Bike Fit

After spending much of my winter working on improved flexibility, I decided that it was time for me to get myself a "proper" time trial bike. When I first started triathlons, I owned a KM40, which is a sweet ride. However, like a lot of us, I was never properly fit on it and suffered from all kinds of back pain. I just assumed that was part of the deal with long distance riding. A few years ago, I was fortunate to have a custom bike made for me and the comfort improvement was huge. In addition, my power output appeared to increase. Back then I wasn't riding with watts, so I have no objective data — I just became faster and more comfortable.

The team setting up the bike

So, armed with my improved range of motion, I started to ask around about the best bike fit experts in our sport. One name came back more than the rest, John Cobb of Bicycle Sports in Shreveport, LA. When I rang the shop up from New Zealand, the guys were helpful and friendly. They must have been wondering why a guy would travel all the way from NZ to get fit on a bike. Well, I was actually going to be traveling from San Francisco, but it's still a big journey.

Those of you who frequent the Internet will quite often see debates raging about the difference between frame materials, frame manufacturers, wheel sizes, shifting configurations, etc. My experience has been that none of this matters as much as achieving a comfortable position. Many of us (myself included) start with a bike position that is too aggressive for our experience, flexibility and body structure. By aggressive, I mean the position of the shoulders relative to the hip joint. The lower the shoulders relative to the hips, the more aggressive the position (some people talk about aerobar pads relative to seat height, but I think shoulders to hips is more accurate).

The hump in my back sits behind the head's wind shadow

After spending about 18 months in a comfortable position, I had decided that it was time to play with the two other position variables, power and aero. It's not everyday that you get a chance to probe the mind of the most experienced bike fit guy in the U.S., and I was really looking forward to my session with John.

John has worked with the full range of athletes — novices up to Tour de France winners (if you head to Shreveport, you will see a few shots of JC with Lance and Lemond in the bike fit area).

Having fit many different bodies gives John a huge internal database of solutions for various challenges. This experience becomes apparent very quickly. After two minutes of watching me ride, John knew as much about my biomechincs as I did. After 10 minutes, he was explaining my body to me, and things that I had always wondered about my riding started to make sense.

Those of you with access to a power measuring device (Power-Tap, Computrainer, SRM, Cat Eye) will already know that body position has a direct impact on power. More specifically, the most aerodynamic position is almost always inferior in terms of power generation. While on the trainer, John illustrated this very quickly by having me ride with the aerobar pads about 2/3rds of the way back from my wrist. He increased the resistance to the point where I was putting out about 400 watts and told me to move my arms such that the aerobar pads were nearly under my elbows (stretching me out and making me more aero). I instantly lost about 50 watts of power. I was working just as hard, but my watts simply disappeared! To put this in context, 50 watts of power (for me) is about 30 minutes in an ironman-distance bike leg. If you are a strong rider, pad placement could be the difference between a podium finish and missing the rolldown. I was amazed.

Flat scapula shows well here

John explained that what had happened was that my longer position had taken out the large muscle groups of my upper body (arms, shoulders and back) as well as reducing the impact of my core strength. I wasn't able to engage my full muscle mass, and therefore, lost power. As well, for a given level of power output, my legs would have to be working harder. This is a key consideration for long distance triathlon where athletes need to run when leaving the bike. Being able to effectively bring the upper body into the cycling leg gives us an advantage.

Cobb Lesson #1 — You can trade quite a bit of aero for a more powerful position. Not surprising when you see the success (and position) of riders such as Jurgen Zack.

Cobb Lesson #2 — Many of the most aero positions can rob riders of valuable wattage. It's not so much the frame geometry (John fits all kinds of bikes), as it is how the overall configuration relates to the rider's biomechnics.

