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Part of Saturday’s ride analyzed in great depth.

Monday, April 14, 2014 by  
Filed under Daily Blog


Fair warning: I’m going to geek out a bit this morning. Specifically, I want to analyze part of a ride I did on Saturday, so I’ll be bringing up stuff like power, watts, Functional Threshold Power (FTP), watts/kg, 8-minute test, VirtualPower, power meters and so on.

For information on all of those terms and a basic primer on training with power, please see my article “Coggan’s Power Based Training“.

You can also check out my indoor bike training center (not-so-affectionately known as my “Bike Torture Chamber”) here. If you’re interested in taking your cycling training to the next level, my BTC article has all the information you need to get started, including plenty of photos and links to all the equipment I use in my BTC.

With that out of the way, let’s proceed to Geekville…

On Saturday morning I did a group ride with the Crazies. The scheduled ride was a short 61 kilometer/38 mile route. I was looking for a few more miles than that, so I met up with my friend William at Kelly Park and we rode to and from the group ride together. That extra distance put me closer to 100 kilometers/60 miles, which is about what I wanted for the day.

Because it was a short route, and considering some of the cyclists I knew would be on the ride, I expected there to be some fun attacks along the way. I was looking forward to that. πŸ™‚

When we reached Wiygul, which is a remote and sparsely trafficked ~6.4 kilometer/4 mile country road, suddenly Daniel Cleaver broke from the paceline! I had no way of knowing this at the time, but as it turns out Daniel was doing some training intervals. Anyway, the temptation was too much for me, and I peeled off and chased Daniel down. I actually hit a new wattage output personal record (as measured by my Stages power meter) during that initial chase, peaking at over 1,000 watts.

Once Daniel backed off (again, I didn’t know this at the time, but he was doing intervals), I decided to keep going. I knew the road was long enough to get a full 8 minutes of hard riding in, and I thought it would be cool to see what my FTP was using the Stages power meter on an actual outdoor ride.

Here’s the 8-minute section of my ride that I used for my impromptu and informal FTP test (click to enlarge):

This is the 8-minute section of Saturday's ~100 kilometer ride that I used to estimate my FTP using my Stages Cycling power meter. My average wattage output was 327, and my peak wattage output was 1,001.

This is the 8-minute section of Saturday’s ~100 kilometer ride that I used to estimate my FTP using my Stages Cycling power meter. My average wattage output was 327, and my peak wattage output was 1,001.


I’ve penned a few articles about how much Strava has evolved beyond timed segments (you can find those, and much more, in the Articles section of this site), and some of their Premium features are extremely useful training/data crunching tools–particularly to cyclists with power meters.

One of the very cool features available to Strava Premium members is their set of post-ride analysis tools. Of particular interest to users of power meters is Strava’s awesome power curve feature. This tool allows users to check out their peak average wattage outputs for any given length of time (among other things), and even compare those results to a user-definable range of dates.

Using this tool, I was able to quickly and easily determine my peak 8-minute wattage output (click to enlarge):

Power curve from Saturday's ~100 kilometer ride: maximum 8 minute power output shown.

Power curve from Saturday’s ~100 kilometer ride: maximum 8 minute power output shown.


Okay, so let’s crunch some of this data!

My peak 8-minute wattage output was 326. FTP is estimated by multiplying the 8-minute wattage output by 0.90, which gives me an estimated FTP of 293. My current weight is 72.3 kilograms (159.4 pounds), so that’s a 1 hour FTP/kg of 4.05.

Note that the official 8-minute FTP test includes two 8-minute intervals. The simple formula is:

FTP = ((P1 + P2) / 2 * .9)

…where P1 and P2 are the average power outputs from each 8-minute interval.

When I do my “formal” FTP test on the trainer this week, this is the formula that will be used. In practice I’ve never deviated more than a percent or two between the two 8-minute intervals, so I think my result on Saturday is worthy of note.

My highest previous FTP was measured to be 294 watts, but that was using TrainerRoad’s VirtualPower and not a real power meter. I recently performed a series of tests between VirtualPower and the Stages Cycling power meter, and found that TrainerRoad’s VirtualPower (using my equipment) was about 12% higher than my Stages Cycling power meter. I disclosed and analyzed my test data in two articles: here’s Part I and here’s Part II.

So, based on that ride on Saturday and the above mentioned tests, I estimate that my FTP using VirtualPower would be around 329. That’s a huge improvement over my previous best of 294 (again, which was measured using VirtualPower).

I’m very excited about performing the actual FTP test on trainer with my Stages power meter to see how the actual numbers stack up to my outdoor ride. I’ll be doing that test sometime this week.

One last tidbit. My peak 5-minute power output from that ride is of interest, as I like to track improvements there, too (click to enlarge):

Power curve from Saturday's ~100 kilometer ride: maximum 5 minute power output shown.

Power curve from Saturday’s ~100 kilometer ride: maximum 5 minute power output shown.


My peak 5 minute wattage output was 332 watts, which gives me a 5 minute watts/kg of 4.60.

My previous best 5-minute watts/kg was 4.24, but that was measured using VirtualPower (about 12% higher than power measured using my Stages power meter). So, apples to apples, I estimate that using VirtualPower I’m around a 5.15 watt/kg 5-minute output.

Either way, I definitely rode personal best 8-minute and 5-minute PRs on Saturday, and have moved into the lower end of Cat 2/upper end of Cat 3 on this wattage chart using my latest 5-minute peak output (click to enlarge):


I’m lighter and more powerful than ever before. These are nice improvements, and exactly what I set out to do when I started my 2014 cut in early January. As I progress with my training, these numbers are only going to get better. I want my 5-minute watts/kg above 5 this season (measured using the Stages), which gets me into Cat 1 territory.

John Stone Fitness Comments

3 Responses to “Part of Saturday’s ride analyzed in great depth.”
  1. John, when you were really into weight lifting *I* got really into weight lifting and bought my own power rack etc and lifted a lot. Now that you have gotten really into biking, you almost single handedly now have me deciding to upgrade my bike and seriously considering whether aluminum with 105 components is ‘good enough’ or if I want to spend big and get whole carbon + dura ace di2 .

    Two important lessons for me.

    #1) Your blog is expensive for me to follow
    #2) I’m the worst kind of pathetic groupie.

    GD Star Rating
      • You have no idea. Although I’ve never been successful from an aesthetic point of view (getting cut or shredded), my performance / strength / endurance / daily capability and just plain day to day living have improved tremendously from my World of Warcraft days (vs say your weed days).

        I fight competitive Judo tournaments, enjoy biking/walking and just generally being much more active. If I could lay off the bad food I could look great too, but one hurdle at a time πŸ™‚

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