Sunday, September 30, 2012

Interbike 2012: non-racing bikes

My last post was of racing bikes. The bikes I'll describe here deviate from main-stream racing machines, although obviously any bike can be raced, and one here is even for a particular type of race ("gravel race").

Ritchey Tandem Breakaway
Ritchey Tandem Breakaway

Ritchey showed the tandem Breakaway frame they'd showed at NAHBS this February. There was finally a formal promise it was going into production, although they were "still working on pricing". I think the Ritchey bikes all look awesome. This is the only stock tandem I've seen which I thought looked really good. Key question is whether we'd choose to travel with it. Certainly the Breakaway boxes would facilitate transport, but packing and unpacking Breakaways is a time-consuming process, not one for a few hours drive to a century or double.

Velo Orange touring bike
Velo Orange touring bike

Velo Orange had a very nice touring bike, something which would have been nicely at home at NAHBS if the frame had been custom. I asked about the bike and was told they don't sell complete bikes, although virtually everything on it was the Velo Orange brand. No single spec is going to please more than one customer, they said: everyone has their own preferences. I agree. Curiously, they had the same bike also set up as a "gravel racer". I didn't think loaded touring and off-road racing were sufficiently similar to share the same frame design, but the guy to whom I spoke in the booth said they both worked well.

Salsa gravel racer
Salsa gravel racer

Speaking of gravel racers, Salsa had their impressive gravel racer on display. I suppose I could have put this in the racing bike post, but gravel racing hasn't yet caught on in the San Francisco Bay area so it would get different use. A big problem is so many of the appropriate roads are on open space land, and open space policy explicitly forbids timed events. This would be perfect for the Grasshopper series or for the recent San Francisco Randonneurs 200 km dirt brevet. Cyclocross bikes have typically excellent in these events (the brevet was "won" by a Ridley cross bike) but cross bikes are really designed for cross races, which involve carrying the bike up anything steep, and geometry designed for an hour of pain rather than endurance. The bag shown on the show bike seems over the top for one-day events, but a smaller frame bag large enough to hold wet weather gear seems like it would be perfect. This wins my personal "most attractive bike of the show" award, as I love riding dirt roads on my road bike, but obviously the substantially fatter tires and mud-friendly disk brakes on the Salsa are the right tools for the job.

Phil Wood fatty
Phil Wood fatty
Phil Wood fatty dual-suspension concept

On the subject of mud, the super-fat tire category has really taken off in the past year. These bikes were originally designed for snow riding. Decades ago racers in the Iditabike endurance race in Alaska would mount fat tires on two conventional rims welded side-by-side. First custom, then mass-production builders eventually hopped on the category as an underexploited niche in the over-saturated bike business. Perhaps to the surprise of at least some of the suppliers, people started buying them for anything but snow rising. It makes sense: after all, off-road motorcycles use fat tires, why shouldn't mountain bikers? Phil Wood showed this concept bike, a full-suspension fatty, which I assumed was intended as a joke. After all, why would you need full suspension when you've got tires like these? I noted this to the guys in the booth and I got horrified stares. "You just point this bike where you want to go and it takes care of the details," they said.

Saturday, September 29, 2012

Interbike 2012: racing bikes

This being Interbike and all, I was surprised by the relative lack of, well, bikes.

There were bikes, of course, but not nearly to the level as the North American Handbuilt Bike Show, a personal favorite. But to be fair I missed the far better forum for bicycles at Interbike, which is the outdoor demo. We've hit a saturation level in carbon fiber technology, where a light carbon frame is a commody produced in bulk quantities in Taiwan, so the sight of a carbon frame barely draws attention. Hey -- is that a new Bonk Breaker flavor? I'll come back to this bike later.... maybe.

Comments on some of what I saw, starting with pro bikes.

Sagan's Cannondale
Peter Sagan's very cool Cannondale Evo

Two bikes which drew my attention were the bikes in the SRAM booth. Peter Sagan's Cannondale Evo was really nice. Notable was that SRAM showed it with its competitor SRM power-measuring crank; SRAM bought Quarq and so was promoting that. But hats off to SRAM for having the confidence and maturity to show Sagan's bike anyway. I'm not a fan of painting over carbon fiber frames, but I understand pro racing has different considerations, and in particular this frame celebrated Sagan's spectacular winning of the green jersey in the Tour de France this year.

Next to it was Levi Leipheimer's "Wi-Fi" Trek Madone. For some reason I was uninspired to take a photo of this one. It showed off both the SRAM/Quarq crank (which now generates a pedal symmetry number) and the "WiFi" medium-cage SRAM Red rear derailleur. I admit though I have negative associations with Trek, especially since they dumped the LeMond brand.

