Tuesday, February 24, 2009

Aero Road

I really enjoy Lennard Zinn's articles on VeloNews. I don't always agree with his views, but I often find insight there. Today was an exception.

Kestrel's latest Talon SL: very slick.


He was asked about the benefit of aerodynamic road frames for mass-start racing. These frames claim to save approximately 1% to 2% of total wind resistance. There's a bunch of them. Kestrel was really the first to my knowledge with their carbon fiber Talon, although that failed to catch on among the mass-start crowd. Cervelo was the first to really break through with its aluminum Soloist, followed by Soloist Carbon (SLC), SLC-SL, and finally this year the S-series. More recently, Felt (with its AR) and Ridley (with its Noah) have jumped on board. There's still others. Chris Boardman claims to be testing an aero road frame.

Yet the pros are sometimes reluctant to take advantage of these. While Cervelo was largely successful with its SLC, and even more so with its S3, at getting pro riders on their aero frame, on Garmin, for example, despite the much-publicized AR series debut at last year's Tour, this year (so far) the riders are all on the "conventional" F1. And when Kestrel broke into the pro ranks with its Rock Racing sponsorship, it's with the RT-900 as opposed to the Talon or Talon SL.

So why? Lennard says aero isn't a benefit in any significant cross-wind. He cites data on the Hed web site, that resistance of aero rims begins to increase above 8 degrees yaw. Let's check out some of the data he references, using Zipp wheels to limit the number of variables other than rim depth:

Hed data on Zipp wheels showing advantage of aero rims for yaw angles to 20 degrees.


As Zinn notes, the resistance does increase for the deepest dish rims above a certain yaw, in this case 10 degrees. However, an advantage over shallower dish is retained out to at least 20 degrees. For a racing bike moving along at typically 10 meters per second or more, a 20 degree yaw represents a near-surface cross-wind component of 3.6 meters per second. That's 3.3 meters per second even if longitudinal relative wind is reduced 10%, a ballpark number for drafting benefit. Basically, 20 degree yaw relatively large under the vast majority of conditions.

The pros seem to agree. For essentially all mass-start races from tight criteriums to epic Tour stages, riders are on deep dish wheels. The days of 25.4 mm are long gone. The only evident exception is the cobbled classics like Paris-Roubaix and Flanders, where while deep carbon is becoming popular, old school metal rims are still relatively common due to their reliability.

Zinn argues that the mass penalty of profiled tube road frames makes them an unwise choice for criteriums, where accelerating out of corners makes low mass a premium. Lennard, Lennard, Lennard. I know you know how to run numbers.

Consider sprinting out of a tight corner from 30 kph to 45 kph over 5 seconds. For a rider + bike totaling even 75 kg, that's 650 watts into acceleration alone, not counting wind resistance. But the mass difference of an aero frame and post relative to a non-aero frame and post is only around 150 grams (compare the Kestrel Talon SL to the Fuji SL-1, for example, each relatively unpainted carbon road frames: paint would increase the differential). The extra power to accelerate the heavier frame over the same 5 seconds is only 1.3 watts. Yet wind tunnel data at multiple yaw angles shows the aerodynamic frame saves at least this much at these speeds. So even in the tight corner the aero frame may be better. The rest of the lap, the aero benefit is just icing on the cake.

So why aren't the pro riders jumping all over the aero revolution? The obvious answers are comfort, stiffness, handling, and/or geometry. Pros like stiff frames, generally, perhaps not for simple reasons of energy transfer efficiency (analysis has shown that substantial majority of energy going into frame flex is returned through the drivetrain into propulsion), but in how the bike feels. With Cervelo, the geometry is the same between the S (aero) and R (conventional) series, but for example with Felt the two differ substantially, the AR having longer head tubes at the same front-center distance. That may be an issue with Garmin.

So I think Zinn got lazy here. He started with the answer he wanted, then kludged reasoning to justify that. But the question is obviously more complicated. From wind tunnel data, you'd think every cat 4 would be on an aero frame just to be competitive. But at the top, pros keep winning races on "conventional" frames.

Monday, February 23, 2009

Moving


Fight Club
was one of the great movies of our time, and one of the worst marketed. Oh, yeah, there was that business about guys cutting loose with the barefisted brawls. I think competitive cyclists everywhere strongly relate. But the real message was its potent yet underappreciated "That which you own ends up owning you." Is there a better summary of culture, our society, our lives?

I've been moving these past few weeks. Peeling away the crusted shells of neglect. Stuff pushed aside, hidden away, suppressed. Old bike stuff. Old mail. Old memories. Course notes from school, written with detailed attention I can't imagine giving today. A different age. A different me.

