Monday, October 1, 2012

Interbike 2012: virtual reality trainers

There were plenty of trainers to catch the attention. So many, in fact, that I found myself who buys these things. Riding an indoor trainer is something I have to drag myself kicking and screaming to. I admit part of this may be that I don't have an optimized set-up, with preferably a heavy-duty fan and direct access to fresh, cool outdoor air. But a big part of it is I'm so spoiled: living in the San Francisco Bay area means access to world-class cycling routes. When the weather isn't to my liking, I switch to running.

But for many people, a trainer is the only way they're going to get the experience of climbing 1st category climbs, or riding without the interruption of traffic signals or heavy traffic. For these poor, wretched souls, being able to escape the drudgery of riding in a small room without stimulation may be worth the considerable expense of some of the latest virtual-reality units.

The first such trainer in my experience was Computrainer. They're still alive and kicking, and while I didn't take any photos of their booth, their latest release is certainly impressive. They were the commercial originators of "spin-scan analysis", which claimed to analyze the L-R balance of your pedal stroke. Without any sensors in either the left or right leg specific power transmission path, however, spin-scan had to rely on the pattern of force in one full pedal revolution. There will be two "power peaks" in the full revolution, and it's generally safe to assume one is from each leg. So comparing these peaks provides a clue about how much work each leg is doing. The issue is both legs are always doing something, so there's some assumptions and approximations to be made in this analysis.

The next trainer which I found particularly notable was TacX. They recorded videos of famous climbs and produced a trainer, the Fortius, which controlled the video play rate based on how fast the cyclist moved the trainer roller, the resistance of the roller controlled based on the grade of the road. There were some issues when the video happened to catch moving objects like cars or other cyclists. Then these would also move at a speed depending on how the cyclist pedaled. But supposedly it worked fairly well.

Computrainer now has a similar system, but TacX is still there producing these videos. I think they sound fun: I'd love to climb L'Alpe d'Huez during my indoor training sessions (if I still did indoor training). But the real attraction at the TacX booth was the virtual reality and the head-to-head competition modes.

TacX trainer hooked up to its amazing virtual reality video game. Not surprisingly, the graphics didn't come out well in the photo.

The virtual reality was simply amazing. It looked like something from EA Sports. The amount of solid modeling clearly went way beyond what I'd expect could be amortized over the indoor training market, a market which I may well substantially underestimate. I tried to take a photo but it didn't turn out well.

Then there was Wahoo. Wahoo had what appeared to be physically the best trainer unit. It followed the example of (defunct?) LeMond Fitness in having the user connect the chain from the bike directly to a cassette mounted on the trainer. This eliminates tire wear. Unlike the LeMond, the Wahoo uses electronically controlled magnetic resistance, which substantially reduces the noise (the major problem of the LeMond). The LeMond uses wind resistance because that yields the most realistic power-speed curve of the most common passive resistance methods, but with electronic control, magnetic resistance can produce whatever power-speed relationship it's programmed to produce.

They also had several apps to control the trainer, but the one which most caught my attention was one which allowed the rider to ride the Strava segment of their choosing. I thought this was fantastic: virtual reality with any climb on the huge Strava database, competing against real times produced by real riders. I spoke with the developer and was amazed he had produced this "in his spare time". His biggest complaint: that when you download segment data with the Strava API you end up with the profile data from the ride which defined the segment, even if that profile data was of relatively poor quality, for example from an iPhone app using topographical data lookup instead of a barometric altimeter in conjunction with GPS. There were work-arounds: he could have scanned the activities at the top of the leaderboard for rides tagged with Garmin Edge computers, preference to Garmin Edge 800's. But then there'd be the risk of a ride with a false positive match.

But these details aside, I really liked the idea of being able to ride Strava segments on a trainer, and this alone would have been compelling to me if I was in the market. Combined with the attraction of the direct attachment to the chain and I think this trainer was my favorite of the three, no matter how impressed I was with the virtual world in the TacX software.

To seal the deal, Wahoo's trainer is it has an API, so users could write their own apps for it on iPad. The possibilities are endless.

Here's a fantastic review by DCRainmaker.

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