Ricardo75,
My M20 which I received in late July 2021, came with Deore M6100 two piston brakes, AR30 Raceface wheelset with centerlock hubs and 180mm centerlock rotors front and rear. I've since changed just about every component on the bike other than the frame, motor and battery.
Those M20's which come with M6100 two piston calipers use Shimano brake hose, SM-BH90-SS. The "SS" signifies a straight fitting at brake lever and a straight fitting at caliper. The only four piston Shimano caliper that accepts a BH90-SS straight fitting brake hose is the Deore M6120 caliper.
All four piston brake calipers above Deore level, i.e. SLX - M7120, XT - M8120, and XTR - M9120, use a SM-BH90-SBM "Banjo" type brake hose. The "SBM" signifies a straight fitting at the brake lever and a crimped "Banjo" type fitting at the caliper. There are non-Shimano brake hose adapters that will convert the BH90-SS straight fitting hose to a banjo type fitting. Personally, I'm not comfortable experimenting around with my brake lines. It's one of those things you don't want to fail.
Shimano has a great compatibility chart which details what works with what components. I learned the hard way to review the chart before buying anything.
I initially installed SRAM G2 brakes, Ibis 935 carbon wheels with centerlock Torch hubs and 200mm centerlock rotors front and rear. They were taken off of my pedal bike which I could no longer ride due to a severe ankle injury. SRAM doesn't make a speed sensor magnet centerlock rotor. I tried several centerlock adapters, i.e. Specialized and Bosch. None of these worked with the bike. I next superglued a Neodymium rare earth magnet directly onto the SRAM 200mm rotor. This worked nicely, however I found that on rides involving a lot of braking, the rear rotor would get hot and cause the magnet to lose it's magneticity. Rare earth magnets will lose magneticity when subjected to heat and regain magneticity when they cool off. My bike would fault code, the motor would cut out for a few seconds and then kick back in when the magnet cooled off, only to repeat on the next run.
Ultimately I said the hell with it and figured since Shimano designed the whole system, I might as well use Shimano brakes. I ended up replacing my SRAM brakes with Shimano XT M8100 brake levers and M8120 four piston calipers. I also installed a 203mm centerlock rotor up front and a 180mm "Speed sensor magnet" rotor on the rear. No more fault codes, "Yes Virginia there really is a Santa Claus."
If you decide to go with a four piston caliper that utilizes a banjo type fitting, i.e. brake hose SM-BH90-SBM, you will be faced with the dilemma of either using an adapter or replacing the rear brake hose. Replacing the rear brake hose is a real treat. Orbea does not provide a separate cable/hose channel inside the frame in which to push cable/hose through. You will need to fish the brake hose through the head tube, down the down tube, past the battery, transition from the down tube up over the top of the motor, out the top of the frame housing, through the black rubber hose guide and into the rear swing arm where the hose exits near the caliper.
There are a lot of electrical wires in the down tube and motor area. You do not want to forcibly push or yank the brake hose or cable housing through these areas. Tolerances are tight and It would be very easy to damage wiring or create a wiring pinch point. I personally like to drop the motor down a few inches out of the frame, where I let it rest on a padded step stool. I use a combination of Park Tool cable routing tool IR-1.2 and my fingers to manually feed the hose through the frame while ensuring no wires are trapped or pinched inside the frame. Good times...Wahoo!
Fox 34 forks have 160mm caliper post mounts. If you go with a 203mm rotor up front, you will need to use a 160 post mount to 203mm rotor adapter. According to Shimano's compatibility chart you will need adapter SM-MA-F203P/P for the Fox 34 front fork. The rear of the Rise is set up with 180mm post mount. If you go with a 180mm rotor, no adapter is needed. If you decide to go with a 203mm rotor on the rear, you will need adapter SM-MA-F203P/PM.
I switched out the Fox 34 on my M20 and went with a used Fox 36. I found I was pedal striking badly with the Fox 34,140mm travel fork. I weigh 205, so go figure.... When you get tired of pedal strikes, buy a Fox 36. I converted the Fox 36 travel from 150mm to 160mm. I also removed one of the two volume tokens that come with the Fox 36 150mm. According to Fox, the 160mm travel fork comes with one token from the factory. It costs about $35 for a 160mm air shaft assembly and the conversion is easy to do. The travel conversion greatly reduced pedal strikes and the bike handles technical downhill beautifully.
Lastly, I would like to add that I am not a professional bike mechanic and I learned by going hands on with my bikes. I'm new to eBikes and it's definitely been quite the learning curve. I've tried to provide the best possible information in answer to your question. If I am in error, someone please point it out to me. Life is a about learning and we learn from our mistakes just as we learn from our successes.
Be safe,
Rod
Shimano Deore two piston caliper "SM-BH90-SS" straight fitting brake hose
View attachment 74768
Shimano four piston caliper "SM-BH90-SBM" banjo fitting brake hose
View attachment 74769
Shimano Brake Adapter Chart
View attachment 74770
Example of a Fox 36, 180mm post mount to 203mm rotor adapter
View attachment 74771
An example of the Shimano SM-MA-F203P/P 160mm post mount to 203mm rotor adapter.
View attachment 74772