Hesjedal's
Ryder Hesjedal's Cervelo from the Giro d'Italia

In the Cervelo booth was Ryder Hesjedal's Cervelo R5 from the Giro d'Italia. Aside from notorious reliability problems (they have a reputation for breaking, then being replaced under warranty) I've always admired the Cervelo "engineering-oriented" design. They don't do things for looks, but rather because they improve the ride. No gimmicks. I also think this year's paint scheme, shown on this bike, looks a lot better than the 2013 scheme which seems cheap: an overt attempt at flash to cover up a boring interior. The most striking thing to me about Ryder's bike, however, is the handlebar drop. I noted this to the guy manning the booth and his response impressed me with its candor: "yes, it's ridiculous". I was impressed. Ryder wins one of the three grand tours and the Cervelo engineer is willing to rip into his bike position. Indeed, Ryder rides with his arms extended downward, looking strained, in contrast to, for example, Alberto Contador who looks balanced and at ease. Hejedal's not as bad as Andy Schleck, at least.

On the topic of the Giro, here's the trophy won by Denis Menchov. I always thought it looked fairly light in photos, but it's made of lead:

Forza Giro!
Giro trophy: very cool

One bike I was looking forward to seeing was the Cipollini line, in particular the Bond. If the bike could escape from criminal paramilitary motorcyclist ninjas, surely it would impress me. Alas, there was no Bond in the Cipo booth. I was surprised at how fat the tubes were on the frames which were there, as far as I could tell the same frames from 2012.

Neil
Neil Pryde Bora SL

A bike which I'd looked forward to seeing going into the show was the Neil Pryde Bora SL. However, when I saw it I was disappointed: it was another of the super-fat-down-tube frames which looks like it's designed more to win the Tour Magazine competition than to be a good ride. To be fair, I've not ridden this frame, but I'm far more attracted to the concept of "tuned stiffness" espoused by such frames as Calfee, Crumpton, AX-Lightness, Rolo, and Parlee than to the "stiffness to the max" school which seems designed to produce impressive numbers in magazine tests. So I spent only enough time here to snap an out-of-focus photo, then moved onward.

Dimond triathlon frame
Dimond triathlon bike

On the triathlon side (also okay for US domestic time trials) is this Dimond cantilever bike. This remainds me an awful lot of the old Zipp bike of similar design. I asked about aerodynamics, expressing my concern the head tube looked too fat and cylindrical. The best time trial frames all seem to pay a lot of attention to the head tube, which is after all the leading edge and especially prominent at low yaw. They said they were planning on going into the tunnel soon for testing.

China
China Pavilion

China Pavilion consisted of a series of companies selling OEM parts and OEM frames. This one is representative. They didn't get enormous attention, it seems, but then they don't need a huge number of customers to make the trip worthwhile. Slap some decals on these bad boys, add 200% mark-up to wholesale price, and you're in the bike business. "Low-Key Cycles": I like it!

Specialized S-Works Allez
Specialized S-Works Allez

Last and best, here's the Specialized S-Works special edition Allez (see description here). The thing glistened in the lights: really fantastic looking. It's an attempt by Specialized to compete with the high-end Cannondale CAAD-10 bikes. Cannondale has been honing it's high-end Al for decades, however, while Specialized has for years relegated it's Al line to entry-level status. This bike may look fantastic, and the component spec is nearly perfect, but reports I've seen on Weightweenies forum claim the Cannondale is a smoother and overall superior ride while being at least as light.

Friday, September 28, 2012

Interbike 2012: food

Another Interbike theme was food. After flying in from San Francisco, having munched on some raw food bars from my back pack, I planned to invest my lunch calories in food samples, which are plentiful.

Powerbar was there with it's high protein bars and a new flask containing fruit mash. I stay clear of protein bars containing isolated soy protein, since I don't digest it well, but I tried the mush. It reminded me of my days eating Gerber's baby food. Actually, I don't remember those days, but it reminded me of baby food anyway. Indeed I've heard of ultra-endurance riders preferring baby food on their rides, so the new Powerbar product has precedent. But I'd rather just eat fruit. They also had gel blocks.

Clif was there in force, with Clif Bars, Luna Bars, their granola bars, and their relatively new Lara Bar rip-off. The Lara Bar varient was good, a lot like Lara Bars. Clif Bars and Luna Bars, like Power Bars, are made with soy protein isolate (probably because it's so cheap) so I tend to avoid them, although the concentration in the traditional carbohydrate-focused bars is a lot less than in the protein-rich versions.

Better than the Clif bars were the real food bars from Raw Revolution. These bars are organic, which is a plus, but that didn't explain why I found their taste superior to Lara and the Clif version of same. I asked the guy at the booth and he said it was the higher fat content which was responsible. I like bars with fat on long rides: it's more satiating, more sustaining. For high-intensity rides like races I stick more to gels and carbohydrate-rich bar.

Hammer had their bars, the only vendor I saw to supply full-bar samples. You'd expect Hammer, with its scientific focus, would have some sort of proto-bar, but their bars are whole food based and are quite good.

