Though patents suggested Shimano may have been working on a pedal-based power meter system, it appears the new Shimano Dura-Ace Di2 R9200 groupset will stick with a crank-based power meter.
This left Garmin, with its Rally power meter pedal system, as the lone Shimano SPD-SL compatible power meter pedal option, until now.
Favero Assioma Duo-Shi
The Assioma Duo-Shi consists of two pedal spindles with power meter internals, and the pods of the standard Favero Assioma Duo power meter pedals, which can be installed onto the following Shimano SPD-SL pedal bodies:
Notably, the Favero Assioma Duo-Shi does not include a set of Shimano SPD-SL compatible pedal bodies pre-installed.
This means anyone purchasing a set will need to supply their own pedal bodies – either a new set or a set they already own.
Favero said it made the decision not to include pedal bodies because it “aims at offering the best value for money to those cyclists who already ride with Shimano [pedals]”.
With this in mind, the RRP for the Assioma Duo-Shi spindles is, at €495, slightly cheaper than the standard Look Keo-compatible Assioma Duo power meter pedals, which cost €569.67.
Consumers will therefore have the task of disassembling the Shimano pedals and attaching the Assioma Duo-Shi spindles to the pedal bodies.
When using Shimano PD-R8000 pedals, the process is very simple, though, requiring only a 17mm and a 19mm spanner, and a compatible torque wrench.
Faverio Assimo Duo-Shi specifications
We’ve had a set in to test, and can confirm that the Assioma Duo-Shi spindles weigh 99g per spindle (spot-on the claimed weight).
This makes for a total assembled weight of 157g per pedal, when used with Shimano PD-R8000 pedal bodies, with a pair weighing just 9g heavier than the standard Assioma Duo pedals.
Otherwise, the spec is almost identical:
- True dual-sided power measurement
- Claimed accuracy of +/- 1 per cent
- Accelerometer-based cadence measurement
- Automatic temperature compensation
- Internal rechargeable battery promising at least 50 hours of use
- Bluetooth and ANT+ data broadcasting
- IP67 waterproof rating
- Easy installation
- Two-year warranty
- RRP €495
The only notable change from the standard Assioma Duo is that the Q-factor (the distance between the centre of the pedal body and the crank arm) on the Assioma Duo-Shi is 65mm.
This is 11mm wider than the 54mm Q-factor of the standard Assioma Duo pedal, and 13mm wider than a Shimano PD-R8000 pedal.
Favero says this increase is due to the increased width of the SPD-SL pedal bodies themselves, combined with the pods on the Assioma spindles which take up room on the axle, compared to a standard Shimano pedal axle.
There is limited evidence to suggest that a narrower Q-factor can be beneficial to efficiency, but the precise ideal Q-factor may be unique to each individual rider, depending on their proportions.
Can I convert existing Favero Assioma pedals to use Shimano SPD-SL pedal bodies?
Unlike with the Garmin Rally power meter pedals (Garmin took a different design approach and built its own SPD-SL compatible pedal body around its existing Vector 3 spindle design), existing Assioma Duo pedal systems cannot be converted for use with Shimano SPD-SL pedal bodies.
Although the power meter internals are the same, the Assimo Duo-Shi uses a different spindle construction in order to be compatible with existing Shimano SPD-SL pedal bodies.
As a result, existing Assioma spindles are not compatible with Shimano SPD-SL pedal bodies.