Quarq - higher reading?
So I just switched my quarq to my bike and I'm using it with my 310xt. Does it give a higher reading than the powertap wheels? I haven't tested in a while, but I doubt my ftp has gone up significantly. Last time I tested it was 215. It doesn't seem like if my ftp was 215, i'd be able to ride 3 hours with an NP of 221. I forgot to set my garmin to autopause, so there's about 5-10 minutes on there of us at the rest stop.
Here's today's ride:
Lap 1 (3:16:15.21):
Duration: 3:12:24 (3:23:15)
Work: 2011 kJ
TSS: 350.2 (intensity factor 1.05)
Norm Power: 221
VI: 1.27
Pw:HR: n/a
Pa:HR: n/a
Distance: 56.759 mi
Elevation Gain: 3978 ft
Elevation Loss: 3938 ft
Grade: 0.0 % (45 ft)
Min Max Avg
Power: 0 873 174 watts
Cadence: 2 123 72 rpm
Speed: 0 33.5 17.7 mph
Pace 1:47 0:00 3:23 min/mi
Altitude: 125 499 291 ft
Crank Torque: 0 857 199 lb-in
Entire workout (174 watts):
Duration: 3:12:24 (3:23:15)
Work: 2011 kJ
TSS: 350.2 (intensity factor 1.05)
Norm Power: 221
VI: 1.27
Pw:HR: n/a
Pa:HR: n/a
Distance: 56.759 mi
Elevation Gain: 3978 ft
Elevation Loss: 3938 ft
Grade: 0.0 % (45 ft)
Min Max Avg
Power: 0 873 174 watts
Cadence: 2 123 72 rpm
Speed: 0 33.5 17.7 mph
Pace 1:47 0:00 3:23 min/mi
Altitude: 125 499 291 ft
Crank Torque: 0 857 199 lb-in
Comments
The one thing I have noticed is that if I keep my bike instead and then go out where it is much warmer or colder the watts seems off for the first 10 minutes or so, but I just zero it at a stop light or while coasting and it goes back to what I would expect.
The other thing to keep in mind is that ride you share has an VI of 1.27 and the average power was 174. I do think it is possible to ride 2 hours at 174 if your ftp is 215.
Not necessarily.
First off, there's absolutely no way his FTP is 215w if he can ride ~3hrs with an NP of 221w. Not a chance. You can certainly use a somewhat hilly route as a test and if you do then you should I would use NP and not AP. It's not ideal but certainly a valid test. The only time AP might be the somewhat preferred number is when the course is relatively flat and the two would be very close in that case anyway.
More often than not, I believe you should be focused on NP, not AP, since that's the number that represents the true physiological cost. Having said that, your testing should be done primarily on terrain where those two numbers will be almost the same.
Thanks, Chris
Definitely looks like it is time from Branan to re-test if he didn't already do it.
Now, given he is actually looking at the wattage as recorded in WKO and not on the Garmin then all of that above is a moot point. As the others have stated, either double check the torque offset ("calibrate") during your ride or its time for a new FTP test (or both).
As Matt suggested, Branan should definitely retest on the Quarq.
Thanks, Chris
On a kinda sorta related note...
In addition to drivetrain losses which "should" make the power reading from a PT lower, every time that you change gears the power number drops off on a PT while I imagine that it does not on a crank based system. This would obviously make very little difference on a truly flat road or a trainer but in the real world doing intervals I find myself changing gears all the time to stay within my desired watts and cadence. Any thoughts?
Not sure. I don't have enough personal experience with a crank-based system and you're probably the first person to bring this up in conversation on a forum or in person.
Funny, I was just thinking about this last night. During the local TT, I was noticing the wattage 'penalty' on the PT for every gear shift (and there are a bunch of them on this loop). I don't really have any answers, but definitely noticed the same.
I wonder how much of it is the actual moment where the chain is shifting, versus sub-conscious easing on the pedals when making a shift? If it's the latter, it should be the same on a crank-based system...
Mike
work = force x distance (where distance is circumference and varies with gear selection)
power = work/time (where time is cadence)
Since power is the dependent variable, any change to force (pedal pressure), distance (gearing) or rate (cadence) will affect power unless you are somehow able to seamlessly adjust all 3 in unison to maintain the same work / rate.
This coupled with the lack of 5, 30 (or any at all) second rolling averages on the 310xt and the 1Hz update rate makes my instantaneous power at any given time incredibly bouncy.
