Only really had to deal with square taper up til now so excuse my ignorance!

Looks like the previous owner of the GF’s Trance has fitted a replacement BB with a too-short axle (68x118mm BB-ES25) resulting in the chainline being off and unable to shift into the inner chainring. It’s a Shimano FC-M442/443 triple chainset, so according to them I need either a 68x121mm BB with a 2.5mm spacer on the driveside, or a 68x126mm with no spacers to get back to the correct 50mm chainline.

So, do Octalink BBs come with spacers? And I’ve guessed that the BBs with an -E suffix are for E-type FDs so I don’t want one of those, but what about -K and -AK suffixes – what are they for?

Octalink doesn’t come with spacers or at least in my experience I’ve never had one that did. You can put a spacer in fixed end to move it out but it doesn’t seem right, it would just shift the whole thing to one side so the other crank would end up closer to the frame. Might work as a bodge…

Never come across the K and AK suffixes. You need to get the right thread which would be English, maybe that is it?

I’d not seen any spacers in either but shimano do show it like that
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/SI_0052A/SI-0052A-001-EN_v1_m56577569830686523.pdf

Yeah, I thought that you only used spacers on external bearing BBs as well… Have found a FB conversation between a guy and Giant UK’s Service Centre which seems to suggest that the original BB should be 68x126mm so I reckon I’ll give that a crack.

Make sure you get the correct splines – you get two types and they aint compatible.