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

The forbidden way... click for larger map. "No Bikes" is all the sign at the entrance to East Road says. The old sign, which said "due to gravel" along with how vehicles and pedestrians were still allowed, was gone. I guess they decided it was time to get serious. That sealed the deal. I turned onto East Road, rather than continue on the more direct route up Alexander. It's all completely ridiculous. There's a few trenches, marked with ominous "open trench" signs, which are filled with dirt and covered with gravel. Sanchez Road between Market and Duboce in the City is far worse. Yet for some reason cyclists, the majority of the traffic mountain bikes designed for riding up fire roads and single-track, is forbidden. Oh, my -- a cyclist might hit the gravel and crash! But so might a motorcyclist, or for that matter any vehicle. During the week the road is completely closed to all traffic, but on weekends, cars and pedestrians are allowed. ...

Here's the model I described, fitting an equation to Minetti's data : Revised fit to combined run/walk data from Minetti I should in theory be able to predict my time running up Old La Honda Road, assuming I am equally adapted to running as I was at cycling when I set my Old La Honda cycling PR last year . From that ride I calculated this was around 299 watts as would be measured by an SRM, Quarq, or Metrigear Vector, or 5.31 W/kg. So what if I could sustain that for the somewhat longer time I'd need to run up the hill? First, I calculate the energy needed to run up Old La Honda. The simple way would be to take the average grade and use that, but instead I divided the climb into segments using iBike data and calculated the work required for each segment. This work neglects wind resistance (it's from treadmill data) so I need to add that. Given a height of 1.69 meters, a width of 40 cm, and a C D = 0.8 with ρ = 1.15 kg/m³, I can calculate wind resistance as a functi...

I attended a nifty New Balance event at Zombie Runner on California Ave in Palo Alto yesterday. Anton Krupicka and Erik Skaggs joined a 4-mile group run from the store onto Stanford campus, then New Balance reps showed off shoe prototypes and promoted the MT100, New Balance's recent replacement to the "cult favorite" 790, which is what I wear. Anton on left, Erik second from right, from Mark Tanaka's report on the 2008 Quad Dipsea Anton and Erik are the two sponsored runners who were used as the model for the design of the 100MT. A nice review of that shoe is here . New Balance engineers gave Anton and Erik shoes, had them run a bunch, then put more padding where they wore the shoes down, removed padding where they didn't. So if you run like Anton and Erik then these shoes are great for you. But then then had more shoes directed towards the minimalist aesthetic. Vibram 5-fingers shoes (more like foot gloves) are selling like crazy. New Balance's protot...

Running this year has been a bit of an adventure for me. I'd planned last winter to the Austin Marathon in February, but I had to put that aside when several bouts of sickness following a RedSpokes bike tour to Southeast Asia set me too far back in my preparation. Instead of the marathon, I did the Woodside Half in Huddart Park, an Envirosports trail race, my second trail race that season. I loved it. So this fall/winter, when I started running again, my focus returned to trail runs. A friend told me about how she'd planned on Skyline to the Sea , but couldn't go. Maybe I'd like to try it, she suggested. Skyline to the Sea is a rare thing in trail runs: a point-to-point race. Point A to point B. It doesn't get any more fundamental than that. I had to try it. There's two routes: the more popular "50 km" course includes an added loop up and down a hillside. The simpler route is claimed to be a marathon: slightly longer than the 26 miles + 385...

Last time I described Minetti's data for running and walking on road grades extenting from ‒45% (descending) to +45% (climbing). After converting grade (the tangent of the angle) to the sine of the angle (distance climbed per unit distance traveled), I applied a heuristic model based on the assumption that in the asymptotic limit both climbing and descending involved an energy cost proportional to the altitude gained or lost. It's time to reconsider that model... First, Minetti shows for every grade tested, walking is more efficient than running. So then why not always walk? Well, obviously human kinetics limit the speed at which walking retains its efficiency, so beyond a certain speed, running is the preferred choice. Really, I don't care about the cost of running a 45% grade. In a race, I'd never run a 45% grade: at whatever speed I can run that, I can certainly walk with less energy cost. So to estimate at what grade walking becomes preferred, I'll make so...

