Stryd with wind detection

After the last post I started thinking about calibrating my Stryd on outside runs (also indoor runs). I wrote that I had let it auto-calibrate when I first bought it a few months ago and it was an impressive 100.0, but I hadn't done any calibration recently due to doing most of my runs on the treadmill. Last weekend I finally found some time for an outdoor run and I blasted through what was supposed to be a slow recovery run with a PR. I was so used to running on the treadmill and Stryd giving me a slow speed that when I went running in the park I was going so fast and I kept telling myself to slow down because it was a recovery run, and I still ended up with a PR. And yes, I made sure the Stryd was set to indoor runs only, and the distance was correct because I was running on a marked course in a park.

So after the run ended I decided to calibrate the old Stryd by turning on the auto-calibration function and running the park again. Yeah, I know I'm supposed to do calibrations on a track and run on the line, but the park has markings and I've ran it for years and Stryd used to be perfect on it even at a calibration factor of 100.0. Stupidly enough this time it auto-calibrated itself to 108.0! Now I'm more confused than ever.

But since I had a new Stryd with Wind detection on order at the time, so I thought I would try calibrating everything again when I receive it. It supposedly has better motion sensors so it might be more accurate. Well, I'm disappointed to say that the Wind version reports an even slower speed than the old one. I've manually set the calibration factor to 109.0 for now and will go for a run in the park and let it auto-calibrate after the most recent tropical storms subside.

For now I'll talk about the outer appearances for a bit. My old Stryd is a Model 11 [Rev 3] and the new one is Model 14 [Rev 4]. Rev 3 is the one sold near the end of last year that wasn't packaged with a wireless charger but instead comes with a wired USB charger.

The revision numbers appear to be:
Rev 2: Wireless charging only.
Rev 3: Wireless and USB dock. But doesn't come with wireless charger.
Rev 4: Current wind version. USB dock charging only.

Rev 3 and Rev 4 chargers are identical. One of the deciding factors for buying the new Stryd was whether the charger can be shared. But when I contacted Stryd about this, I couldn't get a straight answer out of them, they kept saying it comes with a charger! You don't need to worry! It comes with a dedicated charger! But it's easier for me if I could share accessories like chargers and cables. Wonder why they couldn't just give me a simple answer.

The "terrace farming" design of the Stryd looks nicer on the new one. I always thought the very top terrace on the old model looked a bit lop-sided. The clip was a little surprising, the old clip is more rounded on the bottom while the new one is completely flat, you can see this from the shadow in the picture. This is quite problematic for me since the new one's flatness digs onto the top of my foot. I'll probably just have to reposition it from the usual location.

Stryd is slow only on the treadmill

I wrote earlier about how the Stryd felt slower when used on the treadmill, but I finally got fed up by everyone telling me that the treadmill display on my gym is wrong and Stryd is right. So I brought out all my foot pods and tested each one multiple times against the Stryd. Before doing the tests I made sure the foot pods were calibrated correctly. The Stryd is uncalibrated and set to 100.0, while other foot pods were auto-calibrated by my Garmin watch by running outside at a flat open area at a consistent pace. (Sidenote: I've tried auto-calibrating my Stryd and it ended up with 100.0 as the calibration factor. Impressive.)

The result? The treadmill display, two MilestonePods (now called Zwift RunPod), two ANT+ foot pods (identical to the Garmin SDM4), my Garmin Forerunner 935 watch alone (using the least accurate method of pace estimation of arm swinging), my perceived exertion level, my heart rate (measured using Polar H10, the Garmin HRM-RUN, or the watch's built-in optical heartrate sensor), comparison with other runners on treadmills next to me using their own watches or foot pods, all ended up having similar speed and pace, while the Stryd is NINE PERCENT (!) slower. One thing that was surprising (or not that surprising) was that the treadmill display was accurate. Surprising because everyone kept telling me not to trust the treadmill display, not surprising because the very first time I ran on it I felt it was accurate (by feeling alone) and before I got the Stryd I've used other foot pods that also reported similar speeds as the treadmill display.

After repeating the test I decided to set the calibration factor of the Stryd to 109.0, and it started giving me the same results as the other devices. The biggest problem with this is that because the Stryd is accurate everywhere except on the treadmill, I have to manually set it to 109.0 for the treadmill and 100.0 when I'm not on the treadmill. Just setting the Stryd to provide speed and distance indoors wouldn't work, since I also run on an indoor track and Stryd is extrememly accurate on the indoor track.