PR Bar was there. I was a bit surprised they were still around: they go way back, the first of the Zone bars with 40:30:30 carbohydrate:protein:fat calorie ratio. The deal with the Zone diet is this ratio was designed for sedentary people on a weight loss program; it was never designed for on-the-bike. But that aside, the macronutrient ratio isn't the only thing, it's also how you get those calories, and even Barry Sears, who invented the Zone diet, argues whole foods are the best source. These bars taste more like candy than real food. In any case they use soy protein isolate so I passed them up other than a very small taste.

Bonk Breakers
Bonk Breakers take the V with their protein-rich flavors

The best of all, however, were the Bonk Breaker bars. They had two new protein-rich flavors, with easier-to-digest rice protein instead of the cheaper soy protein used by the big names. These were really good, the fats and proteins proving a very tasty gcombination. I'll definitely buy some of these.

Another contribution to the protein selection were protein-rich Jelly Bellys. I don't like jelly beans much, but these were good. They reminded me a lot of Clif's protein shots. The beans are much smaller, however, which ironically probably means a tendency to eat more of them (mass-wise).

Honey Stingers showed they've transcended honey with their various flavors of wafers and gel cubes. Gel cubes pretty much all taste the same to me, functional, so there's not much to say about these. The wafers are tasty but the packaging is hard to open controllably on the bike. I noted this to a guy at the booth and he said they were aware of this and were updating the package.

Gatorade also had gel blocks, which were good. I'm not sure how they compare with the myrid of other gel blocks available, but one thing I liked was they didn't have caffeine. Caffeine has its place in endurance sports: it's a great late-ride boost in competion. But it must be used in moderation to be effective. The virtual ubiquity of caffeine in gels and blocks suggests it's being used in anything but moderation.

In the drink mix market Scratch Labs managed to get their product distributed liberally around the floor. It's good, with a light taste, mixed to only a 3% carbohydrate concentration. Osmo, a product originating close to my home, is very similar. Each is mostly cane sugar and some flavor. I talked to Lisa Hunt, who was in the Osmo booth with Stacey Sims (who is responsible for the philosophy behind their product) and she said liquid is for hydration, food is for calories. Hammer Nutrition has long promoted this sort of separation, perhaps using a thick drink for calories but a low-carbohydrate solution for hydration, getting electrolytes from their tablets. The thing about this is the drink mix may taste good, but I can get the same effect by dumping an appropriate amount of sugar into my bottles. But I'm tempted to get a pack of Osmo to try it out.

Also on the hydration front were samples of coconut water. The growth in the availability of coconut water has been huge lately. I wonder at where all of this coconut water originates: how may acres of land in Thailand are dedicated to supplying the western world with this stuff? I certainly love coconut water, but from an environmental perspective I generally object to hauling fully-constituted drinks back and forth across the ocean. For on the bike, I'll stick with sugar water, although coconut water remains a guilty post-ride indulgence.

So despite technically skipping lunch, I was well fed during my day at Interbike. Afterwards, I joined some good friends at at a really good Pan-Asian restaurant where the food was perhaps on the rich side but neverthless delicous. It was a surprisingly enjoyable trip to Las Vegas, and I suspect I'll be back.

Thursday, September 27, 2012

Interbike 2012: alternate drivetrains

After I commented on the cleverness of the Da Vinci tandem drivetrain, the guy manning the booth told me "we've been here 17 years in a row". I responded, "but this is my first time here." So this may not be new, and I've likely seen it before @ NAHBS, but in any case I considered it cool. The goal is to allow the stoker to pedal independently of the captain, independently coasting, although still constrained to the same cadence. A side effect of this is the pedals can come out of synchronization, although the stoker could time reinitiation of pedaling to synchronize as desired. Despite their longevity they don't seem to have caught on, as most tandem riders seem content to remain locked together with a fixed timing chain.

Da Vinci tandem drivetrain
Da Vinci tandem drivetrain

Da Vinci drivetrain, stoker close-up
Da Vinci drivetrain, stoker close-up

Another curious drivetrain was the "string bike". This was quite remarkable, converting a circular motion on the pedals to a piston-like motion of the strings, the strings rotating the rear hub. Of course nothing's actually new about this: it's similar to what happens (in reverse) to an internal combustion engine, where linear piston motion rotates a drive shaft. I am not sure about the motivation for using a string rather than a chain to drive the reart hub, but if nothing else it may be cleaner.

String bike
String bike drive-train

Then there was the 14-speed Rohloff hub. I've seen this before, at NAHBS. It's truly an amazing piece of engineering. The efficiency is fairly good, as well, approximately 96% to 98% in according to their data depending on the selected gear. The most obvious penalty is mass: the thing is heavy. But for loaded touring, the weight will be hardly noticed, and the advantage of having a fully encapsulated system protected from the elements when riding in remote areas with potentially little access to bike shops is surely attractive. They had it attached to a Gates belt drive, which replaces the articulated metal chain in conventional drivetrains. This is cleaner but if a Gates belt breaks you need to have a hard-to-get replacement, while with a chain you can replace or remove the broken link pair. So if I was touring I'd make sure I had at least one extra.

