When the pro cyclists ride over Cottonwood and Independence passes Wednesday during the USA Pro Challenge bike race, nearly half will be gauging their performance on a device made in Colorado Springs.

The cyclists’ SRM PowerMeters will record the power they use, the calories they burn, the altitude they gain and their heart rate, speed and cadence. And they will see the data in real time.

The PowerMeter is part of a revolutionary system created by the man behind SRM (Schoberer Rad Messtechnik), owner Ulrich “Uli” Schoberer.

Schoberer, a medical engineer, experimented for years with ways to measure an athlete’s power output during actual rides — not while pedaling a stationary bike in a lab.

His first devices were sold in 1986 and now are used around the world by thousands of pro and amateur athletes — mainly cyclists but increasingly by others, including hockey players, skiers and even Formula One drivers. The device is easily installed on any piece of equipment that uses a crankshaft.

“It’s crazy because I’ve been training for years, and my training is really regimented, but it has changed a lot since I got my PowerMeter,” said local cyclist Kalan Beisel, who installed the system on his road bike this summer.

“I used to watch my heart rate and base my training a lot by how I was feeling,” Beisel said. “I was amazed at what I learned using the PowerMeter, how wrong I could be about how hard I was riding.”

Beisel quickly learned that he wasn’t the best judge of his power output (measured in watts), that on some days when he felt bad after a ride he’d actually maxed his power outage. Also that he wasn’t giving his body a break on his recovery, or easy, rides.

Using the meter arms Beisel with information that allows him to dig in when he needs to and take it easy on other days. That has given him more energy for his difficult training rides and, he hopes, future races.

The meter’s electronic components sit inside special crankshafts that SRM can customize for road or track cyclists, mountain bikers or BMX riders. Cyclists can specify the make of crank (Shimano, Cannondale, Specialized, etc.), the crank length and the chain ring size.Data is transmitted wirelessly — as often as every half-second — to a monitor about the size of a credit card that is mounted to the handlebars. A cyclist sees the information at a glance, no fumbling with dials or buttons.

“It’s been really useful, and fun, comparing different rides, different days,” said Beisel, who plans to install a system on his mountain bike before the Dakota 50 race next weekend.

The SRM PowerMeters are being used by eight teams racing in the USA Pro Challenge and were installed on the bikes of the U.S. Olympic team. The faceplates and other components can be customized to match team colors or a cyclist’s bike frame. On Tuesday, technician Stephanie Ward was creating special gold-tone monitors for gold medalists at the London Games.

In another room, SRM’s Rachel Weiss pulled up data collected from cyclist Chris Horner on the Stage 1 ride Monday from Durango to Telluride. Horner and his team, Radio Shack-Nissan, will look at the information to see how hard he rode and how he should pace himself to compete throughout the week. The USA Pro Challenge comes to Colorado Springs on Friday and finishes Sunday in Denver.

“Once you know your average output and your maximum output, you can use that information in the middle of a race. You know the limits of your body,” said Weiss, who, like nearly everyone at SRM, rides regularly and uses a PowerMeter.

If you’re coming into a finish and you know there’ll be a sprint, you can pace yourself so you have power for the end.

SRM has offices in Germany and New Zealand, but if you’re buying a system in the United States, you’re getting a product made and sold in Colorado Springs. And if you need a repair, that’s also done at the company’s sleek office perched on a hill overlooking downtown.

“I wouldn’t train without a PowerMeter now,” Beisel said. “Without it, you’re just guessing.”