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Wicklow200 : rear 26 - 32 / 34 replacement?

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    #2
    kenmc
    Registered Users Posts: 7,276 ✭✭✭kenmc


    deraileur adjustment should be negligible, maybe a little tweaking.
    you MIGHT need a longer chain, but it's hard to tell.
    Other than that they should just fit as a direct swap.
    given that you're on a regular double rather than a compact it would probably be no harm to get yourself a lower gear than the 26.
    good luck!


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    #3
    E@gle.
    Registered Users Posts: 1,516 ✭✭✭E@gle.


    Would a compact crankset be a better option?? A size 34 ring looks ridicously big dont think i have ever seen one before


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    #4
    rob1891
    Registered Users Posts: 1,038 ✭✭✭rob1891


    Be careful running a mountain bike cassette with a road derailleur. For instance, a standard 2008 sora derailleur has a max of 27T on the rear. I've read that this is conservative and 30/32 would probably be fine. Apparently a 34 tooth cassette will almost certainly rub against the jockey wheel of a road derailleur.

    Also, is your derailleur a short cage or medium? If it is short, then you might have trouble with chain tension. If it is a medium and you are running a dual front chain ring setup you should not have chain tension trouble (though as said, it may need to be longer than before ... wrap around the largest front are rear cogs and add two more links).


    Rob


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    #5
    E@gle.
    Registered Users Posts: 1,516 ✭✭✭E@gle.


    Yes i think rob could be right, i always thought that the biggest ring you could run on a road bike was a 27


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    #6
    tripswitch
    Registered Users Posts: 53 ✭✭tripswitch


    rob1891 wrote: »
    Be careful running a mountain bike cassette with a road derailleur. For instance...

    ... snip ...

    Also, is your derailleur a short cage or medium? If it is short, then you might have trouble with chain tension.

    Thanks Rob, they're exactly the kind of pointers I was looking for.

    Yeah that 34 looks kind of weird - the inside ("lowest"?) sprocket looks massively oversized compared to the rest. Will give the 32 a belt so.

    Wasn't familiar with short/long cages either, so a bit of googling based on your message did the job. (e.g. http://forums.mtbr.com/showthread.php?t=284688) It's definitely on the short/medium side. Not sure how to tell whether it's one or the other though. (Update: the distance between the two jockey wheels is 2 inches.)

    Cheers!


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    #7
    rob1891
    Registered Users Posts: 1,038 ✭✭✭rob1891


    Hey, Shimano road is slightly different to mtb for tooth capacity. They have short cage with a capacity of 29T and medium with a capacity of 37T. The formulas are the same though.

    I slapped a 32t cassette I have lying around on my road bike. It has a medium cage ultegra derailleur and I didn't need to lengthen the chain (coming from a 53/39, 11/27 setup). Doesn't mean you won't have to though ...

    It made a slight noise when up on the 32t cog, but the jockey wheel was just about clear of the cog. Also, I forgot to try and adjust the b-tension screw which changes the distance from the jockey wheel to the cassette. I'd say I could have got it running smoothly on the 32t if I had done. The b screw should be the only adjustment you need to make when changing cassette. Also make sure your chain hasn't streched or it won't mesh with your new cassette. Check the last part of this page:

    http://www.sheldonbrown.com/chains.html

    My 34t cassettes are on bikes in the shed and though I'm clearly bored, it's too dark to go fumbling around :-) It was close enough with the 32t, I wouldn't bother with a 34T, plus I don't think there are sensible ones in 8-speed, only that crazy thing you found!

    Check out CRC too, their estimated euro price is 10 cheaper than wiggles estimate!

    http://www.chainreactioncycles.com/Models.aspx?ModelID=5212

    Rob


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