gearing question

holker
holker Posts: 88
edited February 2011 in Workshop
Hello,

I have a shimano 105 equipped bike. What is maximum rear derailler capacity? That is what ia largest rear gog that can be fitted? Could I get a 32 gog for example?

Comments

  • John.T
    John.T Posts: 3,698
    27 with the older 105. 28 with the latest. Both can be pushed a bit but not to 32.
    Just about everything you need to know (and more) in this thread.
    http://www.bikeradar.com/road/forums/viewtopic.php?t=12583566
  • The 12-27 on my 105 (5600) is just touching the inner jockey wheel so I doubt 28t cog would fit.

    To get a 11-32 cassette on, you'll need to have a long cage rear deraillier which tends to be MTB orientated.
    CAAD9
    Kona Jake the Snake
    Merlin Malt 4
  • John.T
    John.T Posts: 3,698
    The 12-27 on my 105 (5600) is just touching the inner jockey wheel so I doubt 28t cog would fit.

    To get a 11-32 cassette on, you'll need to have a long cage rear deraillier which tends to be MTB orientated.
    You should get a 27 on with no catching. A bit of 'B' screw adjustment or a small change in chain length should sort it. 27 is Shimano's recommended largest so it should be fine.
    The GS road long cage rear mech has the same 27 tooth limit. To go bigger (safely) you must have an MTB one.
  • ADIHEAD
    ADIHEAD Posts: 575
    I've run 11/28 with the older Ultegra 6600, no problems if you wind out the 'b' adjuster. Surely if you go lower than 34/28 you'll be going so slow you'll have stability issues?
  • holker
    holker Posts: 88
    Adihead possibly. I live in Cumbria and planning long days in the hills. So far 34/28 hasn't let me down, its just that when you're in that gear on a big pass there's no where to go other than walking. I don't know whether 34/32 would be too small, does anyone have experience of this?

    Another thought. I run a compact, a larger cog would give a greater range on larger chain ring reducing need to change between chain rings on undulating territory of which there's a lot around here
  • John.T
    John.T Posts: 3,698
    Another thought. I run a compact, a larger cog would give a greater range on larger chain ring reducing need to change between chain rings on undulating territory of which there's a lot around here
    That would mean larger gaps between gears and a greater chance of it either being too high or too low.
    I have found that for me anything much lower than 34/27 just makes me go slower but it still seems as hard. One reason I ditched my triple 10 years ago.
  • ADIHEAD
    ADIHEAD Posts: 575
    I see what you mean if you live in Cumbria :lol: Hardnott would frighten the life out of me on anything less than a recumbent with a 15inch gear :roll:

    Regarding the suggestion of keeping on the 'big ring' for longer, surely you'll just be crossing the chain doing that? I always go for the small ring in 'good time' so I don't end up doing just that and risking damaging the transmission, or panicking when I need a lower gear and trying to shift to the small ring whilst the rear is on a big cog and loosing the chain.

    I suppose Sram wouldn't have done the Apex the way they have if 34/32 wasn't useful to some people though hey?