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

As was pointed out to me by Claude B in the comments section of a previous post, Argon has a new aero frame out, the Nitrogen ( web page here ), and with it they show some wind tunnel data: These tests are following a pattern. The Cervelo S5 remains the standard against which new frames compare, and they may be competitive with the S5, but don't beat it. We saw the same thing with the Parlee ESX and Felt AR1. Then lagging behind is a set of usual suspects, including the Specialized Venge and the Scott Foil. The only test I saw where the Scott Foil did exceptionally well was the test data produced by Scott itself. Between the Nitrogen and the S5 is basically a choice between low-yaw and high-yaw drag. The Nitrogen appears to do a bit better at higher yaw. I tend to err towards lower-yaw performance because of ground shear: yaw at the height of a downtube is less than it is, for example, at head-level, let alone at 10 meters. At extreme yaws control becomes a bigger issue...

I previously showed the Canyon Aeroroad. But Canyon's perhaps more popular bike is the Ultimate, a perennial competitor for Tour Magazine's lab-dominated bike of the year ratings. A prime competitor is Storck, a more niche German company known for its engineering-based approach to bike design. Included in that approach is a relatively unique approach to geometry. Here's a comparison of Trek, Specialized, Canyon, and Storck road bikes, where I've left off the endurance bikes this time: Canyon is clearly sticking to the stack-reach design philosophy with both of its models. And for once a bike company does the obvious which is to make the aero bike lower. And the longest Ultimate is incredibly long. It must be those tall Norwegian customers. But the Storck 0.6 is a bit bizarre. The smallest size differs only in stem length, essentially (actually with the head tube angle being slacker than 73 deg, slammed stem will result in the smallest being slightly higher). Th...

Last time I compared Trek to Cervelo for stack-reach. The Madone H1 and the even more aggressive Domane Race were much longer/lower than the Cervelo H1, and even lower than the more race-geometry Cervelo R-series from 2008. The Madone H2 and Cervelo R5 were comparable. The Trek Domane 6 was substantially more relaxed than the Madone H2. It's really designed more as a century bike than a race bike, although it may provide a good fit for some racers. Here I compare the Specialized line to the Trek line. I already looked at the 2015 Tarmac. In the following plot, I add in the Roubaix endurance bike as well as the Venge aero road bike: The Venge is basically identical to the Tarmac. The Roubaix is fairly close to the Trek Madone H2, not nearly as relaxed as the Roubaix: around 2.5 cm spacer difference. The Madone H1 is more aggressive than the Tarmac, however: with two lines of Madone they can afford to be more aggressive on the longer/lower version. This suggests for racing...

More stack-reach comparisons, retaining the tall (Cervelo R5) and long (Trek Madone H1) winners from last time: First, there's a new obvious "tall" winner, and that's the Parlee Z5 tall model. Of course this isn't a fair comparison, as it would make more sense to compare the Parlee tall geometry to the endurance geometries of other bikes, but I put this here for comparison since I recently test-rode a Parlee ESX. The regular Parlee Z5 geometry corresponds to around 2.5 cm less spacer height, and has more traditional road racing geometry (clearly not designed to a stack-reach spec, however, since the curve zig-zags). Specialized is interesting, as the smallest 3 models are essentially constant reach, changing only in stack. This is because top tube length is directly canceled by seat tube angle. This keeps the reach the same as the top tube is lengthened. The bikes still fit bigger riders, however: adding spacers to the smaller frames would bring them to a...

For a long time I've been alarmed by the trend in carbon bikes to go to fatter and fatter tubes in a never-ending quest for higher stiffness-to-weight ratio. Indeed the trend predates carbon fiber: it goes back far further, to Cannondale, and before that, Klein with their fat-tube aluminum bikes. To save a relatively small amount of mass, giving up a large amount of wind resistance. But then as the quest for lighter carbon frames started approaching a limit, there was an effort to gain performance elsewhere. So wind resistance got renewed interest. Starting perhaps with the Kestrel Talon, there were a series of "aero road" frames which, at the cost of around 200 grams more or less, performed much better in the wind tunnel. These frames had a hard time catching on with professional riders, however. Road cycling is performed mostly in packs, with fatigue and avoiding crashing both major factors, so optimizing the bike is a lot more than optimizing speed at a given po...

According to a recent CyclingNews article , Mark Cavendish downsized from a 52 cm to a 49 cm Specialized Venge this year. The article quotes Specialized Body Geometry fit manager Sean Madsen: "One thing about Cav is that he likes to periodically change his position around, based entirely on his feeling," Madsen said. "He may change it back in a couple of weeks, when his mood changes!" So did he change his position? Here's some BikeRadar/CyclingNews reviews of Cavendish bikes: 2011 2013 2014 I took the 2011 and 2014 side shots. Unfortunately these are from relatively different camera positions. To compensate, I did a combination of image scalings, rotations, and perspective transformations on the images to match the bottom bracket positions and the heights of the front and rear tires. This is 3 transformations for 3 constraints. It's not enough to fully match the photos, but it's a lot better than taking them unprocessed. I aligned the fro...

The Specialized Venge made its debut at Milan San Remo this year, and it couldn't have gone any better for the Morgan Hill company, as Matt Goss, a relative underdog, won the race. Move on the Tour de France, and with aerodynamically optimized mass-start road frames more popular than ever, Mark Cavendish has pulled out two impressive sprint victories on the bike in a first week notably unfavorable to sprinters. Last year when HTC was sponsored by Scott instead of Specialized, Cavendish rejected his Scott Foil (then F01) in favor of his tried-and-true super-beefed-up Addict, so once again this looks good for Specialized. Venge spotted at Mike's Bikes in San Francisco But the frame is only a relatively small part of the aerodynamic picture. Far more important is body position. So here's photos of Cavendish during his two victories this year... first stage 5: CyclingNews Then stage 7: CyclingNews These photos aren't cherry-picked: they're the first...

Specialized just revealed a super-cool prototype (it's been called a concept bike, but this seems very functional, nothing concept about it): a tandem version of the Shiv . Wow! Photos stolen from BikeRadar : Interesting phasing on those cranks. One of the cool aspects of this bike is the shaft drive: Super-aero, clearly. But at what cost? Any drivetrain has losses. Losses are generally considered to be proportional to transmitted power, although it's been experimentally shown that for a bicycle transmission efficiency is higher at higher chain tension than at lower chain tension. This is fairly trivial: aspects of drivetrain loss are not necessarily proportional to transmitted power, but rather proportional to chain motion. In any case, a fixed gear drivetrain, such as on the timing chain on a tandem, is quite efficent. For example, 98-99% is typically claimed. An alternate for the timing chain on a tandem is the Gates belt drive. This also claims to be as efficient ...