bck

Hey everybody,

I'm working on a new bike that will be a 650b, allroad/gravel and thinking about flat touring style handlebars. This is my first time working with disc brakes so forgive me if this sounds like a silly question, but what are the differences between an Ultegra disc caliper versus XT/XTR caliper?

From what I can gather, it seems like the road style will accept 140mm or 160mm rotors. Is there anything else I'm missing?

Cheers,

Brian

redlude97

Are you talking about hydraulic? I don't remember which series share the same sized pistons but better to just match the levers with the calipers. The caliper rotor size will depend on the mounting bracket used and the frame mounts

bck

Yes, hydraulic in both cases. It sounds like the number of piston and size might be the core difference?

I was reading about mounting options as well, so thank you for the note on that influencing rotor size.

DrIsotope

Ultegra calipers will almost certainly be flat mount (the 8000s are), the "new standard." Your frame will likely be post mount, but if it's something new and fancy, it may indeed be flat mount.

The 8000 calipers use L02A pads, the same pad used in 105, 9100, and RS305/505/805 calipers (and maybe a few others.)

When you get into XT/XTR, things get complicated. The M8000 XT is a dual piston caliper, almost physically identical to the RS785 caliper. The M8200 XT caliper is a four-piston, and looks to be a slightly reworked Zee/Saint caliper.

So the difference between the Ultegra and the XT (dual piston,) both with resin pads: cosmetics, really. The should perform almost identically.

You'll find more pad options for the MTB-oriented calipers-- there will be resin, metallic, and sintered. But I have only and will only use resin, so that doesn't matter much to me, at least.

I went hydraulic recently and jumped straight to the head of the line with Hope RX4 four-piston. They are absolutely fantastic.

wsteve464

MTB calipers are usually post mount and usually on the seat stay, the newer road bikes use flat mount calipers on the chain stay for a cleaner look. With post mount you can use larger rotors than the flat mount calipers.

bck

awesome - thanks so much for the detailed response guys!