4iiii Dual Sided Power Meter: A Short Test Ride


Last Friday while on the way to the airport from Kananaskis (in the mountains for the ANT+ Symposium) to Calgary I swung by the 4iiii headquarters in Cochrane.  The time I had was rather limited, as I was super time-boxed with daylight on one side, and a flight departure time on the other.  But, it gave me a chance to try out their work in progress dual sided 4iiii power meter.

You’ll remember they announced the unit about a year ago at Interbike, but only started shipping their single-sided unit earlier this year.  The dual-sided unit has continued to be worked away on by engineers as they concurrently worked through various teething items on their single-sided unit.  Of course, virtually all of those since-released updates apply to the dual sided system, so it’s certainly not time lost.  You might remember I encountered some issues with their single-sided system, and basically had to wait there for them to resolve some items.  They handed over a new left crank arm to me on Friday, which should resolve the issues I saw, and I’ll install when I get back from my current trip.

As for the dual-sided unit, you’ll notice things have changed a fair bit in terms of looks on the above drive-side, with the battery pod becoming a fair bit more accessible now.  You can just see the top edge of the backplate if you look directly above the crank equal to where the 4iiii Precision pod sits now, in front of small chainring.

A Ride:


As noted, I didn’t have a ton of time during the ride.  The bike was ready to go, but we had to pair up my head units.  Due to apparently none of us being fully awake, we didn’t quite realize we were pairing to the wrong thing – so we sat there burning a solid amount of time trying to figure out why on earth calibration wasn’t responding as we’d expect.  Apparently we had had written down the wrong ANT+ ID from another device nearby.  Eventually though, the four of us (ok, maybe more of us at that point) got it all set and headed on out.  Unfortunately, that did cut into some of the ride time.


The ride was a simple out and back.  We had wanted about 45-60 minutes to ride, but with everything that ended up being about 30 minutes (and even that I got some unhappy looks at the airport check-in desk).  Still, enough to establish a basic level of functionality.  But of course nothing that would count as a review.

We headed out on a gradual climb, and then came back downhill with the wind.  We threw in a few sprints for the fun of it, and otherwise took turns on the way out going into the wind.


Once we got back, I snapped a few quick photos of the bike – which happened to be well known engineer Keith Wakeham’s bike (seen below a bit further).  It had his PowerTap wheel (hub) on it and the 4iiii Precision (dual) system, and then I stuck on my PowerTap P1 pedals.  Normally I’d have preferred to at least get about 10-15 minutes of settling in any new installation, but I made due here given the time constraints.  I did a few quick sprints around the parking lot and called it done prior to the ride.

Afterwards, I downloaded all the data (which I recorded on my head units) and threw it in the analyzer to see how it faired (shown with 30s smoothed average below):


Overall, pretty good.  The three units tracked fairly closely throughout the entire ride, and the ‘ordering’ was proper.  By that I meant that the P1’s registered the highest, and the PowerTap hub the lowest, and the 4iiii Precision smack in the middle.  This is how it should be, since the highest power output would be closest to your legs, and then would be slightly lower as you get further from your legs (due to drivetrain/etc losses).

One might make the argument that the spread between the P1 pedals and G3 hub was a bit more than I’d like to see – but things seemed to settle about 20 minutes into the ride, which would be somewhat logical given I just had installed them.  So I’m not at all concerned there.  And anyway, the Precision sat in between those two lines – which is really what counts.

As for cadence, the P1 and 4iiii Precision agreed quite well.  There’s only a few seconds you see where they disagree, and that’s more than likely to do with just the way units stop/start as you’ll notice they are all at points where I otherwise stopped pedaling briefly.  That’s pretty common.  I didn’t include the PowerTap hub cadence in this graph because I find that in comparison graphs it ends up being funky during stops/starts because it’s an estimation more than anything.


Oh, and finally, here’s the Mean/Max power graph for the three of them:


Again, ordered the correct way, though the P1’s are showing a tiny bit higher here –but again, it’s probably taking those first 10-15 minutes to settle out after install.

Going Forward:


So what’s the plan going forward for getting these into your (or even my) hands?  Well they’re being a bit shy on details until they’ve got things more concrete.  Right now the official line is that they’ll start shipping “In Early 2016”, so that’s about the best we’ve got date-wise.

They said that as they near that timeframe they’ll reach out to those that have pre-orders for the dual system and get them all squared away.  Until then, I expect they’ll basically be quietly working away on it.

With that – thanks for reading and have a great weekend!

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