Stages track power meter

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 The Stages track power meterpurchasing 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:

  1. 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.
  2. 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.
  3. Two consequtive roller rev-outs. The data really speaks for itself.

Stages accelerationStages big gear start effortStages roller rev out

 

 

 

 

stages hsd revoutTo 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!

 

 

 

 

 

 

Advertisements

7 thoughts on “Stages track power meter

  1. I’ve got the same problem. I got my Stages power meter for my track bike a couple weeks ago, and like you, the cadence and power data are all over the map.

    Unlike you, however, Stages has yet to acknowledge my concerns. I send them graphs of bouncy data a week ago, but so far no response to the support ticket. So much for their advertised 24 hr response time.

    • Hi Tom,

      It is possible that their customer support is a bit flooded at the time being. I have a hunch we are not alone with this matter 🙂

      My experience was rather similiar. I was absolutely relentless in my efforts to get a fix to my problem. The first response I got was trying to belittle the issue, explaining this was somewhat expected behaviour. I did not agree – told that to Stages support team too – and kept sending more data with a request to fix the product. I was still waiting for their response to my earlier notes when I saw the data from the roller rev-out test. That graph really did it for me. I sent them a note saying if the reported issue cannot be fixed I would like to return the unit as faulty nad asked for instructions. I think this was the point when it was escalated to top management.

      Now, based on the communication I’ve had with them of late it seems to me they have recognized there is an issue with the product and they are working on a fix. I hope to get the the promised new firmware to test within the next few weeks. When I do, I will make a quick tweet to announce I’ve got it and post more detailed data from my training/testing as soon as possible. I keep my fingers crossed as based on the high speed data I still believe this is just a bug that can be fixed.

      RB

      • I’ve noted there was a note in the firmware release on the 14th July saying improved track functionality. Is this the upgrade you were looking for?

  2. Pingback: Garmin’s new cadence sensor | Red Baron's Log

    • If the cadence is ok when you have the spike it must be the torque causing this. This does not mean there is an issue with you PM. As this happens only every now and then it could be shifting related. Some of the analysing SW have build in feature that help you to fix those kind of things. Naturally you can go to the raw data and fix it manually. That would seem like the best option.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s