Brim Brothers Zone power meter: It works, and it’s coming

Playing with a working model of the Brim Brother's cleat-based power meter

LAS VEGAS, Nev. (VN) —The Brim Brothers Zone cleat-based power meter is now operational, and less than a year away from production. Engineer Barry Redmond gave a short demo at Interbike, along with a few more details on form and function.

The Zone has come a long way since Interbike last year, when Redmond would only show us an unfinished-looking black box behind closed doors. Now the system looks quite refined and sleek, and Redmond was happy to put it through its paces out in the open at the ANT+ booth.

Brim Brothers’ option is unique in that it measures power at the cleat, calculating watts using piezoceramic force sensors in the cleat’s base plate and accelerometers in a small pod on top of the shoe. A small wire runs from the cleat to the pod, which also takes care of sending data to any ANT+ compatible head unit.

The pod’s sensitive accelerometers provide accurate position data of the foot, vital to the calculation of power (power=torque multiplied by angular velocity). One Zone pod goes on each shoe, and as a result power can be measured from each leg independently.

The system is capable of drawing a complete diagram of each pedal stroke, including foot angle and power data at each point in stroke.

Those same sensors allow for the system to differentiate between pedaling power and, for example, just walking around. The Garmin showed no power output when Redmond was off the bike, but started up quickly when he began turning the pedals over.

As of right now, Brim Brothers is designing the Zone around a Speedplay cleat and pedal, but plans to debut other pedal-system options as well.

The demo
Of course the greatest benefit to a cleat-based system is how easy it is to swap between bikes. In fact there is no actual swapping — just wear the same shoes and you’re all set. For the demo we simply walked the show floor until we came across a bike on a trainer at the ANT+ booth. Redmond simply hopped on, synced his Garmin and began recording. Simple as that.

The only calibration necessary is to let the pod know where it is in relation to the cleat, and is easily achieved by clipping the shoes into both pedals and spinning them backwards four times. Crank length is measured dynamically, no need to set it.

The Zone measures left and right power individually, though that data is not currently viewable on most head units. Garmin is about to release a firmware update for their Edge 800 series GPS that will allow the units to show each as a percentage of total output, though. The ANT+ folks had one such updated Garmin on-hand, so we were able to test the left/right power balance function. It appeared to work flawlessly.

Redmond says he believes the Brim meter will be available around this time next year. He’s still holding out on a firm price, though a source closely connected with the project said the team is shooting for under $1,000. The simplicity of the design and low cost of the piezoceramic sensors could make that a reality.