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L/R Power Balance Road vs. Tri

Below is a copy of a thread I posted on ST.  Looking for power guru's to comment as well as the people from Power2Max... Interested to get some feed back from the Haus as well!





Never gave much thought to the L/R Balance discussion. My Da2 equipped with a Quarq routinely gives me 49/51 and 50/50 readings every ride like clock work... Just got a new Road Bike Cervelo S5 equipped with a Power2Max S and my 1st 3 rides came in at 47/53 , 46/54 , 47/53 ... Initially I though that is just the difference between the Power2Max and Quarq (one of them must be wrong).... So I did a ride on my girlfriends new S3 with a Power2Max S and I got the same 47/53 .... Again thinking its the Power2Max, but after reviewing her 1st 3 rides on that same S3 she recorded 50/50 , 50/50 , 51/49... So its not the PM its Me... 




Can I really be that different Tri vs. Road ? 

Could this just be the variation between PM's calculations? 

If this data is correct, what would I do with it anyway? 

Comments

  • As you've pointed out to me, my power is usually 51/49 on my tri bike. MAYBE 52/48 every so often

    On my Madone however it is pretty much always 53/47 or 52/48.

    I don't think it warrants any change in my training, but maybe someone will tell me differently (at which point I'd be pretty skeptical and ignore the advice unless there was some data behind it...my ROI equation is borderline working for me and so adding drills etc to my rides is doubtful to happen).
  • I’m using Power2Max 2, last IMFL - Pwr. Bal. 49.1/50.9%, I have sprained injury in right ankle (from IMFL) last Saturday 90’ ride Pwr. Bal. 53.8/46.2%.
    Typically I’m on 50 +-1%, it can be you have bike fit issue.

    Doron
  • Tim - I just got off my trainer where I had a few thoughts on this, maybe because I'm using my road bike instead of my TT bike on the trainer for the first time in ... ever.

    • Are you confident the fit on the Cervelo is as good as on the Felt?

    • Are there differences between the two apart from the obvious geometry difference: pedals, cleat position, shoes, crank length, saddle, etc. To paraphrase Dan Empfield, I'm highly conscious and concerned about all the interface points between rider and bike.

    I could check my own L/R data, as I have the Compu Trainer, but I;m afraid I might find something amiss, so I doubt I will. 

  • @Al and Doron , Confident I have a good fit. But as good as my Felt? Absolutely NOT yet anyway... 3 rides on the Cervelo (actually 2 with the 3rd on Heathers but essentially same bike and same PM) and thousands of miles on the Felt so there is lots still to adjust on the S5 to get dialed. Biggest difference is road geometry vs tri-geometry , pedals and shoes are the same, crank is 5mm longer, saddle different... Ref- CT I'm pretty even on the CT within 1 percent anyway... If I had it here I'd throw the S5 on to check it out...

    @Matt, Like you said if someone told me what to do with the data I think I'd actually laugh... I ain't doing NO one legged drills! But its certainly worth noting, discussing, and being aware of while riding... Glad to see I'm not the only one... Your left side is stronger , are you left handed?

    At least the imbalance from road to tri is the same just a larger amount on the road.... The rides I did so far were 2 very low VI rides around IF .90 and 1 was a very high VI ride with 30/30's , coasting, V02 strava segments.... I'll have to do a steady ride and really concentrate on the weaker left leg to see if I can actually change the outcome!
  • Update.

    I found my L/R balance was not because my injury, I used my old SIDI shoes in the last 2 months, today I use my new SIDI shoes (year old) and the balance was 50/50.
  • As a previous P2M owner that now switched to Vectors I can clearly tell you that the L/R-Balance you'll get from a crank-based PM measuring only on one side of the crank you will not get accurate data of your power balance!!

    My P2M showed a 50/50 or 49/51 on almost all of my rides for several thousands kilometers. I did not pay huge attention to it at all but I know that my left leg is not as strong as my right one.
    Now on my Vectors I'm coming in at 48/52 or depending on fatigue even worse ... down to 46/54!!

    As a proof that P2M can't accurately measure this kind of metric just try to ride 30" with only one leg pedaling ... This MUST be a 100/0 (or 0/100) reading as there's absolutely no force applied to the second pedal.
    Doing so on a Vector will show exactly this ... doing it on my old P2M showed something like 70/30.

    I actually haven't had a chance to mount the Vectors on my TT bike but I highly doubt the power balance will change but what WILL change for sure is the Power-Phase as I'm riding Q-Rings there.
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