Forum home Road cycling forum Workshop

Octalink question

RhodsRhods Posts: 400
edited March 2010 in Workshop

Currently running a hollowtech triple but wanting to buy a double. Have seen some very reasonable octalink chainsets, so a few questions:

1. Will an octalink chainset fit my bottom bracket?
2. Will I need anything else with the chainset?
3. What extra tools will I need?

Any other useful info appreciated.



  • sungodsungod Posts: 16,064
    if your triple is hollowtech II, the cheapest way might be to get a compatble double, otherwise the extra tools needed could easily outweigh the price difference

    if your triple is hollowtech/octalink, you'll need several tools

    hollowtech was the cranks that went on octalink, the spindle is part of the bb which runs the width of the shell

    hollowtech II was cranks with a hollowtech bb, the spindle is part of the righthand crank, the bb is two separate bearings, one fits to each side of the shell

    either way, you'd need to get a new octalink bb to use an octalink double...

    if your cranks are hollowtech II, you'd need to remove the current bb cups and fit an octalink bb

    if your cranks are old hollowtech, you'd normally change the bb to one with a shorter spindle to get the right chainline

    so either way, you'd be fitting a new octalink bb (which needs the correct tools)

    with 105 triple on hollowtech II there's a spacer between the left crank and the bb, you just pull this off when ftting a double

    going from a triple to a double, you should change the front derailleur, your existing left shifter will probably be ok, but the indexing will probably mean doing some extra clicks to shift up/down


    the correct tool to remove hollowtech II bb if that's what you've got
    the correct tool to fit/remove an octalink bb
    crank remover if the triple is octalink
    chunky spanner/wrench to turn the above - it can take a LOT of force to remove/install a bb - so make sure you clean threads and grease well before fitting the new one!
    sundry screwdrivers, hex keys etc.

    if you simply swap hollowtech II cranks and fit a new fd then i think you can do it with just the screwdrivers and hex keys

    the park tools website is an excellent source of how-to guides and picture on this sort of thing... ... ield2.y=10

    sheldon brown's site also has bags of useful info...

    shimano's site is excellent, for instance the 105 hollowtech II bb instructions are here, they should help clarify what's typically involved... ... 603698.pdf

    ...but make sure you look at the instructions for your exact model!

    you'll also find detailled instructions for how to fit/adjust derailleurs etc. on this site
    my bike - faster than god's and twice as shiny
  • RhodsRhods Posts: 400
    Thanks for the great info.

    My triple is a tiagra, but the spindle is part of the r/h crank, so i've always though it's a hollowtech II (should have said that in my opening post - forgot the distinction between ht and ht 2).

    Seems like it's not such a great deal considering all the extras on top!

    Thanks again
  • sungodsungod Posts: 16,064
    yep sounds like hollowech II

    chain reaction have some htII chainsets for 45 quid, maybe the cheapest around unless something comes up on ebay, so if your bb cups are ok then i think you can just swap ... elID=29216
    my bike - faster than god's and twice as shiny
  • maddog 2maddog 2 Posts: 8,114

    you have HT2 triple

    just buy a HT2 double chainset (not an octalink) and fit it straight in to your existing cups. You'll need a double front mech too, ideally.

    If you buy an octalink double chainset then you'll need a 108mm octalink BB too.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
Sign In or Register to comment.