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

Kenyan runners, the paradigm of form There is a well-established relationship between cycling power and speed. Power is proportional to retarding force multipled by speed, or equivalently, work done is proportional to retarding force multiplied by unit distance traveled. The retarding force consists of the following: a rolling resistance component, proportional to weight multiplied by a "rolling resistance coefficient", which depends primarily on the tires and their air pressure a wind resistance component, which is proportional to the square of the the relative wind speed, to the air mass density, to the cross-sectional area of the cyclist and bike, and to a drag coefficient which is affected by the aerodynamic efficiency of the rider and equipment inertial force, which is proportional to the rate of change of speed. In addition to the power dissipated to the retarding forces, power is lost in the drivetrain. This is typically modeled as a fraction of total power lost.

I've been riding Speedplays way longer than I care to admit, since they sponsored the Stanford Cycling club, of which I was a member. After one-too-many clumsy clip-ins into my Times, I switched to the double-sided Speedplays, and haven't looked back. I really like Speedplays, not least because they're quite rideable in street shoes, as well, so if I need to cruise across town in my street shoes, no fuss with attaching special platforms or anything. When I got them, there was only the X-series (X-1 and X-2, with X-3 and the Light Action added later). Speedplay eventually released the "Zeros", short for "X-0", although really a separate design. According to someone I recently chatted with, Speedplay Zeros are considered by Speedplay to be "mechanically superior in every way" to the "legacy" X-series. Well, "superior" except that they were more expensive and are heavier: 8 grams more for the cleats. Okay, 8 grams isn'

I have no idea how this would be implemented, but by now it's old news that Sausalito has considered charging $1 for rental bikes to offset the "costs" of the "swarm of locusts" riding through the city each weekend day. The plague of locusts leaves the city. What costs, you ask? Good question. First, there's the lost revenue from car parking. Bike racks are taking up valuable, revenue-generating space formerly occupied by a few car parking spots. "A typical parking space might generate about $3,500 a year in fees and fines." So the bike parking is depriving the city of that much revenue each year, right? Well, maybe according to the pea-brained logic prevalent among the ruling class of Sausalito. But I recommend they review their first-year economics texts on the difference between marginal and average cost.... parking revenue is lost only if a potential parker can't find any parking and leaves, or finds finding parking so frustrating he

Prior to sending my Powertap back to Saris for calibration, I decided to do one more torque test (previous posts: my wheel , comparison with other wheels ), this time bypassing the Powertap internal zeroing, and go directly to the raw torque numbers, which are available in torque mode on the Cervo head unit. My procedure: weigh test load (a bucket of fresh kitty litter) with my Ultimate hanging scale = 14.63 kg go into test mode for each gear tested: shift into gear of interest: 36/12-13-14-15-17-19-21-23-26 on my wheel, 36/13-14-15-17-19-21-23-25-28 on C's wheel. record torque load pedal with mass find orientation which maximizes torque reading record torque remove mass record torque subtract avg of unloaded torque readings from loaded torque reading I plot theoretical torque delivered to the hub on the x-axis, with the y-axis showing the measured value, for each hub. It looks good for C's wheel, but as before, my wheel is off. Curiously, each hub reported a slightly larger n

After my disaster in the Coastal Trail Runs 18-mile Rodeo Beach run where I missed a key turn and cut the course short, I was excited to get it right this month on some of the same trails with the Pacific Coast Trail Runs Pirates Cove 30 km race. Running is starting to cut into my cycling season at this point, but I'm making progress, having a good time, and it's hard to put it aside just yet. Of the route options for the day: 8 km, 20 km, 30 km, and 50 km, the 30 km was probably the best, capturing the best of the Headlands without duplicating any trail sections (the 50 km repeated a loop). To be extra sure I didn't repeat any navigational snafus, I studied the directions along with my National Park service trail map. Indeed, I'd hiked, biked, and/or run all of these trails before, it appeared. I was ready, even with my navigationally challenged brain. I left home in Potrero Hill at 6:47 am and pedaled easily to the start, which I reached in a little over an hour.

At the recommendation of my friend Nathan, I went to Innersport to get my running form analyzed. I felt my form was fairly good, but I'd been suffering pain around my left knee when I became fatigued. Maybe my self-perception of my form wasn't so good... The results were really striking. Let's start with the side view. First, the model: Danny Dreyer, from Chi Running : Not obviously this is slightly artificial since the foot alignment changes during the stride, so the frame was chosen carefully. But in general you can see the body is aligned, as though standing, but tilted forward from the foot. Now look at my position, taken at a somewhat arbitrary position in my stride. I captured the frame myself with Gimp , then did the annotation there (don't blame Dr. Jess for this): I'm bent forward at the hip. Sure, a different frame might show a different angle, but it's clear this degree of bend isn't an artifact of phase. I'm taking my cycling positi

I've not been posting much here lately... all my train commute time and morning sipping tea time has gone towards updating the Low-Key Hillclimb pages . After using the same basic design 2006 - 2009 (and retroactively applied to 1998 , which I regenerated), it was time for a rework. My HTML skills are so behind the times. I'm trying to force myself to get away of such things as <font> tokens and move towards style specifications, preferably with classes. But it's always tempting to just "get it done". The style approach is different: the old HTML approach was functionally based: you don't specify what font style or size you want, you just specify relative font sizes, and text was tagged with such functionally-inspired elements as <em> or <strong>. It was up to the user to set his browser to render these as he prefers. On different terminals, these preferences might differ. But Microsoft basically went after this philosophy with a wreckin