PoorBob

Looking for help/advice on options for hydraulic brakes on a flat bar gravel build.

I have been collecting parts for what I thought would be a drop bar bike, but for unimportant reasons it’s going to be a flat bar bike.

What I have so far is a complete GRX 1x set, including calipers. BR-RX810

I also got a RS700 flat bar shifter that is confirmed by Shimano’s compatibility chart to work with my derailleur

From what I can see there is not a flat bar lever in the MTN range that will work with GRX calipers. Also it appears that the Deore XT flat mount is the only flat mount option Shimano offers.. Nothing I can find on there website that would tell me the Deore levers would work with the GRX calipers?

Any ideas would help,

Bob

veganbikes

I am running Magura MT4 FMs on my bike and so far like them but I like Magura. They had a brief batch that was maybe less than ready to go but they warrantied them and everything is fine now. They do make an XT and XTR and maybe SLX Flat mount caliper but I think technically it is rear mount only but I have to imagine with a different lever you could use it at the front. The nice thing with Magura is they are interchangeable levers so you can run it up or down either side no problem.

I will also say the nicer Tektro/TRP stuff is good. The bike came with Tektro stuff and it worked fine but I am not one to leave things alone so I replaced them but mainly for brake pad compatibility with another bike in my fleet.

If you did go GRX I think you would be fine enough with a 2 piston lever from an MTB group,

t2p

have one flat bar bike with RS700 shifters and following brake components:

BL-M8000 levers
BR-RS785 calipers
SM-RT86 rotors
J05A-RF pads

also purchased SM-BH90-SS brake hose - but got lazy and used the existing OEM BH-59 brake hose

this bike uses post mount calipers - your flat mount RX-810 calipers should work with these brake levers or similar … you would probably need L05A-RF brake pads (or similar) for the flat mount GRX calipers (?)

PoorBob

I am starting to think that would have to work. I cannot see there being that much difference in road vs mtn 2 piston calibers.

it is surprising how little about this turns up in internet searches… That does add a little question of compatibility

veganbikes

Shimano is not known for their want to have things compatible but you could say that about a lot of companies. The real thing is they aren't looking at these odd combinations because they don't see a use for them. Most manufacturers aren't building the bikes we build they are building stuff for the masses so they will use a known quantity we like to mix and match and make something cool.

Can't blame them though going through all the iterations of what might and might not work could be a lot and they probably don't want a lot of people messing about and screwing it up and then going Shimano sucks even though Shimano had nothing to do with what went on other than being the manufacturer of parts used.

t2p

for the most part there is a great amount of compatibility - with possible exception of the early Shimano brake system components (that were not their own in-house design)

you can mix and match most Shimano levers and calipers - including servo wave and non servo wave levers - and the lower end resin piston calipers and the higher end ceramic piston calipers (and / or two and four piston calipers)

you can also mix and match the brake hose (BH59 and BH90) - despite the absence on a compatibility chart and recommendations against this (just need to use the correct hose for the brake lever type and hose fitting type into the caliper (straight or banjo)

there is a difference to be aware of with the rotors and calipers / brake pads: for the most part the lower end stuff uses ‘wide track’ rotors that are intended to be used with resin brake pads (with just one or two exceptions
including RT61 rotor) - and the higher end stuff uses the ‘narrow track’ rotors that will accept resin and sintered pads

of course - there is also the difference in the mounting method for 6 bolt rotors and center lock rotors