Bicycling Australia
Every generation of cyclists benefits from a better way to train for racing. Research into physiological response to diet and exercise, and enhanced technological hardware allow for continuous improvement. Michael Hanslip takes a look at some of the gadgets and gizmos that measure your power output and how they can help you to step up your game.
Introduced in the ’80s, the compact portable heart rate monitor was state of the art for the time. Like most new technology, the price kept it out of the hands of most club-level cyclists and restricted it to Olympians and professionals. By the ’90s the heart rate monitor decreased in price enough that virtually anyone could afford one. Heart rate based training is much more effective than trying to ride at a perceived effort level.
Power meters hit the market in the ’90s. Again, they were expensive. For the most part they were somewhat cantankerous too. Into the first decade of the new century the selection widened and the price got more affordable. Almost every pro and many serious amateurs took the plunge into power measuring. Still the price was high enough to discourage most from adding power to their repertoire.
In the last few years two important things have occurred to bring ‘power to the people’. The first one is that most cyclists now have a GPS-enabled, ANT+ compatible computer sitting on their handlebars. This was important because it mean that adding a power meter to the bike didn’t require changing the display unit (which is a significant portion of the cost). The second is that there is even more competition in the power metering industry; many options are now within the financial reach of most riders.
In a series of articles I will cover both sides of the power training equation – the equipment and how to use it. This first instalment reviews the Quarq Riken cranks, iBike Newton+ computer and Garmin Vector pedals. Each measures power in a unique way, offering certain advantages and disadvantages compared to the others. In the second instalment I will describe why training with power is better than any other method. The third segment reviews yet more power meter options while the fourth segment provides some sample power-based training routines.
iBike Newton + Power Meter
“Any sufficiently advanced technology is indistinguishable from magic” Arthur C Clarke
For every action, there is an equal and opposite reaction (Newton’s third law of motion)
I understand how the iBike Newton functions, but in the middle of a ride it really is like magic. All other power meters require replacing one part of your bike with the metered part (hub, cranks, pedals). The Newton just sits up there on the bars doing its thing. I am amazed!
So how does it work?
The iBike is a display unit that links up to heart-rate straps, speed and cadence sensors and even other power meters (more on this later) through the ANT+ protocol. Internally it contains the electronics to measure barometric pressure, temperature, air speed and accelerations in three axes. It uses these inputs to calculate the forces opposing forward motion of the bike (rolling resistance is the small one, aerodynamic drag is the big one and we must not forget gravity). Couple the internal measurements with input from cadence and speed and the Newton’s brain can calculate lots of parameters of a ride: is the rider sitting or standing (from the extra motions of standing), is the rider drafting another rider (from the reduction in wind resistance), how steep is the hill (from the combined inputs of the accelerometers and the speed sensor), when the brakes are applied and even what gear is being used. For these measures alone the Newton is awesome for remote coaching (revealing too much braking, not enough drafting, core strength insufficient – it is almost like the coach was sitting there on the bike with you).
The biggy however, and the main reason for the Newton, is that it records how much power the rider is producing. The iBike measures the forces opposing motion in the bike so using Newton’s third law; it can calculate how many Watts it takes to make the bike move at a given speed.
The unit itself is a large thing to sit on the bars, but it is very light for its size. The display and user interface are certainly not my favourite. With only five buttons, each one does multiple things depending on how long it is held and where in the menu sequence the Newton is. It is certainly not terrible, but I would hardly commend it for an elegant interface or manual-free operation.
What are the advantages?
Obviously, if the power meter does not replace any parts on the bike, then everything you currently own will be fine after you add the Newton. Crank-based meters require changing the cranks – not a trivial job. And since cranks come in various lengths, it is impossible to share one pair of cranks across a club or team. Hub-based meters demand using only that wheel when you want to measure power. Those fancy race wheels might be just the ticket for this weekend’s club championships, but they won’t coexist with the hub power meter. If you have two mounting brackets, the meter moves from one bike to the next in seconds (and to a completely new bike in around 15 minutes including recalibration). So the Newton is great for the multi-bike owner, the club or team that wants to share the device around and for people with nice cranks and/or wheels they do not want to replace just to measure power.
What are the disadvantages?
