Recumbent Bike Performance
If you’re primarily riding your Bacchetta recumbent bicycle to go fast, then this section is for you! We’ve dedicated this segment to those of you who feel the NEED FOR SPEED and are RIDING FOR THE LONG HAUL!
Performance & Recumbents
There are many reasons to consider a recumbent, first and foremost being comfort. When you ride a recumbent bicycle you will no longer have an aching back, stiff neck, strained wrists or a sore bottom. Recumbent bicycles allow you to sit in a relaxed easy-chair position, allowing you to ride longer with less fatigue and arrive at your destination feeling refreshed. While seated on a recumbent, you are looking straight ahead, providing you with the best view possible of your surroundings. With your head in a more natural position, you avoid the neck and back pain from being hunched over, the position most associated with a traditional bicycle.
Shoulders, arms, wrists and hands no longer bear the brunt of your weight, because in the recumbent position, they are no longer supporting your upper body. Still having those problems straightening your back after a long ride? With a Bacchetta recumbent, your days of cycling misery are over! The reclined position on your new recumbent bicycle takes the strain from your lower back. In the end, you’re concentrating on the ride and not the pain. Eliminating the pain means opening up a world of cycling performance you can only find on a performance recumbent bicycle. You’ll slice through the wind faster and easier, due to reduced frontal exposure. Handling, cornering, stopping, and overall control is enhanced by the recumbent’s lower center of gravity. In fact, many recumbent riders report feeling that the bike seems to be running on rails!
Wind and rolling resistance impose limitations on the performance of any cyclist. All other things being equal, even slight aerodynamic advantages will exhibit significant cycling speed improvements. A performance recumbent bicycle can provide fifteen to thirty percent lower wind resistance (coefficient of drag) over the typical upright racing bike.
Do recumbent bikes climb hills well? This is a common first question by the cycling community and one that we’re always happy to answer. Recumbent bicycles can in fact climb extremely well provided they are geared to do so (as with any other bike) and that the person riding the bike is a good climber. Despite the fact that you cannot stand on the pedals, you can leverage power against the seat. Different muscle groups are employed, and a short period of adaptation to climbing on a recumbent bicycle should be expected. Recumbent bike models with shorter wheelbases tend to do better at climbing than longer models of recumbents.
Recumbent bikes are very versatile machines. They can be used for a wide range of applications: recreational/sport riding, for the daily commute, a fast double century and they are fantastic for long distance touring.
For optimal performance, you must reduce your frontal area as much as possible. Your tires rolling resistance is also very important to bike efficiency, which is why you see racers running the narrowest and thinnest high-pressure tires available..
Depending on the exact configuration of the bike and the tires you are using, the power consumed by air resistance and the tires rolling resistance is typically about equal at 9-12 MPH. But because the power to overcome rolling resistance is linear with speed, and the power consumed by air resistance is a cubic function with speed…by the time you get to 20+ MPH typically over 70% of the overall power you deliver to the pedals will be consumed by air drag!
For example, let’s say that the tires rolling resistance power/wattage equals the aero drag power at 12 MPH, which is pretty typical. So at 12 MPH, we have one unit of power going to overcome rolling resistance (RR), and one unit of power going to overcome aero drag at let’s say a total of 40 watts at 12 MPH. That would be 20 watts for aero drag and 20 watts for rolling resistance at 12 MPH.
When we double our speed to 24MPH, we now need 40 watts of power for RR because it is linear with speed, or 2 X 20 watts. Since the aero power is proportional to the cube of the speed, when we double our speed the aero drag component becomes (2^3) x20 watts, or 8 X 20 watts= 160 watts.
When we add the aero and RR components together at 24MPH, we now have 40 watts + 160 watts= 200 watts @ 24 MPH. We only doubled our speed from 12 to 24 MPH, but the power required went up by a factor of 5 (40 to 200 watts) because of the dominance of the aero drag at higher speeds.
Performance: Seat Angle
On our Bacchetta recumbents, the best efficiency will be attained by reducing the seat angle as much as possible without harming either the rider’s power output or rider’s view of the road (VERY important in real world riding to avoid obstacles!). Many experienced riders find the best angle to be 22-28 degrees from horizontal on our composite seats. Riders typically find lower seat angles increasingly more comfortable with experience.
Note that seat angles lower than 20 degrees (as measured from horizontal on our composite seats, across the lumbar curve area with a straight edge) will result in somewhat lower drag, but this lower seat angle also increases penetration of the torso shadow by the knees and lowers the power output for most riders.
Performance: Steering & Arm Position
The ideal lowest aerodynamic drag arm and steering geometry on our performance bikes puts the arms in a horizontal and straight position, directly in front of and in line with the shoulders. Also, try to get as much of the handlebars at or below the shoulder level as possible.
Applicable to recumbents also, here is a great link from Chris Boardman, world record holding upright time trial/track specialist, on simple methods to reduce frontal area and related power output issues http://www.bikeradar.com/us/gear/article/aerodynamics-made-easy-30981/
As a great example of how fast even our “nonperformance” stock bikes can be when the body position is set up for speed (lower seat angle, arms horizontal, aerodynamic clothing, etc.) a totally stock unfaired Giro recorded a 38.2MPH 200 meter speed at the 2006 World Human Powered Championships! That speed is just one MPH slower than the current World Recumbent Racing Association’s unfaired 200 meter record, set on a track modified, one speed low racer with dual wheel discs.
Wheels, Tires, Forks & Weight/Aero Considerations
On our speed specific models, we use the most aerodynamic components we can afford from the upright time trial and triathlon bikes. Substituting a lighter, but less aero component (like a fork) is almost always a bad choice for efficiency unless you are only concerned with low speed hill climbing.
Although we offer very light and aero wheels on our Corsa and Aero models, further aerodynamic efficiency gains will come from higher wheel surface areas, which decrease drag in real world crosswind conditions. Our Bacchetta team riders typically run carbon disc rear wheels with high surface area front wheels like HED 3’s or Zipp 404’s.
Tire choice can be very important, with low rolling resistance sometimes being at odds with durability. We try to include stock tires on our bikes based on the best compromise of rolling efficiency and durability. For those speed junkie/ frame kit customizers, use your judgment as far as which tires give you acceptable performance on your courses, considering your body weight. For speed, run the narrowest and lightest high-pressure tire you can afford!
*Our very own Rich Pinto (VP of Research and Development) provided the performance information seen here. He will be adding additional information and sources to this segment of our web site from time to time. If you should have any performance-oriented questions, please feel free to contact Rich Pinto at firstname.lastname@example.org.