It's a powermeter as light as a bike computer, with no wires, no special embedded-strain-gauge components, and doesn't cost as much as a complete bicycle. That's the iBike Wireless Pro Powermeter hook. The early adopters and popularizers of powermeters made it possible for the iBike to exist. And we hope that it inspires more advances when it comes to riding with power.

We first saw an iBike powermeter in 2005. It seemed interesting way back then, but didn't seem like it could really mount a challenge to the already-established powermeter leaders. Back then, the makers of iBike were promising a unit that could do what Polar, PowerTap, and SRM did without strain gauges, just taking measurements that came in via a speedo magnet and what was inside the head unit. Just by the way they described it, it seemed too hard to get readings to be consistent, and if the meter can't be consistent, it isn't much of a training tool. We've reconsidered, which is why you're finding it here.

Two big things have changed in two years. The firmware and software have markedly improved. As has our understanding of how the device works. The iBike approach is different and fascinating. Since there are no strain gauges, the meter works off a speedometer, accelerometer (measures acceleration and road gradient), barometer (for altitude), and air pressure sensor (wind is usually the biggest force opposing a cyclist on the flats). Different sensors measure different forces; for example, there are separate sensors for wind speed and bike speed. By using multiple sensors the iBike can measure precisely all oppositional forces from them and determine power readings. The fact that oppositional forces must equal forces applied on the pedal makes the iBike's power measurement accurate.

The iBike unit should be set up reasonably close to level atop the handlebars or stem. Eyeballing the unit should be enough; a level isn't necessary. Inside the mount are batteries that power a device that can read signals from wireless speed and cadence sensors, and heart rate strap. Also, with special firmware the mount can broadcast the iBike’s power signal to another computer such as the Garmin Edge 705.

After installing the iBike, you need to take a reading of your bike and body weight (just step on a scale while dressed and shouldering the bike) and enter that data in. Then you have to put the bike on the ground, take a reading, turn the bike 180-degrees, and take another reading. This sets the reading for "level" which makes measuring hill slope possible. Finally, you do a roll down test from 20mph to 8mph to determine wind and road resistance; this is part of a start menu that tells you to speed up and when to coast. These calibrations create a “profile” for you and your bike. You save the profile on your PC (or Mac!) and unless you change something significant about your bike or your ride position, you don’t have to repeat the calibrations. And one of the many cool things about the iBike is that you can move it easily from bike-to-bike. Just do the calibration procedure for each bike, save each calibration as a separate profile, and you’re good to go.

Data-acquisition freaks will love the iBike's data capture capabilities. It measures and records current, average, and maximum power, wind speed, bike speed, cadence, heart rate, altitude, hill gradient, and temperature. The iBike records elevation gained, clock time, trip time, trip distance, odometer, calories, kilojoules, and total hours logged. It has a clock and calendar in it. It has a battery life indicator. It has an interval timer that allows the user to program in the intervals. Whether you want to do something as simple as five minutes on, one minute off, or something as complicated as different power goals for different length intervals (say five minutes at 300w, followed by five minutes rest followed by four minutes at 320w, four rest, three minutes at 330w, etc)you (or your coach) can create customized interval sets using the free iBike software. In the interval window, there is an up arrow, down arrow, and bullseye next to the power number; if your power effort is over the power goal, the up arrow shows, under the goal the down arrow, just right, the bullseye. And there's a blinking warning for the five seconds previous to the end or start of an interval. The iBike can record ten hours of data in one second intervals, and can be set to go as far as 50 hours at five second intervals.

Everyone can use the iBike to figure out both wind and rolling resistance. For the tech-savvy, this can be great for those trying different bar positions for both road racing and time trials. And for those determining which tire/tube/wheel/pressure setup is the best for their riding.

During a ride, the iBike's data is pretty simple to access. The top of the unit has five buttons; a middle button that functions as a central switch that is surrounded by Avg-Max, Enviro, Hill-Wind, and Total. The four buttons are clearly marked. The screen has three levels, top, middle, and bottom. The basic setup is the "speed" screen, which has speed, distance, and time in the three windows. The "power" screen has speed, power, and the bottom alternates between heart rate and cadence. The Avg-Max button takes you to the averages, if you click it once, and the maxes, if you click it twice. Pushing the center button brings you back to the main screen. The Hill-Wind button can take out the speed and swap it with slope or wind speed. As a nifty little feature, the iBike will automatically toggle between slope and speed on steep hills and stop after the pitch flattens. Clicking on Enviro allows you to see the current conditions in case you wanted visual confirmation of what you were experiencing. And Total tells you ride totals.

