Post by Vespa on Jan 7, 2005 13:27:40 GMT -5
from Bike.com:
What's In A Wheel?
The best wheels for different competitions
From: Hoyt Halvorson, Carmichael Training Systems - Thursday, January 6, 2005
How important are wheels when it comes to bike racing? Some old school cyclists are convinced that equipment is unimportant. It’s all about the rider. Ultimately, the strength of the rider is far more important than any other factor. However, once a cyclist is at the physical level that allows her to compete, choosing the best equipment can greatly impact success in certain events. At the very least, she won’t be at a disadvantage. In making wise choices concerning wheels, there are three critical issues: weight, aerodynamics, and lateral and torsional stiffness. These three issues are involved in making the right wheel decision for the different road disciplines: Time Trial, Road Race and Criterium.
Of the three disciplines, Time Trial owes modern technology the biggest pat on the back. It’s just you against the wind, and for that reason, aerodynamic equipment helps a great deal. Because of advances in carbon fiber technology, Time trialists brag of speeds never seen before. In a flat time trial, there is no question of the fastest wheel combination. Millions of dollars have been spent testing riders in wind tunnels. Lance spent the winter at the University of Washington wind tunnel while Ivan Basso was at MIT with CSC and Cervelo. Both teams of experts came to the same conclusion. In a flat Time Trial, there is no better option than a rear disc with a front tri-spoke or at very least a deep section front wheel of a minimum of 38mm dish. The only variation on this is during races with strong crosswinds. Then the tri-spoke may not be the best option. In that situation, it would be better to choose a wheel with a low spoke count and a low-profile box rim. Weight is of little consequence. Acceleration is not as important. Once you get the bike rolling, it’s all about aerodynamics. Therefore, the idea is to get the air by you as quickly and cleanly as possible. Keeping air from getting hung up on the bike is the whole idea. A disc is perfect, because air passes right by with the least amount of drag to the rider. One might bring up the issue of side-wind that would make a disc unsuitable, but only in extreme situations would a rider face such conditions.
The discipline where aerodynamic advantage begins to fall off is Road Racing: those races involving great elevation change. Since speeds are greatly reduced on a climb, the weight of a wheel is your main concern. The laws of physics teach us that when moving an object up a grade of 5% or greater, the lower the weight, the less force it takes to move that object. Consequently, when Chris Horner is climbing, he wants the lightest wheels he can get his hands on. And, while rims have become extremely light, it is actually the weight of the hubs that cause wheels to be lighter than ever. If there is much elevation change in your next Road Race, grab the lightest wheels you can find.
The last discipline of road cycling is surprisingly very demanding of wheels. In Criteriums, riders circle a 1km city block for 20 minutes to 2 hours. These races can be as fast as 30+mph. There are several different reasons to choose a good wheel for a Criterium. First, when exiting a corner, riders accelerate using 1000-watt efforts or more, which involves a great deal of torque. Since wheel flex can work against a rider, finding a laterally and torsionally stiff wheel is critical for these demanding races. This goes for any situation in which the rider is pushing the wheel on its side, whether cornering, sprinting or climbing out of the saddle. Surprisingly, the other issue in choosing a Criterium wheel is weight. There is not enough climbing to make a light wheel necessary, however, because there is so much acceleration, reducing the rotational weight of the wheel will allow you to come out of corners much faster. A wheel with a light rim will have a greatly increased acceleration at the moment of rotational inertia. A climbing wheel will necessitate a light rim and a light hub to become as light as possible. In a Criterium, acceleration only demands lower rotational weight. So, a good Criterium wheel must have the strength to handle the demands of cornering and sprinting while maintaining a low rim weight.
Let’s sum everything up. Since flat Time Trials are all about aerodynamics, choose a rear disc and tri-spoke or deep-dish wheel. Or if that’s not an option for you, find the most aerodynamic wheel-set you can find. Because hilly Road Races and uphill Time Trials are mostly about weight, find the lightest wheels that you can afford. These will generally have a low spoke count and will have low profile rims. And lastly, when it comes to Criteriums, find stiff wheels with light rims. That way you’ll come out of corners fast and stick the wheel in front of you with less work. These will most likely be made of aluminum or carbon, both of which are stiff and light. As you can see, there is some overlap between the wheels. Once you have acquired a few wheelsets, you will be able to use different combinations for nearly any condition.
Yes, it’s not all about the bike. But, once you have worked hard to make yourself fast, shouldn’t you reward yourself by making your bike fast, too?
