Standard shimano Hollowtech II bearings, bike hasn’t been used all winter, got it out to start commuting to work again and the cranks were quite stiff to spin. There’s no play, so presume they are still good to use, just wondered if there’s anyway I can service the bearings and prelong their life?.

They might be seized and the cranks are spinning on the top hats. I replaced my bearings with the Enduro ones and regrease every 4-6months, just finished their third winter.

IME They are freed up with a spray of TF2 or similar and a spin around the block, but they’re not long for this world, start looking round for another BB…

I beg to differ. The bearings are probably siezed and spinning on the top hats. Not good as they can end up scoring the axle.
Take cups out of frame, take tops hats off then remove the rubber dust seal. Attack with thin solvent like WD40 or GT85, try and get the bearings turning again, then keep lfuching until they turn reasonably smoothly then get some spray grease and spray liberally at the bearings. I got an extra years life out of mine last year and they’re still going ok now.

What bigyinn said. I did that not long ago. Its not dead yet (no play either) but guess will live on for a while yet

Wot bigyin said. If that doesn’t work Deore BBs can be had for little more than a tenner.

XTR bottom brackets available on rose bikes for about £16 last time I checked…

BBs are bobbins these days, better to cough up £25 max for a Shimano XT BB than to have to shell out for a new crankset because the axle is ronnied.

XT BBs from Rose Bikes for £12, XTR for £16.
Nothing wrong with BBs per-se, if you look after them and dont over load the bearings. Obviously not going to be as long lasting as square taper, but you should still get a couple of years out of them.

I got an extra years life out of mine last year and they’re still going ok now.

bet they sound like a bag of nails though 😉