Swapping a compact for a triple

curium
curium Posts: 815
edited March 2013 in Workshop
Most road bikes around and above the £1,000 mark seem to come with compacts these days. I am a fan of the triple because I find a 34 too small a chainring and prefer a 39.

I also like very close ratios so my last bike had 50/39/30 chainrings and 12-23 sprocket.

The reason I like this arrangement is when I'm on the road I have it in the 50t at the front and the close ratios at the back mean it is easy to find the optimal cadence for me and make good progress. When i approach the lights or other object I move to the 39t at the front and then back to the 50t once back up to speed.
This strategy means I don't have to change the rear cog too frequently which is advantageous as due to the close ratios, sudden drops in speed mean I often have to move 2-3 cogs in quick succession which I find inefficient compared to just moving to the 39t and then back to the 50t.

The 30t is available for the steepest hills although, so far, 39x23 has usually sufficed.

Having explained my situation I'll get to my question:

If I purchase a bike with a compact (let's say 105 shifters and mechs) is it a simple job to replace the crank with a triple or will I have problems with the shifters and chainline, etc.

I had considered simply replacing the 34t of the compact with a 39t but am worried about being overgeared on hills towards the end of a long ride with only a 12-23 at the back so like having the 30t in reserve. So my first choice would be to fit a triple.

Thanks for your help in this matter.

Comments

  • Cleat Eastwood
    Cleat Eastwood Posts: 7,508
    you vud at least need a triple front mech and a triple (left hand ) shifter.

    I've used a standard mech on a triple but never the other way round, so not sure whether a double mech would necessarily have the reach.
    The dissenter is every human being at those moments of his life when he resigns
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  • buckmulligan
    buckmulligan Posts: 1,031
    Do some research into the groupset you'll be buying. Most likely you'll need a new LH shifter (the current 105 5700 series certainly has specific double and triple LH shifters, but some cheaper groupsets use a triple shifter for compact/double-set ups too), certainly a new front derailleur and possibly a new rear derailleur depending on the capacity of the rear mech. If you're running a close ratio cassette like a 12-23T you might get away with running a short cage rear mech, but chances are you'll need a long cage one.

    Other than the expense involved in swapping out all of those parts, it's fairly simple if you really want to do it.
  • ratsbeyfus
    ratsbeyfus Posts: 2,841
    I've just gone the other way - triple to compact.

    If you're interested I have an Ultegra triple chainset (6603) and front mech, and a 105 5703 triple shifter. All in excellent condition. PM me if interested.


    I had one of them red bikes but I don't any more. Sad face.

    @ratsbey
  • desweller
    desweller Posts: 5,175
    You'll (probably) need a new shifter and definitely a new mech. If the crank arms are square taper then you might need a new bottom bracket too (pretty unlikely these days though).

    Some frames will not take triples; the chainrings get too close to the right-hand chainstay.

    Sounds like ratsbeyfus has a ready made solution for you though!
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  • curium
    curium Posts: 815
    Thanks for the offer ratsbeyfus but I'll have to hold off until I've actually purchased the bike. Also I need to look into BB standards as the bike I'm interested in (CAAD 10) has BB30 and comes with an FSA crank so not sure Shimano crank is compatible.

    In any case I'm being told that the CAAD 10 in a 61 may not be available until mid-April :shock:
  • keef66
    keef66 Posts: 13,123
    Can you not ask the supplying bike shop what they'd charge to make the swap?
  • curium
    curium Posts: 815
    I imagine it will be full whack. I will ask though.

    They (Evans Cycles, On Ya Bike, Cycle Surgery, Cycles UK) don't seem to have any bikes with triples any more (other than on womens' bikes).

    I know triples have always been seen as quite pussy (granny ring, etc) but they allow me to run really close ratios at the back 12-23 and while I managed to climb Ventoux with the 39-23 it was nice to know the 30 was there and I have used it on 100 mile sportives where they stick short but steep climbs in around the 90 miles mark.
  • keef66
    keef66 Posts: 13,123
    Well I love my triple. I bought my bike from Epic and got to specify every component. Not much dearer than an off the peg bike. The only thing I've swapped in 5 years has been the saddle.
  • essjaydee
    essjaydee Posts: 917
    Have you thought about SRAM's WiFLi option for gearing?
    http://www.sram.com/sram/road/technologies/wifli_tm
  • ratsbeyfus wrote:
    I've just gone the other way - triple to compact.

    If you're interested I have an Ultegra triple chainset (6603) and front mech, and a 105 5703 triple shifter. All in excellent condition. PM me if interested.

    I cant pm yet due to lack of posts but I am running a compact chainset (tiagra 10speed) and would like to change to a triple. Is yours still available?
  • ratsbeyfus
    ratsbeyfus Posts: 2,841
    Still available - email me on alexsue at ntlworld dot com


    I had one of them red bikes but I don't any more. Sad face.

    @ratsbey