June 25, 2019

PowerTap PowerCal


I got a PowerTap PowerCal Dual ANT+/BLE (what a mouthful) recently to use with Zwift. I have a Concept 2 rowing machine and only noticed Zwift because many Concept 2 users were asking for rowing capabilities in Zwift.

Zwift is a virtual biking training environment and requires either a bicycle power meter or a bicycle trainer with speed and cadence sensors. I don't have any of those since I'm not a cyclist and don't plan to be. I tried connecting my Concept 2 rower to Zwift using various hacks and found Zwift to be really fun, but converting the rowing motion to biking just didn't seem right to me, so I tried looking for ways to connect a gym spinning bike to Zwift. After a little research, I discovered that I can simulate a power meter by using the PowerTap PowerCal, so I bought one immediately.

The PowerCal is a heart rate monitor device that works as a power meter by estimating the power / wattage using heart rate and outputs the power reading using ANT+ and BLE. Of course, it's not just a simple conversion formula, but also takes other factors such as how fast heart rate climbs up or drops down and also times of workout since heart rate will creep up as time passes. These are probably done using heart rate variability (HRV) which is the variation between each heart beat.

One quirk of estimating power from heart rate is that normally when you stop pedaling on a bike, your power should be 0, but since your heart can't stop beating estimated power from heart rate would be completely wrong. But the PowerCal formula or maybe it's how HRV works, when you're stopped and heart rate is falling rapidly, the power goes really low or goes to 0. However, it doesn't always go to 0 so it's annoying. Zwift could've implemented a simple software fix that if the cadence sensor is 0 then power should also be 0. Of course, that would require a cadence sensor...

One other issue with the PowerCal is that the power output isn't very stable since heart rate and HRV can't be stable, so workouts in Zwift where you have to maintain a certain wattage is really difficult or impossible to do. The screenshot below shows the result of a pre-programmed workout where I'm supposed to maintain something like 200 W for 5 minutes, then 100 W for 5 minutes. Since I can't really control my heart rate, so even though I did the workout "correctly", the power fluctuated too wildly and Zwift kept prompting me to keep the power within range, and I couldn't receive any stars for the workout.



However, for stable riding such as free riding or even racing, the PowerCal works really well. Since getting the PowerCal a few weeks ago and creating a new Zwift account, I've reached level 13 so far and have ridden up the Alpe du Zwift twice. (I got the Lightweight Meilenstein on the second ride up. Bwahahah! ) Even though I don't have a real power meter to compare my efforts with, my Alpe du Zwift time is 77 minutes and using Strava to look up the overall time from all riders, the time is comparable to my general poor fitness level.

Obviously, the PowerTap PowerCal is no replacement for a real power meter, but it works really well on the spinning bike (or even regular exercise bike) in the gym. Personally I'm not a cyclist and never will be, but I enjoy working out on the spinning bike in the gym for cross training, and using Zwift just adds more fun to it. Without the PowerCal there would be no way for me to use Zwift at all.

Most of the reviews I read on the net say there's no way a power "guesstimator" can be a replacement for a real power meter and give really low marks for the PowerCal. While it is true that you need a real power meter or a trainer for serious training, but for a general user or a beginner who just wants to play with Zwift and doesn't want to invest in a bike and trainer yet, there are no easier or cheaper options. I think it's a really great choice for me since I already have a Concept 2 indoor rower and I already do a lot of running, I just don't have the budget or space to invest in a trainer and a bike that I will never ride outdoors. I think the only professional review that doesn't simply dismiss the PowerCal as completely uselss is DC Rainmaker's review.

Stupidly enough, with all the places saying the PowerCal is not a replacement for a real power meter and that it should not be used with Zwift, the Zwift online store sells it (only the Bluetooth version though, not the dual ANT+/BLE version). Unfortunately, Zwift shop recently changed their policy and doesn't ship internationally any more. And with PowerTap being acquired by SRAM/Quarq the PowerCal's future is bleak.

PowerTap never published the formula for their power estimation , but there is a similar Garmin Connect IQ field called HR to Power that does the same thing by converting the heart rate and recording it into a FIT file. I compared the output between the PowerCal and the HR to Power IQ field and discovered that due to smoothing and compensation for initial lower heart rate when first starting to workout, the HR to Power IQ field actually works much better. But unfortunately since it runs on Garmin watches there's no way to output the power reading.

Maybe it's time to roll my own power guesstimator using a Raspberry Pi.

May 29, 2019

Dark mode


The next version of Android (Q) and iOS (13) all come with something called dark mode or dark theme. I feel so old when I read this. I remember way back when computer monitors were all black with glowing green text. For a while I had a Toshiba laptop with plasma screens that had amber text and it always drew attention whenever I used it. When "active matrix" LCD monitors came out it was said that white backgrounds is more like paper and easier on the eyes. It took me quite a while to get used to the shiny white background, but it was actually such a huge improvement for someone that sites in front of the monitor more than 10 hours a day eventually I got used to the white backgrounds.  However, whenever I need a terminal I still like to have a black TCC/LE terminal or blue PowerShell (actually PowerShell Core is now black too).