Rohloff 14-speed hub schematic
Rohloff 14-speed hub schematic

Rohloff 14-speed hub efficiency
Rohloff efficiency, compared with conventional drivetrain

Finally there was this ordinary which, as is typical, has a direct drive. I thought this was cool enough that I took a photo.

Ordinary
ordinary direct

Wednesday, September 26, 2012

Interbike 2012: Racing Drivetrains

Another big theme of my one-day Interbike experiene was drivetrains. First, shifting...

Shimano had a big booth and supposedly they showed a new electronic shifting system. I missed that as, I admit, I am no Shimano fan and didn't spend much time there. I did try the new Dura-Ace 9000 shifters and these had a very nice shifting action. But then all the big three have a very nice shifting action.

At the Campagnolo booth my focus was on their EPS electronic shifting system. They had the system set up on a Pinarello bike on a trainer. In retrospect I regret not having tried out their mechanical shifters as well, but Vegas-and-back in a day makes for a tiring day and I wasn't 100%. In any case, the EPS shifting nicely on the test bike, and I had no problem adapting to their shifter location. However, it seemed a bit artificial to me, designed for hands familiar with their mechanical shifting rather than optimized specificially for the electronic shifters.

Again, I was negligent at the SRAM booth, but I don't recall there being any shifting demos there. I'd like to have known how the 2012 Red system shifts. In fairness, the real place for these tests would have been the outdoor demo, which I missed.

The big deal at the SRAM booth was the X1 wide-range mountain bike group. The name is clever, since the "1" in X1 seems like it refers to the single chainring, but taking X to represent the Roman numeral for 10, it refers to the 11 cogs in the back. SRAM has had a brilliant debut with the system, which wasn't targeted at cross-country racing where speed and efficiency is the top priority. But then their system was used in winning the World Championship cross-country race. All you need to do is look at how well single speed mountain bikes do in races compared to bikes with 27 or 30 gears to realize gear selection in mountain bike racing is easily overvalued. Sure, one speed is non-optimal, but having 11 useful gears, evenly spaced, may well be close to the saturation point. In road riding, there's long periods riding along on smooth roads of relatively consistent grade, with plenty of time to settle into an finely tuned cadence. Mountain biking is tends to be a lot different, however, with conditions changing constantly, the bike bouncing around so much that optimized cadence tends to be far down the list of concerns, position on the bike changing frequently due to changing trail conditions. Shifting less is more of a priority, shifting to constantly stay at a narrowly optimized cadence less so. So 1x11 may well make a lot of sense. Front shifts are eliminated, and with them a lot of problems front derailleurs present, including a welcome if small reduction in mass. And since the rear derailleur no longer needs to take up the rapid changes in tension associated with changes of in excess of ten teeth on the chainring, it can be optimized for rear shifting. The SRAM 1x11 isn't simply a conventional system with a single front ring: the entire system is optimized for 1x11. This is why I love SRAM: they take a fresh look at every aspect.

The SRAM cassette was truly a beautiful thing: they had a cut-away version so the interior could be adequately admired:

SRAM X1 cassette
SRAM X1 cassette: very cool!

The other things at the SRAM booth were the "WiFi" long-cage Red derailleur and the Quarq power meter. For the derailleur, I don't expect it's that much better than the Rival one which has been available: ceramic bearings in the pulleys and slightly lower mass. The bigger deal is the acceptance of long-cage (or perhaps more correctly "medium-cage") derailleurs at the highest level. There's been a lot of inertia in the acceptance of lower gears, based on an aesthetic from the days of 5-speed freewheels. But as old generations die off and new generations emerge, people realize the enormous performance advantages of using low gears on steep climbs, and as a result roads which had previously been considered impractical for anything other than rare masochistic suffer-fests become roads where speed, rather than simple survival, become the priority.

I took a photo of Peter Sagan's green jersey bike in the booth. Curious feature here is the bike had a competitor's (SRM) spider-based power meter, no Quarq. I was wondering why that had been until I noticed whose bike it was. No WiFi there! Next to it was Levi Leipheimer's Trek with WiFi Red and the Quarq/SRAM power meter. At the time I found it less interesting and neglected to take a photo.

Peter Sagan's bike
Peter Sagan's green jersey bike: no WiFi here!

Tuesday, September 25, 2012

Interbike 2012: pedals

I had three encounters with pedals at Interbike 2012. I'll review them in order of interest.

