double/triple front mech
is there a difference or can you use a double on a triple and vice versa? is it just a matter of adjusting the limit screws?
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presume using a triple cage has no disadvanted on a double then, besides from a little more weight~?0
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I've just changed my chainset from a triple to a double, and use the same front deraileur. I find the shifting is smoother with the double. Just find the extra position on the shifters take a bit of getting use to, as that no longer does anything.0
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Woody. A triple mech has a slightly different travel to a double. If you changed the BB at the same time this should not be a problem but if you are using the triple BB it could be. If set up correctly you should not be able to get to the extra shifter position. It should work as a normal double shifter. You must have the cable too slack.0
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Nothing to do with the cable being too slack, it's just that the mech limits are set up wrong. Set your limits, and you'll have no problems.0
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sloxam wrote:is there a difference or can you use a double on a triple and vice versa? is it just a matter of adjusting the limit screws?
What are you thinking of actually doing?
If you change the chainset from double to triple then you will probably have to change the bottom bracket.
You will also have to consider the gear lever especially going from double to triple. Unless you have a downtube friction changer or Campag multi-step Ergos. Shimano will probably not work.
A double cage front mech' will possibly work but not perfectly.
Triple cages are a deeper drop than doubles to allow for the height difference from large to smallest ring.
The other consideration is triple cages are wider to allow for the larger chain line difference. Unless you can make small increment changes to the double cage then the chain will rub on the sides as it goes from top to bottom on the cassette.
And lastly you will need a long cage rear dérailleur to take up the chain length change required with triple chainsets.
John0 -
I use an ultegra double chainset, with the ultegra triple shifters. The BB is the same, as is the front mech. Just adjusted the limit screws, and removed the spacers from the spindle that are required for a triple. The cable slack is due to the fact that I use the top and middle positions of the shifters for the double, and the granny is now redundant. I could have use the lower two settings, but it works well.0
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Woody. I asume you have a Hollowtech 2 chainset. If so then removing the space has the same affect as fitting a double BB unit with an Octolink or square taper one. As you say, just adjust the limit screws. With the BB set to double now you would be better off adjusting the cable so you are using the granny and middle positions on the shifter. Effectively what you have done is remove the big ring and are using a granny and a middle one. The cable pull in the shifter and the geometry of the mech are designed to work this way. You will find the 'trim' function works better set up this way also.
Cycler. Most 9sp Shimano STI units, other than Dura-ace will work both double and triple.0 -
Thanks john. yes I do have hollowtech 2. I'll adjust the setup this weekend and use the lever positions for the granny and middle.
Cycler - the current 105 10speed sti units will work double or triple, according to shimano website.0 -
John & Woody,
Yes you are correct about later Shimano units although I have not had any experiance of them..
All my bikes have Shimano 8 speed cassettes so i'm speaking from that angle.
John0 -
if i go compact (which is what i'm thinking) i would be getting a new bb too. would the triple front mech be ok?0
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So, on that note, I currently ride a Madone with a triple Ultegra which I am going to remove and put onto my winter bike. Assuming I purchase a double chainset (I am contemplating the Bontrager Race X Lite set), what would I need to change on the triple groupset (if anything) to make it work with the double chainset on my winter bike?
Any help would be much appreciated0 -
Basically nothing.
You may have to fit a different bottom bracket. ( or may be shim it if possible) but try it first. (brackets for doubles and triples are usually different lengths.)
You also may have to alter the hight of the front mech' to suit the diameter of the large chain ring. The mech' stops will need altering to stop the chain overshooting and coming of the chain rings.
And the chain length to suit if required.
But just try it first.
If you are fitting the triple to another bike then you may have to swap the bottom bracket as well anyway, in which case get one to suit the double.0
