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

As I noted last post, the MetriGear Vector ("Direct your forces") is targeted as much as a force meter as a power meter. Get force right, get velocity right, and you get power right. Power associated with mechanical work equals the product of a velocity magnitude ("speed") and the component of force applied in the direction of that velocity. This is equal to the vector dot-product of velocity and force. Virtually every power meter deals with this relationship. For example, the iBike estimates the forces acting on the bicycle, then multiplies those forces times the measured speed of the bike. The Polar power meter estimates the tension (force) in the chain, and multiplies it by the speed of the chain. The SRM and Quarq Cinqos measure the torque (an integral of force times distance) in the crank spider and multiples it by a rotational velocity (a speed divided by a radius). The PowerTap does a similar calculation, measuring a torque in the hub and multipl...

MetriGear is a new company in Silicon Valley California, which has developed a very promising product: a module of acceleratometers and piezeresistive strain gauges which can be inserted in the hollow axle of a bike pedal, provide force, pedal velocity, and power data via ANT+ Sport communication to any sufficiently cooperative ANT+ Sport head units. It is being developed first for Speedplay pedals , although there are other candidates. Schematic of MetriGear Vector Velocity Nation , one of the best techie cycling web sites on the web called the MetriGear Vector "by far and away the most exciting thing at (Interbike)". So what's the big fuss? Well, first of all the Vector looks to be the Weight Weenie leader in power metrology. When coupled with shoes drilled with 4 holes (versus the more common 3) such as Bonts , Speedplay X1's and Zero Ti's, especially when tuned with aftermarket Al bowties , probably have the best combination of functionality and low wei...

I've never been to Interbike. It's always a question of "if I take a day off from work to attend Interbike, that's one less day I can take off for (SuperTour, riding in Europe, flying out to see World Championships, traveling to any place more interesting than Vegas...). Days off are too precious. But honestly, this year I wish I'd been there. Favorite stuff I wish I'd seen at Interbike: MetriGear Vector : Well, actually I was at their open house "dry run" immediately prior to Interbike, so I'm very familiar with what they showed there. But Metrigear are all great guys, I really love their product, and it would have been fun to see how they were received there (by all accounts quite well). the Guru Photon : Wow! A sub-700 gram custom carbon fiber frame. Incredible. It totally fails my $3.50/gram saved test versus my 860 gram Fuji SL/1 frame. And I think I'd be intimidated ordering a custom bike. After all, when I got my Fuju SL/1,...

Out for a Sunday spin, riding north on Broadway.... oh, the tunnel. Right on Columbus... lots of traffic. Okay, left on Filbert. Better. Oh. There it is. Up ahead... Flashback to 2006. Frank Chan leads his famous Steepest Hills of San Francisco ride. The crew from the 2006 Steepest Hills of San Francisco Ride, led by Frank Chan. It's funny; when I did that ride I was feeling like I should do a real training ride instead. But I put aside the racer self, and embraced the explorer self, and decided to have some pure fun instead. A really relaxed ride, for sure, with the exception of many short brief bursts of pain. And the worst of it all: Filbert . Filbert from Levensworth to Hyde is listed in John Summerson (The Complete Guide to Climbing by Bike) as the 4th steepest 1/10th of a mile in the United States: 31.5%. There's even a Wikipedia page on the road's steepness. Nasty. Back to that ride: When the group arrived at the base of Filbert, it was decision t...

Here's a comparison of some geometry numbers from 2009-2010 bike frames. I plot head tube length versus reach. Now it's a standing question in the age of sloping top tubes what's the single best number to describe the size of the frame. The only parameters which can't be adjusted are front-center and rear-center and bottom bracket drop, so these are likely candidates. Considering the body fixed with relation to the bottom bracket by an appropriate choice of seat post length and offset, stem length and angle, the front center and chainstay length, in combination with the bottom bracket drop, determine how weight is distributed between the front and rear wheels. But it doesn't feel right to use these parameters to describe bike size. After all, a touring bike designed for a short person might have longer dimensions than the longest Cervelo road racing machine, the Cervelos known for their tight wheelbases. The next candidate is Cervelo's favorite number: r...

A friend of mine sent me data from his iBike , taken on a climb of Old La Honda on May 10 2009 at 8:47 am. Conditions on Skyline Blvd , the top of the climb, were cool and calm: pretty much ideal climbing weather. The iBike records altitude, road grade, acceleration, and relative wind speed. It uses a coast-down test wherein, since applied power is zero, it calibrates wind resistance and rolling resistance to the rate the bike decelerates, wind resistance dominating initially, then rolling resistance taking over as the speed drops sufficiently. Given this calibration, it can then derive how much power is being applied to the pedals based on how the bike decelerates (or accelerates) relative to how it did so in the coast-down test, adjusting for the measured road grade. Fun stuff. iBike The iBike measures the altitude and road grade separately, but of course the road grade is derived from the derivative of the altitude with respect to distance. A direct measure of road grade is ...

Okay, I couldn't resist on this one.... after clicking a link to a photo-intensive page, my laptop with its measly (????) 1.5 GB RAM came to a grinding, swap-induced crawl. First, I killed the tab for that page. Okay: time to start killing the few aps which were running.... leaving only firefox, with a few innocuous tabs still open, including my training diary which I wanted to finish updating. Then I dropped firefox. Okay, so I screwed up that screen grab big-time. But if you could actually read it, you'd see 940 MB freed up by the death of the bloated firefox beast. Wow. Okay, vent done. Back to cycling....