Least interesting by far was Speedplay. I didn't see anything there, other than the Syzr off-road pedal which was at the show last year. Indeed, this pedal was shown in a different form as far back as 2009 ("almost ready for production"): that's four Interbikes. Yet to my amazement someone at the Speedplay booth still talking about it not being ready yet for production. I remember doing a group ride in San Diego 1990 or 1991 where I guy I don't know who called himself Richard talked about his new pedal prototype which he was going to take into production and I laughed: the pedal market was already saturated with big hitters like Look, Shimano, Time. How was some guy in San Diego going to compete with them? So no criticism of Mr. Bryne and company, but I find the ongoing delay curious. Sometimes, it seems, it's easier for a little guy working in a machine shop to move ahead with something than it is for an established company with enormously superior resources.

Next was the Polar-Look power pedal. I was really looking forward to playing around with this, but on the Thursday I was at Interbike, the model they had at the Polar booth wasn't set up, and I didn't see anything at the Look booth (although maybe I missed it). The pedals were on a stationary bike but the "pods" were in the box. I was super-surprised by this, since the system has been used on pro rider bikes for all of this season, and it's nominally for sale to customers. Maybe they got it set up by Friday.

Garmin, on the other hand, wasn't showing anything of their Vector pedal system except for a poster. I know they received a lot of questions about it. Garmin seems to be taking a "we'll show it when we're actually ready" approach in some contrast to Look-Polar. The close-to-the-chest approach is in striking contrast to the old Metrigear days with the Vector blog, but back to the small-scale versus large-scale development theme described for Speedplay.

Ultra-Lite pedal
Ultralite pedal


Ultra-Lite pedal cleat
Ultralite pedal cleat, slightly warn from walking

Next was the Ultralite Sports pedal. Here's a description from Bike Radar. I really, really liked this. In mechanical design, less is more, and the elegance of this system makes for a lightweight, easily maintained, low-stack-height solution. I'd love to try it but if you add the cost of the pedals to the cost of switching from 4-hole "Speedplay" shoes to 3-hole it doesn't make much sense.

The pedal is inspired, perhaps, by the Aerolite pedal (now 25 years old or so). The engagement is different, however. The Aerolite pedal "snaps on", and disengagement is via supination. With the Ultralite, however, you disengage by sliding the foot inward then pulling out.

Most of my discussion with the guy to whom I spoke was whether the foot would come out in a crash. He said when you hit the ground on the side your foot will hit before the pedal and that will push your foot inward, causing the cleat to release. That doesn't take care of the opposite side, but I strongly suspect in the violence of a crash recoil will send the opposite foot inward at one point as well. Any new pedal system is going to take a bit of training for engagement and release, but somehow it always seems to work out fine. Mechanical simplicity results in low weight, low stack height, and simple maintenance and I love all of these.

As with Speedplay, Polar/Look, and Garmin, however, there was no demo. Maybe if I'd been able to try the pedals myself I'd have been hooked.

One issue which I associate with new pedal designs is how well would they work with Garmin Vector? Here's a schematic of the Ultralite:

Note there's two contact regions between the cleat and the pedal: one at an outer radius and one at an inner radius. The cleat doesn't move much laterally except during release, when it slides inward to disengage the outer radius from the spindle. This relative simplicity of the cleat-pedal interface, I feel, is highly suitable for determining applied force. I personally hope Garmin's able to branch out from their current pedal choice, driven by existing pedal market share, and consider designs such as this one.

Anyway, it was fun finally being at Interbike and I'm always excited by seeing new designs and engineering applied to my favorite past-time.

Monday, September 24, 2012

Interbike 2012: Crankarm-based power meters

I was at Interbike for the first time this year, and a big trend was crank arm-based power meters. There were at least three there: Rotor Power, Pioneer, and StagesOne. The fundamental physics behind each of these three units is the same: to propel the bike force is transmitted via a mechanical path: pedal body to pedal spindle to crank arm to (left side only) bottom bracket spindle to spider to chainring to chain to cassette to free hub body to spokes to rim to tires to road.

You can in theory extract propulsive torque anywhere along this path, and when combined with rate of rotation, convert the torque into power. In the case of the crank arm-based models, torque applied to the crank arm bends it, a bending moment proportional to the torque. To decent approximation the bending is proportional to the moment, and is thus proportional to the torque, so if you can measure bending then with suitable calibration (for example, hanging a known mass from a pedal orientated horizontally) you can determine the torque.

It sounds simple, but the devil's in the details, and it's in the details that these units differ. There's the additional issue that torque is of less interest than power, so you additionally need to determine at what rate the crank arm is spinning. Here as well the units differ.

Rotor Power
Rotor Power (my photo from Interbike)


Rotor Power
Rotor Power (my photo from Interbike)

I'll start with Rotor. Rotor does the "obvious" thing, which is to drill holes in the crank arm and insert strain gauges into the holes (the holes are already there for mass reduction). When the crank arm bends, the strain gauges located at different positions along the arm measure the bending. From a simplistic perspective measuring the bending at different positions seems redundant: the force is applied at well-defined positions (at the pedal spindle and at the bottom bracket spindle or at the spider interface), and therefore it might be assumed the crank arm bends the same way every time, requiring a measurement of strain at a single position only.

