Wednesday, July 18, 2007

Deep Rims All the Time

A very, very long time ago I watched the Coors Light pro cycling team annihilate its opposition in a series of criteriums in the Tour of Michigan. These guys were sort of the "B squad" - no Stephen Swart, no Dave Mann, no Davis Phinney. But when the good pros show up, well, it becomes apparent once the start whistle is blown.

For many of the races these guys would simply power at the front of the field, stretching it thin, tugging hard, and finally snapping the elastic. The field would implode and withdraw to recover. The Coors Light boys would keep driving, time trialing at the front, dragging along anyone who might consider latching on.

What struck me about the Coors Light boys was part of their equipment selection. Their frames were pretty normal, components standard (no CNC machined bits for them, maybe an SRP bolt kit but that would have been it), but when you looked at their hoops....

They all rode Specialized TriSpokes, front and back.

Curious selection I thought.

But man these guys rocked the field. No one, and I mean no one, could stay with them. Everyone else rode box section rims - standard light stuff, great for perhaps a road race, but we're talking crits with hills you need to shift down to at least the 53x14 to climb.

I have to think that the wheels helped their cause immensely. My non-scientific experience indicates that the wheels were probably worth a good 2-3 mph at the 32-35 mph they'd be holding. A great tactic would have been to simply hammer at a very high speed, force all the non-aero-wheel guys to dig deep into their reserves simply to hang on, and after a bunch of laps like that, well, that's when you attack.

And just ride away from the bunch.

I did the Cat 3 Tour de Michigan those years and the first year there was a guy who wore a uniform that looked like the Dutch national jersey - three strips, red, white, blue. He had no teammates, wasn't too big, but he was strong and could sprint forever.

He lost a lot of precious points when his chain broke in the middle of a sprint, causing him to flip over the bars with about a hundred meters to go during one of the "stages". Whatever injuries he sustained couldn't have helped his cause either, but he went on to win the eight race series.

Interestingly enough, he also ran dual TriSpokes, the only one in the race to do so.

If you think about it, such wheels allow you to drag race (meaning race side by side) others to the line while holding a huge advantage. If they hold your speed, they exert more energy - they'll blow up sooner. If you exert the same amount of energy, you'll go faster because your wheels allow you to do so.

When I raced there I selected light wheels over aero ones. As you might expect, the only sprints I placed in were those where a jump counted more than top speed - where the finish lines were close to the last turn. Nevertheless I managed to earn my entry fee back for the whole race. I was reasonably happy with my success.

The next year the Cat 3 Tour de Michigan was won by a very unassuming (i.e. potbellied) Cat 3 from Paris, Kentucky. He rode Zipp 440s front and back - and those aero wheels seemed to give him a little oomph as well. My race was not so good - I didn't make back my entry and I ended up on the deck at least once as well.

After the Michigan experiences I decided that perhaps these aero wheels would be a good thing. I didn't have the light, second generation TriSpokes (the first generation wheels felt like they were made from cast iron). I worked on and managed to get a second generation wheelset and started using them for racing. It was only when I got a clincher front that I trained on a front TriSpoke consistently. This allowed me to acclimate myself to the wheel's handling characteristics, specifically the way you hold a line with it (you have to steer a bit - the wheel acts as a rudder). I also got used to its reaction to crosswinds.

By the mid 90's I'd been experimenting with other wheels - Zipps, a very lightweight disk wheel (some prototype), and assorted aero or light wheels. The TriSpokes remained the fastest wheels although the deep (50+ mm) carbon Zipp 440s were very fast as well.

I raced on these wheels all the time. Guys would question my sanity when I lined up with deep section rims on a day with gusty winds or a fast descent. But I felt comfortable with the wheels, having trained on them consistently. In fact I was squirrelly when I chose to ride non-aero wheels because I got so used to actively steering the bike, a riding technique forced on me by aero wheel characteristics.

I don't think the fact that these wheels were fast was any secret. Pros used them. Amateurs did too.

About a decade later, after various teams used aero wheels, it seems like the last, developmentally stunted Pro teams are finally catching on. It's unusual to see a pro without deep section wheels now. Looking at the specs, there's virtually no penalty in going from the "ultra light" climbing Zipp 202s to the Zipp 404s (+100g per wheel). Why would anyone race the non-aero wheels in anything but a typhoon?

