I've got two road bikes, a Giant OCR-1 with the stock mostly Shimano 105 group on it, and a Trek 1.2 with the stock Sora and lower set of components. I'm thinking that it would be fun to buy the Ultegra groupset for the Giant and put its 105 group on the Trek, thus (I think) upgrading both bikes for around $600 to $700. Fun project for the dead of winter.

I have plenty of standard tools and a bike work stand and I work on the bikes all the time, but I'm not sure if there's more than meets the eye to this potential project. Specifically, I've never pulled a modern bottom bracket nor installed a brifter. Other than that, it looks pretty straightforward.

Assuming I buy the right tools, should the BBs on these bikes present a problem? If the BBs are a big deal, any reason not to just leave the current ones in there and keep the new one as a spare? And is there more to installing brifters than running the cables and setting up the derailers and brakes?

Just browsing Ebay, there are a number of sets for sale. Some are stripped off new bikes and resold, and others are NIB; some are used. If I bought a group without cables included, can I use the cables from the bikes, or would I have to buy new ones?

Don't fear the BB. It is so easy now with the cartridges that it is one of the easiest replacements.

The brifter is exactly as the old brake levers except you do have to thread in the derailleur cable too. Just look where the old one threads as you are removing it.

Sounds like a good project to me. I would use new cables and probably new housings too.

You won't screw up catastrophically if that is what you are worried about.

Might take a while.

Have fun.

I would go all out and do the BBs too. Go to www.parktool.com for instructions. You may use your old housing but I will definitely use new cables. Better yet, get the JagWire Racer Kit which includes everything. You will also need new bar tape. You might be able to use the bar tapes already on the bike if you are careful taking them off. But they are not that expensive and you can get them in various colors and textures to your liking than what came stock. The main thing is to have fun and prolong the job so it will last a while and get to enjoy it longer

One suggestion; your new Ultegra group will come with a bunch of sheets of paper printed in at least six languages and known as "Installation Instructions". I recommend you read them.

Not picking on you, but it's amazing how many questions posed here are answered in great detail by the manufacturer if only people would read the instructions.

BTW, many of the installation techniques for the new Ultegra stuff will also apply directly to the current 105 components as you transfer them.

Park Tools web site is also a great source of instructions for installing and adjusting components and is a very useful supliment to the manufacturer's literature.

+1. I have actually learned a great deal over the years from reading the Shimano sheets (just the parts in English).

Great project. I did this a few years ago when DA went to 10 speeds, I got a screaming deal on a 9-speed group from the LBS. I let the professional wrench put the DA group on the "good bike" and put the replaced Ultegra group on the "backup bike."

It's a fun winter project and you'll learn a lot about how your bike works.