Shimano 105 Set with a change to either Triple or MTB Rear

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Comments

  • Rodu
    Rodu Posts: 16
    Thanks for the advice, that 5 teeth will no doubt add significantly to the circumfrance so I'm not sure if the existing chain is long enough or not. Its a 10 speed chain. I guess there is only one way to find out, but maybe there is no harm in trying to add a few links.

    This all makes for a great business case to buy some gear and tools to give it a go. A great autumn/bad weather project.

    Good luck OP, hope it works out for you too.
  • pinguS
    pinguS Posts: 38
    Rodu

    I'm guessing you did the Moonrider night ride last weekend, which is what I was in. And to be honest I needed an extra lower gear, there were 3 hills i made about 3/4 before I had to get off.

    I had a look at my bike (Spec Allez Comp 2011) and now unsure if it is short or medium cage.

    Looking at the pictures, mine looks inbetween, I need glasses!!!!
  • LongIslandTom
    LongIslandTom Posts: 51
    Hi Pingus,

    Is this your bike? http://www.specialized.com/us/en/bc/SBC ... cname=Road

    If it is, it has a short-cage 105 rear derailleur.

    Personally I've never tried running a 32T cassette with a short-cage derailleur, but I have heard of other people having some success with it. If you want to give it a shot with the short-cage derailleur, just keep in mind it has less chain-slack take-up capacity than the medium cage, so having the correct chain length is critical if you want to try using a 32T cassette with your existing short-cage.
  • pinguS
    pinguS Posts: 38
    Yep thats the bike

    So I would need new a rear d. But I will give the cassette a go first, should be able to check by rotating pedals by hand I assume ?
  • Rodu
    Rodu Posts: 16
    pinguS wrote:
    Rodu

    I'm guessing you did the Moonrider night ride last weekend, which is what I was in. And to be honest I needed an extra lower gear, there were 3 hills i made about 3/4 before I had to get off.

    I had a look at my bike (Spec Allez Comp 2011) and now unsure if it is short or medium cage.

    Looking at the pictures, mine looks inbetween, I need glasses!!!!

    Yes, it was a silly hilly ride in the dark - that thought is still there days after the ride. I don't rememebr the BHF route being that hilly, either it is different or time eases the pain/memory.

    I managed to ride up all the hills but it wasn't easy, sometimes I was riding at walking pace and the consequences were limping up and down the stairs in the house for the rest of the weekend. I don't think hill riding for a fairly casual rider is meant to be like that so I fancy spinning up like I can on my mountain bike.

    I forgot to look at my bike last night but I think I have a short cage so good advice LongIslandTom regarding chain length. I might just have to get a new longer chain if I go this way.

    My gut feel seems to be only to switch over to 32 for hilly rides but that sounds like maybe too much mechanical tinkering back and forth everytime. A ££ alternative maybe is to have a spare wheel with a 32 cassette on to switch over leaving the chain and RD tweaks only.

    Sorry OP for hijacking, but I hope these rather alternative suggestions are of some help.
  • LongIslandTom
    LongIslandTom Posts: 51
    Yes, you can try on the cassette by rotating the pedals by hand.

    Just be careful.

    If it looks like the chain is too short (i.e. the rear mech is being stretched WAY too far to the front when you shift the bike into the big rear / big front gear combination), take care not to damage that rear derailleur. Also keep an eye on the derailleur pulley to make sure it's going to clear the biggest sprocket. If not, tighten that B-tension screw until it does.

    Good luck.
  • pinguS
    pinguS Posts: 38
    Just out of curiosity, if you have medium rear D, the capacity for the Shimano 105 is 39t (this is capacity, not max cog size of 28 which is same and short cage).

    Does this mean as everyone seems to be able to push the rear D to the limit, that with the medium cage, you could actually put a 11-34t cassette on (if the width is correct for Road) as this would on total to (50/34) + (11/34) = 16 + 23 = 39t ??

    Or would that be really pushing the read D to the limit for movement, even if tension screw is adjusted?
  • John.T
    John.T Posts: 3,698
    Both SS Short cage) and GS (long cage) road mechs will take the same size largest sprocket. The difference is how much chain they can take up, the GS taking more as it is for a triple. The latest 105 and Ultegra mechs are for a recommended max of 28 teeth and the earlier ones for 27 teeth. Both can usually be pushed to a 2 tooth bigger sprocket but very careful set up of B screw and chain length is required. You may get away with bigger but this rather depends on how long your mech hanger is, they are not all the same.
    All these mechs in SS form will take about 2 teeth more capacity than recommended. Going beyond this is risky, especially if you are not sure what you are doing.
    For the OP if you have the latest model mech the best you can safely go is a 33 inner ring and a 30 tooth biggest sprocket. Any more and you may or may not get it to work safely. Otherwise you need a triple which will cost a lot more. You can fit granny rings down to about 26 to a 'standard' triple.
    My Fleet.

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