New PT SL - Initial Comments & Questions

Discussion in 'Power Training' started by jeffst, Mar 22, 2006.

  1. jeffst

    jeffst New Member

    Joined:
    Mar 21, 2006
    Messages:
    11
    Likes Received:
    0
    Hi,

    I am new to the forum as I just picked up a PowerTap SL, has the Yellow computer w/o Powertap written on it. Installation went pretty easy and I had no problems getting it to read from the hub. Got a chance to use it tonight for the first time for an hour on the trainer.

    My thoghts so far (as a point of reference I have been using a Polar cs200cad wireless computer).

    1) While the PT display doesn't give you as much data as the cs200 at one time (only 3 pieces of info vs. 4) the computer seems to work pretty well and navigating through the various screens isn't too difficult.

    2) The instructions are baaaaaaaaaaaaad!

    3) Heart rate readings compare closely to the Polar (had both computers running)

    4) I went to the Polar to get away from wires, and so far I have not installed the PT cadence wire but set it up to measure cadence in the hub. I compared this during my ride to the Polar, both in real time and after the ride looking at the average, and the both units are reading pretty much the same. Are most of you using the hub for cadence or the wired sensor and if the latter, why?

    5) One feature I like on the Polar is that it strores a summary for your past 7 rides. As near as I can tell the PT doesn't have a feature like this - so do you have to download your data after every ride and CLR it before your next? Only other way I could see around this was to start a new interval the next day to "split" the data from Day 1 and Day 2 for future downloading..? Or is ther another way?

    Also, as to data sampling, I have it set to every 2 seconds. Is there any reason to go to every second?

    6) Software - my laptop has a COM port but as yet I haven't loaded any software to try and get the data out of the computer. My question is - should I even mess with the LINK SW that came with the PT and/or the POWERTUNED software on Cycle-Ops web page? Or should I go straight to to Cycling Peaks which, if I understand correctly, I can downlaod straight into w/o using any of the Cycle-Ops software.

    Thanks in advance.
     
    Tags:


  2. RapDaddyo

    RapDaddyo Active Member

    Joined:
    May 17, 2005
    Messages:
    5,088
    Likes Received:
    41
    I use the pedal for cadence exclusively. It responds faster and has a higher upper limit. I can max out the PT hub cadence sensor and I don't spin super fast.

    You don't have to start a new interval every day. If you download into CP, it will recognize the rides as separate rides on separate days automatically.

    Better data quality and the only reason to record at longer intervals is because you need to record a long ride.

    I have never removed the CycleOps software from the package. CP is mo-betta.
     
  3. Woofer

    Woofer New Member

    Joined:
    Dec 31, 2004
    Messages:
    599
    Likes Received:
    0
    Wired sensor - why not if it's more accurate.

    Faster sampling - better reflection of your performance. The only reason to go with 2.52 second sampling is if you plan on going riding without downloading for more than seven hours. I never set the sample period to 2.52 seconds.

    Yes you have to download if you think the total ride times adds up to more than the storage capacity otherwise your data stops getting recorded - this sometimes requires a reset of the CPU ( at least in older firmware) so you never want to risk this... If you get cyclingpeaks it will separate your rides into *however* many there are based on start times for each ride, the PowerTap software will not, this is all subject to the maximum memory capacity at your selected recording rate.

    If you are not downloading the data, you are not getting the most from your $1000 purchase. I suggest reading the Power FAQs again.
     
  4. jeffst

    jeffst New Member

    Joined:
    Mar 21, 2006
    Messages:
    11
    Likes Received:
    0
    Hmm, interesting. I did some 120+ cadence sprints and the hub sensor handled it fine..?
    OK, thanks. What I figured.
     
  5. frenchyge

    frenchyge New Member

    Joined:
    Apr 3, 2005
    Messages:
    4,687
    Likes Received:
    4
    I use the cadence sensor on my road bike, but not on my trainer bike. The hub cadence gets flaky/jumpy at higher cadences (ie, above ~100 rpm), but I don't pay much attention to cadence anyway during a normal ride.
     
  6. jeffst

    jeffst New Member

    Joined:
    Mar 21, 2006
    Messages:
    11
    Likes Received:
    0
    Why not to use it - another stinkin' wire! And I guess looking for some feedback on how much more accurate it is...? I currently use cadence as a general idea of how fast I am spinning in an interval and for overall ride duration. Based on my albeit limited sample of 1 hour the hub sensor was within a few % of my Polar.

    Thanks. In most cases 7 hours is plenty of recording time between PC downloads. And re: SW - oh, yes, I plan to use it. Just looking for some recommendations on which path to go down.
     
  7. Woofer

    Woofer New Member

    Joined:
    Dec 31, 2004
    Messages:
    599
    Likes Received:
    0
    It's possible to fool (not that I go out of my way to find situations to do this)the virtual cadence calculated from the hub torque but it's pretty accurate for most situations. If you plan on using AEFP charts you would want the most accurate cadence possible.
     
  8. RapDaddyo

    RapDaddyo Active Member

    Joined:
    May 17, 2005
    Messages:
    5,088
    Likes Received:
    41
    I think the hub cadence maxes out at 140 or 150rpm, which may not be a limitation for you. I think the pedal cadence maxes out at 200rpm, and even that (believe it or not) is a limitation for some.

