On Bicycles, and.... what else is there?

Fulfilling a long-term promise, the Garmin Vector now does pedalstroke analysis! See DC Rainmaker's excellent blog post on the latest firmware update. The new metrics include: pedal force offset: this measures how far outboard or inboard the average force is applied. pedal power stroke: this measures over which angles peak propulsive force is applied seated versus standing time: if you're standing, the pedals support full body weight (non-propulsive), so the Vector can determine how much time you're standing versus sitting (and record whether you're standing or sitting). Various applications for these metrics would be bike fit, technique analysis, and interpretation of performance. For the pedal force offset, that obviously suggests a bike fit application. "Power stroke" suggests both fit and technique. Standing versus seating suggests performance analysis: am I faster seated or standing on short steep climbs? What about long sustained climbs? More d...

After the last comparison, which was a ride with some steep hills in San Francisco, I did a few more rides comparing Vector to Powertap. On that previous ride, my maximal power curve had been somewhat depressed on the Vector. Further investigation showed it appeared to be due to two points where cadence anomalously dropped on the Vector (but not the Powertap). Since Vector multiplied force by cadence by crank length to get power, if any of the three is off, the power is off. The first of these two rides was a spin around Mountain View at lunch, stopping along the way to drop a package at the post office, then pick up some cherries at the local market (Ava's), then after a bit of a loop, a stop at Trader Joe's for figs and apricots. I made good use of my handlebar bag, combing some solid power efforts with fresh summer fruit for the afternoon. Here's the maximal power curve from that ride: The next day I rode into work with SF2G, the Dawn of the Dead variant of Bayway....

Last time I compared Powertap to Vector on my Winter Allaban, I had failed to properly set the crank length on the Garmin 800. I'd set it on the Vector, but the menu item on the Garmin is a bit tricky to find, as it only appears when it is in communication with a Vector, so if you scan the menus without activating the Vector and pairing the Edge to the Vector you'll never see it, as I did not. I actually first confirmed my Edge was asserting the wrong cranklength by running the settings.fit file through fitdump. But this is a digression. I basically repeated my first calibration ride, heading steep 14th Street to Buena Vista in San Francisco and doing one-legged climbing on a more gradual grade, then riding home and doing a sprint. I previously did three comparisons where the maximal power curves of the Powertap and Vector were remarkably coincident after I scaled one of the powers by an empirically determined factor close to the 85% value which I later discovered was the r...

The plot thickens... Another day, another ride. This time I made sure to do a static zero test before the ride. I further checked that I had the latest firmware in my Edge units (Mac WebUpdater says I did). I was full of hope that the crank length fix had corrected things. So I set off on a ride to fetch new contact lenses, but where I took "scenic detours" up five significantly steep, significantly painful climbs in San Francisco. For the record: 17th from Market to Twin Peaks (and on to Twin Peaks summit), Sanchez from 17th to 18th, Church from 18th to 21st, 21st from Church to Sanchez (these two are contiguous, but I took a break in between, not initially planning to ride 21st, which is daunting), and finally, just because I felt like I could, the ever-painful 22nd from Vermont to Carolina. No luck. My suspicion now is that the head unit is overriding the crank length setting. Issue is I don't know how to change the crank length in the head units. In the 510 ...

Last time I did a comparison of my Powertap versus Vector. I'd had strong reason to believe the Vector was reporting low, and the test confirmed it. The maximal power curves lined up fairly nicely when I multiplied the Vector power by 0.84 (emphasis on fit to high powers). Since the Vector should measure more power than the Powertap, this indicated an error somewhat greater than this. You'd expect the Vector to measure more power, because the Vector power includes power which doesn't make it to the rear hub and is instead lost in the drivetrain. This power loss includes losses which are proportional to load (like bending the chain under a high-tension state at the top of the run) and losses which are independent of load (like spinning the pulleys). The result is that drive train losses, as a fraction of total power, are higher at lower powers than higher powers. What I saw was consistent with this, which was a good sign. The obvious candidate was that I'd not inse...

