how do i fit them and how easy is it?
just bought some and dont no wether to get the shop to do it or just buy the tool

Easy, buy the tools

hollowtech, or hollowtech II ? (internal or external BB)

both easy – DIY unless you’re very bad at that sort of thing

For Hollowtech II even I can do it, so very easy. It’s worth learning so you can replace the BB bearings yourself. For the bearing: You just need to know how many plastic spacers you need on which sides, grease the threads before screwing into the BB shell. For the cranks: Don’t over tighten the preloader or you’ll break it, it’s just a bit of plastic so you can seat the cranks correctly. if you spin the cranks and they don’t spin freely, you’ve overtightened it. Everything else is pretty obvious I think.

Bring back the cotterpin. Everyone knew where they were in my day. If you had a hammer and a heavy file, you had a full toolkit.

i can do evewrything else lol

im off to get the tools 😛

Not too complicated at all.

Go on to shimano website-look on tech and read the instructions!

Also Park tool website has some handy tips too.