They're slightly different (narrower) from the previous shimano bottom brackets but I think the road and mtb versions (of this generation of BB with a special BBtool plastic sleeve).

If anyone has any so I keep my BB going (for market research) on the new (to me) frame then its most appreciated. I will pay postage if you can get em out asap...

Please

As far as I am aware they're the same width as all the previous Shimano BBs (2.5mm) I'll have a couple in the garage but they'll just be in a pile of BB spacers.

There are 1.8mm and 0.7mm versions that can be used with a band on mech for fine-tuning the chainline but I've never need to to so.

TBH you'd likely be best/quickest/cheapest getting in touch with a local bike shop as they'll probably have a pile of them too.

Thanks Colin. Yes, the 2.5mm is the same but these newer ones are a bit tighter as the BB is narrower (hence they come with a plastic adaptor)...

See how I get on...

I think I know what you mean Shaf as I've had a couple of those BBs. Will have a look in the spares box in a bit.

I've got some 2.5mm, 1.8mm and 0.7mm spare from a couple BB52's I just installed if they would work for you? Not even made it to the spares box yet.....

I'm lost.

The 2.5mm spacer goes on the threaded part of the BB and against the frame. In what dimension is it different from all previous versions?

I think they're a different diameter Colin, because the M800 BBs are a smaller outer diameter (though obviously the thread is the same). Possibly a normal spacer would work but just stick out a bit.

thenorthwind wrote: ↑Wed Feb 24, 2021 11:07 am I think they're a different diameter Colin, because the M800 BBs are a smaller outer diameter (though obviously the thread is the same). Possibly a normal spacer would work but just stick out a bit.

This... They're a different diameter Colin. So using the previous model spacers means they'll (ie. they are) be baggy.

samwise wrote: ↑Wed Feb 24, 2021 10:52 am I've got some 2.5mm, 1.8mm and 0.7mm spare from a couple BB52's I just installed if they would work for you? Not even made it to the spares box yet.....

Thanks Sam but I already have these spacers but a bit baggy hence just stuck the BB52 BB on for now. Until I find me narrower diamter spacers or someone has a couple spare from a 73mm shell (only need one spacer for it lile usual)

But the bit that fits into the frame is the same diameter as on the older BBs so they can't be "baggy",

A trip to the spares pile in the garage is in order.

ScotRoutes wrote: ↑Wed Feb 24, 2021 11:11 am But the bit that fits into the frame is the same diameter as on the older BBs so they can't be "baggy",

A trip to the spares pile in the garage is in order.

Hmmmm.. Yes, you do have a point there. I'm just stating what I saw yesterday when fiddling. Will get the calipers on both the spacers at some point very soon to get to the bottom of this might have been me being tired

I've just checked my stack of spares and there are some that are 41mm OD and some that are 39mm, which I think are the M800 ones - at least that's what's fitted to the bike that has an M800. Obviously the ID is the same (35mm) so there shouldn't be any reason they wouldn't work, they'll just stick out a bit. You're not using a cassette spacer or something like that Shaf?

thenorthwind wrote: ↑Wed Feb 24, 2021 11:21 am I've just checked my stack of spares and there are some that are 41mm OD and some that are 39mm, which I think are the M800 ones - at least that's what's fitted to the bike that has an M800. Obviously the ID is the same (35mm) so there shouldn't be any reason they wouldn't work, they'll just stick out a bit. You're not using a cassette spacer or something like that Shaf?

Defineilty not a cassette spacer and definitely the m800 ones wwre a more snug fit on the m800 BB... Will check... Watch this space

Managed to find some spacers (and a bit of drillium with an internal dropper post now making a nice 'ping') in an mt800 I thought I had laying about.

Some numbers, to ease the confusion (and why the stabdard spacers from the older BBs aren't as appropriate)...

Mt800 (and newer threaded Shimano BBs) spacer:
2.5mm thick, outer/inner diameters 39.2/34.8mm

Older Shimano BBs (well the BB52 and that leagye of Hollowtech ones... you know)
2.5mm thick; outer/inner 41.8/35.8mm (but its a bit worn so the compression over x amount of years might be playing a part)

Just for completeness of info :
Actual outer diameter on the BB itself of where the spacer sit (measurements taken before the thread as thats obviously the same) Older v newer types: 33.3mm v 33.3 though the thickness of this gap before it meets the threads is wider on the older BB

All measurements taken with a worn out Forge Steel caliper (so it's all probably a bit out )