Rotor Kapic carbon Inspider Power Pack

Video: KAPIC Carbon INspider overview

What is included in the Power Pack?

KAPIC Carbon: low weight and stiffness for modern MTB

The Rotor KAPIC Carbon crank arms were developed for MTB disciplines where every gram matters without compromising stiffness: XC, marathon, XCO and race-oriented builds. They use Rotor's modular architecture with a separate 30 mm spindle. This design allows crank length, spindle and chainring to be selected independently, making future changes easier if the bike or your requirements evolve.

According to Rotor, the pair of crank arms weighs approximately 258 g in 165 mm, 260 g in 170 mm and 262 g in 175 mm. Velo-Perso has also checked a pair of KAPIC Carbon crank arms at around 255 g, confirming that these are exceptionally light crank arms for a product designed for real MTB use.

This low mass is particularly noticeable during repeated accelerations. In mountain biking, pedalling is rarely perfectly steady: exiting a corner, clearing an obstacle, accelerating after a technical section, attacking before a short climb or reacting to a sudden gradient change. A light and stiff crankset gives a more immediate and responsive feeling under power.

INspider MTB: power measurement without a major weight penalty

The INspider MTB is positioned at the centre of the crankset, between the crank arms and the chainring. This location allows it to measure the total power generated by both legs at the spider. Unlike a true dual-sided system with an independent sensor on each side, the INspider measures combined total power and provides an estimated left/right balance.

The power meter is CNC-machined from 7075-T6 aluminium, with a weight of approximately 99 to 100 g without the chainring. It communicates with compatible bike computers and devices via ANT+ and Bluetooth Smart. Cadence is measured by accelerometer, so no magnet needs to be installed on the frame.

A complete crankset weighing around 540 g

One of the key advantages of this setup is that the total weight remains very low despite the addition of a power meter. In Rotor's reference configuration with 170 mm crank arms and a 34-tooth round chainring, the claimed weights are:

* Rotor data with 170 mm crank arms and 34T round chainring. Weight varies slightly depending on crank length, chainring size and selected configuration.

165, 170 or 175 mm: which crank length should you choose?

Rotor offers the KAPIC Carbon in 165, 170 and 175 mm. The right choice naturally depends on your body dimensions and riding habits, but modern MTB setups increasingly favour shorter crank arms.

• 165 mm: more ground clearance, lower risk of pedal strikes and easier cadence. A very interesting choice on modern bikes with low bottom brackets, technical trails and for riders who want a freer pedalling motion.
• 170 mm: an excellent compromise for most XC and marathon riders.
• 175 mm: retains more leverage and can suit taller riders or cyclists already perfectly accustomed to this length.

Round NOQ or oval Q RINGS chainring?

The Power Pack can be configured with either a round Rotor NOQ chainring or an oval Q RINGS chainring. Both use the 100x4 BCD interface of the INspider MTB.

The INspider also provides access to OCA (Optimum Chainring Angle) data, which can be useful for analysing how you produce torque and fine-tuning a Q RING setup when using compatible Rotor tools.

Shimano and SRAM Eagle compatibility

Rotor BCD 100x4 MTB chainrings use a tooth profile intended for modern 1x drivetrains and are announced as compatible with Shimano 1x12 and SRAM Eagle 1x12. This allows you to keep your existing drivetrain while upgrading to a carbon crankset with power measurement.

The available chainring sizes for this generation of INspider MTB are 30, 32, 34 and 36 teeth. The right choice depends on terrain, cassette range and rider level: 30 or 32T for maximum climbing capability, 34T for a very versatile setup, and 36T for fast courses or powerful riders.

Which bottom bracket should you use with KAPIC Carbon?

The KAPIC Carbon uses a 30 mm spindle. You therefore need a bottom bracket that matches both the spindle diameter and your frame standard. For a threaded BSA frame, a BSA30 bottom bracket is required. For a BB86/BB92 pressfit frame, a 41/30 bottom bracket specifically designed to accept a Rotor 30 mm spindle is needed.

Why is a power meter especially useful for MTB?

Power output is far less stable in mountain biking than on the road: gradient changes, repeated accelerations and technical sections create very short power spikes that heart rate cannot follow instantly. A power meter therefore allows you to quantify exactly what you are producing even when effort changes every second.

• On long climbs: control intensity and avoid going too hard too early.
• In XC: analyse repeated accelerations and efforts above threshold.
• In marathon racing: manage energy over several hours using data that is less affected than heart rate by heat, stress or cardiac drift.
• In training: track progression, structure sessions and compare performance objectively from one ride to another.

A central, protected sensor designed for off-road use

Positioning the sensor at the spider makes particular sense for MTB: the electronics remain grouped at the centre of the crankset, with no external module added to a pedal or crank arm. The INspider MTB has an IP67 rating, making it suitable for water splashes, mud and the conditions typically encountered off-road.

The integrated battery is rechargeable via USB and provides up to 350 hours of riding time. This avoids frequent replacement of coin-cell batteries. For regular use, simply keep the unit charged and pair it with your compatible ANT+ or Bluetooth bike computer.

KAPIC Carbon + INspider or adding the power meter to an existing crankset?

This Power Pack is the most coherent option if you want to start directly with a complete carbon setup. If you already own a compatible Rotor KAPIC crankset and only want to add power measurement, the INspider MTB 100x4 with chainring is also available separately.

Main specifications

FAQ – Rotor KAPIC Carbon INspider MTB

Does the power meter measure the left and right legs separately?

No. The INspider measures the total power produced by both legs at the spider. The displayed left/right balance is an estimate and should not be confused with a true dual-sided system using two independent sensors.

Can I use it with a Shimano 12-speed drivetrain?

Yes. The BCD 100x4 chainrings used with this generation are designed for Shimano 1x12 MTB drivetrains as well as SRAM Eagle 1x12.

Is the bottom bracket included?

No. The Power Pack includes the crank arms, spindle, INspider and chainring. The bottom bracket must be selected according to your frame standard and the Rotor 30 mm spindle.

Which spindle should I choose for a Boost frame?

The correct choice depends on the chainline required by your frame: Rotor notably offers a 52 mm chainline with the 135 mm spindle and a 55 mm chainline with the 141 mm spindle. Do not choose based on the word “Boost” alone: check the chainline recommended by the bicycle manufacturer.

Can I fit a 26T or 28T chainring to this INspider?

On the current BCD 100x4 INspider MTB, Rotor specifies chainrings from 30 to 36 teeth. Smaller chainrings available for some KAPIC Direct Mount setups should not be confused with the chainrings specific to the INspider.