This article is part of the Power Up series. And if you're a regular visitor here, then this probably is the segment you've been waiting for: it's about the gear. The powermeter I've chosen for this series is the Quarq. And the computer I've been happiest using is, surprisingly, my iPhone. So let's jump right in. I'm going to give you a brief overview of the gear landscape in this area, explain why I picked the devices I did, and then get down to the nitty gritty about how they work.
The decision to use the iPhone was simple - I already had one, and had the Wahoo ANT+ adapter to pair it with a power meter. I figured it would be a stop gap solution until I got a "real" head unit. But I ended up really loving it as is. I'll get to that later. The bigger decision to make was which power meter to get.
The first decision I made was to go for a crank-based unit. Why? Because getting a power meter is expensive business (and no, I didn't get this one for free). I wanted something that was going to last, and would be able to come with me from bike to bike. I figured this was going to be a relatively long-term investment. The crank-based power meter is a product category that has matured a lot over the years thanks to SRM, Quarq, and others. In general, cranks are some of the most equipment you'll find on a bike, and I expect to get many years out of mine.
So the next step was which crank to get, and I settled on Quarq. As part of the growing SRAM family, Quarq has an incredibly bright future ahead of it. They've shown a real commitment to making their devices user-friendly, and that's huge. The battery can be changed by the user, and so can the slope calibration (more on that later). They're also about 30% less expensive than the SRM's, and while the German cranks have advantages for riders who need data at faster intervals, or who ride at extremely low cadences, the Quarq was more than sufficient for my purposes as a triathlete.
The next step was to pick which kind of crank I wanted. You see, Quarq doesn't actually produce crank arms themselves. Instead, they make a device that replaces the chainring spider on certain cranks whose spiders are removable. Originally, they supported a wide variety of cranks, but now that they've been acquired by SRAM, you can probably expect that compatibility to wane a little bit.
But for my purposes, I had to go with a non-SRAM crank. You see, I ride 165mm cranks, down from 172.5mm I used to use. The change has been great, because that 7.5mm difference actually results in 15mm of additional hip clearance at the top of the pedal stroke, making me more comfortable in aero. But as of this writing, the only Quarq unit that comes in 165mm is the Rotor 3D. And while I have an irrational love for anything made of carbon fiber, the lack of short cranks on the SRAM side was a deal breaker.
But of course, SRAM is a smart company, and the official word I got from Quarq is that "SRAM is aware of the growing trend towards shorter cranks," and that's all they would tell me. My guess is that something is on the way. So shorty crank users, don't despair. I'm sure a snazzy carbon Quarq will be in your future.
One perk of the Rotor 3D (which would also have been true of a SRAM crank) is that because it's based on a 24mm spindle, it works pretty much everywhere. I can mount this puppy into just about any bottom bracket out there, either natively or through the use of adapters. I'm in the middle of reviewing the new Specialized Shiv, and it's no problem to swap the crank back and forth, even though the Shiv is BB30 and my Speed Concept is BB90. I don't foresee that changing too dramatically, even with the new BB standards coming out. After all, the Rotor uses the same spindle envelope as Shimano's Dura Ace 7900, and manufacturers do make a point to make their bikes compatible with that crank.
So that's the long version of why I picked the Quarq. Hit the jump to read about exactly how this thing works.