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...

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...

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 ...

Last time I proposed an algorithm for pedal smoothness. I can hardly take credit for it, it was basically the reciprical of Coggan's variability index without the 30-second smoothing. It's fairly obvious to apply it to the pedal stroke, as well. Here's some data left over from the old Metrigear Vector blog, showing measurements taken with the Metrigear-era Speedplay Vectors. These data are at a much higher sampling rate than would be recorded by an Edge computer: they show the detailed power and cadence during just a few seconds of a longer "ride" (on the trainer): I used Plot Digitizer to pull points off the plot (off-topic: I really like Plot Digitizer; it's replacing g3data , which I previously used). Here's a view of a subset of those data. Curiously, the left leg is going negative power, while the right leg does not. The plot also shows total power, the sum of the L and R legs. This shows a strong oscillatory character: it goes from a ma...

In anticipation of the release of the Garmin Vector, or perhaps the Rotor Flow, Garmin added a pedalstroke quality field to its Edge-series head units in the recent firmware update. But consistent with the Vector-team's approach to not release anything which they won't stand behind, on the first public release of the Vector power meter, that field remains unpopulated. It's an interesting question about how important pedal technique actually is. I think most cyclists think if they can pedal in a smoother, more uniform fashion, their cycling will improve. This has been difficult to demonstrate in the laboratory, however. For example, a recent work by Arkesteijn, et al, used force-feedback to encourage riders to pull up more on the upstroke. This worked, improving the uniformity of force application around the pedal stroke, but gross energy efficiency of their cycling failed to improve. On the other hand, it appeared the smoother pedaling increased the ability of the c...

There's now three minimalist pedal systems on the market, as I pointed out in a previous post : Aerolite : the original, from 1979, very early days for clipless pedals. Cleats are set up for 4-hole mounting, like Speedplay but with a different spacing, although they can also be mounted in 2-hole (mountain bike) shoes or 3-hole (using 2 of the 3 holes). Ultralite Sports : I became introduced to these at Interbike last year: very slick. They have a novel clip-in, clip-out mechanism. TriRig Mercury : still in limited release, closer to the Aerolite than the Ultralite Sports, but with 3-hole cleats rather than 4-holes. Aerolite makes 3 models of pedal. The lightest is "time trial" version with holes drilled in the Turcite sleeve which surrounds the axle, and also the spindles have minimal length to keep the feed close to the bike, which was considered more aerodynamic back then. Then they have a "criterium" pedal, also with short spindles, in this case no...

There's a new pedal out called the TriRig Mercury , a continuation of a theme which began with the Aerolite in 1979 (and still available!), continued with the UltraLite Sports , essentially attach a cleat to a bare pedal spindle. You lose pedal float, but it's the lightest solution around: you spare the added mass of the pedal body. Here is it: Originally this was advertised as 71 grams, but now it's been upgraded to 93 grams. The cleats adds only 58 grams, so the total solution is very light. But not as light as they were when they were 71 grams... So what happened? What happened is they eliminated the "weight limit" of the original design. Of the 22 additional grams, 18 are due to a change from a hollow to a solid spindle, 4 due to a shift in the flange from the bearing sleeve (nylon)to the spindle and retaining screw (metal). As the web page describes: The additional material adds just 9 grams of weight to each spindle, but makes a world of differen...

I had three encounters with pedals at Interbike 2012. I'll review them in order of interest. Least interesting by far was Speedplay. I didn't see anything there, other than the Syzr off-road pedal which was at the show last year . Indeed, this pedal was shown in a different form as far back as 2009 ("almost ready for production"): that's four Interbikes. Yet to my amazement someone at the Speedplay booth still talking about it not being ready yet for production. I remember doing a group ride in San Diego 1990 or 1991 where I guy I don't know who called himself Richard talked about his new pedal prototype which he was going to take into production and I laughed: the pedal market was already saturated with big hitters like Look, Shimano, Time. How was some guy in San Diego going to compete with them? So no criticism of Mr. Bryne and company, but I find the ongoing delay curious. Sometimes, it seems, it's easier for a little guy working in a machin...