The main reason, I think, for the aero wheels is the UCI rules, specifically the minimum weight rule. It states that bicycles must weigh a minimum of 6.8 kilograms, a hair under 15 pounds. With the sub 1000 gram frames, sub 350 gram forks, and the ever lighter components, a pro team would be hard pressed to build a bike that actually reaches the limit.

The limit then becomes an envelope within which one builds the bike construct.

In other words, you can tweak the bike by using excess lightness and using a part that is a bit heavier but stiffer, stronger, or more aerodynamic. For example, from examining Cancellara's Cervelo, it is apparent that he's chosen to ride a heavier aluminum crank rather than the "nice" carbon one. He also uses Zipp 808s (another 100 grams heavier than the 404s). As a rouleur, the wheels are a natural choice. I'd think a sprinter might select them too, perhaps in the rear for stability, with a slightly lighter, slightly more "twitchable" 404 up front.

I'm sure that a team like CSC is not willing to handicap their riders too much. One can assume that Cancellara's bike is around minimum weight. Instead of adding weights or other gimicky things, the team (and/or the rider) added functionality to the bike.

In 2006, PowerTap's most famous rider, Floyd Landis, opted to use 200 grams of his 6800 gram allotment to carry around a PowerTap hub (200 grams is the typical penalty for the PT hub versus a normal hub). With the bike already extremely lightweight, the PT did not penalize him as far as weight went. Nowadays you'll see SRM cranks all over (but some of them are only +30 grams from the non-SRM version of the crank). The minimum weight has opened doors for some tweaking and adjusting without making the racer feel like they're penalizing themselves.

Once you get your bike down to the minimum weight, there are three, perhaps four areas which offer opportunity for performance enhancement.

1. Efficiency/rigidity - if you can use a bicycle which transfers power more efficiently, you'll use more of power to propel the bike forward. Typically this area is improved by using more rigid frames, bars/stems, cranks, and/or wheelsets. Usually increased rigidity means a bit of extra weight but for those with the luxury of being under 6800 grams, this is one area the ride can improve to bring up the bike's weight.

2. Aerodynamics - if you can make the bicycle more aerodynamic, it requires less power to go the same speed. You can improve this by using an aero frame, aero wheels, aero components, or an aero/TT position. Often these aero components are heavier. If you're starting with a 6000 gram bike, you have 800 grams of "aero" to add.

3. Strength - in a race that goes over rough roads or for skittish racers, using a heavier part may do more for the rider's confidence than having a really light bike. Witness Hincapie's second crash of the 2006 Paris Roubaix when his steerer tube failed. Obviously his first fall, although seemingly harmless, exceeded some kind of limits in crash resistance, resulting in the steerer tube failing spectacularly. I'm sure a slightly stronger steerer tube wouldn't hurt his confidence for the next Paris Roubaix.

4. A semi-category would be fit, ergonomics, and monitoring. The first would include variations in fit (arch cleats, forward seatpost, crank arm length variations, etc). The second, ergonomics, might include things like electric shifters (instead of cable-actuated - doesn't that sound ancient? - shifters), proper gear selection, maybe a more comfortable seat or bar. The third would include devices that allow racers to monitor their engines (i.e. themselves) like power meters, cyclometers, etc.

Any of the categories listed above can help improve overall bicycle/racer performance. However, the easiest, most cost effective, and most versatile improvement will come from slapping on a set of aero wheels.

What it comes down to is that in today's bike racing game, aero wheels are here to stay. Get a pair, train on them.

And level the playing field in your favor just a bit.


Anonymous said...

So true....

My Cervelo P3c with Zipp 606 wheels (808 rear and 404 front) is the perfect combination of weight, aero properties, and controllable characteristics even in moderately windy conditions.

No One Line said...

I found this photo, remembered this mention of the Coors Light Team, and had to find this post again to share it.

Aki said...

haha that hair! wow!

No One Line said...

The hair, and the posing, and something about David Mann's smile. Maybe it's the contrast with Mckinley's smouldering glower. Wow indeed.