Giant SCR 2 Triple to compact . Advice please

1964johnr
1964johnr Posts: 179
edited January 2017 in Workshop
I posted previously on this topic and received a couple of replies telling me that I could swap my 10 year old tiagra square taper crank set for a compact double. I was also advised that I may need to change the bottom bracket as well. My question now is when I swap it over, What issues can I expect with gearing e.g. front and rear mech adjustments. Will it be straightforward or am I likely to get in to difficulty. Any advice would be gratefully received.

Comments

  • Mad_Malx
    Mad_Malx Posts: 5,161
    I did this years back. Went from 9 speed square taper triple to hollowtech 105 compact double.

    I'm pretty ham fisted but will have a go at most stuff, and it was a doddle. Think there were a few clicks under high load initially but these seemed to disappear after a short while. My bb fitted without having to reface the bb shell (which many sources advise) so I'd advise trying first to see if you get a good fit. If not your LBS should do this for reasonable cost.
    Mine is still working smoothly after about 20k miles commuting all year round. Dismantled Bb and crank for first time this year and all looks ok.
  • Mad_Malx
    Mad_Malx Posts: 5,161
    I swapped the FD at the same time but could probably have got away with just changing the limit screws.
    Also changed the rd but again it's not essential.

    My advice would be try swapping just the crank and bb. Should be fine.
  • yorkshireraw
    yorkshireraw Posts: 1,632
    Mad_Malx wrote:
    I did this years back. Went from 9 speed square taper triple to hollowtech 105 compact double.

    I'm pretty ham fisted but will have a go at most stuff, and it was a doddle. Think there were a few clicks under high load initially but these seemed to disappear after a short while. My bb fitted without having to reface the bb shell (which many sources advise) so I'd advise trying first to see if you get a good fit. If not your LBS should do this for reasonable cost.
    Mine is still working smoothly after about 20k miles commuting all year round. Dismantled Bb and crank for first time this year and all looks ok.

    Did almost the same - original 9 speed sq taper BB, to a 105 double (not compact tho). I did replace the whole groupset though - shifters, mechs cables etc. so can't comment if simply swapping the BB & crankset will work with the front mech ok.

    If you have the right tools swapping the BB is pretty straightforward, assuming the old one isn't seized in place.
  • gozzy
    gozzy Posts: 640
    You might need to reposition the front mech a little and you might need to alter the chain length. You will need to alter the limit screws on the front mech, but the rear one shouldn't need adjusting at all. If you're keeping the triple shifters make the inner ring shift the redundant one.
    It ought to be straightforward to set up afterwards, youtube videos and shimano techdocs are useful if you need help.

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