Rear derailer for a 12-32t 10 speed cassette
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  1. #1
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    Rear derailer for a 12-32t 10 speed cassette

    I am nearly finished building my OCR Touring bike. Can I run a (long cage) Ultegra rear derailer with my 10 speed 12-32t cassette without any problems? I am told it will not work and I could only find the specs for the Ultegra (short cage) derailer on Shimano''s website. If not, can I run an XTR 9 speed rear derailer with my 10 speed shifters? If none of this is possible and I just need to switch back to a 9 speed cassette and derailer, can I still use the 10 speed shifter without dropping the chain into the spokes? I really like the fit, feel and smooth shifting of the 10 speed shifters and I am trying to keep the uphill gearing I came to enjoy on my mountain bike. At this rate I might as well completely cannibalize my mountain bike.

  2. #2
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    who even makes a 12-32 10 speed cassette?

  3. #3
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    Interloc Racing makes that cassette. It is a bit heavier than I would like though.
    http://store.interlocracing.com/10elcas.html

  4. #4
    p != b
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    The ultegra can probably be made to work. May not be flawless, but will probably work.

    XTR should work as well.

    I'd drop the IRD folks a line and see what they suggest.
    I love the sound of cowbell in the morning.

  5. #5
    vegan wrench
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    I would guess that an xtr is most likely to do the job the best. however, an ultegra may work. my wife has a 9sp ultegra derailleur with a 12-32 9sp cassette on her ride.
    <a href="http://www.willlaw.org">vegan cyclocross</a>

  6. #6
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    Wow 12-32 now that is big jumps in gearing. Why would you not just have a triple, it seems like if you need that gearing what your climbing should be walked?

  7. #7
    pi makes wheels go round
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    Quote Originally Posted by bloodthirstylust
    I would guess that an xtr is most likely to do the job the best. however, an ultegra may work. my wife has a 9sp ultegra derailleur with a 12-32 9sp cassette on her ride.
    Is it a long cage ultegra, or short? I wonder if there is a difference in top pulley locations between the two.

    And for a touring bike... or anything but a dedicated racer, the gearing gaps in a 12-32 10sp cassette should be a non-issue. But then again, i like my fixie and my 'crosser has an 11-28 8sp cassette, so i may be too biased the other way... I'd rather have narrower cranks, atmo.

    -Damon

  8. #8
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    from cyclingnews.com back in november when the ird cassettes came out:

    "Interloc Racing Design recently announced the addition of three wide-range 10spd cassettes to its Elite steel lineup, including 12-32, 11-32, and 11-34T varieties, to go along with its 12-28T offering it introduced last year.

    Why bother with super wide range road cassettes? Loaded tourers, tandem riders, and cyclists who were simply seeking ultra-low gearing have been using 9spd mountain bike cassettes and rear derailleurs for years now, but the prevalence of 10spd drivetrains on the road had made it increasingly difficult to maintain the low transmission ratios with modern equipment. Co-Motion has already begun to spec the new cassettes on its touring tandems.

    According to officials at IRD, the new cassettes must be used with Shimano-compatible mountain rear derailleurs only. Although 9spd by design, IRD claims the derailleurs can be "coaxed" to shift 10 without much issue."

  9. #9
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    A long-cage mtn derailleur will be your best choice. A long cage road derailleur will probably work as well, but I would guess that a mountain one would be the best. The derailleur doesn't care how many cogs there are, but it is designed to shift well with the 12-34, etc.
    cheaterbar.blogspot.com/

  10. #10
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    you can get by with a medium cage mtn derailleur. medium cage works with up to a 32 and leaves less room for pulley cage to flex and potentially take out the wheel.

  11. #11
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    According to the published specs, Shimano road rear derailleurs are designed to take nothing larger than a 27 tooth rear cog. Short or long cage does not matter.

    Any Shimano MTB rear derailleur should work. Rapid Rise (low normal) rear derailleurs will behave the opposite of road derailleurs, however--if you try to upshift with the STI lever it will downshift instead.

  12. #12
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    I am going with an XT derailleur

    Thanks for your advise everyone. I have decided and ordered an XT derailleur. Your advice and the fact that Co-Motion uses XTR with their tandems showed me this is the best way to go. I would have like to gone XTR but those are too much right now. At the moment I am probably going to use an IRD 11 or 12/32 10 speed cassette. I am still thinking about using a 9 speed mountain cassette. They are much lighter and cheaper than the IRD. I am not convinced of using a 9 speed cassette with 10 speed shifters although I hear many people have done it.