I've been using the Stryd for about seven months before doing the test. Yeah, at first I didn't really care (or know) about it being so much slower. I actually thought the Stryd was more correct than the others, since it gave very consistent results (1% variance) while other foot pods could give me up to 5% variance. And I attributed the slowness to factors such as the treadmill being uneven or lack of fans leading to my body overheating and thus giving false exertion factor. But after I started using Zwift running, I would join group runs or races, it's incredibly annoying to find myself lagging behind everyone else even when I'm running really hard. I tried speeding up the treadmill to my typical outdoor speeds according to Stryd and always felt that it was way too fast for me to keep up or even run safely because the belt was going so scarily fast! In fact, I "cheated" a few times by not running on the treadmill and still have Zwift open on my phone just so I could be faster.

Oh, and also some people said that pace shouldn't matter, only power matters, I also discovered that since power is based on speed, changing the calibration factor to 109.0 also increases power by 9%. Yeah, I was running my butt off on the treadmill, and it was giving me really low power numbers.

The weirdest thing is that my Stryd is completely accurate when not on the treadmill, so I suspect it must be my treadmill running form that's affecting it somehow. Running on the treadmill is really running in place with no actual forward motion, only leg motion and the belt carrying the legs, so I don't know if my Stryd is faulty in that it doesn't sense the "simulated" forward motion, or if it's the belt being softer than ground, but none of these factors can explain why other lesser foot pods are consistent with each other. The original thought of the treadmill being inclined was wrong too, because I managed to find some with 0% incline didn't change anything. Of course, one can argue that only the Stryd is right and everyone else is wrong, but that won't explain my perceived exertion level, and how could everybody all be wrong by the same amount? I realize I didn't actually measure the distance of the belt, so... who knows?

Anyway, I'm happy with the 109.0 setting for now. Zwift needs its own calibration but since the treadmill display is accurate I easily calibrated Zwift by setting the treadmill according to Zwift's calibration prompts. Stryd recently announced an updated model with wind detection and improved next gen motion sensor. I don't really care for wind detection but the new motion sensor sounded useful, so I ordered one immediately. I should be receiving the new Stryd real soon now and I can't wait to test it against the old Stryd on the treadmill.

Update: someone shared my post to the Facebook Stryd Community and started a large discussion, mainly to shoot this post down. I must say I really do like the Stryd but I wish they would do a study on running form across a wider range of amateur runners instead of always blaming it squarely on the treadmill. Anyway I quit my gym membership recently so I no longer have access to a treadmill and I'm back to outdoor running. No more unhappy with Stryd speeds since it's perfect outdoors.

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.

Update: I discovered that because heart rate reacts slower to physical stress it's actually better to set the power display option in Zwift to instant rather than 3 sec avg. This lets the power display react faster and more inline with my actions.

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 or consistent, 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.

Milestone Pod

I'm not a very fast runner so all the new-fangled running dynamics are wasted on me. However, I like having foot pods on my shoes, especially now that I have a new watch that supports linking to multiple sensors of the same type. Meaning I can have one foot pod on each pair of shoe I have. The reason I like foot pods is to get real time pace. As I just said I'm not a fast runner, so getting pace from my watch instead of running "by feel" is much more useful for me.

However, I was no longer able to get cheap foot pods locally, and as the running fad boomed, running accessories got even more expensive than before. But while out looking at running shoes one day, I came across the Milestone Pod. I was a little surprised since I had never heard of the Milestone Pod before seeing it in that store. The box seemed to suggest that it needs a dedicated app, but a quick online search revealed that it can be used as a realtime foot pod using Blueooth. For reference the Milestone Pod is only 1/3 the price of the Garmin SDM4 foot pod locally.

I decided to let my SO have a go at the Milestone Pods since the app is so pretty and has automatic shoe mileage tracking. Unfortunately, in real life the Milestone Pod doesn't work so well with her Fenix 5S. I know the 5S has trouble with sensors, but we never had issues with the older ANT+ foot pods. And some of the trouble I see online seem to suggest that it's due to distance. She's not that tall so I didn't think it would be a problem. Actually, at a indoor track where we often run, the pod wouldn't connect at all. It's probably due to interference from the Bluetooth lap counting system they use, but it's just completely disappointing and I wish I had bought ANT+ foot pods instead.

After a lot of fiddling I decided to swap my ANT+ foot pods with her and I took both of the Milestone Pods for myself. I have the Forerunner 935 which works somewhat better, but I notice even with the 935, a lot of times I look at the pace while running the field is showing blank, and a lot of times after the workout I find the cadence field to be erratic.