In denial of our throw-away society. Old computer boxes, packed with form-fitting styrofoam. Sure, the boxes can be "recycled". But the foam? Where does that end up? Put it on the curb, let them haul it away. Would hanging on to it change anything?

Old modems. Why when you sign up for new DSL service is a new modem mandatory? Out with the new, in with the newer. Something's fundamentally wrong.

Old letters.... fond memories, suppressed guilt. Neglected relationships... family... friends. Some still living, others gone.

Some stuff stays; some goes. I tend to be fairly obsessive about not wasting. If I can't use something, find someone who can. Craigslist. Freecycle. This makes the process longer. Don't pack what's easily replaced, they say. But isn't that accepting the throw-away society? I, consumer. A trivial cog in an out-of-control machine of production, of destruction, of greed.

But it's all self-deception. When I'm gone, it's all going into the landfill or ocean or incinerator anyway. The machine grinds along. Yet I like to believe it has meaning. I have a responsibility to my stuff. To take care of it, to get proper use from it, to not waste it.

Moving is like a bit of a new birth. Reorganize, resort, trim down. But wouldn't it be wonderful to be free of it all? To start from scratch? That's the message of Fight Club. We need not be owned by our stuff. To be human is far more than that.

And it's that humanity I think we discover on our bikes, or when we run. We break free from the machine. We meet ourselves, with whom we spend far too little time.

Saturday, February 7, 2009

Lance wait-listed (or not...)

I just heard from my coach Dan Smith that Lance Armstrong was wait-listed at the Cherry Pie Crit. I can see it now, long reg lines.....

(Pro 1/2 line) "Next..... license and waiver?"

Rider hands over license.

"Pre-registered?"

"No."

"All fields are full, but I can add you to the waiting list."

"Okay."

(writing) "Lance Armstrong. Austin, Texas. 38. Astana."

"We'll call your name if there's room.... NEXT?"

Expect to see the city Napa in flames, the greater population in a rampage of uncontrolled looting and anarchy, if Lance doesn't get that start line position.

Oh yeah, 2007 US Elite Criterium champion and 6-day racer Daniel Holloway of Garmin is also on the list. No riot for him, I'm afraid.


update: So much for rumors: Lance is leaving town... No cherry pies in his diet plan.

Thursday, February 5, 2009

More bikes on board

First, an apology. Last blog post, which I subsequently deleted, I commented on a power metric which I didn't fully understand. I like playing with formulas, I don't deny it. It's sort of my job (in semiconductor devices, not in cycling). I love trying to model stuff. But if I'm suggesting limitations in someone else's model, I'd better be really sure I understand what they're modeling! I'll still post my models here at some point, but in a more constructive fashion.

Today I attended the CalTrain meeting on increasing bike capacity on trains. It's fantastic Caltrain recognizes that given the profound limitations of public transit on the Peninsula, the bike + train combination is a uniquely attractive option. Indeed, it amazes me that anyone tolerates the solo-driver commute from the City. Living in San Francisco with a job on Palo Alto simply would not be an option for me if I were compelled to drive.


Caltrain bike car. You've gotta be nuts to days your carbon-fiber wünderbike here... but what choice is there for those Wednesday Noon Rides? :)

Caltrain proposed removing seats from the bottom level of all bike cars to expand bike car capacity, from 16 to 32 bikes on the newer Bombardier cars (leaving 3 seats), and from 32 to 40 on the older Gallery cars (removing all seats). San Francisco Bike Coalition's response what that this represented on the Bombardier cars, which lack line of sight between levels, a "stand or steal" choice with only the passengers able to watch over the security of 32 bikes. Theft, or other mishandling of bikes parked at the racks, is an obvious concern. Instead, SFBC wanted 80 bikes per train, with two bike cars per train, placing addition racks on the Bombardier cars at their mezzanine level. Caltrain rejected mezzanine-level racks as an bottleneck for pedestrian access between the two levels. SFBC in return advocated a one month delay in the decision, to allow a cooperation between the two in discusssing the tradeoffs of various options.

I proposed security cameras with monitors on the second level to allow those sitting upstairs to monitor their bikes below, but was told this was a "high six-figure" proposition which would require funding "possibly from the department of homeland security". Funny. I'm not worried about "the homeland", just my bike.

Silicon Valley Bike Coalition, which has a history perhaps of being less assertive than its San Francisco counterpart, proposed a more limited expansion on the Bombardier cars, from 16 to 24 instead of 16 to 32. This would allow the retention of more seats on the lower level, which would provide more options for those with a strong preference for sitting withing sight of their bikes, and in any case would provide more eyes to identify suspicious activity.