  13. #13
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    Quote Originally Posted by soulknight
    Thanks for your advise everyone. I have decided and ordered an XT derailleur. Your advice and the fact that Co-Motion uses XTR with their tandems showed me this is the best way to go. I would have like to gone XTR but those are too much right now. At the moment I am probably going to use an IRD 11 or 12/32 10 speed cassette. I am still thinking about using a 9 speed mountain cassette. They are much lighter and cheaper than the IRD. I am not convinced of using a 9 speed cassette with 10 speed shifters although I hear many people have done it.
    Using a 10-speed STI shifter with a 9-speed cassette is unlikely to result in smooth shifting across the whole range of the cassette. With each click of the 10-speed shifter the derailleur will try to move the chain 3.95mm, but the 9-speed cassette cogs are 4.34mm apart.

    What are your gearing needs? Do you ride in the mountains with a heavy load, or mostly on the flats with an occasional steep climb? What high gear and what low gear do you want? Sheldon Brown's gear calculator is useful for mapping out different gearing combos: http://www.sheldonbrown.com/gears/

    What crankset and chainrings are you running now? Do you have a double or triple crankset? You might be able to solve your gearing problems with a chainring swap or a different crankset. I would hesitate before building my whole drivetrain around an expensive part that no other company besides IRD makes.

  14. #14
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    Apparently there is a way to use a 10-speed shifter with a 9-speed cassette. Here's Sheldon Brown's detailed reply to somebody on the iBOB list asking how to get low gearing with a 10-speed drivetrain:

    >I have a Madone with an Shimano Ultegra 10 speed triple drive train.
    >
    >I'd like to get lower gearing than my 12-27 cassette gives me.
    >
    >Somewhere on the internets I've read that it is possible to change to
    >a 9 speed STI brifter, a mtn bike xt or xtr derailleur and a mtn
    >bike cassette.
    >Is this really true?
    >
    >I'm guessing if it is something that can work it would
    >require a standard (high gear normal) mountain bike derailleur. Has
    >anyone here tried something like this?
    >
    >Another possibility I'm considering is the Harris Cyclery Super
    >Century 9 speed cassette 13-30.
    >Has anyone here used one of these with STI brifters?

    I get asked about this so often that I've prepared a boilerplate
    response, viz.:

    We do lots of custom cassettes in 9-, 8- and 7-speed. Most of these
    custom cassettes involve adding a larger rear sprocket for a lower
    gear.

    Unfortunately, the design of Shimano's 10-speed cassettes features a
    recess in the spider mount for the larger sprockets, allowing the
    innermost sprocket to be closer to the spokes than the shoulder on
    the Freehub body.

    This makes it impossible to substitute a different low-gear (largest)
    sprocket. As a result, we are unable to offer custom 10-speed
    cassettes, at least at this time.

    The largest 10-speed sprocket currently available from Shimano is 27
    teeth, and there is no way for us to install a larger one on a
    10-speed system.

    We have recently received IRD brand 10-speed cassettes in 11-32 and
    11-34 sizes. They're expensive but they work well. See:
    http://harriscyclery.com/10

    Here's another option: Most 10-speed setups will allow you to
    install a 9-speed cassette, and these are available in a much wider
    range of useful gears. The 10-speed shifters will index a 9-speed
    cassette if you use the "alternate cable routing" shown at:
    http://sheldonbrown.com/derailer-adj...html#alternate

    9-speed cassette options are shown at http://harriscyclery.com/9.

    Note, if you have a Dura-Ace 7800 hub, or a "10-speed" Ultegra 6800
    wheel, those will _not_ accept a 9-speed cassette. Other
    Shimano-compatible hubs will work with 8-, 9- or 10-speed cassettes.

    If you want to go for a sprocket bigger than 30 teeth, you will
    likely need to replace the rear derailer, but those are not expensive.

    There is supposedly a Miche 10-speed cassette that goes to 29, we
    have these on order, but they seem to be vaporware at the moment.

    Another, easy and cheap way to lower your climbing gear is to replace
    the 30 tooth chainring with something more useful, typically a 26 or
    24.

    See: http://harriscyclery.com/74 for details on this.

    Sheldon "How Low Can You Go" Brown
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