On my relatively new randonneuring bike, which got its first serious long-distance test in the Memorial Day Ride (MDR) this past week, I've been using Garmin Vector Pedals I was lucky enough to get. The Garmin Vector, of course, offers the advantage of "true" left-right power, since it is effectively two independent power meters, one for the left, one for the right. But even though I've had the pedals on there for awhile, I've been ignoring the power data. I didn't trust it. It's not that I didn't think the Vector is a good product, but rather I didn't trust the installation decision I made to not install any washers. Of course, I could have just added the washers, but that would lose interesting data. I wanted to do a direct comparison with Powertap to quantify what the reduction in power, if any, was. Being generally lazy about this sort of thing, I procrastinated... until today. In this post I compared power data versus climbing rate on ...

Yesterday, full of self-loathing, I sat addicted to my laptop watching the final 45 km of Liege-Bastogne-Liege. I can't help it. I'm addicted. But the spring classics are done now, right? I'm free, right? I'll be able to resist the daily lure of the Giro, right? Sigh. But it was an exciting finish. Caruso and Pozzovivo got a gap which looked like it might just hold... then Daniel Martin of Garmin-Sharp, last year's winner, bridged up, passing the weaker Pozzovivo and just about reaching Caruso. One more corner, then 300 meters to the repeat victory... But amazingly, he crashed in the corner. Jonathan Vaughters, his manager, reacted: Heartbreak. — Jonathan Vaughters (@Vaughters) April 27, 2014 Here's the video on YouTube . As reported by CyclingNews , Daniel's post-race comments were: “It’s one thing to make a mistake or know what you’ve done but we figure that there’s a patch of oil or something. I think I had tears in my eyes before I even h...

In Dec 2011 I compared Strava power estimates to Powertap measurements for the Cortland Hurl , a previously popular climb for SF2G . Unfortunately the Hurl has gone out of favor with the Google riders, but recently I did a ride with a leisurely spin up the climb, which has been an occasional fitness test for me. New to the ride was my use of Garmin Vector, mounted on my heavy (10.5 kg) Winter Allaban. You'd expect a relatively high watts at a given VAM with the big bike with fat tires at relatively low pressure. So I was curious to see how the watts I reported on the climb compared to my previous trend. Here's the result: The data are sparse, and it would have been a lot better had my Vector ride been at a higher VAM. But it is strongly compelling that the Vector is reading low. The Strava estimates are certainly low in particular due to an underestimation of mass. The Strava method of asking for "bike weight" and "rider weight" omits the weight of eq...

I've seen blogs where people just post their power numbers week after week. It gets quite dull. I'm risking making the same mistake here. But I started this blog as sort of a depository for whatever I find interesting, and this was sort of interesting. I took a break from running this week to give my legs a chance to recover from the Lake Chabot 30 km trail run. But I've been seriously craving cycling, especially riding to work in the morning (75 km), and this week gave me an opportunity to get a few SF2G rides in. I have gotten comments from 2 independent sources that 75 km commutes aren't "recovery". But riding at my commute pace, while fatiguing, is much less traumatic than running. And getting some endurance work in should keep my metabolism pointed in the right direction. It's a small gamble, but then I do miss riding, and need to get my little fix before starting another running ramp to the shining goal of the Woodside Ramble 50 km trail ru...

Recently I've been experimenting with the Garmin Vector pedals, which measure L-R power balance. I've long been curious about L-R balance. How symmetric am I? How does the symmetry vary with different conditions? What I've not done yet is to validate the pedals against my Powertap. One reason for this is I'm out of 357 batteries. I ordered a pack of 20 via Amazon for $3. $3??? That's cheaper than a pair at Walgreens. I'm not sure what I'm going to do with twenty 357 batteries. Anyway, on the Vector, I've had a few issues. One was an anomolous 1-second right-foot-only power spike of 900 watts. I've not looked into whether this was a torque or cadence anomaly. The other was when I was carrying my bike off the train and accidentally slammed the pedal into a metal column. That wasn't a good thing, but it's neither the first or the last time I'll do such a thing. For that ride, the Edge 800 was reporting no left pedal data. Bu...

