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I have a 3-ear old Specialized Roubaix Comp triple. It has an Ultegra triple and a 27 granny on the Ultegra rear cassette, Ultegra shifters, and Ultegra derailleur front and Dura-Ace rear. I live where it is flat as a pancake, but I like riding mountains - such as the Blue Ridge Parkway. Anyway, I am thinking of changing to a compact chain ring. I don't use the middle ring in local rides and in the mountains I usually use the small ring climbing and the big ring descending, so it seems to make sense to go to a compact.
Can I do so without other major component changes? Do I need a new rear wheel hub?
I suppose the chain is different? Ultegra compact the way to go? What will this normally cost to have the LBS do it? Need advice and recommendations and opinions. Thanks.

One other question: If I go to a compact, is it possible to go to a bigger cog in the rear such as, say, a 29 ?
 

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i think...

you will only *really* need a new crankset. chain is the same, hub is the same. i think you might be confusing hub with cassette. you can get a different cassette if you really want, but 29 seems rather large.

if you keep the shifters and front mech you will have "extra trimming."

another thing to look into is the rear mech. they have a max amount of tooth differential they can handle.

Brone said:
Do I need a new rear wheel hub?
I suppose the chain is different? Ultegra compact the way to go? What will this normally cost to have the LBS do it? Need advice and recommendations and opinions. Thanks.

One other question: If I go to a compact, is it possible to go to a bigger cog in the rear such as, say, a 29 ?
 

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If you need the 30/27 combination you're probably best sticking with what you have. The nearest equivalent in a compact would be a 34/30, and then you have to replace your cassette (with a non-Shimano) or add a 30T cog. If you can live without that last gear, a 34/27 is very close to a 30/24, so you'd be fine. Or if you're willing to swap wheels or cassettes when you head to the mountains, it might be worth it to get one cassette for the flats and one for the mountains.

You probably already have the long-cage rear derailleur, so there's no problem there. I think the triple front derailleur will work with a compact also.
 

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The max gear for a Dura-Ace (or any shimano road) derailleur is 27...although I've been able to run an 11-28 IRD 9 speed cassette with an Ultegra 9 speed short cage rear derailleur just fine.

-Chain is the same, just needs to be shortened
-Rear derailleur is usually a long cage for a triple, short cage for a double. But the long cage will work fine with a double setup
-Rear hub is the same
-If you want to run lower gears in back (like a 11-32 cassette), look at getting an XT or XTR mid-cage derailleur
-The Ultegra Compact is a good choice
 
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