Powertap and virtual cadence vs sensor

magliaceleste
magliaceleste Posts: 748
edited December 2009 in Training, fitness and health
I realise this may a topic for workshop, but as there are knowledgeable people with regard to training and equipment here...

The Powertap + will send cadence and speed to the Garmin 705 without the need for a GSC10 sensor I believe.

The cadence is "virtual cadence" and I have read that the PT calculates a revolution by the torque applied to the cranks on the downstroke.

My question is: does anybody here really use a PT+ series with a 705 without a GSC10 sensor. Does the virtual cadence (and speed) really work accurately (i.e. as well as a sensor?)

Thanks

Comments

  • magliaceleste
    magliaceleste Posts: 748
    OK just read that according to Saris it'll only work between 40 and 130 rpm

    I can't imagine this matters from a data perspective, since anything < 40 rpm is probably just coasting.

    I'm more interested in weird fluctuations/numbers/dropouts etc.
  • chrisw12
    chrisw12 Posts: 1,246
    I use my powertap with a garmin and do NOT use the gsc sensor.

    I honestly don't see the point. Cadence is pretty irrelevant when you're using power anyway. Ok the powertap way of doing things may be inaccurate but so what, I honestly would not worry about getting accurate cadence data.

    Saying all that I don't even think the powertap is inaccurate when measuring cad.
  • magliaceleste
    magliaceleste Posts: 748
    Thanks.

    Personally I find cadence quite useful (hence the question). Also cadence vs power is quite interesting sometimes isn't it?

    Also, I hate having inaccurate data :lol:
  • hopper1
    hopper1 Posts: 4,389
    I don't have a 705, but the Power Tap can still be used without the sensor.
    I tried it without, but prefer to use it with the sensor as it seems to update real time info quicker.
    It's hardly a ball ache, attaching a wee sensor to your stay and one on your crank, too.
    Start with a budget, finish with a mortgage!
  • GavH
    GavH Posts: 933
    If the GSC10 is NOT used, where is speed/distance info generated from? GPS or PT?
  • Anonymous
    Anonymous Posts: 79,667
    GavH wrote:
    If the GSC10 is NOT used, where is speed/distance info generated from? GPS or PT?

    Enter the wheel size and it goes off the speed at which the hub goes round!

    I don't use the cadence sensor, not least cos my pt is wired and it's a mess!
  • xlr8
    xlr8 Posts: 2
    I use the PowerTap+ hub without a cadence sensor (with the PowerTap head unit mind, not a 705). I find the cadence results work pretty well for me (> 1 yr of training in this mode), and haven't found the need to attach a dedicated cadence sensor. It seems to work well from low-cadence intervals at say 50rpm up to fast sprints at 180rpm. One thing I have observed is that the cadence works best when you're putting out say 130+W. Below that perhaps there's just not enough pressure on the pedals?

    Nice clean lines on the bike too with a wireless hub and a head unit, and nothing else. If it doesn't work out for you, you could always buy an additional cadence sensor later so why not give it a try?
  • chrisw12
    chrisw12 Posts: 1,246
    hopper1 wrote:
    I don't have a 705, but the Power Tap can still be used without the sensor.
    I tried it without, but prefer to use it with the sensor as it seems to update real time info quicker.
    It's hardly a ball ache, attaching a wee sensor to your stay and one on your crank, too.


    As the president of your club below points out, that little sensor is one more thing to spoil the lines of your bike. :wink:


    How do you join the titanium owners club? and yes I do have a titanium bike before anyone says that.
  • Anonymous
    Anonymous Posts: 79,667
    chrisw12 wrote:
    hopper1 wrote:
    I don't have a 705, but the Power Tap can still be used without the sensor.
    I tried it without, but prefer to use it with the sensor as it seems to update real time info quicker.
    It's hardly a ball ache, attaching a wee sensor to your stay and one on your crank, too.


    As the president of your club below points out, that little sensor is one more thing to spoil the lines of your bike. :wink:


    How do you join the titanium owners club? and yes I do have a titanium bike before anyone says that.

    Post a pic of your bike in the Bikeradar Titanium Club thread in the 'Your Bikes' section!
  • magliaceleste
    magliaceleste Posts: 748
    I already have a GSC10 sensor but it would be nice to get rid of it, that's why I'm asking if the PT is reliable source. I like clean lines too.

    Thanks for the observations everyone.

Categories