    The other question about cadence relates to how one manages power. You will quickly find that power is far more variable than any other measure of intensity you have ever attempted to manage. Everybody finds his own way to manage (current) power. For example, some increase the current watts averaging interval to dampen the variability. I went the other direction, preferring to keep the current watts averaging interval short. I manage power with cadence, so I want the most accurate, direct measure of cadence available. There is not a right or wrong answer to this question, it's just something you're going to have to figure out for yourself on the bike.
     
  9. Spunout

    Spunout New Member

    Joined:
    Sep 21, 2005
    Messages:
    667
    Likes Received:
    0
    It fails to deliver over 140 rpm. I use the cadence wire during the winter on the trainer when I'm doing most speedwork. It comes off in the summer and I go from hub. No biggie.
     
  10. jeffst

    jeffst New Member

    Joined:
    Mar 21, 2006
    Messages:
    11
    Likes Received:
    0
    I got around to dumping that file into software and see a lot of "noise" where cadence jumps to 141 on an occasional sample, which if I read correctly the wired sensor doesn't do. So now I see what the issue is. Assuming you want to see that level of detail in cadence. Not sure yet what I will do, just know that with the Polar all I have been able to record is average cadence, so that's what I focused on.

    With the PT I not only have Power to look at but also a lot more data samples vs. just avererages for things like cadence, HR, etc. Hadn't considered this much in my decision to get the PT.
     
  11. F1_Fan

    F1_Fan New Member

    Joined:
    May 9, 2003
    Messages:
    97
    Likes Received:
    0
    I wouldn't say it's "virtual". That would be reserved for things like Shimano FlightDeck that determine cadence from speed and gear.

    The PT gets cadence from the torque peaks in your pedal stroke... that's a real as counting a magnet pass in my books. Where the PT falls down is ultra low and ultra high cadences where the torque peaks get lost in the signal and/or noise.

    In my experience with the PT the best way to create an error is to roughly engage the freehub (after coasting or soft pedalling). The resulting vibrations seem to trigger the 140 rpm spikes.
     
  12. frenchyge

    frenchyge New Member

    Joined:
    Apr 3, 2005
    Messages:
    4,687
    Likes Received:
    4
    It really messes with its mind when I start pedalling those ultra-refined circles with no peak torque values at all. ;)
     
  13. F1_Fan

    F1_Fan New Member

    Joined:
    May 9, 2003
    Messages:
    97
    Likes Received:
    0
    Maybe you've highlighted a new use for the PT. We can work on our pedal strokes until the cadence readings are affected. :D
     
  14. frenchyge

    frenchyge New Member

    Joined:
    Apr 3, 2005
    Messages:
    4,687
    Likes Received:
    4
    Yeah, I was just thinking that I'd need to hook up the cadence sensor once my PowerCranks come in. ;)
     
  15. Woofer

    Woofer New Member

    Joined:
    Dec 31, 2004
    Messages:
    599
    Likes Received:
    0
    I would not call the hub cadence real cadence, either, because it's wrong often enough when I monitor it and pedal steadily. It's neat that it works well most of the time off of the torque pulses of pedaling but that doesn't make it the same as measuring cadence directly.
     
  16. Spunout

    Spunout New Member

    Joined:
    Sep 21, 2005
    Messages:
    667
    Likes Received:
    0
    Here's a question: What would it read? Would it read 0, 1, 140, or 'ERR' ?:D
     
  17. frenchyge

    frenchyge New Member

    Joined:
    Apr 3, 2005
    Messages:
    4,687
    Likes Received:
    4
    If you're going to pedal circles you should first switch the hub from 'power mode' to 'efficiency mode' and then it reads out from 0-100% on the display. I think there's a dipswitch deep inside the hub which allows this, but it requires complete disassembly to access. ;) :D
     
  18. DanP

    DanP New Member

    Joined:
    Oct 5, 2003
    Messages:
    104
    Likes Received:
    0
    Still confused about something then - done only 3 rides with my new PT SL.

    Did the 1st, downloaded.

    Did the 2nd, then a 3rd ride hours later, BUT pressed the two buttons to clear the values for my second ride. When I downloaded I only had the 3rd ride and the 2nd one was lost.

    So - what do I need to do to reset the distance, time and av speed and cadence between rides without clearing the memory?
     
  19. PhilH

    PhilH New Member

    Joined:
    Nov 15, 2005
    Messages:
    21
    Likes Received:
    0
    Dan,


    To be able to just see the distance, time, ect for another ride when you still have previous data still in the unit just put the computer into interval mode and start a new interval. You will get the info displayed for the current interval. If you are not in interval mode you will get the total that is stored in the unit.

    Phil


     
  20. RapDaddyo

    RapDaddyo Active Member

    Joined:
    May 17, 2005
    Messages:
    5,088
    Likes Received:
    41
    If there is a large enough gap between two rides on the same day, CP will automatically recognize them as two separate rides. If you want to load them as one ride (with a long rest), just drag/drop the 2nd ride on top of the first. If you want them to be loaded as two separate rides, drag/drop the 2nd ride onto a separate row in the ride calendar. If the gap isn't sufficiently large that CP automatically recognizes them as separate rides, you can do the split after you drag/drop the ride files. The 2nd ride will show up very clearly with a time gap between the two rides. Just create a new ride file (File > New), then select the 2nd ride segment and cut/paste it into the new ride file. You can have multiple ride files on the same day.

    Better to not clear the PT computer until you are certain you have downloaded all the rides.
     
Loading...
Loading...