Read some reviews slating them, some saying they’re ok but not a power meter.

For a steady, say zone 2, ride would they provide anything more than what I’d get by trying to keep my heart rate in zone 2 for the ride?

If I got fitter and thereby generate more power – how is this unit going to recognise that? Or that I’m going faster for a particular heart rate?

Hmmmm, I think I might have tried to find out about these things a while back, and the response was similarly sparse…..

No one got one?

I have one. It’s ok for getting a ballpark TSS and a NP for rides when I’m not using a proper PM. Instantaneous power is all over the place but if you set it to 30s it’s not too bad. I needed a new HRM anyway and it wasn’t much extra. Not a substitute for a proper PM if you want to accurately ride to power though.

A couple of others on here have them too and may comment. I’ll try and write more later too. I got it off the back of the dcrainmaker review, and I think he says it works better for some than others (if you are a good fit for their algorithms) and I think that’s probably correct.

Thanks MrBlobby

So if its just based on heart rate and some fancy algorythms would it be any better for steady training rides in a particular power zone than just training to heart rare?

Probably not. If you need a new HRM strap then it’s worth a punt, not sure I’d recommend one otherwise. Best read the dcrainmaker review though.

Have two – I pass one around the club. It’s a useful device, but not a power meter in the normal sense, more an AVERAGE power meter. I set my Garmin to 30 second averaging when I use it, and it gives me reasonable numbers (within say 10% of my Stages). The Normalized Power is normally very accurate.

I use it on the nice bike(TM) rather than switch the crank over. Here is a race I did with it two weeks ago, if you would like to see real data (shelled out the back after 14/18 laps 🙁 ).

Better than it has any right to be. I have deconstructed the algorithm (for my own data as opposed to the population that the makers have), and I think it makes sense. Uses rate of change of HR not just HR. My own algorithm used second derivative and cadence and wasn’t much better!

If you need a new HR strap, I think it is worth the extra £25.

Ok, so if I’ve got a heart rate strap (or three) already then probably not worth it?

Stages is a BIG chunk more ££££

I like mine, use it on my commutes, steady club rides, almost everything except the race bike, I think it is worth it, personally. Just respect the limitations – peak power is miles off (I’m not that good). If you are using TrainerRoad on a turbo, you can calibrate it relatively easily. Might ride a few sessions on the PowerCal next week to see how it goes.

How does it need calibrating? I do have trainerroad.

According to BikeRumor there is a 30% trade in November for PowerTap hubs, so send those broken G3’s back to them.

Saris Announces Trade In Program For Power Meters & A Chance To Win Ultimate Indoor Cycling Experience

Think “mental calibration”.

I could run direct comparison using speed of Tacx vs power on PowerCal, but was really just thinking about ballpark for target power. I do have separate garmin and laptop to record too, so I’ll have a look-see.

More UK detail on the trade in here.

“This trade in program offers an ideal opportunity for cyclists to upgrade to a better product with better accuracy,” said Justin Henkel, PowerTap Product Manager.

I’d rather stick with my old Pro than risk an “upgrade” to a G3 if the forum chatter is anything to go by.

Good point Tired!

If I got one I could compare it to Trainerroad, I could then find roughly what readings I needed from the Powercal when out on the road.

TiRed, how did you get on with that? Tried something similar and found PowerCal data to be much closer to that of a real PM when riding on the roads rather than on the turbo. Suspect it’s because there’s more variation in HR on the roads which gives the PowerCal more data to figure out what’s going on. Turbo figures seemed way out in comparison (usually much lower than real PM.)

So, it seems you can buy the powercal without the speed/cadence sensor?

I presume I need the speed/cadence sensor, or how else does it know to equate heart rate to effort?

Or does it not provide figures in Watts?

No link to a speed/cadence sensor. Works just off HR, mostly rates of change I think. Probably some clever algorithms based on quite a bit of modelling. Provides figures in watts. (Note it only needs to know angular velocity if it’s measuring force/torque, which it isn’t.)

Obviously has lots of limitations, it’ll tell you you’re producing a certain amount of watts when you’re not even pedalling. Over the course of a ride though it seems to even out to be in the ballpark of a proper PM.

Haven’t TT’d yet to compare. But yes the cadence sensor serves no purpose and I bought mine as standalone units. I use it for power on everything except the TT and race bikes, and HR for those. The algorithm is hard coded into the HR monitor which does not talk to the speed cadence sensor. I’ll run a callibration later this week – should have two powercals, two garmins and a turbo.

I did consider contacting Garmin, as there is no reason why a guestimated power based on speed, cadence and HR change can’t be hard coded into their head units.

Right, I’ve ordered one of these, not really bothered if it gives true power readings, just hoping it will give some good feedback on some steady rides over the winter.

If I pair it with my Garmin as a power meter, does it transmit both heart rate and the “power” figure to the display?

yes, the device sends two separate ant codes and they are detected separately – I use it for HR only on the bike with a Stages and HR and power for all others. The easiest power meter to transfer between bikes – and errr any other activities you care to mention 😉

As I’ve said before, it’s not a power meter, but it is better than it has any right to be. Been off TrainerRoad this week as I’m resting – well actually just tired and a niggly new-cleat-was-in the-wrong-position knee soreness that is now going.

Ok, so I’ve just done Revolver (Sufferfest) on Trainerroad which is basically warm up then 1 minute full effort, 1 minute recovery x 15.

I’ll have a look in closer detail when I get a bit more time but the power reading provided by the Powercal seemed to track the virtual power that trainerroad output. And it tracked heart rate too. Perhaps unsurprising for a system based on heart rate.

Its probably obvious, but in realtime it seemed to track a change in effort better than a steady state effort. The power suggested by Powercal dropped off during a period of steady effort – where in reality I was still pedalling as hard as the initial effort.

Not sure how useful it will be on a steady state ride because the reading fluctuates more than heart rate, so it would be easier to stay in a particular heart rate zone than to try and stick at a steady “power” output. Thats with the Garmin displaying a 30sec average.

I’ll try it on the commute tomorrow…