A detailed walkthrough of my 4:30AM 90-minute trainer workout

I’m flying at 41,004ft, headed southeasterly over Nahr az Zab, Iraq with a glaringly bright sun shining into the cabin of my very empty airplane.  But this morning certainly didn’t start out in the sun.  Nope, it started out in the cold and dark.  At 4:04AM when my first alarm went off.  After hitting snooze a few more times, I stumbled downstairs and got on my bike for a 4:30AM start.

I didn’t get as much sleep as I wanted to last night.  I had attempted to go to bed early, but lots of little last minute things kept on pushing that back closer to 11PM.  Then once there I just couldn’t fall asleep for a while.  All in all, only a pitiful 2 hours – with a resting heart rate during that timeframe much higher than I’d normally be (I’m usually between 39 and 42BPM).


Still, time to get the ride done.  With the focus shifting back towards triathlon now, there’s little room for skipping on bike workouts.

It took a minute or so to get the tires pumped back up to the right pressure.  By keeping my tires at exactly the same pressure each time I use the trainer, I can minimize how much time I have to spend re-adjusting resistance during the calibration.  Done correctly, zero adjustment is required post-calibration.


After inflating the tires, I’m good to get on.  The night prior I had arranged everything I needed to minimize time in the morning.  While getting on the trainer sounds simple, in reality there’s a lot more steps once I consider adding in product tests.  Here’s the run-down of prep:

1) All test five bike computers fully charged: 2xEdge 800, 1xEdge 500, 1xO-Synce Navi2Coach, 1xAnother Unit
2) WASP ANT+ to WiFi data logger bridge online and plugged in
3) iPhone dedicated to recording WASP data fully charged, connected to WASP WiFi network
4) Heart rate strap ready to put on, sitting on aerobars
5) Water bottle filled up
6) Nutrition/breakfast on bike (in this case, a banana)
7) Workout instructions printed (in this case, a sheet for that month has been sitting nearby), provided by my Coach, Alan Melvin.
8) Entertainment charged ready to go (oddly, I decided on Pawn Stars, a US TV series about a pawn shop in Las Vegas), headphones attached
9) Fan pulled over and plugged into the dedicated US voltage outlet (my favorite fan isn’t euro-friendly)

After getting on the bike, I pedal for about 30-40 seconds.  Just to get things barely warmed up on the electronics front.  I do an initial calibration of the power meters at this point, just to get things ballparked.  I always calibrate pre-ride, and then again about 10-15 minutes into the ride.  If you don’t do this, you’re power data is probably more or less useless.  Really, it is.  Power meters are getting better in this area (actually, Stages being one of them), and auto-zero helps, but you’d be surprised in the shifts you’ll see otherwise.  You’ve gotta be religious about it. And, religious about understanding if you’ve got a bad calibration value.  Otherwise, that new +20w PR you just set isn’t real.

By calibrating pre-ride I’m setting a baseline based primarily on temperature in the room.  Given my previous ride was outdoors at about 38*F, that’s a big difference to the slightly warmer than normal 74.9*F in the room.  And a quick check of the calibration numbers shows a solid difference between where they left off Saturday afternoon outside, and where they are now.  I’ll get back to calibration in a few minutes.

This morning’s ride has a scheduled time of about 1hr and 30 minutes.  It’ll likely end up a minute or two less.  My trainer rides aren’t based on total time, nor distance, but rather a series of individual blocks that make up a given workout.

In the case of this morning’s workout, it’s got effectively three major components:

1) The warm-up, and then subsequent build (wattage + heart rate build)
2) The main set: 3 x 10 minutes @ a touch under threshold power (actually, it’s probably my current threshold power)
3) Some final sprints, and then cool-down

With everything double and triple checked on the power meter recording front (biggest item is ensuring all sensors are reading and reporting roughly accurate power of data), and my initial calibration done, I’m ready to begin.

The first 10 minutes is just an easy build in intensity.  Nothing structured.  Just build to Z2 by the end of it.  Given I’m still a bit sleepy, I took my time getting to Z2.  Further, I took this opportunity to consume the banana.  Sorry my head is cut-off, the camera was situated more for aero than sitting up.


With the 10 minute warm-up complete, I’m onto some spin-ups.  For about 10 minutes I do 30s (30-seconds) on, 30s easy, building up to 130RPM.  By the end of this, I’m closer to a Z3 heart rate.