Philip Skiba developed metrics (" GOVSS "), comparable to the "training stress balance" (or his version, "BikeScore" , which has been implemented in Golden Cheetah ) used in cycling, for running to allow multi-sport athletes to extend their training stress calculations across the two sports. Since runners generally don't have power meters, it becomes necessary to estimate training stress using speed and altitude profile. For that, Skiba taps into the work by Minetti and coworkers published in 2002 in the Journal of Applied Physiology. The authors first measured base metabolic rates of subjects at rest as a baseline. Then they walked or ran on a treadmill at various degrees of inclination, extending over a range of grades from ‒45% to +45%. Metabolic rate was measured in each case and found to be proportional to the speed, but with nontrivial function of slope. In cycling, it's relatively simple: at a given speed, there is a power component pr...

Last time, I described how it's not so simple to come up with a model for the power required in running without a detailed analysis of human body kinetics. Bicycles are so wonderful because they act as an interface between human kinetics and propulsion. Assuming the bike fits the rider, the details of human kinetics cease to be important, and the simple power-speed relationship of the machine versus the road are simply analyzed. Ed Coyle's model as described by Ed Burke is simple: 1 kcal per kg per km traveled (assuming standard Earth gravity). But obviously that's simplistic. Running up the World Trade Center stairs, for example, obviously takes more energy than running a similar distance on level ground. The record in the Empire State Building Run-Up is held by Australian Paul Crake, in 9:33 in the 2003 race. That corresponds to a VAM of 2010 meters/hr for 9 min 33 sec. That's 0.558 meters/second. Then this VAM corresponds to running 1.675 m/sec = 1.675 W/kg. L...

Last time I came up with an analytic model for the power "wasted" in running: the power required to bob the center of mass up and down, and to life the feet and calves during each foot strike. Unfortunately, like so many models, this one is almost useless. There's two big problems: There is no predictive model for α, the fraction of time both feet are off the ground, and there is no predictive model for h foot , the height to raise the feet, and the optimal cadence calculation is simplistic. Now it's true my calculation of optimal cadence matched precisely my preferred cadence, that's only because I set α to get this result. α = 70% is a fairly high fraction of the time off the ground, and the result of over 200 "wasted" watts (watts in excess of those you'd get on a bicycle, where these power terms are not present) is obviously a high number. The model predicts as α drops, optimal cadence drops in proportion. But of course this isn't true in ...

Last time on this subject , I introduced the idea of modeling the power required for running. Time for some equations. Suppose I "run in place", bouncing up and down. When I'm in the air, my trajectory is determined by gravity, out of my control. So if I want to move my center of mass upwards, the more I move it up and down, the less often I can move it. "Cadence", which is the rate at which each foot contacts the ground, is directly related to the motion of my center of mass. So if I run at a particular cadence, and am in the air a given fraction α of the time, then the amount of energy it takes to raise my center of mass each bounce depends on the cadence and on α. Consider the bouncing ball example. Flying upward under the influence of gravity with acceleration g , simple integration yields that the relationship between its maximum haight h (the vertical displacement of the center of mass) and the time t is: h = ½ g t ², where t is the time taken fo...

My off-season (well, not so off-season at this point) focus on trail running this year has really killed my legs. As a result, I've been generally suffering on Old La Honda during the Wednesday Noon Ride. Guys I am accustomed to staying with have been simply riding away from me, chatting in a relaxed voice, while I suffer, gasping, in their wake. But now that's going to change. It occurred to me during my recent Pirates Cove Trail Run that my Powertap, which as I've documented hasn't been reporting accurate power anyway, can be put to a far better use. The key is the piezoelectric effect. The Piezoelectric effect, as applied to measuring power, results in the following relationship: voltage = (torque ‒ τ 0 ) × K, for some τ 0 and K. However, trivial algebraic manipulation yields: torque ‒ τ 0 = voltage / K, where torque ‒ τ 0 is "useful torque" sufficient to overcome the built-in tension in the powertap hub. What this says is if instead of forcing a c...