Shimano Zee M640 Disc Brake

by Nick Zuzelski

Arguably the biggest star of Shimano's Zee lineup is the brake, which offers riders many of the same technology advancements and features of their big brother Saint. Luckily for us, Zee brakes come at a pretty substantial cost savings of about $140 per pair over Saint.

Zee Brake Highlights

• Servo wave lever pivot
• Shorty levers
• High rigidity ceramic pistons for heat insulation
• Anti-slip dimpled lever blade
• Radiation fin pad with new metallic compound to improve control and consistency
• Super stiff high-power 3-layer brake hose for a more consistent lever feel
• One-way bleed for easy and clean servicing
• 4-piston caliper
• 160/180/203mm rotor options
• Approximately 320g per brake
• MSRP $249.99 per brake

Coupled with Shimano's ICE Tech finned 203mm rotors (sold separately), these 4-piston brakes have everything going for them as far as heat dissipating technology and raw stopping power goes - something every downhill enthusiast can appreciate while pinned at race pace down a steep course. One quick glance at the unique pads with radiation cooling fins is evidence enough that great measures were taken to reduce a brake's worst enemy - performance killing heat.

Initial Impressions

Provided you don't ride a downhill tandem, there is plenty of hose length provided on the pre-bled setup for any bike frame. Rather than run a spaghetti mess of cables in front of my bars, I immediately trimmed the lines shorter for aesthetics. Shimano provides extra hardware for this with every brake so there are no excuses not to. I was able to get away without bleeding the brakes by being very careful. If desired, Shimano's new bleed process is a piece of cake.

Installation of the levers was a breeze and did not require removal of the grips since the clamp hinges open for quick install/removal of the lever. The rotors also mounted up very quickly using Shimano's Center Lock design on the Zee hubs - a design I am growing very fond of after doing a fair bit of airline travel, forcing me to do frequent teardowns/rebuilds of my bike. Time is money my friends, and simple things like this streamline otherwise tedious processes.

After mounting up the brakes, and grabbing hold of the bars, I was immediately impressed by the new compact levers. They feel great with one finger, offer a comfortable lever bend, hold your finger tip securely, and pull in smoothly to pad contact. Squeezing the brake tightly with one finger, there is no lever contact with the thumb or other fingers. The perch also appeared to be stiff with no noticeable flex when pulling hard, likely because the lever is so short. After adjusting the reach (note that there's no tool-free reach adjustment on these, so bust out your trusty allen wrench) it was all systems go and time for some abuse.

On The Trail

Before the first run I broke in the new pads. After just a few full stops could feel the incredible power and modulation building. Once on the trail, it quickly became clear how light and effortless the one-fingered activation of the brakes was. Given how quickly they activated when compared to the brakes was previously running, I actually needed a bit of mental readjusting to feel completely comfortable with the new characteristics. That said, it was a change I was happy to learn. After a few more runs and with speeds picking up, braking once again became second nature and I was pumped on the added power the Zee brakes offered. I could get LOTS of power, fast, which is crucial given the last second nature of downhill riding and racing.

Halfway down the rocky trail I was shuttling was a fairly slick, muddy section with a few corners and key braking points. It was a perfect place to truly test how well these babies modulated. To my surprise, I was easily able to keep my traction and control my bike through the grease. They aren't what I'd call "touchy," and instead offer plenty of usable power without causing the bike to break loose.

Being extremely picky about my bike set up, I was expecting to have to adjust the lever reach at least once throughout the day. Much to my surprise, no adjustment was needed - in fact I have barely adjusted them in the several months since. That said, it still would be nice to have a tool-free reach adjustment offered on these just in case. After dozens of days of ride time, the brakes are still running strong and haven't needed a bleed or any service since I first installed them. I also haven't felt the need for the added free-stroke adjustment found on the pricier Saint brakes.

In dry conditions, rotor noise is pretty much non-existent. In the wet, a very slight howl sometimes happens at slow speeds, but only for a split second - likely long enough to clean the water from the rotor. Shimano chalks this achievement up to improved pad compounds.

Speaking of pads, Shimano brought a number of improvements from their Saint brake to Zee in the name of better heat management, including an optional finned pad upgrade. The technology improvements havebeen noticeable on the trail and brake fade has not been an issue, even at the bottom of a long, steep trail that's notorious for burning up brakes. Pad wear has also slowed down as the resulting temperature decrease is easier on the materials, so expect to enjoy less frequent pad purchases.

The finned pads occasionally make a very slight but audible jiggling noise on smooth trails. Pulling the brake levers a small amount stops the noise. Some riders will notice this, others won't. To me it isn't much of a bother.

What's The Bottom Line?

Power and modulation often times don't go together in the same sentence. Shimano's Zee brakes certainly don't adhere that statement, instead offering both power and modulation in a very usable package. I really appreciate that Shimano was able to bring the cutting edge technology found in the high-end Saint brakes down to a price point that doesn't put a major hurt on your wallet. The new Zee brakes have proven to be a strong performer and they'll be staying on my ride for some time to come.

For more about the race-ready Zee lineup, cruise over to www.crusheveryline.com.

About The Reviewer

Nick Zuzelski began riding motocross at a young age, a sport that would eventually lead him to the world of downhill. As a Colorado native, racing downhill, dual slalom, or a chill dirt jump session was never far away, and he eventually worked his way up the ranks to the Pro level. Now residing in Eastern Pennsylvania, he recently changed it up from the Rocky Mountain dust to East Coast loam, world class dirt jumps, and rocks... lots of rocks.If a trail has fast flow and some fun gaps, he is grinning ear to ear and getting after it. Living by the assumption that basically everything feels better with a short stem and wide bars, you can count on him keeping it real with a laid back attitude and flat pedals most of the time. Mechanical Engineer by trade, rider by heart, he enjoys riding it, finding out how it works, and making it better.