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Thread: Double Chainring Ratios / Clearance.

  1. #1
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    Default Double Chainring Ratios / Clearance.

    Hi All,

    Currently have a 2 x 10 set up. Rather than going all out to 1 x 11 just yet (trying to get fitness up first), am looking at reducing the gap between the big 36T and tiny 22T (ruins cadence everytime). I can buy a 64BCD ring with up to 28T - this may be a stretch so more likely 26T with 11-36 rear. Question is -> These normally come as a set with defined difference between rings (shimano) would there be any issues (clearances, derailleur settings?) in going to 36/28 or 36/26?

    Thanks gang.

  2. #2
    Senior Member The Duckmeister's Avatar
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    The main reason for the defined sets is the alignment of the shift ramping. You can run mismatched rings, but shifting, especially up to the big ring, can get a little bit crunchy.
    Just ride the bloody thing and enjoy yourself!

    I build wheels... :wink:

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    You can compensate for the cadence issue by shifting up one or two gears at the rear when you drop to the smaller chainring. Once you get the hang of it, its not far from any other downshift depending on the jump between chainrings. Back in the day of triple chainrings, it was pretty easy as the jump between chainrings wasn't so much so you only needed to shift up one gear at the rear to compensate. A 36 to 22 jump is pretty big, so you'd probably need to shift 2 gears to get an acceptable jump.

    Of course, this is a lost art these days of 1x drivetrains.

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    I have 34/22 x 11-34 and my wife 36/24 x 11-36 and both these work fine ,I agree 36/22 is a bit of a jump without a double shift.
    It depends on the terrain you ride ?
    scarey but cool

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    Wow I seem to have that effect , as soon as i post something the thread shuts down.
    Its either they are still digesting my wisdom or they are speechless about the fuckwittery ?
    scarey but cool

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    Yeah I run 36/26 and even with this i find myself downshifting at least one if not 2 gears when going to the smaller chain ring, although i very rarely use the small change.

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    Thanks guys. Yeah I know the double shift and all but even then it's still a PITA due to the large gap. I can get buy on my usual trails with around a 0.75 ratio so a 26 at the front would be fine. Can the FD be tuned to change shift ramping? (never even touched the front derailleur...)

  8. #8
    Senior Member The Duckmeister's Avatar
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    Shift ramping is built into the big chainring; FD just mashes the chain against the ramps. A 38T ring to pair with a 24T small ring will have different ramping to the same size ring to pair with a 26T small ring, due to the larger climb from the smaller small ring.

    You could get a triple.... Bigger range, smaller jumps between rings.
    Just ride the bloody thing and enjoy yourself!

    I build wheels... :wink:

  9. #9
    Senior Member Flow-Rider's Avatar
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    Maybe try dropping into the small ring a bit later up the climb. I'm the only one running a 3x and 2x in my main riding group and I'm not having any issues of spinning out.
    Most of the Xt stuff of the same speed and year seems to work ok, you might just need to adjust the way you up shift. Sometimes just a good fast flick or hold the lever depressed for a bit longer for a better shift going up.
    Last edited by Flow-Rider; 13-07-2017 at 07:12 PM.
    "To avoid criticism say nothing, do nothing, be nothing." ~Aristotle.

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    Senior Member stirk's Avatar
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    Quote Originally Posted by rowdyflat View Post
    Wow I seem to have that effect , as soon as i post something the thread shuts down.
    Its either they are still digesting my wisdom or they are speechless about the fuckwittery ?
    Nah, not you, most of us cool kids went 1x years ago and so have nothing to add.



    Personally I'd be using a spreadsheet to calculate all the different ratios I'd get changing any ring combination and base it on required granny and what big ring I could actually push downhill to go faster. Using the data you could see where the optimum shift point is for front and rear to keep ratio jumps smooth through the range.
    Fertilising my post count

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