The power measurement is inferred. There are times when it may not be as accurate as directly measured power would be. I noticed near-zero wattage readouts, for example, during an extremely windy ride when I know I was pushing hard on the pedals. This only occurred with specific wind angles. Yet the manufacturer is so confident in their measurements that they actually provide a power data comparison window in the software. Based on my experience with several other power meters, the iBike’s power figures are entirely believable most of the time. As with all power meters, improper calibration leads to nonsensical figures.
PowerStroke
Newton also has an upgrade option termed PowerStroke. This extra-cost firmware mode increases the recording rate, permitting the software that comes with the Newton to analyse the rider’s pedal stroke. With the cadence sensor fixed to the left chainstay, the relative position of the feet are known. The large mass of the rider on the small mass of the bike means that the bike moves during pedalling the same way a lightweight shell moves in a rowing race. During a ride, the Newton measures wasted power (movements that did not contribute to going forwards) and deficiencies in the pedal stroke (just because your feet are forced to go in a circle by the cranks does not mean they are actually being pushed in perfect circles).
Two days after a big race, when I was tired, I got a shocking PowerStroke report back. My wasted power was high and the diagram of my pedal stroke looked just like the often-stated ‘pedalling in squares’. I quickly checked out how I had gone the week before on the same ride to find that my wasted power was less than half as much and my pedalling was much more circular. You cannot escape the harsh realities of analysis with power meters in general and PowerStroke adds another realm where you can suck (or excel) to the list.
Mobile wind tunnel
For me, the coolest feature (another firmware upgrade for a fee) of the Newton is the ability to pair it with any other ANT+ power meter producing a portable wind tunnel. Most of the time, according to iBike’s own information and all of the comparison tests I have seen, the power reading of the Newton and the other good power meters on the market are nearly identical. If a cyclist purchases a time trial bike and wants to set it up to get the best competitive results, this set-up is even slicker than hours in the wind tunnel (and way cheaper).
Calibrate the Newton for a baseline position and then try new positions by hitting the road. The second power meter continues to produce directly measured power readings while the Newton continues to produce inferred power readings. The difference between them is due to changes in the aero drag. With heart rate as a reference it is even possible to detect changes in rider efficiency across changes in position. Yes, it takes a lot of patience and time to make this work, but then so does a visit to the wind tunnel or a blind trial-and-error approach. Arguably the Newton’s results should be the most reliable as they are measured out on the open road actually riding.
Summary
The Newton is an intriguing device. It does not directly measure power production but it accurately calculates the opposing forces and thus determines power production by seemingly magical means. Once set up to do so, it can swap across as many as four bikes in only seconds, while adding in another bike is only slightly more involved. It offers several options that no other power meter can. It is light, relatively unobtrusive on the bars, fairly easy to use and comparatively inexpensive. I am really impressed.
Distributed by: Velo Comp
RRP: $562.60
Garmin Vector Power Meter
Vector (noun): a quantity possessing both magnitude and direction.
There are quite a few power meters on the market now, most of which have their measurement hardware located in the crank spider. After years in development, Garmin has recently delivered a power meter with the hardware located in the pedal axles. Short of locating the hardware inside the shoe, this is as close to the power source as possible. It makes the measurements a very true reflection of power production (the further away the meter, the more opportunities there are to modify the measurement).
Instrumented pedals
In reality, the Vector is two power meters – one for the left foot and one for the right foot. Two meters means the Vector can analyse input from the left side separately to input from the right side. Currently this is limited to leg balance analysis (are the rider’s two legs producing the same amount of power at any given time?). The potential, however, is for Garmin to develop the software side of things much further. One example would be to use the Vector pedals during bike fitting sessions. Instead of trying to observe when a too-high saddle causes loss of control at the bottom of the pedal stroke, or asking the rider to self-monitor, the Vector could report back definitively. Vector pedals actually measure the force vector (amount of push and the direction of it) and, I imagine, will lead to observations that aid in developing a good pedal stroke.
Vector pedals are based on the Look Keo compatible pedals produced by Exustar. Pedals in general are extremely easy to swap between bikes, and the Vector version is only slightly more complicated by the fact that the pods (which hold the battery and the transmitter) have to be slipped over the axle first and spaced away from the crank arm by an appropriate amount of (included) washers. This means that one power meter could be shared amongst several personal bikes or between teammates with relative ease.
