Hi – I’m helping a workmate whose bottom bracket is knackered – lots of play etc. I’ve taken the crank arms off and cant figure out what type of bb it is and whether i need a special tool to take it out/replace. The cups look threaded into the frame and are circles apart from straight edges (like cones on the cup and cone hubs) where I presume you get a spanner on (35mm apart driveside, 15mm non-drive. Trouble is there is very little metal to get decent purchase with a std adjustable spanner. Its not an expensive bike and its a sq taper bb. just wondered if anyone has come across these and any tips for removal and fitting a better one.
some pics
here
and here
and here
and here
any help much appreciated

adj may work, vice is best, otherwise you need the proper tool.

I’d just ask LBS to remove it. Any square taper will replace it (of the correct length) LP26 or UN54/5 from shimano work well and are easy to find – and need a futher tool to fit.

cheers – i’ll try a vice

ahh….these pictures remind me of when i worked on a bike recycling project i set up once.
its the predecessor the standard square taper bottom bracket and can be a bit of a pain to remove.
you can get it off if you have the correct tool but these are now very rare so the option would be to stick it in a vice and then get a large adjustable spanner on the flat parts of this pic…

if this doesn’t work then the other option is to place a flat screwdriver against the flat edges and tap with a hammer until it comes loose…be careful not too get too giddy with the hammer though as a lot of patience is required for this method but it does work on both sides of the bottom bracket and they unscrew the same as a normal bottom bracket….good luck