Wattbike set up shop in the village this week to get the word out on their indoor trainer. I swung by try out the ergometer that British and Australian Cycling rave about.

The Wattbike was developed in conjunction with, and eventually endorsed by, British Cycling. To earn that endorsement it had to, among other things, offer precise power output readings and pedal like a real bike. Having plotted the resistance graph of the LeMond Revolution, which mimics road riding almost perfectly, I was curious to see Wattbike’s approach.

Resistance

I’ve wondered about trainer resistance for a while now. A trainer with high inertia, low drivetrain resistance and progressive air resistance (LeMond) feels like motorpacing at 30 mph. It’s a pleasure to ride and a real easy way to log your winter endurance hours.

Trainers with low inertia and high drivetrain resistance (anything with a tire/roller interface) feel like riding through sand – they really make you work through the dead spots. Being an awful climber I’d always wondered if I should’ve spent more time on my Kurt Kinetic, but my knees could never take the abuse.

The Wattbike has both a wind and magnetic resistance unit built in, and both are variable. The user can mix and match to dial in the precise pedaling feel they’re after. Dial both units down and you can spin like you’re flying downhill. Add magnetic resistance and you’re still flying, but pushing hard on the flats. Dial up air resistance and the flywheel slows right down, and now you’re working through the dead spots, as if on a climb. It’s noticeably harder, but more realistic than the ‘pedaling through sand’ sensation of most trainers. You can lock in a wide range of cadence/power/inertia combinations. I was pleased to confirm that the Wattbike did indeed pedal like a real bike, and can simulate different terrain.

Here’s the wind resistance unit. With the resistance at 1, the ports are closed, and the air within the unit spins with the turbine and produces little resistance. To get the wattage up you’ll have to spin fast.

As you dial up the resistance, the ports open up to draw air into the turbine, and resistance ramps up. 

The turbine is more like an air pump or a riverboat paddle than a fan. Air is drawn in from the side and blasts out down here. The Wattbike is pretty silent with the ports closed, but when they’re open the Wattbike is loud like a wind trainer. (Side note: why can’t the exhaust point up at the rider? Opportunity lost!)

The magnetic resistance unit sits opposite the fan. Pretty self explanatory on this side.

Power

To get British Cycling’s endorsement the Wattbike had to nail power measurement. This is accomplished with a sprocket that bends the drive (lower) run of the chain. As power increases, chain tension goes up and the the chain wants to straighten out against the sprocket. That force measurement is translated to power, and is claimed to be accurate to 2% of the full range of the unit, but more importantly, to 1% where most of us train. Wattbike claims that power measurement does not need to be re-calibrated over the unit’s life. Another sensor detects crank position for cadence and other fun data. Which leads us to…

Software

The Wattbike comes with a head unit that displays all your numbers, as well as a pedaling technique plot (think Computrainer Spinscan). It can plug into a laptop for a more detailed view with their free software (PC only for now). Using the software, you can color code your zones in all of the Wattbike’s data so when you’re tongue’s dragging on the floor all you have to do is make all the number fields turn green.

Here’s the head unit, with the rudimentary pedaling technique display. The big screen displays the same plot in the background.

Live data can feed to a laptop. Here’s a look at one pedal stroke. Picture this as if you’re looking at the cranks from the left side of the bike, and the point on the plot represents where your left pedal is. On this particular pedal stroke the rider pushed harder with his left foot than the right, and didn’t pull through the dead spots very well. This plot resembles a peanut, but should look more like a sausage (Wattbike’s analogy, not mine).

Here’s an aggregate view of every pedal stroke I took while playing with the Wattbike, including time I spent trying to make bunny doodles by pedaling funny. The software can also simultaneously display up to 20 riders for group training or racing.

Here’s a software generated pdf of a representative interval from my session (aka non-bunny-doodle time). I was pleased to see that I work the dead spots pretty well (sausage not peanut), but my left/right imbalance is pretty big (45/55).

This pedal technique plot is pretty cool. A fitter could tweak your saddle height by zeroing in on the point where you’re too high to pull through the bottom, or too low for maximum power. British Cycling have already used the Wattbike in conjunction with wind tunnels to find the fastest balance between maximum power and minimum CdA. A bike fitter could definitely have a good time with this.

Bottom Line

The Wattbike comes in two models, the Trainer for mortals and the Pro for Olympic level athletes. Both retail for $2995 direct from Wattbike. Its size and price make it prohibitive for most individuals (though if I were made of money I’d have one), but look for it to infiltrate shops, coach’s studios, and spin classes. I for one look forward to a utopic future where there’s strict accountability in spin classes and my dominance over ‘citizens’ is graphically verified on a projection screen.