Review: Shimano XT BR-M8020 4-piston disc brakes
Switching over to a 4-piston caliper can offer more braking power and better modulation. Shimano hit the nail on the head with the M8020.
Shimano introduced the XT BR-M8020 4-piston disc brakes at the 2017 Eurobike. The caliper is based off of previous designs, but is updated with XT level technology. It is made for Trail or E-MTB riders who need more braking power and modulation, which is exactly what I was looking for. I weigh 94 kg, ride stiff suspension and have a playful riding style that require as much braking power as possible.
The new XT 4-piston brakes.
First impressions
The brake lever is the same as the proven M8000 disc brakes, but the new voluptuous housing of the 4-piston caliper is 30 g heavier. The cooling fins on the brake pads and the cooling sleeve on the brake hose clearly show that Shimano has made the caliper to be durable when it comes to consistent braking power.
The short, ergonomic brake lever feels good and the reach adjust can be done without tools. Adjusting the contact point requires a flat head screwdriver. The second generation I-Spec mount integrates the brake and shift lever for a clean cockpit.
The finish of the lever and caliper is of high-quality and leave a good impression, just I would expect from a disc brake in this price category.
It uses the same lever as its 2-piston brother.
The lever is very ergonomic.
4-piston vs. 2-piston
The basic function of a 4-piston brake caliper is the same as a 2-piston. When more hydraulic fluid is pressed into the hose by pulling the brake lever, the pistons push harder on the brake pads, which in turn push against the brake rotor stopping the bike. The more pressure, the higher the braking power.
The difference between 4 and 2-piston lies in how the pistons push against the brake pads. 4-piston calipers press 2 different sized pistons on to each brake pad, instead of just one. This increases the contact area of the brake pad to rotor and the overall braking power.
A 4-piston brake caliper also as has a larger housing, which is better at transferring heat from the pads. This is especially useful on longer descents. Combined with IceTech technology and larger cooling sleeves on the hoses, the 4-piston caliper takes longer to heat up.
They works in all conditions.
Installation
Shimano is known for quick and easy installation of their brakes, and the XT M8020 is no different. The brake lever can be installed without removing the grips, thanks to a split clamp. Installing the brake caliper is equally as easy because of the large gap between brake pads and rotor.
Shortening the brake hose and then bleeding the system is super easy due to Shimano’s One-Way Bleeding technology. They brake also use mineral oil as hydraulic fluid, like all Shimano models, which is both environmentally friendly and easier on the skin than DOT.
The 4-piston brakes offer tons of modulation and power.
The testing conditions were perfect. Wet, muddy and technical.
I need a lot of braking power and the XT gave it to me.
On the trail
Before hitting the trial, I bedded in the resin pads on the street. This step is important so that pads and rotor can both wear off surface glaze and contamination. After, the brakes are reliable and ready to shred.
As soon as the bedding in was finished, I hit my local wet and steep trails. At first, I did not require the full braking power, but instead smooth modulation. The 4-piston caliper did a great job helping me find the perfect point between grip and slide and controlling the point with the brake lever was also easy. Being able to modulate the braking power is important, because braking power that only block the wheels movement is useless.
However, when things got sketchy, the XT M8020 did a great job of stopping me in my tracks. Even with my 94 kg, there was never an issue and heavier E-MTBs will definitely appreciate the added power. I recommend also riding with a 200 mm rotor in the front, if you a looking for the most out of these brakes.
I was especially impressed with the Servo Wave technology on long descents. It helps save my forearms because the ratio of pull in the lever keeps my finger from having to muscle the lever around. Servo Wave is also helpful because it pushes the brake pads to the rotor faster at the beginning of the lever stroke, but maintains modulation when the lever is pulled farther.
If you need maximum braking power, go for the XT 4-piston brakes.
Is a 4-piston caliper worth it?
After riding the Shimano XT M8020 brakes for over a month, I think they are worth it. The organic resin brake pads work great in combination with the 4-pistons in wet conditions and are extremely quiet without showing any signs of increased wear. I also never had a problem with air in the closed hydraulic system.
I would recommend the XT M8020 to riders who are looking for maximal braking power and fading security. The increased weight of the caliper, compared to the M8000, is worth the increased modulation and overall better performance. The ergonomic brake lever, durability and high-quality finish round out the M8020 to be a top-tier disc brake at the XT level.
