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Going from a Triple to a Double Advice Please....(6 posts)

Going from a Triple to a Double Advice Please....peterkg
Oct 7, 2002 10:28 AM
I'm interested in swapping out my CODA triple crankset with a Shimano double on my Cannondale R600. Nothing is really broken, but I just would like to move to the double. Do I need a new bottom bracket, shifters, or front/rear derailleurs? Thanks.
Lots of changes...Matno
Oct 7, 2002 10:41 AM
You'll almost certainly need a new BB. The double cranks typically use a different spindle length. I can't remember off the top of my head which length is which. Also, Shimano front derailleurs are double/triple specific. Some shifter models are compatible with both. Maybe someone else knows which ones are... Rear derailleur will not have to be changed, but you might want to. (If you were going from double to triple you would almost certainly have to switch). Triples typically require a longer RD, while doubles can be used with shorter ones. I think the longer RD will work fine with a double setup, but it will require more chain length and thus, unnecessary weight).
yes_rt_
Oct 7, 2002 10:54 AM
you will need to replace pretty much everything on your drivetrain but your cassette & chain: cranks, bb (spindle length will probably be a 109.5, but you should definately check before buying), front & rear ders (you can use a short cage rear der), and shifters....it is possible to set up your shifters to accomodate a double but the set up will be far from ideal & you may have a problem with the chain being thrown to the inside when shifting from big ring to small ring. based on experience, i would highly recommend replacing your shifters.

depending on how worn your chain is you may need to replace that as well since you will be running new rings on the front.

rt
other optionsbigrider
Oct 7, 2002 11:23 AM
I agree with the major changes that are written up above. I would wear out what I had and upgrade after I needed to replace components. One option is to put a 12-27 cogset on the back and only use the larger two rings in the front. It would save on shifting but not on weight.

I have never had a triple but I know a lot of tough riders that use them and whip me routinely on hill climbs. I am too frugal (tightwad) to not use them until they are worn out. It will probably cost you over 400 bucks for ultegra parts to go to a triple. That includes crank, bb, left shifter, front der. You would probably be money ahead to sell the bike and buy another with a double setup if you were passionate about switching.
You don't NEED to change much...timfire
Oct 7, 2002 6:12 PM
Though you COULD change the entire drivetrain, despite what others have said you only NEED to change the BB & cranks.

Except for DuraAce, it is my understanding that all of Shimano's shifters are triple/double compatible. Looking at the Shimano Website should confirm that. You will need to get the front derailer re-adjusted, though, to make sure that it doesn't shift funny. A triple rear derailer is longer than you need it to be, but it will work fine with a double. For that matter the front derailer will also be longer than you need it to be, but again it will work with a double. I say just leave leave them on. It's cheaper and according to the Shimano Website the weight difference is only... 5g... (Hmmm, Hey Weight wenies! according to the website the triple rear derailer weighs LESS than the double).

Anyway, that just leaves the BB and cranks. Those have to be changed.

Something else to consider as someone else said is that you may want to get a wider cassette if you're riding something tight. But I would wait on that. Get used to a double first, and then see if you need those lower gears.

--Tim Kleinert
Sorry, that's for 105...timfire
Oct 7, 2002 6:16 PM
Those weights I listed were for 105. That's what you have on a C'dale r600, right?

--Tim Kleinert