I’ve been thinking about getting a power meter for my track bike for quite a while. I’ve had Quarq in my road bike for about 3 years now and I’ve really liked it. The crank based solution offered the best fit to my needs back when I was purchasing my Quarq 3 years ago, and knowing I would have a separate set of wheels for training and racing a crank based solution was pretty much the only solution for my track needs also. Unfortunately there seemed to be but one option for thrack cycling, the SRM with a hefty price tag. As the only inside training facility is my own storage room, it really did not seem like a sound investment. Then some time last winter I heard about Stages.
I got the Stages crank mid February. The new toy took my mind off the OTS I was battling with at the time and gave me someting to look for during my recovery. Anyways, I’ve been testing the Stages Dura-Ace Track 7710 crank for about month and a half now. At first everyting seemed ok, probably because I was too excited about the data and about the future opportunities to get some tangible feedback of my race efforts. After a while, being used to the quality of data I get from Quarq, I started to notice how unusually angular the Stages power and cadence graphs from hards efforst looked. The closer observation led to another discovery. The data was cluttered with spikes.
Below I have attached three screen captures that illustrate the problem. To explain the graphs:
- A hard big gear trainer acceleration. Notice how the cadence curve look more like a saw edge than a curve. The cadence at recording points jumps up and down in the range of ±10rpm.
- This is a big gear trainer acceleration also, but with a heavy fly wheel. Max cadence should not go over 120rpm, yet the spike you see is 147rpm.
- Two consequtive roller rev-outs. The data really speaks for itself.
To get to the bottom of this I also made recordings with the High Speed Data option Stages has in their own iPhone app. Here’s the HSD output of the rev-out drill. As you can see the data is just perfect and the amount of information you can draw from it is just amazing! Looking at this chart I came to conclusion that there is something iffy going on with the Stages algorithm, the way they process the data coming from the strain gauges and the accelerometer producing the cadence data. Would not be the first time a new product had a bug, or was released a tad “raw”… Mobile phone companies do that all the time!
I came to coclusion that the firmware Stages uses to process the data, cadence data in particular, has a major flaw. Since the cadence data is used to calculate power (Power=2*pii*(rpm/60)*measured torque), that – power – is also off. With this info – the first two pictures – I contacted Stages support team. The first response I got was explaining the basick logic behind the cadence data: There are four points per revolution where the crank identifies it’s position and because of this it can be a little off. But the average is still good and accurate. Somehow I got a feeling my message was not getting through. I was not about to give up so I took another shot with more data – revouts included – and explanation of why accurate cadence data is important for track cyclist and that being off by more than 20% was not acceptable.
The prominence behind their next reponse was a surprise. I was truly astonished. Suddenly the Stages team was demonstrating something I have almost forgotten about. Customer care. They did listen. One thing they said was that the cadence data should be very accurate and that the positioning error should not be more than ±1°. For the errors I had reporter it was more like quarter of a crank revolution per two full revolutions. We had a very candid discussion about how to go forward, what my options would be, how I would like to proceed etc. The heavy emphasis on “what I want” was already quite overwhelming, but nothing prepared me for the proposal they pulled from their sleeve. It totally blew my mind…
So what happened? I guess I’m not too far off by saying I became a sort of field tester for the Stages Track crank. So here I am, writing this post, waiting for a new firmware release from Stages – expected to be ready in next few weeks. I remain excited about their product as the high speed data alone shows there is a lot of potential. The one thing that has been the geatest surprise in a very good way has been their attitude. They certainly take their customers and service very seriously and are trying to improve! What a fresh breeze in a world where so many companies seem to have forgotten who pays their bills!