But reality is rarely simple. For example, in addition to a propulsive component of stress on the crank arm there is also a twisting moment: the further out the position at which the force is applied to the pedal, the greater this twisting moment. Twisting the crank-arm does not directly contribute to propulsion. For two different twisting moments, for the same propulsive torque, it's possible a single gauge will measure different readings. Measuring at multiple positions can in theory at least allow a more precise extraction of the propulsive component of stress. I've not modeled this but it would be interesting to see a finite-element analysis of the crank-arm to see if it's an important factor, and if multiple strain-gauge positions can help isolate the propulsive torque.

Pioneer
Pioneer, view from outside of crank: sensor pack is behind crank arm (my photo from Interbike)

The other two meters, Pioneer and Stages, take a different approach, attaching external modules to the crank arm. They measure the deflection externally: at the crank arm surface. Since the modules are relatively compact, the measurement is restricted to a relatively local portion of the crank arm. Given the choice between more or fewer sensors, I'll always take more, but I can't comment on the degree to which precision is compromised by the external sensor approach.

Of equal importance to extracting torque is extracting rate of rotation. I asked Rotor how they extracted this, if they used a magnet, and I was told "of course you need a magnet". From what I could tell from the conversation, they follow SRM and SRAM/Quarq's example of using a single magnet which records a pulse every time the crank rotates. This is a problem because from it you can only extract the average cadence during the period since the last rotation. Since cadence is constantly varying, for example when stomping up a steep hill at low cadence, or when spinning along with eccentric chainrings such as those Rotor sells, the rate of rotation is varying in a fashion which is correlated with the applied torque, and as I've described before, that introduces an error which can easily exceed the claimed 2% accuracy which is industry standard. Additionally, for cadences less than the reporting rate (typically 60/min), for some power reports, no cadence number may be available. Rather than wait for a cadence number to become available, delaying the reporting of a power number, the unit is forced to make assumptions. This can be a relatively large error for that power number.

Bonk Breaker
No photo of StagesOne, but these Bonk Breaker "high protein" bar samples were exceptionally tasty (my photo from Interbike)

So while Rotor wins in my estimation on torque precision they lose on cadence estimation.

Pioneer also use magnets but they use a multi-pole detector which generates blips multiple times during the crank rotation. They need this to plot their pedal-force diagrams showing how the force vector varies around the pedal stroke. This has the additional advantage that torques can be better synchronized with the cadence, improving power extraction precision.

Stages, on the other hand, uses accelerometers for cadence extraction. There's two primary ways to get cadence from acceleration: one is to use gravity (which is measured as an acceleration) which spins in circles relative to the crank arm as the crank arm spins. The other is to use the centripetal acceleration associated with the sensor in the crank arm orbiting in inertial space. The challenge is that there are acceleration components in addition to the centripetal component: gravity (just mentioned) and acceleration of the bike itself. The likely trick here, suggested to me on the WeightWeenies forum, was that the sensor measures acceleration at two different positions along the crank arm. If the crank arm is rigid these differ only in the centripetal component, so subtracting the two signals yields the centripetal acceleration of the pedal spindle multiplied by the ratio of the sensor separation to the crank arm length. The alternate approach, using the changing direction of gravity, requires taking the difference between subsequent measurements, and this is inherently sensitive to time variation in the other acceleration components. My money's on them using the centripetal acceleration taken at two different radii.

If this is what they do then I give Stages the win on cadence, followed by Pioneer, with Rotor a distant third.

But the deal-killer for me with Stages is that, at least for now, it's a left-crank-only system. Spider units get away with a single measurement because whether power is transmitted through the left or right crank arm, it goes through the spider. On the other hand installing a gauge in a crank arm measures only power transmitted from that side. Stages takes the left-side power and multiplies by two. This would be fine if people applied the same power from both sides, but they don't. Even if users could calibrate their L-R balance into the system, measuring it with a system which allowed for that (like Pioneer or Rotor), the balance varies depending on cadence, power, fatigue, recent injuries, etc. Stages claims 2% accuracy but if your L-R balance changes from 50% to 51% that's already a 2% error in power, not even considering the other sources of measurement error. So despite their claims that L-side-only isn't a problem, it absolutely is a problem, both from absolute accuracy and from precision over time for a given rider. I asked them about this at Interbike and was told "what we do for one side we can do for the other". So hopefully they'll come out with a two-sided system in the future.

Both Rotor and Stages rely on existing head units. Rotor uses ANT+ Sport communication protocol championed by Garmin. Stages goes one further by supporting both ANT+ Sport and Low-Power Bluetooth. The latter is supported by many smart phones, allowing phone apps to be used instead of dedicated head units and without adding hardware to the phone (there's ANT+ sport modules available). I'm a fan of specialized hardware: dedicated cycling head units will always outperform phones, I feel, although I exploit the convenience of the Strava Android app during short rides where the battery life and inferior display of the phone aren't important But for rides I care about I'll always use a dedicated unit like a Garmin Edge 500 or 800. Still, points to Stages for the flexibility of low-power Bluetooth.

