For many mountain bikers, the mere mention of ‘power meters’ is enough to make our eyes glaze over. As Rachel Sokal discovered though, there’s a bit more to these 2INPower cranks from Rotor.
It might be a bit odd to start a review of the only two-sided MTB power meter by talking about a chainring but that’s exactly where Rotor started out with its development.
Rotor was the first company to bring oval chainrings to the market (successfully that is, anyone recall Shimano’s ill-fated Biopace system?) and their power meter followed as a way to accurately measure the ring’s effect.
The concept of an oval chainring is that it effectively reduces in size at the weakest point of the pedal stroke, and increases at the strongest. This means that your legs have most to do when they’re most effective and least to do when they’re in their weakest position. The theory is that this will reduce fatigue and increase power output compared to riding a round ring.
The majority of oval chainrings have a fixed orientation due to their crank mounting. But of course different riders don’t have the same pedalling dynamics so only if you’re dead-on average will your strongest and weakest points reflect the shape of the ring.
To address this, Rotor’s chainrings are designed that their orientation can be adjusted – either by a direct mount fixing or multiple positions to mount to a spider – to match your pedal stroke. Whilst you can do much of this by feel (an optimally positioned oval ring shouldn’t feel oval) Rotor’s power meters were developed to calculate the best position with a lot more accuracy.
The Rotor MTB 2INPower DM is the only two-sided mountain bike specific power meter currently available.
There are a couple of advantages of a two-sided meter over a single-side one. Firstly, by measuring the power from each leg separately, a two-sided meter is more accurate than a single-sided one, which takes one reading and simply doubles it. Secondly, measures from each side will highlight any imbalances between legs and how these change in different circumstances.
The 2INPower’s right-side meter is housed in the crank arm, while the left power meter sits inside the axle for protection against the elements. Unlike Rotor’s one-sided INPower cranks the 2INPower is only available with a 30mm axle and with Boost spacing.
Cranks are available in three different lengths: 165mm, 170mm and 175mm. They’re pretty stealthy looking in matt black and come with coloured rubber boots to protect the ends.
Our 165mm test set came with a 32t oval direct mount chainring (the DM in the name – both round and oval rings are available) and weighed in at 684g (and an additional 17g for the rubber boots). This puts them in line with Rotor’s claimed weight of 695g for a 170mm set.
Fitting the two piece crankset is straightforward once you’ve sussed out what bottom bracket and spacers you need. For the ten months I’ve been using these cranks, I’ve had them fitted to two bikes – one with a PF92 shell, and one with a regular threaded shell. Rotor offers a range of BBs to fit most mountain bikes on the market, but they don’t supply one with the crankset. I used a Hope BB in both cases, and no issues.
Still, it’s worth taking a bit of care with installation as there is a specific sequence and torques for the pinch and centre bolts, and I can tell you that getting this wrong leads to much cursing and swearing whilst trying to tease them back out.
The 2INPower is powered by an internal rechargeable battery rather than a disposable coin one as with many other power meter cranks. The charge port sits under a thin plastic cover on the drive side axle and has a magnetic cable attachment which makes for easy charging.
One potential issue is the thin cover seal, which on a couple of occasions popped off its fixing screw when I moved it to attach the cable. This was solved with a bit of electrical tape, but isn’t really something you should have to do with a £1k crankset.
On the note of sealing, Rotor states the 2INPower cranks are rated to an IPX-7 level, which means you could dump the whole crankset under a metre of water for up to 30 minutes, and the electronic gubbins will apparently survive. I had no issues throughout testing in typically wet and muddy UK conditions, but for anyone looking to ride underwater for longer than half an hour though, these might not be the cranks for you.
The 2INPower uses ANT+ or Bluetooth to connect with your bike computer, home computer and phone. Calibration is just a matter of pressing a few buttons on your device(s) and a quick spin of the pedals.
Slightly different data is collected and analysed by different devices. A bike computer (in my case a Garmin 1000) will record the usual power metrics including left / right balance without any additional software.
Rotor’s phone app (Android and iOS) covers the standard power data metrics, but also analyses your pedalling dynamics in much greater detail. This includes torque graphs and calculation of the optimum angle and position of your oval chainring – this data is only available through Rotor’s software.
Finally there’s a desktop program that will display and analyse the standard power data, live torque data and chainring position data. You can connect the cranks to your computer using Bluetooth or an ANT+ dongle.
On The Trail
‘The On The Trail‘ section of this review is for members only. If you have an account, please log in. If not, you can get access by registering here for free.
Members get access to exclusive content like this but they also get..
- Fewer ads
- Post comments to stories
- Join in forum discussions
- Sell unwanted kit for free in our Classifieds
- Automatic shop discount on Singletrack merchandise
- Access more members only content
Premier members get more
- Magazine content in print 6x/year post free
- App access to every new issue of Singletrack
- Ad free website
- Big discounts on shop merchandise
- Access downloads like GPX files, PDFs and even iBooks
- Full mag archive access to all Singletrack back issues
Premier membership starts at just 1.99
|Product:||2INPower MTB Cranks|
|Price:||£999 for power meter, £59 for chainring|
|Tested:||by Rachel Sokal for 10 months|