Rotor has announced an updated version of its INspider power meter designed for Shimano’s range of direct-mount mountain bike cranks.
With a 100mm bolt circle diameter (BCD), the Rotor INspider MTB Shimano Compatible enables riders to use the smaller, 30 to 36T chainrings typically found on the latest mountain bike groupsets.
It uses a four-bolt chainring pattern and is only compatible with 1x drivetrains.
According to Rotor, the INspider MTB Shimano Compatible is also among the lightest power meter spiders currently available, weighing a claimed 99g (spider only).
That’s 50g less than the 110mm BCD INspider power meter, designed for use on road and gravel bikes.
Available now, the Rotor INspider MTB Shimano Compatible costs €449.
Now Shimano compatible
Having recently updated its 2INpower SL power meter crankset, Rotor is now updating its mountain-bike specific spider-based power meter.
This type of power meter sandwiches in between the crankset and chainrings, and measures the total power produced by both legs.
As Rotor notes, this has advantages and disadvantages (the perfect power meter doesn't exist, after all).
On the one hand, spider-based power meters are typically less at risk of impacts, for example.
On the other, though spider-based power meters measure the total power produced by both legs, they don’t measure each side independently.
This means they can only estimate left/right power balance, as opposed to measuring it.
The Rotor INspider MTB Shimano Compatible is, as the name suggests, compatible with Shimano’s range of direct-mount mountain bike cranksets.
This includes cranksets from XTR M9100, Deore XT M8100, SLX M7100 and, in theory, any other crankset that uses the same direct-mount interface.
This is a key standard for a power meter brand such as Rotor to target, because while Shimano has made power meter cranksets for road bikes since the introduction of Dura-Ace R9100 in 2017, it has yet to release a power meter designed for gravel or mountain bike use.
As a result, third-party power meter brands such as Rotor, Stages, SRM and Power2Max have looked to exploit this gap in the market.
Rotor INspider MTB Shimano Compatible pricing, details and specification
The Rotor INspider MTB Shimano Compatible is available now and costs €449 (international pricing was not available).
Rotor claims the INspider MTB power meter is accurate to within plus or minus 1.5 per cent, and uses accelerometers to measure cadence (meaning no frame magnets are required).
It can communicate with bike computers and other smart devices via ANT+ or Bluetooth.
Rotor says it has also recently updated its Rotor Power app (available for iOS and Android devices) to enable the firmware to be updated using a smartphone.
Previously, the INspider could only be updated using Rotor’s INpower application for Windows and Mac computers.
The Rotor INspider MTB power meter is compatible with 30, 32, 34 and 36T chainrings.
As you'd expect, it’s also compatible with Rotor’s ‘Q-rings’ – a range of non-round chainrings claimed to improve efficiency by varying the effective gear ratio during the pedal stroke.
It uses a rechargeable lithium-ion battery with a claimed life of 350 hours (riding time).
Rotor INspider MTB Shimano Compatible specification
- Price: €449 (spider only)
- Power meter type: Spider
- Crank compatibility: Shimano direct-mount
- Bolt circle diameter: 100mm x 4 bolt
- Claimed weight: 99g (spider only)
- Claimed accuracy: +/- 1.5 per cent
- Battery type: Rechargeable Li-ion
- Claimed battery life: 350 hours
- Waterproof rating: IP67
- Connectivity: ANT+ and Bluetooth
