The Rotor INpower 3D+ MAS power meter is a crank-based powermeter, with the electronics and strain gauge housed in the left-hand crank arm and crank spindle.
I fitted the unit to my Kona Private Jake cyclocross bike, and have been battering and beating it with British weather for the last three months of racing and training. It is holding up well; so I thought it was about time to report back in a review.
First though, a bit of context to the power meter debate…
What kind of power meter is best?
The hunt for the best power meter is like looking for an elusive golden ticket. What was a rare product a few years ago, has now become a marketplace of many different brands and models.
Are pedal power meters better than crank based systems? Are hubs as reliable? What will be most accurate? What will be most durable?
For me, the crank based system currently tops the ranks. Here's 3 reasons why…
- Less vulnerable to damage - Pedals and rear hubs are vulnerable to crashes, spray and constant bike washing. Water and impacts don't mix well with electrics; so hiding the electronics of your power meter inside the axle/spindle of the crankset, places it nicely out of the way.
- Still fairly transferable - People claim that pedals and hubs are better because they are more transferrable between bikes. However removing and installing a crankset is usually only a case of one or two hex key bolts, and if you're running similar chainsets (speed, chainring size and bottom bracket spec) across your bikes, then it shouldn't take long to fit a different crankset.
- Lower rotating weight - We all know that rotating weight is the worst kind of weight to have on a bike - because you're constantly fighting against it. However, rotating weight in the crank spindle is least-worst kind. It has a significantly lower effect on inertia than if the weight is in the wheel or pedal; and it is also positioned lower down in the centre of the bike - helping to improve handling and stability.
Simplicity through design
The Rotor INpower 3D+ Power Meter is pure simplicity through design. There are no external boxes, vulnerable strain gauges, fiddly hex bolts, or low hanging dongles. All the electronics in the Rotor power meter are housed within the axle, making the unit more shockproof, waterproof and resistant to contamination, than most other models.
Even battery replacement is incredibly simple. You just remove the plug at the end, and insert a new AA battery. You'll get around 300 hours from a good quality battery.
Simple, but effective
The key with power meters is that they remain consistent in their readings. If they don't then it makes comparing metrics and results pretty useless.
The Rotor InPower 3D+ MAS Power Meter Crankarms has remained consistent throughout testing, without any abnormal readings.
The 4 strain gauges within the left hand crank arm (you can also get a double-crank arm meter too - the Rotor 2INpower Power Meter http://www.wiggle.com.au/rotor-2inpower-power-meter/) provide metrics on Power, Cadence, TORQUE 360, OCA, torque effectiveness and pedal smoothness. You don't get left-right balance with just the left hand crank-arm unit, but I'm not convinced by the benefits of this metric anyway.
These metrics are effectively and reliably transmitted to your head unit of choice via ANT+. Then you can analyse them to your heart's content on software like TrainingPeaks and Strava.
These power metrics are all that you should really need to build an incredibly effective training programme. The Rotor INpower power meter delivers them all, reliably and consistently.
One of the main concerns with crank based power meters, is whether they will fit in your frame.
The good news is that Rotor has a 'Universal Bottom Bracket' set up, which means that their 30mm spindles can actually be fitted into almost any bottom bracket shell on the market today, if you use the correct Rotor bottom bracket. That means that whether you frame is a BB92, an Italian Threaded BB, or any other kind; you should be able to fit the Rotor Power meter, with the correct bottom bracket.
The MAS part of the Rotor INpower 3D+ MAS Power Meter name refers to the brands 'Micro-Adjust-Spider'. This dish-like bolt plate allows you to micro-adjust a Rotor Q-Ring by as little as 2.5 degrees. If the word Q-ring confuses you, you can read more about it here: 'Testing the advantages of Rotor Oval Q-Ring Chainrings'. The good news is that the MAS set-up also allows you to mount standard chain rings to the crank arm, quickly and easily.
To summarise, the Rotor InPower 3D+ MAS Power Meter Crankarms is easily one of the best I have used to date. Its simple design houses all of the electronics safely within the crank axle, and provides a lightweight, effective and reliable power reading option.
The crankset itself feels stiff, strong and well made; and the quality of the electronics seems to follow suit. 100+ hours or cyclocross testing, and this is still running beautifully smoothly, and working effectively.