While historically I’ve done CompuTrainer calibration at about the 10 minute marker, I’ve noticed (with as many power meters as I have on this bike lately), that I still see some residual drift a touch bit longer than 10 minutes.  So I’ve recently switched to the 20 minute marker, which fits well in between workout segments.  15 minutes might be absolutely perfect calibration-wise, but it doesn’t fit into my workout blocks.

With the CompuTrainer, calibration requires spinning up to 25MPH and then letting it coast down.  Standard spindown/rolldown procedure.  In my case, the numbers are spot on 2.00, so I’m good to go there.  I then move onto calibrating the other three power meters on the bike.  I get off the bike and stand over it, applying no pressure to it.  I start with the PowerTap, validating that the torque shows zero, and that it comes back with a calibration value where I’d expect it to be.  Next up is the Quarq and Stages Power.  I arrange the cranks pointing up and down (required for stages).  I’ll do these at the same time, and both come back quickly with numbers where I’d expect.


For those curious why I’m using a CompuTrainer as opposed to the Wahoo KICKR, it’s not because I enjoy dealing with all the wires.  Instead, at the moment it allows me an additional power meter to compare against during sessions (for power meter testing).  With the Wahoo KICKR I lose the rear wheel, and thus lose the PowerTap in that rear wheel hub.  By using the CompuTrainer with CTANT+, I can send a total of four streams of ANT+ power data over to the WASP, all time-synchronized.  Since the introduction of CompuTrainer ANT+ broadcasting from TrainerRoad this past weekend, I’ll probably switch over to that, just to clean-up things on the software front.  Below, you can see all the power meter streams being recorded (screenshot from last week).  The ‘PPS’ is the number of values being recorded per second from that device (often upwards of 4x that of a typical ANT+ head unit would record).  The screenshot below isn’t 100% real-time, more just for quickly checking sensor connectivity, so there’s some variance expected in this screen.  Interestingly, you can see the temperature (Garmin Tempe’s) and geocaches (Garmin Chirp’s) hanging out. Also an ANT+ weight scale and a bunch of speed/cadence sensors down lower.


With the calibration all set, I’m off to begin the build portion of the workout.  This is sub-divided into three segments.  First is a 3-minute segment into Z3, then two 5-minute segments building up into Z4A and staying in Z4A.  In effect, this is really just a tricky way for my coach to actually add another interval on there without me realizing it (5+5 = 10min, interval length = 10min).  The thing is, I’m onto it.

These three shorter pre-main set segments go well, though I was probably a touch bit behind the curve on attaining the higher heart rates, and thus, higher wattages.  If you look at this section below (highlighted), you’ll see it lags slightly compared to the others.  Additionally, the drop you see prior is because of the calibration.  Ideally that would have been a bit earlier so that I’m carrying through the fatigue of the 10-minutes bordering on Z3 prior to it.  Essentially, I just needed to ramp-up the wattages sooner.


Up until this point in the workout, the workout has been driven by heart rate.  But now is where it switches over to power.  I’ve established a power level for today that will allow me to maintain a given HR zone, and will be utilized for the next 3x10min sections (with a slight reduction offset of 5w).  In this case, that’s 285w per the CT.  If I exceed an upper HR limit that’s set, then I’m to reduce wattage to maintain my HR within the HR zone.  Effectively, a cap, or limiter.

After a two-minute easy spin, it’s into the first set I go.

I swear, the first two minutes of the first set is always the worst.  It’s that point where you know you’ve got a long way to go, and it already sucks.  I find this true whether on the trainer or the outside on the track (running).

Thankfully, by the third minute life is OK again, and I’m just cruising along.  My body has stabilized and I’m good to go.

I’ve got Pawn Stars up on the iPad.  I’d actually never used the Amazon video service thingy before, but decided to check it out, and after failing to find half the shows I wanted to watch on there with any recent episodes, I stumbled into this.  I hadn’t watched it since living in the States last spring.  You can’t just channel surf your way into the Discovery Channel (or TLC?) and watch a few hours of mindless Pawn Stars or Storage Wars over here.


I also had forgot it’s only a 30 minute show.  Or, without commercials as is the case here, 21 minutes.  Thus, I went through 4 of them during the ride.

At any rate, as I’m nearing the 8-minute marker on the first set the CompuTrainer CTANT+ software decides it’s too early to be up.  And crashes.  A first for me.  In doing so, I lose all resistance instantly.  Luckily, I catch it quickly and get it back up and running.  Though, it imparts a non-graphically pretty mark on my otherwise perfect intervals.


