One day I need to post pics of the bikes you guys have helped me fix-up/build... So here is my question: I just got a great deal on a brand new Scott CR1 10 road bike (2014). The only component I'm not 100% thrilled with is the generic Shimano compact crank. The front and rear derailleur are Ultegra 6700, and I would like to install an Ultegra Crankset. The current bottom bracket is a press fit Shimano. I haven't kept up with BB technology, so I don't know much about them. If I buy a new Ultegra crank, what BB do I use? Is the exterior bearing BB they say it pairs with going to work in the BB shell of a 2014 Scott CR1 10? I've replaced cranksets that use sqaure taper, Mega Exo, Hollowtech Shimano, and Octalink. It's been awhile since I've gotten a "modern" bike, so I'm a little out of my element here.

Pressfit = HT2 in terms of crank spec, so no need to change

For the crank, what do you expect to get better than the current one? It's similar to 105 level, has regular rings, so easily replaced, unlike Ultegra 6700, being realistic, you won't notice any difference in use if you changed.

Shimano Hollowtech 2 road BBs, whether pressfit or threaded, accept any shimano hollowtech 2 road crankset. Swapping cranks is a breeze, you don't need any new bearings. Make sure to read the manual on proper installation/removal. And check your shifting afterward- you may not need to make any adjustments at all, but I couldn't swear to it.

You won't save any weight moving to the 6700 (aside from $200 from your wallet ), but I'm a fan of the shifting on those hollow chainrings (it's not something you'd notice in a blind test, but the difference is there), and the 6700 crank is much more aesthetically pleasing than the current one. Once you've done the crank swap, the only other upgrade I'd ever possibly bother making on that bike is the wheels, and that's only if you love the fit and feel of the bike, you have $600+ burning a hole in your pocket, and you want to shave a pound off the bike.

Hmmmm...the weight is surprising. I assumed the current crank was closer to a Tiagra and would be much heavier. I definitely don't want to spend extra money and negate the good deal I got on this one. Glad to hear the swap would be easy, I am seeing good deals on lots of the 6700 compact Grey cranksets now, and the looks are definitely an improvement. Not wanted to spend $200 though just for a prettier crankset. Thanks!

The Hollowtech already has weight savings built into the design. There's only so much one can do wit weight on a BB without compromising strength or greatly increasing cost, and no matter what you do the savings are measured in ounces, which is insignificant when you look at total bike/rider weight.

So it sounds like what I am hearing is that my current crank, a Shimano compact R series something, (565?) with solid arms is not substantially heavier than an H2 Ultegra. Correct?

Not found an exact weight for the R565, but Googling gives approx 800g, a 6750 (the 50/34 Ultegra) is 712g according to WeightWeenies; you need to decide if that 88g saving is worth the cost of the new cranks.

Can't control what you're hearing, but what I'm saying is that to me it's foolish to choose a crankset with weight as even a secondary consideration, as the differences are so small. The above mentioned 88 grams (3 oz) is one-tenth of one percent of a rider+ bike weight of 150 lbs, for example.