CaltrainCaltrain expressed reluctance for the additional delay in action proposed by SFBC, preferring to move ahead immediately with the SVBC proposal of a 16 to 24 bike capacity increase on the Bombardier cars. This would be applied to all existing bike cars, which would result in some sets with 48 bike capacity. On the Gallery sets, there was unanimous agreement that the original Caltrain plan of increasing capacity from 32 to 40 bikes was a worthy idea, and that was approved.

I further recommended that the allowed per-rack capacity be increased from 4 to 4.5. While 5 bikes per rack sometimes creates a constriction in the isle, 4 on one rack with 5 on the opposing rack does not. This recommendation was not responded to. In any case, it requires only a change in policy, not in infrastructure, so could be implemented instantly. I also recommended space around the racks be used for bicycles. For example, bikes can be propped behind the racks, if the first bike on the rack is mounted with handlebars in the proper direction. Again, no response to this suggestion (which I am less optimistic will be accepted).

Overall, though, I have to be happy with the result: a substantial increase in bike capacity on the trains, directly addressing the Bombardier bottleneck. Caltrain needs to focus not only on total capacity, but on reliable capacity, and if there's the substantial chance of a 16-bike-capacity Bombardier set showing up at the stop, you simply can't have confidence you're going to get to your destination on time.

The cost: $200k, or $600 per seat removed, or around $3600 to $4800 per rack. A chunk of change for some really simple hardware. Still, a worthwhile investment to support Caltrain's most loyal customer base, one which has the least impact on other capacity constraints such as parking and station access. Thanks again to Caltrain for moving ahead with this.

Sunday, February 1, 2009

Recommended Peninsula rides

A Canadian rider asked WeightWeenies forum about good rides to do for a racer visiting Santa Clara county (the San Francisco Bay area) on business. Cara recommended I post the list here, so here it goes. These are rides taking place now, in February. More options open up during Daylight Savings time. And, for example, the fall offers the the Low-Key Hillclimbs, near and dear to yours truly.

A description of local climbs is available from Stanford Cycling. This wonderful compilation is largely the work of Sergei Morozov, who unfortunately last time I checked was in exile in New York City. A frustrating fate for a climbing addict....

Keith Vetter's Klimb is a must-see route tracking utility for the San Francisco Bay area and Sonoma. It runs on a broad range of platforms. If you are thinking of charting out a route, you really need to give this a look. It's largely based on Bill Bushnell's comprehensive statistics, meticulously collected in the 1990's.

Another must-have local resource is The Krebs cycling map. It's not available at a bike shop in the Bay area, it's probably just because it's out of stock.

Local rides worth checking out, off the top of my head. There's others: a more comprehensive, not 100% up-to-date, list is maintained by Fremont Freewheelers:
  • The Palo Alto Morning Ride: leaves 6:20am Tue & Thu from Starbucks on University Ave. Fast group ride with sprints.
  • The Noon Ride, leaves noon SHARP from Page Mill and Old Page Mill near Foothill/Junipero Serra:
    • Mon: short, moderate pace,
    • Tue: race pace, longer. For example, here's motionbased data of the Corte Madera route.
    • Wed: climb OLH (390 vertical meters), descend 84. For example, here's some of Chris Hipps' data.
    • Thu: like Tue.
    • Fri: like Mon but longer, blast over short hill at end with sprint after.
    You can find data for these rides from MotionBased.
  • Wed 9:10 am, Peets in Los Altos, Dave's Morning Ride: epic stuff. Really high quality riders, friendly, quality race training. Of course, work has a pesky tendency to get in the way of this one.
  • Saturday: Spectrum Ride, approx 9:15 am from Los Altos (Foothill @ Edith) catching the group which starts 9am further south. Similar to Tue/Thu noon ride, but faster.
  • Saturday, Peets in Los Altos, 9:10 am: Alto Velo B ride: a moderate pace group ride with climbing with generous regroups.
  • Sunday, Peets in Los Altos, 9-9:10 am: Alto Velo A ride: a fast group ride with considerable climbing and limited regroups. Hard road race training.
  • sanctioned races: See http://www.ncnca.org/ and http://www.ncncaracing.com/
  • The Beat the Clock Series raises money for the the Lance Armstrong Foundation with its occasional time trials on Canada Road starting at 7:30 am.
  • touring rides: interesting routes, with very generous regroups: Western Wheelers . Also Grizzly Peak Cyclists and the Alameda County Touring Cyclists occasionally organize group rides on the Peninsula.