Calibration
After every installation the head unit (a Garmin Edge – the 810 in the case of this test) has to calculate the pods’ angle relative to the crank in order to get accurate readings. Prior to every ride, the meter should be reset to zero for the same reason. While a small hassle, these calibration processes are normal for power meters. The process with the Vector is as easy as pushing a few buttons on the Edge and following the displayed instructions.
Once the Edge is paired with the Vector, the screen display can be filled with power related measurements: current power, average power for the ride or the lap, max power, left-right balance and so on. These options are much the same as every Garmin offers for speed, heart rate and cadence. Anyone who has never ridden with a power meter before would probably be surprised with the fluctuations – the number never sits still. This is due to the ‘lumpy’ power production from two legs. The only reasonable method of riding to a set power in an interval training session is to have both current and lap-average power displayed. This way it is possible to target the desired average and try to keep it there. It is worth noting that it is extremely easy to get mesmerised by the displayed power numbers and to lose focus on where you are riding your bike. Please be careful!
Distributed by: Garmin Australia
RRP: $1,699
Quarq Riken
Quarq started back in 2006 building power meters. In 2011 SRAM purchased Quarq and subsequently most of their product is now based on SRAM cranks (they still provide an option for Specialized and Cannondale brand cranks). The Riken unit on test consists of SRAM S900 carbon cranks with the standard alloy spider replaced by one which measures power.
Installation
As I had SRAM cranks on my bike, installation was very straightforward: remove pedals, remove cranks, install power cranks then install pedals. But wait, the Quarq requires a magnet as a reference point. Three options are included: a ring that installs under the bottom bracket cup with a magnet attached, a bracket that fits under the bottom bracket cable guide with a magnet on the end or some epoxy putty and a magnet that can be permanently affixed to the frame. My race bike has a press-fit bottom bracket and no external cable guide, so my only option was gluing a magnet to the frame – except this was a short-term test so I didn’t really want to do that. Instead I put the Quarq on my commuting bike with an external BB using the ring magnet.
In pairing the Quarq with my Garmin, it asked me if I wanted to calibrate the cranks. All power meters should be calibrated prior to every ride, so this automatic request is very handy. Exactly how this is done is meter dependent. As the Garmin asked me if I would like to calibrate every time I turned it on, it was really easy to remember to do so. Other power meter-display unit combos may require you to dive into the menu and manually find the calibrate option.
Q is for Quarq
Quarq meters have undergone a lot of evolution and refinement over the seven years they have been in business. All of them have a distinctive button with a Q on it – this is the battery compartment. The prominence of this shows the bunch you are power-equipped and also makes changing the battery (available at any supermarket or corner store) a trivial matter.
The Riken has a single red LED on the spider. This manages to communicate what you need to know – it blinks once when you wake it from sleep (like most ANT+ products it goes to sleep after a few minutes of inactivity and wakes up when movement is detected) and it blinks a sequence after a self test relating the outcome. Finally, the ANT+ ID number is prominently displayed on the spider – some receivers permit you to pair via the ID number and most display the ID number as confirmation of successful pairing. If you see the wrong number you’ve just paired with someone else’s device.
Installed and calibrated, the Quarq is invisible. Just ride your bike while cadence and power measurements are transmitted to your display unit where you can watch or record for later upload. Aside from the expense – nearly $2,000 dollars is still a lot of money unless you are planning on seriously training with power – the Quarq experience is very easy. The cranks look and feel like ordinary ones; they take standard chainrings and no particular maintenance or procedure is necessary. Just replace the inexpensive battery every 300 hours of riding (about six months of use for a keen rider).
Distributed by: Monza Imports
Echelon Sports
RRP: $1,849.95 – GXP
RRP: $1,899.95 – BB30
Summing up
All three of these meters worked very well in the months I had them on my bikes. The Quarq is the only one of these three that is effectively invisible when installed – the Vector pedals have the pods hanging down (looking vulnerable but it would take a freak crash to see them impact anything) while the iBike dominates the top of the handlebars (where it too might be vulnerable in a crash). Yet Quarq does not make a meter in my chosen crank length, so for me it is not an option. I would have to swap pedal systems to go with the Vector option (expensive when I have so many pedals). In other words, you are probably going to have to make a number of sacrifices in order to move into the world of measuring power. From the up-front expense to the regular calibration and even the extra time required to make use of the data, there are changes to be made. If you are at all serious about your riding then these are sacrifices worth making.
