The easily transferrable power meter has come of age with the system now internal in a vastly improved platform
When power meter pedals arrived on the scene they seemed like the ultimate solution.
The pros: easily transferrable between bikes, unlike cranks; suitable for all rides, events and all weathers, unlike wheels. But there were complications – in Garmin’s case the expensive strain gauge lying precariously outside the body of the pedal and at risk of injury or accident.
The arrival of the Garmin Vector 3 (and single sided Vector 3S) pedals – which will be available early this year – heralds a brave new world in which these complications appear to have been eliminated.
The power meter is housed inside the pedal – a pair of which weighs 324g (claimed weight is 316g). The pedals themselves, initially made by external brand Exustar, have become an in-house project, produced by Garmin. They weigh less, use needle bearings instead of bronze and can support a rider weight up to 105kg, which is an increase.
They’re now both Ant+ and Bluetooth compatible, which makes them friendly to more software options without the use of a dongle (though we’re still awaiting a software update that will allow for Bluetooth Smart transmission, which will make connecting to Zwift et al possible).
The pedals can be purchased as a pair – ‘Garmin Vector 3’ – or as a single pedal in ‘Garmin Vector 3S’ form. The latter measures power from the left pedal and uses an algorithm to establish output.
Garmin Vector 3 Set up
That wasn’t the case at all with the Vectors. The pedals were easy to fit, easy to connect and calibrate.
The pedals are Look style, and the box comes with a pair of cleats. As an existing Look user I stuck with my own.
There’s no special trick to fitting the pedals: remove your old ones, apply a little grease, add a supplied spacer if there’s risk of rubbing (in my case there was not) and they’re fitted. The battery indicator is in the space where you might use an Allen key to tighten the pedals, but you can use a pedal wrench.
Since the power meter is now inside the pedal, there’s no worry about getting the torque exactly right in order to get accurate readings, as was the case with previous models.
To connect to a GPS computer – I was using a Garmin Edge 1030 – you simply go into your settings > sensors, and search for sensors.
The power meter should come up – it did so for me in less than a minute – at which point you can rename it so you don’t get confused (I did not, which led to some minor irritations when comparing power meters which is why I mention it). You then set crank length and calibrate.
Calibration needs to be performed ahead of every ride. Thankfully, it was very easy: I just had to select the sensor, hit ‘calibrate’, unclip from the pedals and wait a few seconds.
Updates can be administered via your Garmin Edge unit, and you can also adjust settings using the Garmin Connect mobile app – including scaling if you’re using the Garmin 3S (single pedal) version and know you have a power discrepancy between left and right leg.
Battery life is a claimed 120 hours and they take four LR44 or SR44 coin batteries. These are a bit rarer than the normal CR2032 commonly used but easy enough to get hold of.
Changing the batteries is as simple as using an Allen key to open them up, and slotting new batteries in. This was a revelation when compared with locating the specific plastic tool used for my Powertap hub, prising the (now chewed up) plastic hub top off with a flat head screwdriver (amid much swearing), before swapping the coin batteries. The bolt fixing seems robust enough and I’m not concerned about rounding out the Allen key slot.
The pedals themselves
The pedal itself is light enough that I’d never have any concern over performance. They come in at 324g a pair, as a comparison Shimano Ultegra Carbon R8000 pedals have a claimed weight of 248g. Personally I’m not concerned about 68g, though some may be.
Stack height is low at 11.5mm and there’s 13.7″ of clearance. I didn’t have any concerns over cornering though I’ve not crash tested them for ultimate resilience.
The connection between cleat and pedal felt solid and reliable.
One of the most interesting elements for me was Cycling Dynamics. This is available only with the Vector 3 pedals – the Vector 3S (single pedal) does not offer this.
Cycling Dynamics is Garmin’s own system for measuring pedal stroke – it can be displayed on a Garmin unit, in Garmin Connect or on compatible apps like TrainerRoad.
The ‘dynamics’ include left/right pedal stroke, time spent seated vs standing, Power Phase (at what point during the pedal stroke power is being produced) and Platform Centre Offset (where on the pedal axle power is being produced).
Left right intrigued me because I’ve found when riding hard for long durations, for example during time trials, my right leg always feels fatigue much more strongly than my left, and I’ve had some injury issues on the left side.
It’s never been clear which side is actually weaker, but the pedals were able to confirm there’s not a huge discrepancy, around two per cent at times, though this became much higher under fatigue and during sprints. The dominant leg varied depending on whether sprints were seated or standing, which was really interesting. Knowing this could be very useful in the next few weeks of training.
