings. But I always thought you could use all the cogs when in the second chainring.

    So the question is: have I just somehow not figured out the perfect adjustment for my front derailleur or am I just running up against the limits of the components?

    Thanks!

  2. #2
    Elitest thrill junkie
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    Therein lies the problem with the front derailleur over the years, especially in the 3-speed configuration. This is why SRAM always had a micro-adjust gripshifter on the left side, so you could "trim" the front derailleur out, usually by shifting it over, then backing off a click. This can easily be an impossible goal on many bikes and setups (no rub). Usually you get some rub at once of the extremes.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  3. #3
    mtbr member
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    ^^^ yep. To paraphrase Shakespeare, "Therein lies the rub." And on road triples too. There are always some shifter trim positions needed to prevent rub in some gearing combinations. It's even been common to have trim positions on road doubles. Some mtb triple shifters do have a trim position for the middle ring. Does yours not?

    Analyzing and understanding what you've got should allow you to make the best of it. A little rubbing in extremes may be what you wind up with.
    Do the math.

  4. #4
    Bicyclochondriac.
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    I have gotten the middle position on some 3x cranksets (3x9 and 2x9), not to rub but some I could not. In think it depends on the shape of the FD..... or maybe just how much time I was willing to put into it.

    It can take a lot of experimenting. You can mess with the height of the FD, as well as the angle.

    I have generally had more luck with 2x9 conversions, and I am guessing that is because I have more leeway in how I position the FD due to not having to worry about shifts into and out of the big ring.
    15mm is a second-best solution to a problem that was already solved.

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