I wrap up the set and after a quick 2-minute rest interval, I dive into the next set.  At this point, I’m pretty much on auto-pilot.  Just me, strange things for sale on Pawn Stars, and a relentless trainer which doesn’t budget on the wattage.

Some of you may wonder about aero-position.  I had hoped to have some pics of me and all that jazz, but despite having a 32GB card in the camera I neglected to turn-off the RAW image duplicates, so I burned through that card in just over 20 minutes…leaving you with no photos of me in the main or build sets doing aero.

As far as the gadgets go, for these sections I moved the O-Synce unit up to my desk so I could use my aerobars.  As I’ve noted previously, your arms pretty much wrap right around all this mess on the bars.  Obviously I wouldn’t use this in a race (just the single Barfly in the center), but for capturing data in training that’s fine.


At this point I’m wrapping up my third interval, and thus far they’re looking pretty darn close to each other.  Looking at the intervals, you can see they’re quite close.  And you see a slight increase in average HR for each set.


Finally, with the hard parts done, I’m onto the sprints.  These are fairly straight-forward.  I have four sprints, timed to start every 2 minutes.  It’s 20-seconds on at a high wattage, and then the remainder of that 2-minutes easy.  Normally I’d like these to be closer to 600w+, and instant on/off with the resistance.  But with the way I have the CompuTrainer configured to support the ANT+ power meter testing, it’s difficult to do with CTANT+ because it takes so darn long to manually increase from 100w to 600w.  So it’s a bit wonky.  With something like TrainerRoad I could likely eliminate this issue (note: I don’t generally like using the structured workouts on either platform because it ends up being too much of a mess to maintain/create in the workout creators).  I’ll investigate that for next week though.

This week, they ended up only about 550w before I had to spend 20+ seconds getting back down to 100w (so 20s button pressing + 20s at wattage and 20s desperately trying to reduce the wattage back down).  Not ideal.  It should be 100w one second, and then 600w the next. Boom.


With the sprints done, I’m in the clear.  Just five minutes of easy pedaling.  I usually set it for 100w for easy pedaling and/or any rest intervals.  Just a simple number to get to, whether on the CompuTrainer or the KICKR.

So how does the breakdown then look at the end of the workout?  Well, you can see how things are generally in one of two camps.  Either easy (around 100w), which is my initial warm-up, my cool-down, and the rest intervals (2-3 minutes), and then a bit of a gap, followed by the work intervals between in the 250-325w range.  Because of the way power meters record, you’re not going to see a perfect 281w for the blocks, rather, it’s going to be splattered all around those points, hence why I have three large blocks in that rough region.



And, another way of looking at it.


With the workout done, I’m roughly on schedule time-wise to get the airport.  I had aimed to be done about 6:00AM, and given the setup and what not it’s just after, at 6:05AM.

A quick shower and I’m more or less ready to go by about 6:20AM.  Plenty of time until my 8:15AM flight out of Paris Orly.  I took a couple extra minutes before leaving the house to get all the data downloaded from all the units, so I wouldn’t have to drag nearly half a dozen GPS units through airport security checkpoints repeatedly for the next 4 days.

From there I headed out into the cold and still dark Paris streets.  Two days ago it would have been light out.  With our time change yesterday though, no luck.  Given the national holiday today, it’s completely deserted.  Save for the newly added graffiti on the green boxes that arrived overnight.  Who tags on Easter?  No worries, it’ll be gone within a few days.  The city is lightening quick in this area with removing it.


A hundred or so meters away I find taxis hanging out at the taxi stand.  I love the taxi line, always there, always taxis.  Had I a bit more time I would have just taken the train, but this early in the morning and on a holiday the schedules are sometimes funky.


A short 20 minute ride later and I’m at the (empty) airport.


Flying in and out of Orly is like flying in and out of Washington National in DC.  Close to the city, quickly through security, and virtually no distance to walk.  From the drop-off point through customs and security to my gate it takes me roughly 4 minutes.  Beautiful.  Compared to CDG, it’s more like Dulles. Generally a mess in every respect.

By 7:45AM I’m seated on my first flight of the day, a quick hop up to London before connecting on my long-haul wide body airplane.


And now, I’m ready to sleep, and it’s only 8:45AM.

More from my next destination tomorrow…

Thanks for reading!


