Thinking about changing my crank from a compact to a triple?
- Thread starter Matt B
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andrew_s
Legendary Member
- Location
- Gloucester
Assuming a 12-27 cassette, it would drop the bottom gear from ~34" to ~30" - 1 extra gear at the low end. You would have the option to fit a smaller inner ring (down to 24T), which would take it down to 24" (about 2 gears lower, 3 extra over the compact). You also get smaller jumps in gear when changing a chainring - some people don't like having to change 2 rear gears when they swap chainrings on a compact.
Cost is the chainset, and new STI levers if the ones you have aren't triple compatible - the LH lever should have 3 clicks/4 positions if it is (remember to back off front mech limit stops when checking).
You may also want a new BB with a longer axle. Try if the one you have is OK before buying. Does the small ring clear the chainstay?, does the mech move far enough in to reliably drop the chain onto the small ring?, does the mech move far enough out to lift the chain onto the big ring?
Cost is the chainset, and new STI levers if the ones you have aren't triple compatible - the LH lever should have 3 clicks/4 positions if it is (remember to back off front mech limit stops when checking).
You may also want a new BB with a longer axle. Try if the one you have is OK before buying. Does the small ring clear the chainstay?, does the mech move far enough in to reliably drop the chain onto the small ring?, does the mech move far enough out to lift the chain onto the big ring?
It needs a change of crankset/BB, front and rear mechs and, as pointed out above, possibly new shifters. If using shimano 8 or 9 speed then just fit a MTB cassette and rear mech so you can use an 11/32 or 12/28 to expand the gear range. If using shimano 10 speed then perhaps the new SRAM cassette and rear mech in the same way.
Ok, front shifter is compatible, it's 105. On the cassette, I'm running a 105 11-25 10 speed. Front and rear mech is 105 too, bottom bracket is Shimano FC-5600. The frame should be ok, because the bike I've got was available in a triple option too.
I like my compact, but because I'll be carrying panniers and tent etc, some easier gears for the hills would perhaps make more sense.
Would it be worth changing the chainset but leaving the existing cassette, or would it be in my interest to go for something like a 12-27? All in all I'm considering 50.39.30 with 12-27 cassette - up from a 11-25
I like my compact, but because I'll be carrying panniers and tent etc, some easier gears for the hills would perhaps make more sense.
Would it be worth changing the chainset but leaving the existing cassette, or would it be in my interest to go for something like a 12-27? All in all I'm considering 50.39.30 with 12-27 cassette - up from a 11-25
GrasB
Veteran
- Location
- Nr Cambridge
Or you could go for a 26/36/48 crankset & keep your current 11-25 cassette to give you a wider range (a bit higher & a bit lower) than a 12-27 30/39/50 setup. OhI'm not so worried about the cassette being changed, my thoughts are more about the rear mech.
I take it that you're going to be using seriously lightweight camping kit? Otherwise a road triple and even 12-27 cassette is still totally inappropriate for loaded touring unless you have legs like chris hoy...
ALso, what bike is it? some road bikes (or rather their wheels!) won't like having any considerable weight on them but if it's something a little more robust than a lightweight racing snake machine then I'm sure it'd be OK.
Road triple front mechs are always available dirt cheap on sale.. e.g.
http://www.chainreactioncycles.com/Models.aspx?ModelID=13622
You will need a med/long cage rear mech to cope with the wider range up front:
http://www.chainreactioncycles.com/Models.aspx?ModelID=13595 (the medium cage is what you'd need)
Then it's just a case of getting a triple crankset, the suggestion above about going for something like a 26/36/48 is a good one. I'd recommend getting a shimano MTB triple, whilst many go for something like a stronglight impact for touring use, it doesn't have the ramped teeth to assist shifting and without those you really need friction shifters for decent smooth operation and even then it can be an annoyance (I speak from personal experience, I'm sure that plenty of people are far less picky but I like my bikes to be 100% functional without compromise despite being filthy dirty).
ALso, what bike is it? some road bikes (or rather their wheels!) won't like having any considerable weight on them but if it's something a little more robust than a lightweight racing snake machine then I'm sure it'd be OK.
Road triple front mechs are always available dirt cheap on sale.. e.g.
http://www.chainreactioncycles.com/Models.aspx?ModelID=13622
You will need a med/long cage rear mech to cope with the wider range up front:
http://www.chainreactioncycles.com/Models.aspx?ModelID=13595 (the medium cage is what you'd need)
Then it's just a case of getting a triple crankset, the suggestion above about going for something like a 26/36/48 is a good one. I'd recommend getting a shimano MTB triple, whilst many go for something like a stronglight impact for touring use, it doesn't have the ramped teeth to assist shifting and without those you really need friction shifters for decent smooth operation and even then it can be an annoyance (I speak from personal experience, I'm sure that plenty of people are far less picky but I like my bikes to be 100% functional without compromise despite being filthy dirty).
