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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.
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:
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.
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.
Very well-priced power meter that's easy to swap between bikes
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road.cc test report
Make and model: PowerTap P1S Power Meter Pedals
Size tested: One
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
An affordable way to measure power at the pedals.
Doubles left pedal measurement to calculate total power.
Easily swap between bikes for a vast range of compatibility.
BRINGING POWER TO THE PEDALS FOR THE PEOPLE
Built to be just as robust and just as precise as its world-renowned sibling, the PowerTap Single-Sided Pedal has all the innovation of the P1 pedals – at a fraction of the price. Named for its single-sided nature, the PowerTap Single-Sided Pedal doubles the watts produced by the left pedal to calculate total power. The PowerTap Single-Sided Pedal also touts the same plug-and-play installation, easy-to-swap, cross-bike compatibility, along with dual-band ANT+ and Bluetooth as its bi-lateral counterpart.
Ideal for the bike enthusiast, the weekend warrior or the power-training curious, there is no better way to get started with accurate pedal-based power than the PowerTap Single-Sided Pedal.
Tell us some more about the technical aspects of the product?
Weight: 390 grams per pair of pedals (without batteries)
Thread Type: 9/16"
Cleat Interface: 3 bolt
Cleat: Red, 6 degree floating
Spring Type: Adjustable Elastomer
Proven PowerTap accuracy
Release Tension: 6-20 Nm
Stack Height: 14mm
Center of Pedal: 53mm (measured from crank to pedal)
Lean Angle: 25.5 degrees (based on 175mm crank length, 75mm BB drop and 147mm Q-Factor crank)
Firmware Updates: Over the air
Connectivity: ANT+ and Bluetooth SMART
Battery: AAA Lithium (alkaline and/or rechargeable alkaline batteries not recommended for extended use)
Battery Life: 60 hours
No weight limit
PowerTap Single-Sided Pedals are not capable of providing advanced pedal metric data. In order to display advanced pedal metric data you must be using dual sided P1 pedals.
Fit and finish is very tidy.
Easy to pair with Garmin head units and with the PowerTap app on an iPhone. Consistent power readings with no odd spikes or drop-outs.
They're not the lightest pedals, thanks to having all the electronics contained in the body, plus an AAA battery, but the weight disadvantage is well worth it for the function.
This is currently one of the cheapest ways to get into training with power. Take into account the ease of swapping between bikes, reliability and PowerTap's track record in the sector and they're very very good value.
Tell us how the product performed overall when used for its designed purpose
Very well; provides consistent power readings with no unusual behaviour.
Tell us what you particularly liked about the product
Ease of use: fit the pedals, set the zero offset, and away you go.
Tell us what you particularly disliked about the product
Having to get used to single-sided pedals after years of using Speedplays.
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
Use this box to explain your score
I'm tempted to give the PowerTap P1S pedals an extra half a point over the dual-sided P1 pedals because they're only a little over half the price, but I'm going to agree with David Arthur and give them four stars because they're very good, but I suspect the Garmin Vector 3 and Favero Assioma pedals are going to put them under serious pressure for weight, features and price.
About the tester
I usually ride: Scapin Style My best bike is:
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: commuting, touring, club rides, general fitness riding, mountain biking
John has been writing about bikes and cycling for over 30 years since discovering that people were mug enough to pay him for it rather than expecting him to do an honest day's work.
He was heavily involved in the mountain bike boom of the late 1980s as a racer, team manager and race promoter, and that led to writing for Mountain Biking UK magazine shortly after its inception. He got the gig by phoning up the editor and telling him the magazine was rubbish and he could do better. Rather than telling him to get lost, MBUK editor Tym Manley called John’s bluff and the rest is history.
Since then he has worked on MTB Pro magazine and was editor of Maximum Mountain Bike and Australian Mountain Bike magazines, before switching to the web in 2000 to work for CyclingNews.com. Along with road.cc founder Tony Farrelly, John was on the launch team for BikeRadar.com and subsequently became editor in chief of Future Publishing’s group of cycling magazines and websites, including Cycling Plus, MBUK, What Mountain Bike and Procycling.
John has also written for Cyclist magazine, edited the BikeMagic website and was founding editor of TotalWomensCycling.com before handing over to someone far more representative of the site's main audience.
He joined road.cc in 2013. He lives in Cambridge where the lack of hills is more than made up for by the headwinds.