After putting a box of kitty litter on my pedal wrench to precision-torque a pair of Garmin Vectors, then replacing one of the batteries (which was dead), I was ready to roll. The goal was to ride over to Sports Basement in the Presidio, from where I was going to do the gorgeous run to Sutro Baths and back. It turned out to be a bit more of an adventure than I'd anticipated, including scaling this staircase out of Baker Beach. I don't recommend it, since it ends at private property, presently under construction. The Sutro Baths were spectacular, however: Here's the full thing, with an 800 meter distance shortfall due to my GPS crapping out on me and Strava interpolating a straight line through a very nonstraight trajectory. I love the instant upload from the Strava iPhone app, but the Garmin Forerunner 610 is likely more reliable. This capped off a 103 km running week for me. That's a personal record. That risks being excessive. Less than one week to m...

On the subject of pedals... I like Speedplay and have used them for more years than I like to admit. They're light, simple, have a low stack height, easy to clip into, compact, and double-sided (wait, that's implicit with "easy to clip into"), and works fine with standard street shoes (I'm not always wearing cycling shoes). But they don't handle dirt well and the cleats are not compatible with walking. These are okay issues for many bike races, where you clip and go, but for other types of riding, being able to walk gets a higher priority. That's where mountain bike pedals come in. Speedplay came out with a mountain bike pedal, the Frog. But it shares only a few of the assets of the road pedal. It's heavy, clunky, has a large stack height, isn't so easy to clip into (it has a phantom clip-in mode so you need to verify engagement once you feel a click), and doesn't work well with street shoes. So Speedplay announced the Syzr at Interbike in...

Favorite pro racing helmet POC. I really like the design concept: to make a helmet which is race-light but goes beyond the minimal standards of the usual tests. It puts material on the temples and lower back of the head where it will do some good, avoids sharp angles which could twist the head and contribute to concussions, and it comes available in an orange color which flaunts fashion in the name of visibility. Plus it's round, which should fit my head, although I have yet to see one let alone try one on. Favorite pro racing bike frame Not counting fit issues, it has to be the Cervelo R5. In particular, the R5-CA, but the R5 is close enough to have some of the credit for that $10k frame to rub off. The Cervelo white paper on the R5-CA design is really extraordinary: a wonderful balancing of aerodynamics, stiffness where it's wanted (not where it's not), and light mass. I'm not sure about the head tubes, but if the bike fits you... BTW, I also like the Cann...

When I got fit at 3D Bike Fit , it was recommended I switch from Speedplay to Shimano pedals due to the more stable platform and greater resistance to pedal wear. I gave these a try, and indeed the feeling of connectedness was palpable. I expected to feel claustrophobic, accustomed to the freedom of Speedplay's rotational float over many years, but with Kevin Bailey's expert cleat placement, my foot was where it wanted to be and there was no need for it to be anywhere else. As long as I didn't think about the fact my foot was constrained, I was fine. And the pedals were light (248.0 grams on my scale), especially considered in combination with the cleat hardware, which is much lighter than a Speedplay cleat with adaptor plate (although I have no adaptor plate on my Bont Speedplay-drilled shoes). The only time I noticed the constrained position was when coasting. I found that when I coasted, I liked to move my foot around a bit to stretch the muscles. This isn't ...

When you think about power meters what professional team comes to mind? Only one... Indeed, there's a web site devoted to photos of Chris Froome looking at stems . Staring at his SRM display, many have claimed. Sucking the humanity of out racing by reducing it to pre-programmed efforts determined by power analysis? Hardly, obviously, but traditionalists always oppose change. He even does it in Pro Cycling Manager , a video game: So it's a major change in the world as we know it when it's leaked that for 2014, Sky is discarding their trusty SRMs for Stages power meters: Stages measures power on only the left leg, assuming the right leg is the same. This, not surprisingly, results in errors. I looked at Stages power data in this blog post . For example, comparing Stages power / 2 to Vector left-leg power is a good match, according to DC Rainmaker's data: But compare it to the Vector right leg data, and things get uglier: It typically takes two legs...