Need to replace my dying screw thread shimano BB that came with the XT m8000 groupset. Was about to buy the m800 on crc but people are warning that the cup sizes have changed and a standard tool won’t work?

Have I missed something? I’ve always used the standard BB tool…

M800 one is smaller, so needs a different tool or the plastic adapter and your normal tool.

Plastic adapter comes with the BB if you buy it from an actual shop not CRC

Yep they made it smaller…
The BB should come with a plastic converter BUT that converter won’t fit in some of the non Shimano tools so you’d either need to check it will fit in your tool or just get the Deore level one which has got the same cups as ever (at least for now)

Bought one from CRC last week that came in retail packaging with the adaptor. Fits okay in the standard shimano tool unsurprisingly.

I’ve got a superstar tool. Will it fit that?

My bb is the mt800 at the moment. Have they only recently changed the size?

I can live with deore in the interests of keeping it simple

MT800 hasn’t changed – always been the smaller fitting (and black in colour).
Previous XT one – BB70B was silver in colour, and same larger fitting as the BB50B and BB51B Deore ones.

The one I got from CRC did not come with the adapter so I got one of ebay for £3. Part tl fc25.

Guessing it’ll be the same size as the old XTR BB’s,used to get the plastic adapter with them too, which worked fine with my Park bb tool

Guessing it’ll be the same size as the old XTR BB’s,used to get the plastic adapter with them too, which worked fine with my Park bb tool

Xtr and Dura ace use a 39mm od cup
Ultegra and xt us a 41mm od cup
Older xt, deore, tiagra, campag and various others use 44mm od cups

As Andy said, if you need to order the tool, make sure you get tl 25, not 24 like I did.

Thankfully the awsumz guys at Bird sorted me out.

Thankfully the awsumz guys at Bird sorted me out.

8)