Although everything had gone white there are some exceptions, for example Photoshop has always had a dark interface, which I feel is beneficial since it allows focusing on the work. This is the same reason I like having a black Kindle since it makes the text easier to read. But dark mode? Everything is backwards all over again. Since when is black easier on the eyes?

May 4, 2019

iPad mini 5 (2019)

I got the very first iPad years and years ago. I love it but I never bought any of the later iPads mainly because it's just too cumbersome. It's not as convenient as a smart phone that I can take any where and pick up any time, and no matter how much Apple promotes the Pro models, it's not as convenient as having an actual notebook. I kinda like the iPad mini, but I have a Kindle Paperwhite for the ebooks, and never really found any use for a tablet.

However, as I got older I found that I don't really want to stare at my notebook or phone so much any more, and sometimes I don't want to sit in front of the TV. So when the iPad Air 3 and iPad mini 5 came out, I decided to get one again. 10.5" screen on the iPad Air 3 is nice, but I feel a smaller tablet would be more convenient and I could carry it around with me. But my main reasons for getting an iPad: using Zwift when I'm at the gym, watch Netflix without squinting and getting a headache, and play tablet games (ha-ha).

Except for a brief time when I paid for Apple Music around three years ago, It's been more than seven years since I last looked at the App Store, and the first thing I noticed was that all the 99 cents apps have disappeared. Everything costs so much, and since I've used Android these times and paid little attention to the Apple side of things, it's filled with apps that I've never heard of. Some apps in the paid apps section offered me to download them though. I looked and realized I've bought many of them back when I had the first iPad. For example, one of the top paid apps that I already have is Notability for $9.99. I looked and I bought it in 2012 for $0.99.

I decided to check my email archives to re-discover all the stuff I bought back then. It's quite sad to see how many apps have gone dead. I had all these multi-service chat apps that have gone into disuse since everyone have moved onto LINE here in Asia. I even have a game called Starbase Orion that I don't even remember having. I searched and it came to me that it was a 4X game inspired by Master of Orion. The greatest surprise came when I downloaded Starbase Orion and it asked if I want to continue my game.


I looked at Starbase Orion's website and discovered that the single developer never managed to make an Android version, and Starbase Orion 2 is still unfinished due to lack of time. Even though I like to buy games mainly to support the developer but I could never find the time or patience to play them, so I understand how he feels. (Yeah, other bigger games I got for my Android phone include Uciana, another 4X game, and Stardew Valley, both of which I've started playing but got nowhere.)

March 20, 2019

Logitech R500 Laser Presentation Remote

I have the Logitech R400 Laser Presentation Remote and I love it. So when I noticed that the R500 was released I looked for an excuse to get one. Unfortunately, since the R400 is so good, I had a really hard time of coming up with an excuse, until I was driven to the brink of madness by a user who doesn't know the difference between "press" and "hold".

Whenever I let others borrow my R400, they have a really difficult time of figuring out all the buttons. It's just not obvious for some people that the right-pointing arrow button with the bump on it is the next slide button, and the left-pointing arrow button is the previous slide button. And let's not talk about the start/stop slide button and the blank screen button. And with all the keys placed close together they keep accidentally pressing the wrong button and gets totally lost and confused. And as mentioned above, what always drives me crazy is that I like to set my key repeat rate really fast, and they often press and hold the next slide button and end up on the very last page then exits the presentation. Gah!

The R500's three separate, giant buttons really helped with the wrong button problem. The huge button with the right-pointing arrow is instantly obvious that it's for going to the next slide. And to my greatest surprise, the R500 no longer has the repeat button problem. Powerpoint slides will only change when the change slide buttons are pressed and then released. It doesn't change immediately when the buttons are pressed, but rather changes when the buttons are released, and if you realize you made a mistake or changes your mind about changing slide, just keep holding down the button and the press will be canceled. (Note: not true, see paragraph below.) No more accidentally going through multiple slides with a long press. I feel a lot of thought must've gone into designing this feature and after using it for a few minutes it became second nature to me. Unfortunately, as I'm writing this I have a bad feeling that the users will be confused again, especially since the slide change action happens at button release rather than button press.

One other difference is that the R400 sends out PgUp/PgDn keypresses to the computer, while the R500 sends out Left/Right keypresses. A side effect of this change is that when using the R400 to change pages in PDF documents, in can scroll until the very end. The R500 couldn't page down to the very end since the Left/Right keys only changes pages but won't scroll to the very end like PgDn does.

Oh, since the R500 has less physical buttons, the start/stop slide and blank screen functions can only be enabled by installing a driver (Windows / MacOS only) and holding down buttons. But I think for most users the driver installation would be unnecessary and press and hold will only confuse more people. Ooh, I just realized what I wrote above about holding down a button to cancel the press is actually hold down for second function. Yeah, I'm totally sure that so many people will be confused by this. Therefore, installing the driver is totally not recommended.