Hopefully, you found this post useful. The website is really a labor of love, so please consider becoming a DC RAINMAKER Supporter. This gets you an ad-free experience, and access to our (mostly) bi-monthly behind-the-scenes video series of “Shed Talkin’”.

Support DCRainMaker - Shop on Amazon

Otherwise, perhaps consider using the below link if shopping on Amazon. As an Amazon Associate, I earn from qualifying purchases. It doesn’t cost you anything extra, but your purchases help support this website a lot. It could simply be buying toilet paper, or this pizza oven we use and love.


Post a Comment

Your email address will not be published. Required fields are marked.
If you would like a profile picture, simply register at Gravatar, which works here on DCR and across the web.

Click here to Subscribe without commenting

Add a picture



  1. Hubert

    Really courageous to wake up so early!
    Marathon of Paris is coming soon, get some rest :-)

  2. Daniel Calo

    one question : how did you manage to ride on the trainer so early without making a lot of noise and waking everybody ?

    • Mark

      I bet his neighbors hate him. =)

    • DC Rainmaker

      Fear not, no neighbors. :)

      We’re kinda lucky actually. We’re on the 5th/6th floor (well, 6th/7th depending on how you count it), which is the top of the building. There are no buildings that high on one side, and the other has a stairwell attached to us.

      Below us is a seasonal rental, and nobody is around right now. Though, our apartment is a beast when it comes to soundproofing. We’ve never heard a single peep from anyone below or next to us. About the only thing that we hear at the bells from the church and the never ending pigeons that dance on our tin rooftop early in the morning…

  3. Duane

    Glad to know I’m not the only one who does early morning trainer sessions. I’ll be doing it a lot less often now that Spring has come, but over the Winter I did this at least once a week. I find the hardest part is getting warmed up and settling into that first hard set, but the quality overall has been better than evening trainer sessions.

  4. Tim

    What gadget and app was used to record the RHR and other data in the first screenshot?

  5. Amedeo

    a morning like this proves you are really an Ironman! :-)

  6. kate

    I have the same question as Tim re: gadget and app used to record RHR and the platform for the first screenshot image in the blog post. Thanks much!

  7. Jackson

    These posts are great and inspire people like me – Thank you for posting!

  8. You mention that the Stages meter is getting better. Is it reliable enough for use yet or does it still change too much?

  9. Paul

    I had to stop using CTAnt+, as it crashed on me about 50% of the time, and this was on a new, powerful, Windows7 computer dedicated to the CT (NOTHING running on it, not even anti-virus, etc.). Happened with old CT Coaching software, new RM1, and ErgVideo. Tried contacting the developer 3 times, never got a response, so finally gave up. Yet another reason to give up on the CT… will try Kickr next winter.

    • DC Rainmaker

      Yeah, the only reason I use the CT lately is just for the additional power meter data stream for testing. Can’t wait to swing back to the KICKR.

  10. Harrison

    I love the setup around the bike, between the various GPS units, the tablet, and computer.

    Seeing the posts with a tablet displaying data really makes me want one. I usually run my entertainment through my laptop to the TV (race footage), a metronome for a cadence, and a small whiteboard with the workout.

  11. Satish

    Hi. I love your blog! Keep up the good work! A question about how you zero the powertap on the trainer: do you do it with the resistance unit applied to the rear wheel or unclamped?

    • DC Rainmaker

      I have the resistance unit applied. The key is ensuring the torque value shows zero. In doing so, I’m able to get the 4 PM’s to agree (within slight variations based on different measurement points).

  12. FDS

    Regarding calibration, I am on a similar system that requires spinning up to 24ish mph and spinning down. For a smaller woman this is not a very easy speed to reach on the trainer, and if I reach it once and calibration doesn’t work, there is no way I can repeat the process multiple times to make sure everything is properly calibrated (my boyfriend has no such issues). I’m wondering if this is an issue for your wife too, and if you have any recommendations to get around it or know of folks working on a solution that doesn’t require this degree of spin-up?

    • DC Rainmaker

      For most trainer platforms I’ve used that require the spindown system, the actual load is usually very light. However, your gearing in certain situations may make it more difficult than others.

      To make it easier, spin in the gear that produces the highest speeds. You can toy around, but typically it’s the big ring in the front, and the little ring in the back. That does take slightly more effort, but since you’re after speed, you’ll have a much higher speed than a little ring in the front/big in the back.

