Buy the PowerTap P1S pedal power meter now from Wiggle
If, like me, you have long harboured a desire to add power measurement to your pedalling, then the PowerTap P1S pedal power meter may be a foot (or perhaps a cleat) in the door.
As easy to install as screwing in a new set of pedals, the P1S measures power from the left hand pedal only, then doubles it to produce a reading.
Related questions you can explore with Ask Cyclist, our new AI search engine.

At £500 they are cheaper than their dual sided counterparts – but at what cost to performance?
In reality, very little.
Of course it is not as accurate as a dual sided system and does nothing for monitoring power imbalance, but for riders who are looking to power to enhance fitness rather than compete at elite level, the PowerTap P1S pedal power meter will arguably give you pretty much everything you need.
Namely, a consistent measure of your power application from session to session to guide and evaluate your training.
One-sided systems are nothing new. Both the Stages and 4iii crank based systems offer the same functionality at a similar price point, but without the level of convenience and transferability you get with a pedal mounted meter.
In that respect the Garmin Vector 2 is perhaps the Powertap’s most direct rival. The Garmins are a little pricier, however, and still require an external ‘power pod’ installed alongside the pedal – not quite as neat or simple as the Powertap’s all in one package.
(Garmin’s new Vector 3S now removes the pod, but we’re yet to get our hands on a review sample.)
Installation
Installing the pedals was a case of screwing them into the cranks.

Unlike some other pedal based power meters, there is no external gubbins to fiddle with. Good news for those new to power meters (or even cycling altogether), and even better news if you are lucky enough to own several bikes that you may want to transfer your power meter between.
Offering both Bluetooth and Ant+ connectivity, pairing them with a Garmin head unit was intuitive and instant, as was pairing them with my iPhone which was used to update the firmware via the free PowerTap app.
The whole process from unboxing to installing, pairing and updating took minutes.

At 437 grams per pair (with battery), they aren’t light - although I found the added weight does mean they always hang the right way for easy clipping-in.
The pedals come supplied with their own PowerTap cleats, but work perfectly well with Look Keo cleats should you need to replace them.
The power meter itself is powered by a single AAA battery, which is easy to access and replace with a 4mm allen key.
An important advantage of the AAA over the more common coin-cell batteries seen in power meters is availability and cost – there aren’t many places on earth where an AAA battery won’t be commonly on sale.

The P1S battery cap
Accuracy
For a closer look at the accuracy of the P1S, I mounted them on to the Concept2 BikeErg to see how things compared.
The pedals gave consistently slightly higher readings than the BikeErg, but this could be largely explained by the fact that they were taking power from only my dominant left foot, which I tend to put more power through, while the BikeErg measures power at the flywheel.
This is the price you pay for a more affordable single-sided unit, but again the raw numbers, if a few watts out, are not as important for a rider at my level as consistency, which appears to be good.
A quick look at the graph afterwards in Garmin Connect shows no errant readings or anomalies and readings appear to track in line with the Bike Erg.
Overall
Longer term testing will be required to evaluate durability and build quality, but installation, interface and usability are all strong starting points for the PowerTap P1S pedal power meter.
Certainly for those beginning in power measurement, the PowerTap P1s represents a relatively affordable, useable package that will take the rider to a considerable level in terms of data and training metrics.