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Brim Brothers’ new approach to measuring bicycle power

  • By Caley Fretz
  • Published Sep. 24, 2010
  • Updated Jan. 28, 2011 at 4:57 PM EDT

While the big collaborative efforts of Look/Polar and now Garmin/Metrigear to bring a pedal-based power meter to market are getting a lot of attention, there is a small company lurking in the shadows of these relative giants with a system which may not be too far from hitting the market.

Mad scientist? Perhaps. But he's come with a very cool product.

The beauty of this small manufacturer’s idea is that it eliminates some of the primary concerns of a pedal-based meter while maintaining many of the benefits.

Brim Brothers is a two-and-a-half-year-old Irish company solely focused on bringing a cleat and shoe based power meter to market. Brim co-founder Barry Redmond took a moment Thursday at Interbike to explain his device to VeloNews.

The Man

Redmond knows a thing or two about electronics. He has worked in electrical engineering for decades, spending time on industrial monitoring systems before becoming the Computer Engineering Department Head at the Dublin Institute of Technology.

He is, of course, also an avid cyclist.

“I started this two-and-a-half years ago because we were out riding with our club, and we were looking around at these other power meters and thinking they were so heavy and expensive, and we couldn’t move them from bike to bike,” he said.

Over a series of Sunday morning rides, he and his partner hatched their plan. “We started this because it’s what we wanted; we wanted to train more and get better.

“Ironically, it’s had completely the opposite effect. I’ve spent so much time on this, my riding has just gone to hell,” he said with a laugh, adding that “I want to get this going so I can step back and ride again.”

The Machine

The basic idea behind the Brim Brother’s power meter is a two-piece system. The first is a cleat (no, he won’t say what type) which contains force sensors to measure pressure on the pedals. These piezoceramic sensors, similar to those used by Metrigear, and a more advanced version of the stuff that provides a spark in some gas lighters, produce a current when compressed or stretched.

The guts in the box.

They are not, however, strain gauges. Brim eschews the strain gauges that form the core of the SRM and PowerTap. The sensors “are extremely robust, dependable, and accurate. You couldn’t break them if you tried,” Redmond pointed out.

The second piece of the puzzle is a small box which sits on top of a rider’s shoe. This box contains all the electronics and accelerometers, taking in sensor measurements, making calculations, holding the battery and transmitting it all via an Ant+ radio.

Since power equals torque multiplied by angular velocity, accurate positioning data is of utmost importance.

Data will be measured every few hundred milliseconds. Redmond wouldn’t provide an exact figure, simply noting that the rate would be determined with both battery life and accuracy in mind.

The box also contains a small USB-rechargeable battery that provides 15-20 hours of run time between charges. The entire package – black box and additional weight added to the cleat – weighs only 15 grams. Redmond had a prototype of the box in his bag, and it is certainly nothing fancy yet.

“It’s an engineer’s idea of a box,” he joked. “You ask me to make you a box, that’s what you get. We’ll make it pretty later.”

The entire system will be completely water proof, though the current prototype is not. Redmond says stepping in a foot of water should not be a problem, noting that “we’re based in Ireland, so we know what waterproof is.”

Why cleat based?

There are certain advantages and disadvantages of having a cleat/shoe or pedal-based power meter. The ability to read left and right outputs is attractive, and the ease of swapping from one bike to another would be unmatched. However, impact and wear are big issues of concern. A pedal strike in a criterium, for example, could do serious damage to a pedal-based system. Cleats, meanwhile, have to be replaced because they simply wear out.

Redmond says impact won’t be an issue with this power meter since all of the breakable parts sit on the top of the shoe rather than underneath it. The cleat itself will only contain the robust, and relatively cheap, sensors.

When asked about potential power spikes from impacts, Redmond explained that since the meter knows where in the stroke your foot is it can assume that you aren’t creating massive amounts of power at the very bottom of the stroke and can self-correct. He likened it to the algorithms used to eliminate noise from road vibration.

While Redmond hasn’t yet fully addressed the question of cleat wear, he suggested that a relatively cheap replacement could be sold separately from the black box.

Vaporware?

Walking away from an interview with Redmond left more questions than answers. But he is adamant about avoiding the “vaporware” title, and feels that the best way to do so is to hold off on divulging release dates, pricing or compatibility information until he is actually sure he can hit them. He’d rather pick a target once he can see it, rather than shooting blindly into the dark and simply moving the target after missing.

That said, he let slip that he’d like to see his meter make it to market within 12 months. With working prototypes already on the road such a goal is not out of the realm of possibility.

“We’ve got it, it’s working, and now there are just a whole bunch of tiny things we just need to keep knocking over,” he said.

As for cost, Redmond simply stated that the Brim Brothers power meter will be competitively priced. As to precisely what that means, your guess is as good as any.


Editor’s note: Caley Fretz joined VeloNews as an editorial intern in May 2010 and has stuck around ever since. Beyond his journalistic pursuits, Caley is a Cat. 1 road and cross racer, pro mountain biker, Cat. 2 track racer, and former President of the Colorado State University cycling team.

FILED UNDER: Bikes and Tech / Interbike TAGS: / /

Caley Fretz

Caley Fretz

Tech Editor Caley Fretz came on board with VN in September 2010, and now splits his year between Boulder, Colorado and Annecy, France. Beyond his journalistic pursuits, he is a category 1 road, 'cross and track racer. He also holds a pro XC mountain bike license, though unlicensed racing is now more his style.

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