John Cobb, bike fit and aerodynamics expert, recently took the time to answer Endurance Corner team member questions. We're sharing his responses as part of a series throughout the summer. In this installment, John answers some questions about equipment selection.
EC: If I want to spend money on speed, where are the greatest returns to be found in terms of equipment?
John Cobb: It still amazes me when I go to a triathlon and there are racers there with no aerobars. Bars really work, get a set for your bike. The next thing I believe in is having your bike fit to you properly. If you have a $10,000 bike but can’t stay down in the aero position because of discomfort, you really didn’t get your money’s worth. Keep asking and looking around till you find somebody that will help you get comfortable.
EC:What's the real difference between all these different types of race wheels -- are there material differences between the different depths and brands?
John Cobb: There are some differences between wheel brands but generally, deeper is better. Lighter wheels cost more money because of the more expensive carbon and hubs. But light weight alone doesn’t guarantee a fast wheel. Wheels that have a sharp inner nose section and a defined “V” shape usually handle worse in cross winds. I’m not really sure if the wide rim principal is worse or better, time will tell us all that answer. I usually tell people that the consumers are the ultimate testing facility, products that are gimmicks are soon found out and go away.
EC: Do you consider the tip of the saddle on your VFlow to be the actual tip or the highpoint which is located approximately 5cm from the tip?
John Cobb: On my standard VFlow model the nose is the like a normal saddle and this is a great area for racers that like to sit way far forward when riding. On the Plus and the Max model seats, the nose would better be described as being 5cm behind the end of the seat. The drop down areas of the Plus and the Max are to help with lessening any interference of men’s “package” or women’s pubic bone/soft tissue area. All of my seats a designed to have you rotate the pelvis forward and down into the seat. Having the handle bars too high puts extra pressure on the sit bones so try to run your bars lower and rotate your pelvis forward and down into the saddle.
EC: What is the real differences between aero helmets (short tail versus long-tail)?
John Cobb: There are two basic back shapes that all riders fit into. Group [A] which is the classic flat back with an acute bend at the waist and [B] a more rounded back with a pronounced hump or flex point right in the upper back at the shoulder blades. About 75% of age group racers are the [B] type back, about 60% of the professionals are the [A] type back. The [A] backs usually benefit from a longer tail helmet (Spiuk, LAS Laser, Specialized are this type) with an enclosed bottom, this pulls the air away from the head and shoulders and down the center of the back. [B] style riders benefit from shorter tail helmets (Rudy Project Wingspan, LG Rocket, Giro are a few) and the general helmet position is not real important. Many times these helmets are faster with the tails sticking up in the air so I wouldn’t sweat trying to keep the tail down on your back. The reason for this seems to be two things, less frontal area with the tail up and a smoother solid surface for the air to go around with the tail up.
EC: What are your thoughts on aero helmets and the overheating/dehydration risk counteracting the aero benefit?
John Cobb: I think the heat factor has to be considered but all aero helmets are not created equal. There are a couple that have plenty of ventilation, just stay away from a face shield and the aero helmet should be worth wearing.
EC: Can you share your opinion on hydration packs?
John Cobb: I’ve never found that CamelBaks and related products hurt the rider's aerodynamics very much and have often improved them. I have also found it difficult to convince a sprint or olympic distance racer to use one because of the extra five seconds to put one on! For training rides I think they are very good.
EC: What are your recommendations for buying a new bike from a local non-triathlon-specific bike shop?
John Cobb: Take some measurements and try to get the right size. Whatever size a shop recommends, unless they are a very, very, good tri shop, get the next smaller size. On almost any bike you purchase you will need to change the stem and the saddle location. On a new bike you should consider going for shorter cranks and a better saddle -- these things add up to big speed. Nobody should get a bike off the floor and go race it, the odds are just not very good that the bike will really fit correctly. Bike fit is more important than wheels or helmets -- you're planning to spend a lot of time on that bike so why not be comfortable.
In case you missed it:
Part I - Bike Fit
Part II - Hilly Courses
John Cobb is a world leader in cycling aerodynamics and bike fit. He's based in Tyler, Texas and can be reached via his website (www.CobbCycling.com).
