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when a watt is not a watt

Dave TalloDave Tallo
in General Training Discussions

This probably gets covered in 'Training and Racing with a Powermeter,' but I'll ask here anyhow.  Why is it that watts on a slight decline, or with a slight tailwind, come easier than the exact same watts going up false flats or into a wind?   I have an out-and-back section on my regular route that i must have been on 100 times, and there is easily a 5-10 bpm difference between directions, and a perceivable difference in RPE.   No possible way this could be owed to cooling.  What gives?    

Comments

  • Mark MaurerMark Maurer
    Dave, have you looked at your cadence in those sections? Your cadence are probably higher in the declines or tailwind section than in the uphill headwind sections. If your cadence is higher then your pushing the pedals with less force than at a slower cadence to create the same watts. At a faster cadence there's also some momentum that you get kinda like a flywheel.
  • Coach RichCoach Rich
    IMO, higher cadence reduces the RPE of watts. So slight downhill = higher speeds = usually higher cadence = lower force @ the same watts = lower RPE.
  • Dave TalloDave Tallo
    Sorry ... a conscious very 90rpm out, 90rpm back. Because this has had me puzzled for so long, this little stretch is now a science lab.

    Can't imagine wind speed makes any difference either - I think it becomes a wash, unless there are significant differences in wind speed that day.
  • tim cronktim cronk
    2 Thoughts....
    1. Reverse the order you do the out and back... See if you get the same results.... Is it always the first leg that is easier?
    2. Pay attention to how you grip your bike with your hands/arms on the incline vs decline....If wind is a factor I can see using more energy to hold on , stay aero , etc , IOW using more body energy to put out the same amount of watts... So maybe this applies while riding in no-wind but incline vs decline!

    FWIW .... watts is watts measuring the work performed but I am with you in that they arent all created equal.... I notice this on headwind(RPE much harder) vs tailwind for the same numbers... I'd say the same about TSS , I know its just math , but lots of variables that make it feel different.
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