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  1. #1
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    What chainring for cx50 crankset?

    I'm looking to knock the 36 tooth chain ring down to a 30 tooth chain ring, supposing that my short cage derailleur will still work and the FD will still work with the 30-46 combo. I have something like a 12-28 in the rear.

    What chain ring do I need?

  2. #2
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    The smallest ring you can fit on a compact road crankset is a 33t. You're out of luck unless you decide to put a triple on that bike. In that case, you would need a new shifter and rear derailleur, in addition to a new crankset.

    Another option, if you want, is to install a bigger 32t cassette and a compatible rear derailleur, along with a 33t chainring. That 33/32 low gear will give you nearly the same gear as the 30/28 that you're envisioning with your current cassette and a new chainring.
    I've made some bad decisions like taking the gears off my bike. So here's the warning: Do not as I say, nor as I do.

  3. #3
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    Am I able to use a 12-30 tiagra cassette with a short cage rear derailleur and 36 to 46 double?

    Also, is there such a thing as a 10 speed specific hub that only certain 10 speed specific cassettes can fit on? How do you tell what type of hub you have?

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    A short cage may be able to handle that set-up. You have a total tooth difference of 28t and the Tiagra short cage can handle up to a 31t difference ((big cog - small cog)+(big chainring - small chainring)) so that part will work, but the biggest cog that a Tiagra short-cage derailleur can handle is a 27t. The derailleur may be able to squeeze under that cog, but if it doesn't you can use a longer screw on the B-knuckle.

    8/9/10 speed freehubs are all the same, so nearly any modern wheel that you can find will work with a 10-speed cassette. I don't remember off the top of my head which cassettes are narrower, but if you install the 10-speed cassette and it's still loose, put a small spacer behind it to tighten everything up.
    I've made some bad decisions like taking the gears off my bike. So here's the warning: Do not as I say, nor as I do.

  5. #5
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    The short cage I have is a 105. Will that still work?

  6. #6
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    According to the Shimano website, yes. And it has a 28t max cog, which makes it a bit easier to stuff that 30t cog under it.
    I've made some bad decisions like taking the gears off my bike. So here's the warning: Do not as I say, nor as I do.

  7. #7
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    I wonder what the hell they were thinking making a cog that big (30t) on a tiagra cassette when none of the derailleurs will work with it.

    I really need to go IGH. This **** is ridiculous. You'd think they'd have some sort of consistency to their systems, but no. It's like they're hell bent on making crap incompatible with other crap.

  8. #8
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    I'm really not sure what to tell you. A 30t big cog is approaching mountain-bike territory, and such low gears generally aren't necessary on a road bike. At low, yet comfortable cadence on my low gear of 39/27, on a hill that approaches 20% grade most of the time, I still maintain ~5-6 MPH. Any lower of a gear or cadence and it's easier and more efficient to walk.
    I've made some bad decisions like taking the gears off my bike. So here's the warning: Do not as I say, nor as I do.

  9. #9
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    Then why have a granny at all? On a MTB or road bike?

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