John's Big Slam position has received a lot of coverage over the last little while, and we talked a bit about it. John mentioned that he has been using a traditional TT position for years and this has proven very effective for many riders. Indeed, I think the position that we ended up with for me is a traditional TT position. Listening to John, the evolution of the Slam position appears to have come from a desire to help riders blow through a plateau. The idea is to change the set-up to involve different muscle groups. By changing the rider's position, John is able to help athletes break through to a new level in their riding. The principle of superior adaptation by variable stimuli is one that I am familiar with from my weightlifting background.

After insert placed to lift right shoe -- equal extension

Cobb Lesson #3 — Riders who have reached a plateau can quite often benefit from a change in position, if only to help stimulate new muscular adaptations.

When we started, John asked me my race distance, my years riding and my performance over those years. Not having reached a plateau, we started with a more traditional TT set-up. I think this is something that most age group triathletes should keep in mind. A comfortable, traditional set-up is probably the best starting point for most athletes.

On to that traditional position... once again, it was an eye-opener! Indeed, John mentioned that we don't really "know" anything about aerodynamics until we "get in the wind tunnel" and really see what's happening. I'd be willing to bet that John's logged more time in wind tunnels than anybody else in our sport, and it was fun to listen to him describe how the wind really moves around our bodies when riding. Things were not as I had understood and John pointed out that he is constantly learning new things each year. Here are the key lessons that I learned as they relate to my own fit.

If you have a look at the side view photo of my final position, you will see that there appears to be a hump in the top of my spine. I asked John about the hump because I had always read that the goal was to get the back as flat as possible. John pointed out that my back was flat, at least the part the matters. The spine sits in a wind shadow behind the head, so it is less important. Cobb Lesson #4 — The key part of the back to be flat is the scapula and beyond.

Rounded shoulders, flat scapula, elbows shadow knees -- minimal frontal area

Previously, I rode with the very popular Syntace C2 clip on bars. They are an excellent product and served me well. Once again, I had read that more narrow the elbows, the more aero the position. So I worked something fierce on my shoulder flexibility and managed to get my pads nearly side by side. Have a look at my front view photo and you will see that my elbows are relatively wide (for me at least). Cobb Lesson #5 — The elbows need only protect the legs.

Go to any bike rack in our sport and you will see that there is a wide variation in aerobar height and forearm angle. Again, I had read that a slight upwards angle (15 degrees) is best as this helped guide the air down and around the body. Turns out the tunnel showed otherwise, yet again! Cobb Lesson #6 — The bottom of the forearm should be parallel to the ground to avoid pushing any air down into the legs. Like the back, the faster the air moves across the body the better. Trying to "steer" the air is counterproductive.

So, we had my fit dialed in. This is the most aggressive set-up that I have ever been able to ride and I was amazed at how comfortable it felt. As well, I have to admit that receiving the thumbs up from Lance's bike fit man is a mental boost.

I'll leave you with two final tips. If you have a look at my position you will see that I don't have any bottle cages mounted. I asked John for his opinion on the ideal set-up for me. Best of all is a CamelBak, but if I had to mount cages, behind the seat is superior to on the frame (for my bike). John also mentioned that the best rear mount systems are those that leave the bottles low and behind the legs. We didn't discuss brandnames, but I know one popular brand that leaves the bottles sitting high and exposed to the wind leaving the rider's back (not good at all).

The Man - John Cobb

Finally, I asked him his view on the best wheels for an ironman distance race. Here is his recommendation: The new 2002 Hed Disc rear and a Hed-3 front. If you are in Kona, a Hed-3 rear and either a Zipp 303 front or a Hed Alps front. How superior are these combinations? Well, I already own twin Hed-3s and I put my name down on the waiting list for the new discs. If you are serious about speed, this wheel will make a material difference to your riding.

There was a little bit more, but I am sure that you'll understand if I save a few watts for myself!

See you at the races,
gordo - April 2002

John, Mike and Dave are the key guys at Bicycle Sports. You can reach them at jcobb@bicyclesports.com, and check out their website at www.bicyclesports.com. John charges $150 for a bike fit session, and I think that this is the best deal going in triathlon.