PowerTap P1S Single Side Powermeter Set

PowerTap P1S pedals are the single-sided version of the popular PowerTap P1 power meter pedals. They're easy to set up and to swap between bikes and if you're not bothered about measuring power from both legs, they're well worth a look.

The big advantage of measuring power at the pedals is supposed to be that pedals are easy to swap between bikes. However, only the PowerTap P1 pedals have really delivered on that promise. Garmin's Vector 2 pedals and Look's similar Keo Power pedals require you to faff with their external electronics pods, while the intriguing Favero Assioma pedals only started shipping at the beginning of August, so it's too early to tell how well they work.

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The PowerTap P1S pedals are a single-sided version of the PowerTap P1 pedals that Dave Arthur reviewed a couple of years ago.

That means that only the left pedal contains the necessary strain gauges and electronic gubbins to measure your power, and it simply doubles the reading to work out your power.

Superficially that sounds like a bad idea, but other single-sided power meters such as Stages and 4iiii produce good, useful data, at considerably less than the cost of a double-sided system.

And this is what we find with the PowerTap P1S. You can pick up a set for £440 against about £800 for the double-sided version. That makes the PowerTap P1S pedals a very cost-effective way of getting started with training with power. There are slightly cheaper systems, but none of them offer the PowerTap P1S's full range of features:

• Easy switching between bikes
• Compatibility with any bike, regardless of transmission manufacturer
• Compatibility with a wide range of head units
• Both Bluetooth and ANT+ communication protocols

The important question here, then, is does it matter that you only get power readings from one leg?

The short answer is: no.

I fitted the PowerTap P1S pedals to a bike mounted in a CycleOps Hammer direct drive trainer. Power readings from the P1S closely tracked the readings from the Hammer, though they were consistently slightly higher.

That's to be expected. The closer to your legs that you measure power, the higher the reading, because power is lost in flexing the cranks and in friction in the chain. None of these losses are large (unless your chain is very dirty) but power meters are sufficiently sensitive to detect the few watts we're talking about.

Using a double-sided power meter indicates I have a slight difference in power between left and right legs too, and my left leg is the stronger one. That's the leg the P1S is measuring, so that accounts for some of the difference in power readings between the pedal and the Hammer trainer.

Does that matter? Not really. As long as the P1S is consistently accurate from one ride to the next, then it's not a big deal that it's over- or under-reading by a per cent or two. Us regular punters are going to use a power meter to make the most of our training time. We're going to measure our functional threshold power in one of those 20-minute torture sessions coaches are so fond of, then tailor our training accordingly.

You can do that just as well if your power measurement is out by a couple of per cent as if it's bang on, as long as it's consistently out. The P1S is. In several tests on the trainer and on the road, it's read slightly higher than a crank power meter or measurement at the turbo.

Now, if you're going up against Chris Froome, it's a different story. You need accurate power measurement because you have a target: Froome's 6.25 watts/kg power-to-weight ratio. If you think you're generating 6.3 watts/kg, but you're actually only putting out 6.1 watts/kg, you're in for a nasty surprise on l'Alpe d'Huez.

The increased accuracy of the very best double-sided power meters is therefore a must-have for elite riders. For the rest of us, not so much.

Aside from that, everything that David Arthur had to say about the double-sided P1 pedals applies to the P1S. They're well made, easy to set up and use, and very easy to switch between bikes.

I did have to update to the latest firmware after unboxing the PowerTap P1Ses, but that's very easy with the free CycleOps Virtual Training iPhone app, which you can also use to set the zero offset before a ride.

The only significant gripe is that PowerTap is very cagey about compatibility with Look Keo cleats. Lots of people (including our Davey) have found that you can use Keo cleats with PowerTap pedals. However, PowerTap strongly recommends that you use the supplied PowerTap cleats, and replace them with the same when they wear out.

PowerTap cleats are available with either six degrees of float (the red cleats) or none, in black. They can be found for about £18 a pair whereas a small amount of clicking around will find Look Keo cleats for under a tenner.

If you've got several pairs of shoes, you'll need to budget for some extra cleats.

> Buyer's Guide: Your power measuring options

The only thing that would make me hesitate about dropping £440 on a PowerTap P1S right now is the Garmin Vector 3. In the latest version of its power-measuring pedals, Garmin has incorporated the electronics into the pedal body; the pods of the Vector 1 and 2 are no more. The Vector 3 also supports Bluetooth, softening Garmin's previous singular devotion to its ANT+ protocol.

The Vector 3 has caught up with the PowerTap P1's advantages, then. The decision will then come down to price (a Vector 3S is £500, and is lighter and arguably tidier than the P1S), and whether you're prepared to go through the waiting-for-a-firmware-update rigmarole that goes with any new cycling electronics.

The PowerTap P1S pedals work extremely well with the latest firmware. If you want a sensibly priced power meter that can be easily swapped between bikes, and you want it right now, the PowerTap P1S pedals deserve your very serious consideration.

Verdict

Very well-priced power meter that's easy to swap between bikes