Though the iBike gives amazingly good results in nearly all ride situations, there are a few places where it isn’t quite as accurate as other models. When drafting behind a single person, the iBike tends to under-report power readings by about 15%. The reason is that the iBike is closer to the ground than the rider’s upper body and is more shielded from the wind than the rider's upper body. Fortunately, most people riding in the pack aren’t working anywhere near their power thresholds so this underreporting doesn’t generally make a big difference in total ride stats. Also, the iBike is also sensitive to vibrations caused by rough roads and high-speed downhills, either of which can also throw off readings. New software that comes with the iBike fixes this problem: it analyzes each ride file, finds high-vibration trouble spots, and fixes them automatically. Rides that are analyzed with the software are scary-accurate. Finally, for riders who want to get best on-the-bike results, there is a VRK (Vibration Reduction Kit) available that mounts inside the stem. This VRK essentially eliminates the vibrations that can cause inaccurate readings.

As we've discussed before, accuracy and consistency are two different things. Ideally, the powermeter on our bike will be both accurate and consistent. Our initial concern was that the iBike would be neither. But as they've made improvements they seem to be getting closer to both. Australia's Ride Cycling Review did an extensive powermeter test in their Autumn 2007 issue where an earlier iteration of the iBike firmware and software was tested. It wasn't the most accurate or consistent meter out there, but for many riding conditions, it was pretty close in both categories. And it is getting closer. We’ve seen side-by-side ride file comparisons of the iBike with all major competitors and, with the improvements they’ve made, today’s iBike performs impressively. While the iBike may not yet have the endorsement of the pros, it’s more than good enough for someone who enjoys getting a better read on their solo and group rides, time trials, and indoor trainer workouts. And those who love knowing their climbing stats in addition to power will love its ability to measure the ups and downs of riding.

iBike has their own software that ships with the units and it's good to download the ride files into the software before making bold assumptions about a ride because of the corrections the software can make on ride data. It is both Mac and PC compatible. And for those who want to use CyclingPeaks software, iBike is compatible as well. Because of the corrections the iBike software makes, it is recommended to first download into iBike and then export to Cycling Peaks. iBike assumes a good portion of their customers will be using CP, so they've made the exporting easy.

Battery power runs iBike. The iBike, wireless mount, and three wireless sensors all use the light and commonly-available CR2032 battery. But while the sensor batteries last one year or more, battery life in the iBike itself is much less. In warm weather, the iBike’s battery can last 40-80 hours. In the cold, it can go 5-10 hours. The iBike folks have done extensive cool-weather testing and tell us to save the batteries that seem kicked in the winter. They've found that they still have plenty of life remaining when the weather warms up. The good thing is the battery life indicator, when checked, should inform you of when the time is right for swapping out the battery. It is supremely frustrating to have a meter go dead on a ride, particularly an important one.

The people at iBike are bullish about the way they're improving their units. The basic unit has been the same for two years, and they expect not to change it for years to come. Any improvements will be backwards compatible and often times free. Firmware and software upgrades that improve functionality are and should continue to be free. They're currently on their thirteenth firmware improvement, and have more improvements on the blackboard. Hardware, firmware, and software upgrades that add functionality will cost something. For example, there is firmware to make the iBike compatible with stationary indoor trainers. The wireless kit will allow the iBike to communicate with a Garmin 705 when riding for the ultimate in data acquisition.

The iBike Pro Wireless ships with the iBike head unit plus a stem mount. The mount is wireless and uses battery power to pick up the transmitter signals from the heart rate strap, the cadence transmitter, and the rear-stay-mounted speed transmitter. Batteries are included. A heart rate transmitter strap is included. The spoke magnet is included, though any magnet will work. There is a USB adapter for communication between the iBike and a computer. The kit also ships with the iBike software CD and Cycling Peaks trial CD. Wireless mount and sensors weigh about 53g in total, while the iBike is 62g. Total weight is 105g.