I have a 2017 BMC Alpenchallenge AC01 that came with 105 (5800 series) components. I've been slowly collecting upgrade parts as I find them on sale or for killer deals. The last of it, the crankset, arrived today and the upgrade will be done this weekend.
I am upgrading from 105 (5800 series) to the new Ultegra r8000 series. The 105 that came on the bike has a 50/34 crank that's 175mm and an 11-32 cassette.
New components to be added:
-Ultegra r8000 Crankset 50/34 175mm
-Ultegra r8000 front braze on derailleur
-Ultegra r8000 rear mid-cage derailleur (compatible up to 11-34 cassette)
-Shimano Ultegra CS-HG800 11-34 Cassette
-Shimano Ultegra CN-HG701 Chain
All in this ran me $398 which I'll consider a very good price all things considered.
I'll update the thread after the install / upgrade is complete.
Photo of bike with the 105 components on:
After this is complete my next (and maybe final upgrade will be the disc brakes and rotors.