Milestone Pod's support people suggest the reason I was having issues was because I used both the Milestone Pod app and my Garmin watch to calibrate the foot pods. They suggest that I should disable the watch's calibration and set the calibration factor to 100.0, and only use the Milestone Pod app to calibrate the pods. Unfortunately, I find the MP app to be unrealiable and it would keep going back and forth between calibration values. On one run it would be way too fast, but after calibration the next run it would be way too slow, rinse and repeat. Finally I decided to delete the app entirely and only rely on the my watch's auto-calibration, which works much, much better for me.

Update: I kept having more and more issues with cadence on the Milestone Pod, until finally the cadence would completely disappear when I pause. However, the Milestone app still records the cadence perfectly. This time the MP support people suggest that the battery may be too low for broadcasting BLE, even though it's still reading medium-high in the app. I decided to change the battery and sure enough, that fixed the cadence problem. I remembered reading somewhere that the MP can eat through batteries, so I checked the official specs and it indeed says four to six months. Also places like Zwift support says battery on the MP may be enough for other devices, but may be too low for Zwift.

So yes, I'm tentatively in love with the Milestone Pod again. But let me go out for a few more runs and see if the new battery works out.

Ultimate Ears Wonderboom

I've wanted to buy new Bluetooth speakers for ages. I rarely have time to sit down to listen to music, but I want something to listen to while working out. Ultimate Ears lowered the prices of speakers recently, so I went online to check them out. The Wonderboom Patches (Freestyle Collection) one caught my eye with the bright colors, and after checking out online reviews I ordered one immediately.

Unfortunately, what the reviews didn't talk about was that colors of the actual Wonderboom is nothing like the colors in the pictures. The colors of the actual product are faded and to me it looks like dirty jeans with printed pictures. I took a picture of the actual speaker and... it turns out that the colors look much nicer in the photograph for some reason. Normally photos will look faded compared to real life, but in this case, the colors stood out and it looks wonderful compared to the real thing.

Yeah, the colors are disappointing but luckily the speaker sounds awesome for the small size and it's helping greatly with my workouts.

Garmin Forerunner 220 foot pods

I've been running (as a form of working out) off and on for the past few years. As an engineer, data analysis is important to me, even if I'm a poor and slow runner. I first started with a Garmin Forerunner 205 to track and analyze my runs a few years ago. The 205 is a "GPS watch" and it relies on GPS signals to track distance and speed. The 205 only works as a GPS and doesn't support linking to "foot pods", which is required for running indoors (no GPS signal) or on a treadmill (no movement).

Of course, at the time I bought the Forerunner 205, I didn't think I would ever run on a treadmill since I don't have one at home and I didn't plan on getting a gym membership. But eventually I realized that I had to run indoors during rainy seasons. Anyway, so I decided to get a Nike SportBand. The SportBand uses a foot pod (placed inside the shoe on specific shoe models or tied to the shoelace using an accessory or duck tape) to measure the foot's movement instead of relying on GPS for movement. So it works both outdoors and indoors, but unlike a GPS, it's not able to map the course of the run, and it needed calibration to the individual in order to be accurate.

A lot of people say the Nike+ system is inaccurate and without calibration it makes most people think they're actually faster than they are, usually by 5% or more. Since I have both the GPS and the Nike+, I discovered that my Nike+ is actually slower than my GPS by about 5%. After calibration I get 99~100% accuracy compared to my the Garmin GPS.

Fast forward to 2014. Recently I finally got tired of using two systems and constantly having to convert my workouts between systems (details in another post), so a few weeks ago I upgraded to a spanking new Forerunner 220 with a foot pod (purchased separately), so I can use one system for both outdoor and indoor runs.

The Garmin Foot Pod (usually called the "SDM4" to distinguish it from generic foot pods) costs way too much locally, but I managed to find Adidas miCoach Stride Sensor locally for half the price of the SDM4. Contrary to popular belief, the miCoach Stride Sensor is available standalone, although I have no idea where it's available online (I searched) as I found it at a local shop. (The miCoach sensor is half the price of the Garmin locally, but only because they sell the Garmin at twice the price they should be selling.)

The Adidas Stride Sensor looks exactly like the Garmin SDM4 Foot Pod, apparently being manufactured by the same manufacturer. They both use the same ANT+ protocol, so they are completely compatible with each other. Strangely enough, it does NOT fit inside the Nike+ hole inside my Nike shoes, despite everything I read on the Internet that the ANT+ sensor is exactly the same size as the Nike+ sensor. But the Garmin / Adidas sensor is microscopically bigger and it does not fit.