What's In A Wheel?
The best wheels for different competitions
From: Hoyt Halvorson, Carmichael Training Systems - Thursday, January 6, 2005
How important are wheels when it comes to bike racing? Some old school cyclists are convinced that equipment is unimportant. It’s all about the rider. Ultimately, the strength of the rider is far more important than any other factor. However, once a cyclist is at the physical level that allows her to compete, choosing the best equipment can greatly impact success in certain events. At the very least, she won’t be at a disadvantage. In making wise choices concerning wheels, there are three critical issues: weight, aerodynamics, and lateral and torsional stiffness. These three issues are involved in making the right wheel decision for the different road disciplines: Time Trial, Road Race and Criterium.
Of the three disciplines, Time Trial owes modern technology the biggest pat on the back. It’s just you against the wind, and for that reason, aerodynamic equipment helps a great deal. Because of advances in carbon fiber technology, Time trialists brag of speeds never seen before. In a flat time trial, there is no question of the fastest wheel combination. Millions of dollars have been spent testing riders in wind tunnels. Lance spent the winter at the University of Washington wind tunnel while Ivan Basso was at MIT with CSC and Cervelo. Both teams of experts came to the same conclusion. In a flat Time Trial, there is no better option than a rear disc with a front tri-spoke or at very least a deep section front wheel of a minimum of 38mm dish. The only variation on this is during races with strong crosswinds. Then the tri-spoke may not be the best option. In that situation, it would be better to choose a wheel with a low spoke count and a low-profile box rim. Weight is of little consequence. Acceleration is not as important. Once you get the bike rolling, it’s all about aerodynamics. Therefore, the idea is to get the air by you as quickly and cleanly as possible. Keeping air from getting hung up on the bike is the whole idea. A disc is perfect, because air passes right by with the least amount of drag to the rider. One might bring up the issue of side-wind that would make a disc unsuitable, but only in extreme situations would a rider face such conditions.
The discipline where aerodynamic advantage begins to fall off is Road Racing: those races involving great elevation change. Since speeds are greatly reduced on a climb, the weight of a wheel is your main concern. The laws of physics teach us that when moving an object up a grade of 5% or greater, the lower the weight, the less force it takes to move that object. Consequently, when Chris Horner is climbing, he wants the lightest wheels he can get his hands on. And, while rims have become extremely light, it is actually the weight of the hubs that cause wheels to be lighter than ever. If there is much elevation change in your next Road Race, grab the lightest wheels you can find.
The last discipline of road cycling is surprisingly very demanding of wheels. In Criteriums, riders circle a 1km city block for 20 minutes to 2 hours. These races can be as fast as 30+mph. There are several different reasons to choose a good wheel for a Criterium. First, when exiting a corner, riders accelerate using 1000-watt efforts or more, which involves a great deal of torque. Since wheel flex can work against a rider, finding a laterally and torsionally stiff wheel is critical for these demanding races. This goes for any situation in which the rider is pushing the wheel on its side, whether cornering, sprinting or climbing out of the saddle. Surprisingly, the other issue in choosing a Criterium wheel is weight. There is not enough climbing to make a light wheel necessary, however, because there is so much acceleration, reducing the rotational weight of the wheel will allow you to come out of corners much faster. A wheel with a light rim will have a greatly increased acceleration at the moment of rotational inertia. A climbing wheel will necessitate a light rim and a light hub to become as light as possible. In a Criterium, acceleration only demands lower rotational weight. So, a good Criterium wheel must have the strength to handle the demands of cornering and sprinting while maintaining a low rim weight.
Let’s sum everything up. Since flat Time Trials are all about aerodynamics, choose a rear disc and tri-spoke or deep-dish wheel. Or if that’s not an option for you, find the most aerodynamic wheel-set you can find. Because hilly Road Races and uphill Time Trials are mostly about weight, find the lightest wheels that you can afford. These will generally have a low spoke count and will have low profile rims. And lastly, when it comes to Criteriums, find stiff wheels with light rims. That way you’ll come out of corners fast and stick the wheel in front of you with less work. These will most likely be made of aluminum or carbon, both of which are stiff and light. As you can see, there is some overlap between the wheels. Once you have acquired a few wheelsets, you will be able to use different combinations for nearly any condition.
Yes, it’s not all about the bike. But, once you have worked hard to make yourself fast, shouldn’t you reward yourself by making your bike fast, too?