I just started using a Quark with the 310xt and I had the "Power" field as the the main one. It jumped around constantly to the point where I had to ignore it because I could never get a firm read on what my actual power number was.
To follow up, I did retest. I went to a flat area and retested the other day. The results were posted in another thread. I also road an incredibly hilly route last night and have yet to download the results. I'll post both tonight for comparison purposes.
Oh, the mentioning of cadence above brings up a (dumb) question that I was thinking about last night. Is a watt a watt? Meaning, are 200 watts at a cadence of 80 the same as 200 watts at a cadence of 95? When I say same, I mean does it place the same stress on you physically?
200 Watts at 45 RPM requires much more muscular force (watts equal torque times RPM), and therefore start to elicit some slightly different physiology. But it's not really worth worrying about. Most people prefer a cadence somewhere between 85 - 95 RPM, and in that narrow range, it's pretty much all the same.
Mike
Mark,
I run several different screens with different fields for different purposes, but I change them around quite a bit and still don't think I've "nailed" it as far as what I want to see on screen at any given time.
My main screen, what I use for general riding is: Time, Speed, Cadence, Power
I think my second screen is my summary screen and is something like: Distance, Average Power, Average Speed, Average HR
My third screen is my interval screen and is something like: Lap Time, Power, Lap HR, Lap Power
My 4th screen I think is just all my instantaneous stuff: Speed, Power, HR, Cadence
My power can still be all over the place, which is why they thought of rolling averages on other devices, but I've gotten better at reading it. Alternatively there are a few things you can do, you can turn your auto-Lap on and set it to something small like a mile, then just keep an eye on your lap power. The problem with this is that I do manual laps to do my EN-style intervals and I don't want it auto-lapping every mile. I really havent' found an ideal solution to this but rather I simply keep tabs on my power, Lap Power, and overall Average Power throughout the course of a ride to determine how hard it is that I am currently and have been working.
@Branan,
I don't disagree with Mike but I think that optimum cadence is something that is unique to each person and their physiology. I've read some claims that suggest that a higher cadence offloads work from your legs to your heart, which when I think about it makes sense to me. It seems to me that heavier more ‘beefy’ riders tend to favor a lower cadence that more heavily utilizes leg musculature where a lighter rider must make up for a lack of raw ability to perform work by increasing the rate at which they perform that work. Personally, I definitely favor higher cadences in general and there are definitely times when a 10 rpm drop or gain in cadence could make a profound difference in my rate of perceived exertion (RPE) to maintain the same wattage.
Having the unit display actual watts will be pretty useless and extremely frustrating. Set it to show you an average over a few seconds. My Garmmin 500 lets me do 3sec average. My Ergomo did it base on crank revolutions but it served the same purpose. This doesn't impact the fidelity of the data being recorded so don't worry.
Therein lies the problem, the 310xt does *not* have any rolling averages, 3 second or otherwise. My personal theory is that Garmin is withholding features in order to artificially differentiate their product line. I.e. if you want 'premium' cycling features go buy an Edge 500, never mind that you already paid several hundred for a 310xt.
Last night (hilly):
Lap 1 (0:51:16.85):
Duration: 51:16
Work: 601 kJ
TSS: 101.9 (intensity factor 1.097)
Norm Power: 232
VI: 1.18
Pw:HR: n/a
Pa:HR: n/a
Distance: 15.126 mi
Elevation Gain: 1629 ft
Elevation Loss: 1623 ft
Grade: 0.0 % (9 ft)
Min Max Avg
Power: 0 598 196 watts
Cadence: 2 108 77 rpm
Speed: 5.7 34.2 17.7 mph
Pace 1:45 10:37 3:23 min/mi
Altitude: 190 488 345 ft
Crank Torque: 0 662 214 lb-in
Last Tuesday (new test):
Selection:
Duration: 42:05
Work: 519 kJ
TSS: 69.8 (intensity factor 0.998)
Norm Power: 211
VI: 1.02
Pw:HR: n/a
Pa:HR: n/a
Distance: 14.851 mi
Elevation Gain: 206 ft
Elevation Loss: 192 ft
Grade: 0.0 % (15 ft)
Min Max Avg
Power: 0 785 206 watts
Cadence: 5 181 81 rpm
Speed: 4.3 25.5 21.1 mph
Pace 2:21 13:60 2:50 min/mi
Altitude: 112 175 142 ft
Crank Torque: 0 797 216 lb-in
Absolutely!!!