Not sure how accurate their PM will be but here's what I find interesting for a spin bike:



I'm assuming the cranks are proprietary (maybe I'm wrong?... I'll email them).

Edit: oooohh the PM5 has Ant+ and Bluetooth output. They have a list of supported 3rd party apps and, IMO, there's no reason to believe that TR or Zwift won't be able to pick up the power data.

I assume the power meter will be the exact same as that used for their rowing machine... So, I'm not sure how the accuracy will compare against other power meters, but it will almost certainly be totally consistent... A big upgrade over Wattbikes, in that regard!

IIR, C2 ergs—and this basically an erg—don't measure power; they calculate power based on flywheel deceleration. The spindown measurement and calculations based on it, although set at the factory, may drift over time (why we use drag factor, and not fan settings 1-10). I guess this measurement could be validated by throwing on some Vector pedals, and comparing them vs the C2 PM5 display

Also, from the photos: the body of this spinbike looks a bit elongated, and the seatpost and crank appear to be way too far from the flywheel and "cockpit", and not adjustable.

I'm guessing this product is targeted towards the crossfit crowd, who are concerned with calories (and maybe a few watts).

C2 makes great ergs, and satisfactory oars. It will be interesting to see if their brand recognition is enough to sell those spinbikes.

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This will be a killer product if the power is accurate. It looks like you can interchange regular bike parts such as seats, pedals, crank arms. I cant wait for some DCR testing on it.

It may be that the target is crossfit gyms as someone else said.

Their stuff is great, I am wondering why it took so long to get in this space...

I'm not trying to be snark, but what is the benefit of a stationary bike over a bike on the trainer? Stability? Longevity?

Re-read my post. Power is calculated—not measured—with the PM5. So not as accurate as a powermeter. The bike body is not adjustable, and from the photos looks too long, unless you're a 100kg, 2.2m tall male.

I'm not sure this gear is DCR's purview. From first glance, this seems to be more of a gym toy (crossfit) or a cross training tool for injured rowers, than a high performance cycling/tri training tool.

Lastly: their stuff—oars and sculls—is not that awesome; it's satisfactory enough but with a high defect rate/low qc, IME.

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It appears that there is a ton of fore/aft adjustment on the reach by moving the entire cockpit in and down or in and up. Saddle fore/aft appears to be reasonable for a road position from what I see on the video on the landing page as the nose of the saddle appears to be only a few cm back from BB in the lower positions when the woman is riding.

As for the accuracy of the power numbers calculated by speed of the flywheel, as long as they give an FTP that is 10-20% high, then it is definitely ST approved. If it reads low compared to a quaq or SRM, then it may as well not exist for ST bragging rights.:

Off topic, but is that a new development? I don't have philly1x years of rowing in the bank, but 11 years of rowing, almost all with C2, and I am not sure I ever experienced any defections. I snapped an oar handle once mid stroke, but just chalked that up to being a beast :-)

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@adamwfurlong

Adam, not really no. I remember visiting the factory in 99, and bringing 4 sets of sculls with me. They didn't bother to repair them (various issues) and replaced them outright.

More recently: we have a few sets at VBC that need help. This happens nearly every year.

The ergs are certainly durable, if maintained.

And you are (were?) a beast. If only you'd have used Crokers. ;)

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"ST approved"? "FTP"? Wrong language. This device is developed for, and geared to, two markets on earth, not here, in outer space. 😜

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I think you will find the Concept2 more accurate than a set of power pedals. The fan setting affects the amount of air flow, thus feel, but the way power is calculated there isn't drift of power reading over time. There is drift of feel over time as dust builds up restricting the air flow at a given setting, 200 watts will still be 200 watts after several years whatever the damper setting.

However there is a study which shows Concept 2 measures approx 25 watts less than a force measuring system, but it was only about 6 rowers.

Concept 2 will certainly be more consistent than force measuring systems as temperature, air pressure etc don't affect the accuracy of the measurement but power calculated at the Concept2 fly wheel may prove to be a little different to force measuring devices.

Over the years I've used hundreds of Concept 2 rowing machines, some apallingly maintained. Different damper setting needs to be adjusted for the same resistance but I never found one which gave dodgy power numners, unlike Wattbikes which used force measurement at the chain.

Given the pathetic power readings given by most gym cycle machines the Concept machines will hopefully soon be found in as many gyms as Concept 2 rowers.

It really is useful to be able just turn up at almost any gym in the world and be able to train and get consistent comparable power numbers.

It will be interesting to see how experienced power meter users find the Concept power numbers compare.

The trouble is C2 can't use the same logic to calculate power for a bike as they can for a rowing ergo. For a rowing ergo you can use the recovery phase and the deceleration of the flywheel to effectively calculate the air density. But for a cycling erg then you don't have that phase where you know no power is being applied.

Good point. Anyone from Concept able to explain how they get round the difference between rowing and cycling and make the calculations, as it's the deceleration that they use to calculate? Are there decelerations through the pedal stroke?

I emailed to company for a correct answer but there is no way to be certain this is not a different method of measuring the power. I asked if the power coorelates directly to bicycle based power meters such as pedals, hubs, cranks. I will post when I hear.

To be fair, Bike power meters don't measure power either. They calculate it . Most bike power meters measure strain, then calculate force and then work and then power.

They don't measure it directly, but they do measure the inputs of the power=force x velocity equation directly. C2 seems to track metrics that infer those inputs with assumptions thrown in to get them there.

Force isn't measured from the power meter. It is calculated from the recorded strain of the crank. These assumptions that you're talking about aren't assumptions. They're variables. You can calculate power based on acceleration of a free wheel too. As long as the mass and rotational inertia of the wheel are known it will be accurate.

Actually most PMs doesn't record the strain, they measure the resistance change for a metallic foil pattern as the pattern deforms on the body of observation. Strain/Stress is inferred from the resistance change.

Who wants to be the next pedant to correct me?

Updating what I had previously written.

I spoke with the CEO of the company which created the previous version of the C2 performance monitor. It was explained to me, for this specific device: since the weight of the flywheel is known, and the RPMs at any given time are known (wheel deceleration does not necessarily need to be factored into the calculated power measurement), a relatively accurate power measurement can be derived at any time. So, probably, the data for the power displayed should be of value.

We also agreed that this was a tool, created by a recognized brand, probably targeted at the XF market, and secondarily the rowing (injury rehab, cross training) market.

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Would be nice to see how it compares to Powertap P1 pedals.

Air density is unknown though and given the resistance comes from the fan accelerating air then you would still need to measure or estimate this as for example the watt box does for the lemond turbo.

AFAIK the concept2 is a flywheel attached to a fan. You can build a power vs speed curves for the generic system but that doesn't mean each unit will be accurate.

It should be in the same class as using a trainer and virtual power. I doubt it will be in the same class as a powermeter.

You're literally describing a strain gauge.