As you can see in the ‘L/R’ balance chart below, the ideal would be that the pink line sits exactly on 50/50, with the occasional anomaly which you’d expect to occur from time to time.
Power Phase was also really interesting to explore. A circle-shaped diagram shows where power is being produced. I found mine was showing the most power at the front of the stroke and very little during the pull phase – in fact I could only get a full circle when completing minute long single legged drills.
Though interesting to look at on screen, the definition of ‘perfect pedal stroke’ depends upon who you ask. As a result, I was never entirely certain what I was actually aiming for. It might be interesting to track changes over time if I were to up the number of drills I performed, or, using the Trainer Road focuses sessions follow its guidance.
Platform Centre Offset, like Power Phase, really needs to be used in conjunction with expert advice. A negative value indicates that force is being generated toward the outside of the pedal, and a positive means it’s toward the inside of the pedal. Joe Bloggs could determine that a massive discrepancy between the two, or a high number either way, probably means a cleat adjustment is in order – but fine tuning seems like a job for a bike fitter.
Compatibility with non-Garmin headunits
I tested the Vector 3’s with a Garmin Edge computer, and the brand is still very much the market leader. But it’s got competition, and therefore it’s worth being aware that there are some connectivity issues.
Firstly, Cycling Dynamics is Garmin’s own construction. It has opened it up to other power meter and computer brands to use, but so far it’s not been widely adopted – though Trainer Road now incorporates it.
Asked if Cycling Dynamics could be displayed on a Wahoo Bolt computer, a spokesperson from Wahoo told Cycling Weekly: ‘The Garmin pedalling dynamics is technology native to Garmin power meters and head units. The ELEMNT will not be able to record that metic so it will not be included in the .fit file which is produced at the end of a workout and synced with a 3rd party website (such as Strava, Training peaks, Garmin Connect etc).”
We tested this with a Wahoo Elemnt Bolt, and indeed found that though left/right was displayed, peak power phase and pedal offset were not.
There may also be some other compatibility issues. Wahoo added: “To get the most accurate power meter data, make sure the crank length is entered using [a Garmin Edge computer] before connecting to the ELEMNT. This will save the crank length data to the power meter itself, so when it is connected to the ELEMNT this will be transferred to it.”
The stated accuracy is +/- 1.0%.
Most power meters will give slightly different readings – based upon where they’re reading power from. So this one per cent refers to drift from the unit itself – in this case 250 watts measured by Garmin Vector on Monday will be within one per cent of 250 watts measured by Garmin Vector on Wednesday.
Generally speaking, power meters that measure from the pedal as opposed to the hub give slightly higher readings because a few watts are lost in transmission.
I found that, as a rule, the Garmin Vector pedals read a bit lower during short bursts when compared to my Powertap hub, but a bit higher than the Wahoo Kickr I was also testing at the time (remember to factor in drivetrain wastage usually around five to six watts). Over longer durations, the numbers were generally very slightly higher than the Powertap and lower than the Wahoo – which was rather generous.
Below are numbers for a couple of durations. All the figures below come from rides of 90 minutes. However, it’s worth bearing in mind that the Vector 3S and Powertap hub were compared on the same ride, outside, whilst the Wahoo Kickr was used alone, inside during a controlled effort which will have an impact. This said, the efforts completed on both rides were near identical and my heart rate across 20 minutes was only a couple of BPM different (lower by 5bpm in the case of Wahoo test, in fact).
|Vector 3S||Powertap hub||Wahoo Kickr|
|Normalised (90 min ride)||199||195||197|
All power meters show some discrepancy between the numbers. However, for most riders, what a power meter needs to do is maintain consistency with itself – which the Garmin Vector pedals did.
A pair of Garmin Vector 3 pedals will come in at £849.99, whilst a single pedal in the 3S form is £499.99. Powertap P1 pedals have an RRP if £1,050.00 so the price seems fair.
If it’s beyond your means, you can gain access to power data for as little as £379 with a 4iii crank arm (Shimano 105 spec) which measures one side and is therefore comparable with the 4S. The price difference isn’t huge though, and you’d lose out on that easy swapping.
The pre-existing ease of between bike swapping of the Garmin Vector pedals, combined with improvements to the system including the internal housing of the power meter itself make for an excellent product that's hard to fault. Fitting, connection and battery changing are all easy, accuracy seems as good as any other and the Cycling Dynamics remain a nice addition, though not necessarily easy to put to good use without guidance. In future iterations, compatibility with other headunits could be an area for improvement - but this is largely out of Garmin's hands.