| Tech Talk- Review Ibike Pro Power Meter |
by Greg Pelican Bethel Cycle November 14, 2007
Buyers beware! Usually something that seems too good to be true often is. One exception to the rule is advances in technology. So although the Ibike seemed too good to be true the theory behind the technology was interesting and worth testing out.
The benefit of measuring power on the bike is well documented for training and racing. There are some well proven power meters on the market that do an excellent job. Powertap has a design that incorporates a strain gauge (which is used to calculate power) in the rear hub and SRM measures strain in their crank and bottom bracket. The major downside for these units is cost which is well over $1000. The Ibike has a retail price of $429 which opens the door to new users.
What makes Ibike unique is how it measures power. It actually has a port on the front of the computer that measures air pressure. This makes the unit big and a bit ugly, but it is a lighter solution than having a special hub or crank.
I installed and tested the Ibike in late April of this year and tried to get it to work for two months. In the end I gave up and removed it from my bike. Here is a recount of some of the problems I experienced. The first challenge was mounting the unit on my tri bike with aero bars. The front of the unit needs to be unobstructed from the wind for it to work correctly, and this requires purchasing a special mount from Topeak called the BarXtender. Ibike stocks the adapter, so I took their advice and bought it with the unit. Even with the adapter it took me about 2 hours to mount the unit in a reasonable spot that didn’t interfere with my hands yet kept the head in the wind. This took some trial and error and I had to re-route the speedometer cable each time. And the BarXtender, besides being hard to adjust and tighten, was big, ugly and weighed 116 grams. I was beginning to wonder about the extra wind drag caused by the mount in this critical frontal area of the bike. And the extra weight of the mount negated some of the “weight savings” claimed by the manufacturer. Another potential problem for triathletes is that it would be impossible to use Profile Design’s Aero Drink system as the bottle mounts in the same place as the Ibike.
Once the unit was mounted to the bike it had to be calibrated. Compared to a normal cycling computer, there are several extra steps requires to calibrate the unit that make it cumbersome to use. Hey I just wanted to be out riding on this nice warm spring day! You must accurately weight yourself with riding gear and the bike. This data is entered into one of the setup screens. Imagine standing on a scale in your Sidi shoes with your helmet on and your bike in your arms. Fortunately no one came to the front door when I was doing this as it would have been hard to explain what I was doing. Next you need to have the Ibike calculate the slope of the head unit by facing the bike in two directions in the same place on the floor. This is very critical to determining the actual slope on the road and resulting power. For example if you hit the Ibike by mistake on a ride and it moved a degree there will be a huge error in the power calculation.
Finally I got the unit mounted and was anxious to go and test it out. I went to the local Industrial Park where we race as I now had to do a coast down test to finalize the calibration process. This process requires accelerating to a designated speed and then coasting down. The Ibike then calculates the drag of you and the bike. But it took about 5 times before the Ibike got a reading that it would accept. And although I’m not insecure, the whole idea of coasting at 12 mph on my Cervelo P3 with a skinsuit and an aero helmet, 200 yards from Cannondale’s corporate headquarters wasn’t very appealing. In theory the coast down process would need to be done anytime you made a change to your bike (such as wheels or tires), riding position or even clothing.
O
K, done, all calibrated and finally ready to ride. I headed south on route 53 and I saw what seemed like reasonable power readings. Since I have owned Powertaps in the past, I have a good idea of what it feels to ride at a given power. But once I started going downhill the unit freaked out. The power started increasing and was quickly reading over 2000, even when I wasn’t turning my legs. Hey I just hit a personal best! Something was really wrong here. Once the road flattened out the power reading got back to normal. But then I encountered my next problem. After hitting a few potholes the BarXtender mount loosened up and the Ibike started vibrating. This totally messed up the readings. What a waste. After all the time spent calibrating, now I had to head home, tighten the mount and repeat the whole process.
The next two months were just more of the same. I also encountered problems with short battery life and software installation. I wasted a lot of valuable training time emailing the problems, and talking live with tech support. I even uploaded new firmware that was supposed to address some of the problems. In one of the conversations I gleaned that there was a known problem with the algorithm that calculated power when descending. This explained the high wattage values when coasting or pedaling downhill. For me this problem made the unit unusable as the average wattage is totally skewed from this error.
After two months of frustration I gave up and removed the Ibike. I feel this is a case of a good idea and poor execution. When I was a product manager for Fuji Film I was responsible for thoroughly field testing new films before introducing them to the market. I have to wonder if Ibike bypassed this important step before launching the product for sale.
Note: For more info email greg@bethelcycle.com or call 203 792-4640
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