I’m toying with the idea of replacing my ancient brake callipers (M675) with something newer, possibly the new M7100 which I’ve seen for 21€ each online (I don’t really need 4 pots) and using my old levers.

I’ve got a couple of sets of BH90-SB (which I assume relates to the straight & banjo connections) but I’ve noticed that the callipers give BH90-SBM as their recommended hose. I was under the impression that all Shimano hose (such as BH59) was interchangeable with the correct inserts as only the internal bore varies so I assume that the BH90-SB hose I have will be fine, but I’m intrigued as to what the M relates to (I’ve seen hose packaged as SB & SBM variants so it’s clearly something); can anyone enlighten me?

I was going to post this very question. I want to try the new 4 pot slx caliper on my current slx brakes. Current one uses SB but new 4 pot ones state SBM. From my google fu i think the M stands for magnesium so can be bolted into magnesium (according to someone on the mtbr site about 5 years ago)??! But my guess is they are basically the same otherwise, but await someone with more knowledge than me to confirm.

The specs for BH90-SBM on the Shimano Europe website state that it’s for XTR systems and comes without a banjo bolt and seems to suggest that different bolts lengths are needed for XTR & XT versions; I’ve no idea how this would affect SLX users and whether the SB variant is useable.

The XTR 9100 callipers seem to have straight connections & use the Deore BH90-SS hose.

Well, it took a while, but I finally got a response from Shimano which I’ll post up here in case it helps anyone.

Thank you for your message but our apologies for the delayed response on this for you. I have checked in with our tech team on this and can confirm that there is a difference in the banjo between the SB and SBM that allows for greater heat dissipation.

If you are using the 2 piston caliper then either the SB or SBM hose will be suitable
If you are using the 4 piston caliper then please only use the SBM hose.

I guess that heat dissipation isn’t a problem for the non-series BR-MT520 4 pots that use a straight connection.

👍thanks for the update. Good to have an answer from shimano. Need to decide if i go slx caliper  and new hose or non series and stick with the hose i have…….hmmmm