  13. Stephan

    So does the spin-down calibration process not rely on anything but the devices perception of the speed? Therefore you can (as you referenced) just use a gear that gets you into that range, even if it’s very easy? I have the PowerTap Pro.

    Speaking of which…would you recommend calibrating that each ride? I recently calibrated it, but still felt like the power was then very far off (felt way too easy to me). Also…it always spits out 255 RPM to my Garmin Edge 500, and doesn’t change? Ever seen that?

    • Stephan

      *Edit* I meant PowerBeam Pro.

    • 255 is the value to indicate unsuported. I am supprised the Edge is not recognising it as such.

    • DC Rainmaker

      Correct, purely speed. It’s merely measuring the resistance of the wheel pressure (tire pressure + rolling resistance + clamp-on pressure). It does this by determining how long it takes to coast between two speed points.

      I definitely recommend calibrating every ride. As noted, I do it pre-ride, and then at the 10-20 minute marker (per the procedure above).

      255 as Ifor noted means something is up. Consider updating the firmware on your PowerTap, or giving the CycleOps Customer Service folks a quick ring (they’re among the best out there for CS).

  14. I had no idea the Powertab G3 needs frequent recalibration…
    I did not calibrate mine since the initial use and never had weird powerdata…

  15. Thor R

    Loving all the multi-boards (power strips) and the double stacked plugs; that’s the sign of a true test lab environment! ;-)

  16. John S.

    I take it that Garmin has yet to fix the issue with collecting/recording power meter data for the 510 and 810?

  17. Josh Yko

    You are the freakest freak ever. Totally insane. You are ill !!

  18. Tim

    How much of a zero offset shift do you notice on the powertap (before and after warmup)? I have auto-zero on, but on the trainer that will likely not kick in unless I intend for it to.

    From my use of 2 PowerTap training wheels I personally haven’t noticed much of a shift from cold to warmed up (assuming sitting on the trainer in a cool basement the whole time)

  19. Jacov

    Stephan, I was also wondering about the strange cadence of 255 I get, especially when using my Cycleops HR/Power strap.

    Ray, you should seriously have a look at Perfpro Studio. It has ANT+ capability included (and lots of other cool things, such as sending your Computrainer data back to an ANT+ device using a second ANT dongle in your computer). Programming Computrainer workouts is a breeze. It has never crashed on me on an old pentium computer running windows XP. Includes an auto-pause calibration setting. You can also probably set up your additional power meters as ‘stationary bikes’ and record all the data to one place and see it live on your computer screen. And finally, the included Analyzer software shows your data in zones/ graphs/ numbers in any way you can dream up!

  20. Anon

    What iphone app is that in the screenshot showing the two temperature sensors and four power meters? If anyone could tell me what apps can read multiple power meters at once, I will be grateful.

  21. Paul

    ok, so you’ve been asked about keeping the noise down for neighbours, which you fortunately don’t really have any and from your posts I know your better half trains as well, but surely she wasn’t up at 4:00 a.m. training as well.

    Any tips on keeping the trainer noise to a minimum as to not disturb your sleeping beauty?

    • DC Rainmaker

      The walls are so think that we literally can’t hear it even in the next room. It’s crazy. Even sitting in the kitchen 5 meters away, there’s no sounds with the door closed. So with the bedroom upstairs, no issues at all.

  22. psywiped

    Just got my Kickr yesterday and was amazed at how quiet it was, I think the boxfan I was using for cooling was making more noise.

  23. Jen B

    I love this sentence……makes me feel better, except I generally think this for more than 2 minutes ;-)

    “I swear, the first two minutes of the first set is always the worst. It’s that point where you know you’ve got a long way to go, and it already sucks.”

    Can you make a post about the wasp?

    • DC Rainmaker

      Yup, I’ll definitely be posting about the WASP. Probably not so much a product review, as more of a ‘here’s how it works’. It’s not something they’re looking to sell as a consumer product, but it’s targeted more towards companies looking to leverage it in various solutions. For example, the WASP is used within health clubs to do large-scale spin-class data consolidation.

      That said, I think it’s cool enough to show off, and I think that perhaps there’s a market that’s untapped for a consumer variant.

  24. Eli

    I’m confused with the PPS numbers from the power meters. The power meters should be sending Ant packets at approximately 4.0049Hz so I’d expect the PPS number to be ~4. The screenshot makes it seem like it is receiving less packets then the power meters are broadcasting which means some packets are being dropped.