Even though the USB dongle is now tiny compared to the one on the R400, the R500 supports Bluetooth connectivity which is a really nice plus for computers that no longer have standard USB ports (Macbooks) or for mobile phones. Reviews on the net says there's frequent disconnect with Bluetooth but I had no such problems. Another change is the R500 uses a single AAA battery vs. two on the R400. Probably shorter battery life. Oh, and no power switch on the R500, so if you leave it in your bag, accidental presses could shorten battery life. Another tiny difference is that the laser on the R500 is "less stable" than the R400's. Probably not noticeable for most people, but I noticed with cheap laser pointers or low powered laser pointers, the laser point tends to flicker or drift, and the R500 does this, but as I said, not really noticeable and most people probably can't hold the remote that steadily anyway.

The one drawback I found is that the R500's plastic body and buttons feel really cheap. I don't really care for so called "premium" leather body products, but the R500 just feels cheap in the hand. As for the buttons, if I have to make a comparison, it's as if the R400 has high quality laptop style keyboard keys, while the R500 has cheap calculator keys.

March 17, 2019

Stryd running power meter

I got fed up with my other  foot pods giving me somewhat random readings at times, and I kept hearing good things about the accuracy of the Stryd foot pod, so I decided to get one a few weeks ago. Stryd is supposed to be a running power meter, which as I discovered is not useful for me at all since I live in a completely flat country, plus I'm a really slow runner, and the main reason for having a running power meter is to maintain a constant power when going up or down hill. But I just wanted accurate pace and speed.

The Stryd was heavily advertised and reviewed as having a wireless Qi charger, but mine came with with a USB charging dock instead, but it can also be charged with any standard Qi charger. The Stryd website doesn't really advertise this change, so this took many people by surprise including myself. I also notice the Stryd website has many unlinked products and pages, and their support people will only provide the links as necessary. So you really need to be on their Facebook community as well as the online support forum to get the most out of the Stryd.

My greatest surprise came when I went to use Stryd on the treadmill. Since the main reasons I got the Stryd was my other foot pods just weren't that accurate, but Stryd tells me that I'm running much, much slower than the treadmill's display and by feeling. Again, hidden somewhere on the Stryd website they give an explanation. Strangely enough, the other foot pods give me higher pace and speed compared to the Stryd, more inline with what I'm feeling. But Stryd is more consistent in that when I look at results of my treadmill workouts, graphs from the Stryd is always a constant flat line, while the other foot pods often give jagged lines, most likely due to cadence changes or variations in stride length.


I haven't written to Stryd support about the "slowness" but I suspect they will simply tell me to trust Stryd's pace and speed since it's accurate. And indeed I trust it very much, I've tested Stryd at my local park and local indoor track. The park's running loop is marked at 1.75 km and the indoor track is marked at 412 meters. I get slight variations at the park's loop since there are crowds to avoid and the ground isn't exactly flat, but I get exactly 412 meters at the indoor track, every single time.

Update 1: after reading a discussion on Stryd's forum I discovered the treadmill that I always run on at the gym is inclined at 2%. There are other treadmills which I don't use unless my favorite one is occupied because I found them to be uncomfortable are actually inclined at 3%. (I had originally thought they might be tilted somehow and I was right.) The incline is probably what's causing me to feel that I was running fast but actually going slow.

Update 2: I figured out a really easy way to test and prove to the idiot trainers at the gym that their treadmills aren't level. I have some Chinese hand-exercise balls (no, not Ben Wa Balls!) and simply putting them on the treadmill belt and they'll roll in the direction of the incline and they're much easier to use than spirit level apps on my phone. Anyway, I discovered that the treadmills aren't just inclined, some of them aren't horizontally level (i.e. inclined left/right instead of front/back) which explained why I was feeling leg pain on some days.

November 2, 2018

Windows 10 vs. Helvetica


More than three years after general availability of Windows 10 we finally rolled it out to the users. Well, one reason we didn't roll it out faster was because the big bosses wouldn't buy new computers, so some users got stuck with old computers running Windows XP for ages.

Immediately after setting up the brand spanking new desktops, users came crying that their ERP reports look different than before. I started explaining to them that it's normal since every version of Windows had different fonts and drivers, so even if the same fonts were used it could look slightly different, especially if it was a big jump from XP to 10.

But this time the users pointed out to me that the fonts looked completely different. I looked again and sure enough, printouts from Windows XP had serif fonts, while printouts from Windows 10 were sans-serif. Hmm, this suggested that it could be a font substitution problem. I examined the fonts closer and realized the serif fonts from XP were Tahoma, while Win 10 used Arial.

Now the problem got interesting. There shouldn't be any reason for a type change from Tahoma to Arial, especially if it was a font substitution issue. Upon further inspection of the reports, I realized the ERP reports were all created with the default font Helvetica. I looked at Windows' font substitution setting, and sure enough, Arial is the standard substitution font for Helvetica.

So there lies the big mystery, this suggests that for the past 10 years, all our Windows XP and Windows 7 computers have been substituting Tahoma for Helvetica. While Windows 10 actually fixes the issue and correctly uses Arial? And now I have to put in the wrong value so users get to use the wrong font?