In contrast, Pioneer has its own head unit, allowing it to display polar force diagrams for the pedal stroke. Additionally, it calculates a "force efficiency" metric, for which it has received support from Dynastream (who handles the ANT+ Sport protocol) and Garmin (who will incorporate it as an option on their Edge-series cycle computers). I've always had an issue with the concept of "force efficiency", since there's no reason to believe static force alone is a concern, and indeed in my discussion with the developer he admitted optimizing "force efficiency" was likely undesirable. However, no matter what you call it, it is likely an interesting number, to see how different pedal strokes correlate with the measurement. If you then see your number change, it implies your pedal stroke is in some way qualitatively changing, so it provides a degree of biomechanics feedback. The issue is there's infinitely many pedal stroke patterns which yield the same value for "force efficiency", so simply shooting for a target value isn't enough.

My real question, however, was how they measure the full force vector. When you apply torque via a crank arm, you bend the crank arm transverse to its length, like a diving board with a diver perched on the end. However, the perpendicular component of force is associated with the crank arm compressing or expanding along its length (like trying to shorten the length of a diving board by pushing on the end). This is the crank arm's stiffest direction, and I find it surprising they would be able to precisely extract a longitudinal strain. It would be easy to test, however: hang a weight from the crank with the crank hanging down (6 o'clock). If the meter can't accurately measure the weight then there's an issue.

So in summary, I like Rotor for being what appears to be the most robust design for measuring propulsive torque, but it's cadence extraction, despite being a tried-and-true approach which SRM has used for two decades, is suspect, especially for eccentric chainrings. StagesOne appears to have solid engineering but suffers from being left-side-only, something they'll need to remedy if data junkies are going to take them seriously. Pioneer promises the most, but ranks highest on the "I'll believe it when I see it" scale. If I had to commit to one of the three, Rotor clearly wins. Robust engineering counts for a lot in my mind.

Sunday, September 23, 2012

Fourth Place

They say fourth is the worst place: the lead medal, just off the podium. I don't agree with this, having gotten more than my share of 4th places in last year's Low-Key Hillclimbs. But the Low-Keys don't put medals around riders necks. The races which notably do so are the Olympic Games and the World Championships. I thought it would be interesting to review who got the 4th places in the individual elite road events at these competitions this year:

Olympics Games:

  • Women's Time Trial: Linda Melanie Villumsen, New Zealand
  • Men's Time Trial: Taylor Phinney, United States
  • Women's Road Race: Shelly Olds, United States
  • Men's Time Trial: Taylor Phinney, United States

World Championships:

  • Women's Time Trial: Emma Pooley, Britain
  • Men's Time Trial: Tejay Van Garderen, United States
  • Women's Road Race: Amber Neban, United States
  • Men's Road Race: John "Arnie" Degenkolb, Germany

Impressive showing here by Team U.S.A. with a remarkable 5/8 (updated with mens' world championship road race results).

Surprising seeing Degenkolb, who's built like Schwarzenegger in his prime, making it to the top of the Cauberg with the leaders...

Wednesday, September 5, 2012

Lance Armstrong and the Death Penalty

A year ago, Troy Davis was executed for murders he is claimed to have committed, in Georgia. From an article in Time:

In the 48 hours leading up to Davis' execution, the nation heard that the case against Davis was built entirely on eyewitnesses who said they saw Davis gun down off-duty cop Mark McPhail. But of the nine witnesses who testified against Davis in his original trial, seven would go on to change their mind and recant.

So nine people, who didn't know him, claimed to have seen Troy commit the crime. Seven later recanted, and yet he was still killed by the state.

In contrast, there are reportedly ten independent people, each of whom knew him, including teammates, an ex-wife, and an ex-fiancee, testifying that they observed Lance Armstrong either self-administering illegal drugs, or describing his method and practice of doing so. Additionally, Lance is reported to have encouraged others to use these drugs. He left behind blood samples which have been tested by two independent agencies for illegal drugs. He has tested positive for cortisone. Activegan, an illegal doping agent which Tyler Hamilton claims they injected into their veins, was found in the team trash bins. He is reported to have tested positive for EPO for which he bribed the UCI to cover up. He is on record having made substantial money payments to the UCI as "donations". Approximately 90% of the top ten riders in each of the years he won the Tour have been involved in doping scandals or rode on teams for which systematic doping has been determined to have been practiced. The rate at which he climbed hills was unprecedented in the prior history of cycling, or in the history of cycling since. In short, the evidence against Armstrong makes the evidence against Troy Davis look flimsy.

Here's an excellent review by Laura Weislo of CyclingNews of reports on the Lance Armstrong doping scandals and on evidence which has been explained away.