(Oh, the Stride Sensor is a different product from the Adidas miCoach SPEED_CELL. The SPEED_CELL has built-in memory and will upload workout information to your computer after the workout without having to have a recording device at the time of the workout. I guess it might also function as a regular foot pod, but I don't have one to try it out.)

Stupidly enough, one thing that caught me completely off guard about the Forerunner 220 and the ANT+ foot pod is that the watch only supports linking to one foot pod at a time. This is unlike the Nike+ system that supports up to 10 sensors. When I was using the Nike+ system, I actually bought one sensor for each pair of shoes I have, so there's no need to swap the sensors. I don't quite understand why I can only link to one ANT+ foot pod on the Garmin. Am I supposed to move the foot pod to whichever shoe I decide to wear before I start my workout? Completely illogical.

Nike LunarGlide+

The Nike LunarGlide+ is out in the stores. The blurrycam is even blurrier this time. Maybe I can use the blurriness as an excuse to get a new phone.





Last one is the women's version.

Nike Air Structure Triax+ 12

Blurry cam strike again!

Apparently this is just called the Nike Air Structure 12 now. They should stop changing names and confusing me. No flywire on this one.

Update: apparently, it's officially called the Zoom Structure Triax+ 12. Oh my.

Nike Air Span+ 6

The Nike Air Span+ 6 showed up in the shops locally eventhough it's supposed to have a February release date. My regular running shoes are the Air Span 4+, and the 6's flywire feels uncomfortable to my hands, but I didn't actually try them on.

Sorry for the blurrycam pics, but I only had my phone with me.

See you in London 2012

The 2008 Beijing Olympics ended after 16 days. The closing ceremonies was as spectacular as the opening ceremonies. I was a bit disappointed that my favorite singer, Stefanie Sun, didn't make an appearance even though she was supposed to. Or maybe she was standing behind all the other megastars.

Congrats to all the athletes! And to all the people that worked hard behind the scenes, a job well done! I know someone who is a military police in Beijing and he worked 24-hour shifts for almost a whole year leading up to the Olympics.

I also know a lot of Chinese and all they seem to know how to do is complain that the added security during Olympics is giving them trouble in bringing foreign snacks back home to China and moan that the government is blowing money away on showing off. In fact, hosting the Olympics brings in huge revenues as well as improving the overall infrastructure of the country. Oh right, the money isn't flowing directly into their pockets.

Baltimore Bullet wins as usual

Wow, just watched Michael Phelps win his eighth gold medal at the 2008 Beijing Olympics. Congrats! Michael broke seven world records at the Olympics this time, and yesterday he beat Milorad Čavić by 1/100 of a second!

Almost (?) all the swimmers at the Olympics are wearing the Speedo LZR RACER. This high tech swimsuit coupled with modern training techniques assure that more records will be broken in the future.

2008 Olympics opening ceremonies

The opening ceremonies of the 2008 Beijing Olympic Games was completely spectacular. I watched it live on TV since there's just an hour's time difference between here and Beijing. I tried to find video clips of the event on YouTube but they were all taken down due to copyright issues. These are some of the pics I found online that I really like. Copyrights belong to their respective owners.

The lighting of the Olympic flame performed by former gymnast Li Ning was awesome. Li Ning was a six medal winner at the 1984 Los Angeles Olympics and after retirement, owner of the sportswear company named after himself. Unfortunately, the harness carrying him didn't seem to be completely in sync with the unscrolling of the images on the video wall in the background. He was going too fast at first, and when they slowed him down it was too slow and the music seemed to end before he reached the flame lighting point. Plus they already had a flying kid with the kite running in the air during the performances.

Later... I found clips of the complete opening ceremony at HiNet and they appear to be viewable from anywhere in the world. Part 1 and Part 2. The same site has shorter clips of the individual performances of the opening ceremony too and clips of competitions that are constantly updated. Check them out!

Flying GPS

Last week I took a whole week off and went on a much needed R&R trip to China. I've always wondered if GPS devices could work in a commercial flight, and this was the perfect opportunity to find out for myself.

My GPS is a Garmin Forerunner 205 which actually a sports GPS, but it could be used as a general purpose GPS for tracking, but not for navigation.

The flight was between Bangkok and Beijing. The distance from take off to landing was 3,511 km and the total flight time was 4.5 hours. Max airspeed was 905 km/h. The yellow line in the image is the actual flight path taken from the Garmin software.