There are four types of Loctite that you should have in your toolkit for bicycle related repairs:
Loctite 243
This is the blue coloured Loctite which you can use on just about any bolt on your bicycle that can vibrate loose. It is a medium strength retaining compound so you can disassemble with hand tools and without having to use heat.
Loctite 263
This is the red coloured Loctite. It is a high strength retaining compound suitable for threadlocking where Loctite 243 is inadequate. Do not use on aluminium bolts, you will round out the hex head on a soft alu bolt before you break the threadlocking properties of 263.
Loctite 641
This is a retaining compound for use in press-fit applications like making sure your suspension bearings are retained properly. Don't use it unless the interference fit of the bearing in question is becoming a little sloppy (if you've got lots of slop, then you may need to use Loctite 638 which can bridge larger gaps.
Loctite Zinc Anti-Seize
This is specifically formulated for use with aluminium components. Use it on things like bottom bracket threads and on the interface between spoke nipples and the rim. It prevents binding and galling on assembly and disassembly.