Yet despite this, a group of California senators are calling for the USADA decision against Armstrong to be "reviewed". There's insufficient evidence, they claim. He "never tested positive" they say.

I think it's a sad, sad, state of affairs when our representatives in government hold apply a far higher standard of evidence to sports results than to application of the death penalty. Of course, being rich and white versus poor and black is a huge factor here. They come across as total buffoons. It's unfortunate, because among the authors of the letter is Alan Lowenthal, who championed the 3-foot passing bill which has recently passed the legislature and is awaiting Governor Brown's signature. Clearly he has time on his hands now that this important work is done.

Tyler Hamilton's book is released today. Maybe he should send a copy to each of these senators.

Tuesday, September 4, 2012

changing trends in cycling and the ever-present doping question

In the Vuelta this year, Joaquin Rodriguez has been untouchable. Not only is he able to outclimb Chris Froome, arguably the dominant climber of the Tour de France, but he's able to respond to every one of Alberto Contador's attacks. Sure, Contador is a convicted doper, and without the good stuff he's simply not going to be at the same level he was before, but it's almost unprecedented in cycling history before the EPO era that riders were able to so dominate stage races they they never once lost time to a rival. Not only is Rodriguez able to mark his rivals, but he's able to finish these climbs with absolutely ferocious attacks which put 5 seconds or more on everyone else (excepting perhaps Valverde when he's still with him) within the last 500 meters. I've never before seen a rider who was able to do that, nor am I aware of any rider in cycling history who could combine such searing intensity with the ability to excel on extended climbs. And that he's attained this degree of dominance only at age 33, having begin his career in 2000 with ONCE, is even more remarkable.

Indeed, in addition to the combination of intensity and endurance exhibited by Rodriguez is the "35 is the new 25" phenomenon. The most obvious example of this was Chris Horner and Levi Leipheimer, riding better than ever before into and through their mid-'30's. Then along comes Bradley Wiggins, going from never having won a pro time trial to becoming untouchable at 31-32. Joaquin Rodriguez, at 33, has been unleashing his ferocious attacks at the summits of 1st category climbs in the Vuelta, making everyone else, including Contador, look silly. There's a rational explanation for this: the biological passport, and endocrine thresholds are established with age-independent limits. You set the limits so a 21-year-old, his hormones running full gas, can pass, and you provide a lot of head-room for that masters-aged pro who needs to replenish what time has taken. I know, they say that the reduced racing schedules associated with increased specialization, at least for men (Merckx and Hinault basically raced all year long) results in less wear and tear. But if that were true then in other sports with less wear-and-tear in cycling we'd also see athletes peaking in their mid-'30's. It simply doesn't happen.

A third change in cycling is the German bodybuilder-road sprinter phenotype. First Andre Greipel, then Marcel Kittel, and now Degenkolb have all come to the scene within the past few years with bodies which looked more suited to a remake of Conan the Barbarian than to surviving 240 km road races.

Traditionally cycling road sprinters have been road racers first, sprinters second, which limited them to a relatively slight physique, although with the door open for some impressive leg definition. Here's the amazing legs of Sean Kelly, probably the top sprinter of the 1980's:

Sean Kelly
Sean Kelly's legs (VeloRambling.org)

Kelly's supremacy was followed by those of Djamolidine Abdoujaparov, Mario Cipollini, Eric Zabel, Robbie McEwen, and now Mark Cavendish as the best sprinters in the stage race game. Each of these riders had (or has) impressive leg muscles for sure, but still relatively light. It's hard to move a lot of muscle mass in circles 70-120 times per minute, 60 minutes an hour, 4-6 hours per day.

Abdu, whose career ended with a suspension for steroid use, had particularly impressive legs:

Abdujaparov

But then these German sprinters entered the scene, looking more like track specialists than roadies. Greipel puts his predecessors to shame:

Greipel

Kittel was next: Kittel

Then John, who while not to the standards of Gripel and Kittel, still has tree-trunk like legs with which he's totally dominated stages in this Vuelta:

I am reminded of baseball in the early 1990's when the body shape changed. Players to that point had been relatively lean, natural for a sport where running faster is correlated with success. The power hitters tended to be bigger and slower, but they were the exception. Then that all changed. Rosters became dominated by guys who'd adopted a markedly spherical shape, with necks as thick as my waist. These guys looked as if they should be hardly able to move, yet they were still obviously able to run down balls in the field, to turn a bat quick enough to hit a 160 kph pitch. The argument was made that players had discovered the weight room. Excuse me? Something as simple as doing what every high school athlete does, lift weights, doubles a player's home run output and top-level pro players took 100 years to discover this? Of course it was later revealed steroid use became rampant during this era. Baseball claims to have cleaned itself up but the body shape remains. That alone is proof enough for me.

Similarly with cycling. When things change in profound ways it's a good sign something's up. The story will come out eventually; it always does.