    BTW how accurate is the RSSI data to approximate how far a device is from the Ant receiver? (Its supposed to indicate signal strength so the farther the sensor is the weaker the signal)

    • DC Rainmaker

      Hmm, I’m seeing varying rates by different power meters, though the rate changes over the course of the ride. I get within the recorded file the average of all data points for that one-second, per metric recorded.

      I’ll ask why there’s a difference. I had wondered about the RSSI aspect, and will do some tests. In this case, the WASP is sitting at the base of my front wheel.

  25. …and The Girl didn’t wake up? You mean that if I would buy a trainer and ride in my living room while my wife is sleeping, the trainer is silent enough that she wouldn’t wake up and kill me?

  26. Champ

    Rey, what do you use to monitor your HR during your sleep?

  27. Jacov

    I’ve been playing around with the Computrainer calibration – I’ve seen before somewhere mentioned that a benefit of a hometrainer tire is better stability with calibration numbers. I’ve been testing out my gatorskins vs hometrainer tire on different wheels. I’ve found that it definitely does make a difference with the time it takes to get a stable roll-down resistance and it stays constant the whole ride. (I usually calibrate at 9 minutes, and then sometimes test at different points in the ride and at the end.)

    Obviously that doesn’t help too much when you’re wanting to use the same wheel indoors and outdoors :-(

  28. Tom Nichols

    ” I always calibrate pre-ride, and then again about 10-15 minutes into the ride. If you don’t do this, you’re power data is probably more or less useless. Really, it is.”

    Is this just a trainer issue? Do you do this on all of your outdoor rides? Events? I always calibrate before a ride, but never during. Maybe I’m just fried from a long day and am not comprehending why this is the case.

    • DC Rainmaker

      Nope, both indoor and outdoor. Most PM’s are sensitive to temperature changes, with only a handful having temperature compensation these days (Power2Max, Stages PM). So as the temperature changes, the offset does not.

    • Eli

      So is it correct to say in the generic sense the calibration for each ride is mostly to deal with the temp changing? Autozeroing wouldn’t be enough for how things change as the temp changes? Going by link to cycleops.com it seems like the old powertaps (those instructions are from the pre ant days) only did zeroing of power. But then a powermeter like stages can’t be calibrated like that as weight is still on the pedals while coasting.

      Looks like if you can get a display that can show torque from the PM there is a calculator to see how accurate the PM is for a static load: link to cyclepowermeters.com

    • Eli

      Also thinking that if change in temp causes the PM to need to be recalibrated it would seem like head units that have a way to measure temp could have a feature where they prompt the user to recalibrate if temp changed by more the x degrees. Maybe instead of the device saying auto pause when coming to a stop it could say that with some ability to do a calibration (i.e. do it while you’re pausing for some other reason)

    • DC Rainmaker

      PM’s like Stages and Power2Max are doing continual temp compensation. PowerTap does it when you autozero, but note that won’t happen during long climbs, because you won’t ever coast.

  29. How much pressure you put on the wheels when you use the trainer? thanks in advance!

    • DC Rainmaker

      There’s no set number per se from a ‘turns’ standpoint, as that will vary wheel to wheel. But, I start with it snug enough that if I hold the flywheel and then hold my rear wheel, I shouldn’t be able to make them slide if I turn them in opposite directions. No squeaking! This generally gets me at about 2.50 for the initial calibration value, but that will decrease quickly as it warms up (over 10-15 minutes).

      Post-calibration on the CompuTrainer I try and get to 2.00 for the roll-down value. Technically 1.80 to 2.20 is acceptable, but I really aim for 2.00.

  30. Mariano Kamp


    I have a power tap and there was no documentation whatsoever regarding calibration in the package. So I didn’t even know I needed to do it before I read this post.

    It would be great if you could write an article explaining how the calibration works and what your protocol is.

    • DC Rainmaker

      It’s actually something I’m working on. :)

      In short, for PowerTap my procedure is:

      Pre-ride: Standing over bike holding bike but not sitting on it. Manually calibrate via menu from bike head unit (it should return a zero offset value when complete). It doesn’t matter what that number is, you’re just looking for change to that number over time.

      About 10-15 minutes in: Stop and do the same again.

      Now, you can always use auto-zero, but that only works if you coast (for the PowerTap). So for example, if I do a 90 minute climb (as I did a few weeks ago), there was no coasting, thus significant drift.