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

SRM claims to be the most accurate power meter according to a test done in Triathlon Magazine , a German publication. Here's a link to the PDF article (German). I can't understand German, but the second-hand report I read was that the various power meters were compared to a Cyclus 2 ergonometer . This is a trainer system after the LeMond trainer / Wahoo fitness model: it has a cassette to which the chain directly attaches, the trainer replacing the rear wheel: Here were the results of "accuracy": place power meter accuracy 1 SRM FSA 0.50% 2 SRM Campagnolo -1.3% 3 Power2Max -2.0% 4 Quarq/SRAM 3.6% 5 Look/Polar -4.0% 6 Rotor-3D 6.1% - Powertap ? The Powertap wasn't measured since it's built into a rear wheel, and the trainer replaces the rear wheel. They used a treadmill to test the Powertap, comparing it to the SRM, but didn't include the results in the data table since this was a different platform. These results look strong for SRM, ...

Last week I rushed to my bike to catch my morning train and the tire was flat. There wasn't nearly enough time to swap the tube, but there was an old Mavic Open Pro wheel laying there with an old Continental Supersonic 20 mm tire. I grabbed the wheel, inflated it to 100 psi (it held!), put in on my bike and caught the train. I couldn't believe we used to race, let alone train, on these things. Every bump felt like it threatened to cause a pinch flat. Even the speed bumps in the parking lot at work seemed like they'd launch me into ballistic trajectory. Ellis Randonneuring bike, 2011 North American Handbuilt Bike Show (James Huang, CyclingNews ) The improvement in ride quality going from 20 mm to 23 mm tires is profound, and it's even better making the jump from 23 to 25 mm or 26 mm. I love my Michelin Pro 25's, and my Grand Bois Cerf 26's. They're even good for a little fun on the dirt, riding fire roads and smooth hiking trails. But even 26 mm ti...

One issue with wheelsize is angular momentum. Jan Heine claims that 622 mm rims (700C) are best for up to 32 mm tire width, then 650B are good up to 42 mm, then "26-inch" are best for larger size. The idea is the wider tires yield larger mass and also yield a larger rolling radius relative to narrower tires at the same rim radius. This results in more angular momentum. Turning requires changing angular momentum, so more angular momentum creates more stability: more reluctance of the bike to change direction. It's been commonly asserted that trail is what controls bike stability, not angular momentum of the wheels (the "gyroscopic effect"). Trail's important, for sure, and you can make bikes where trail is the only contributor to stability (for example, ski-bikes), but the detailed analysis by Andy Ruina at Cornell has shown that angular momentum and trail both contribute, as well as center of mass. Bikes are a complex dynamic system. Angular momentu...

I was floored by what I've seen by the new Cervelo RCa , which was just announced. The thing comes closest to perfection in a diamond-shaped bike for it's geometry that I've seen. A very brief digression: In the past, bikes are designed for fit and stiffness and mass. Aerodynamics was always a factor, but it was relegated to fit: for 100+ years riders have realized they could go faster if their backs were flatter. But all bikes were made out of the same 1-inch steel tubing, as this worked well. That changed in the 1980's, when Klein came out with his Al frame. With Al, the tubing can be made thinner with the tube diameter larger to get improved stiffness at lower mass. Other companies, like Cannondale, picked up the same trend. This flaunted aerodynamics, since the fatter tube bikes have more wind drag. But the effect of the increase in wind drag was quantitatively hard to assess, while weight and stiffness are directly detectable, and riders kept winning rac...

I have a soft spot for Milan-San Remo since I rode the final portion of the course in 2010. My picks this year, in order of probability of winning: Thomas: Sky's been preparing in Tenerife. Traditionally preparation has demanded that riders do either Paris-Nice or Tirreno Adriatico. The only question is which. But Sky's shown remarkable success in their training on Tenerife, doing specific training in an isolated controlled environment. Sagan: The guy's amazing. It's very tempting to put him first: do I go with the amazing team or the amazing rider? I went with the team. Haussler: He was a very close second in 2009 and claims he's feeling good. Bassen-Hagen: Sky's back-up man. Gilbert: Has been slow getting out of the blocks this year and last but he's a proven candidate for this race. He just needs to control his aggression. Cavendish: Cavendish came into last year's race as a favorite and Liquigas sacrificed themselves to drop him. Liquigas i...

On Saturday, I got an email from Tim telling letting me know that Murphy's Spring Classics was going to start up Marin Ave. I'd missed that. Murphy announces his courses the day before, and indeed it was already well into the night before when the course announcement went out. I'd skipped over the details, jumping straight to middle and end games. Marin? I laughed at the irony, because not long before when he'd told me he was choosing to repeat the Nifty Twn Fifty which we'd done together last year versus selecting Murphy Mack's Stage Mullett two-day, I responded I didn't think I had it in me to ride Marin Ave two years in succession. Well, so much for that. I was committed, so I went downstairs to swap my 11-26 cassette for my Recon 12-27. The name is easily overlooked: "Marin Ave" fails to strike the same impression as, for example, "Redwood Gulch" or "China Grade". But among those in the know, Marin Ave is infamous i...

I take the train around 450 times per year (one-way) and I've been doing that for around 11 years, so that's around 5000 train trips. Caltrain runs around 90 trains per day, or 450 during the week, about the same number I take in a year. Caltrain hits a pedestrian or vehicle around every 3 weeks, so at least one per month on weekday trains. I ride the train around 2/3 the total distance. That means I'd expect to be on a train which hits a pedestrian or car around once every six years. But I've never been on such a train, until now. I'm on the train now, logged in to a wireless network which happened to reach this position. There's two bike cars per train. I usually get on the southernmost. That's what I did this evening. The northernmost is the lead car for the evening commute. The engine is to the south, pushing the train set ("consist" in train-speak). Cyclists in the northernmost car, the other bike car, reported the collision was l...

During a ride yesterday Cara told me she thought my shoulders looked more relaxed than before. I'd been doing yoga recently and also had had a very nice massage at Doctor's Orders (World Gym, Potrero Hill). I have had a chronic issue with shoulder tightness for as long as I can remember: I tend to sit both on the bike and, more significantly perhaps, at a computer with my shoulders rolled forward. Stay in a position long enough the the body decides there's clearly some natural selection advantage to being there so semi-permanently adapts (this is over-simplistic, I realize). Anyway, I need to constantly focus to rolling my shoulders back, which is to say not roll them forward. The consequence of this on the bike is if I have my shoulders rolled back that brings my chest forward. This means I bend in the hips, lowering my torso. But if my bars are so low my torso is already as low as it can go then this position becomes unsustainable. The only options are straighten...

I've been playing around with BikeCad , thinking about randonneuring bike designs. I've been fascinated with randonneuring bikes for a few years now, since I started reading Bicycle Quarterly . They seem an excellent option for a wide range of riding, including commuting to work, since a little carrying capacity goes a long way and having a handlebar bag would be super convenient for all sorts of things, liberating me from carrying a backpack for my work clothes, for example, and allowing me to carry more clothing option on certain rides. Fatter tires would be quite nice on the rough roads often encountered around here, and the rolling resistance of performance-oriented 650b/42mm tires has been proven in tests published in Bicycle Quarterly to be quite acceptable. Additionally, Cara wants to do a loaded tour, and while a randonneuring bicycle isn't optimized for a loaded tour, it's far better for that purpose than a traditional racing bicycle. BikeCad is a wonderfu...