Bicycle trainer
From Wikipedia, the free encyclopedia
A trainer or "indoor trainer" is a piece of equipment that makes it possible to ride a bicycle indoors without moving forward. They are primarily used to train for races.
A trainer consists of a frame, a clamp to hold the bicycle securely, a roller that presses up against the rear wheel, and a mechanism that provides resistance when the pedals are turned. In a wind trainer, the roller drives fan blades that create air resistance. These are typically the least expensive and noisiest trainers. Magnetic trainers have magnets that resist each other, and are moderately expensive and moderately noisy. Some magnetic trainers have handlebar-mounted control boxes to change the level of resistance during a training session. Fluid trainers use liquid-filled chambers to create resistance. They are the most expensive and most quiet trainers. A small number of trainers use a centrifugal pressure mechanism to create resistance, involving pressure plates, ball bearings and specially shaped grooves. These are similar to fluid trainers in price and performance.
Trainers make it possible to build bicycle skills and power very efficiently in a highly controlled environment, without the unavoidable interruptions of outdoor riding. For instance, in hill training, instead of being limited to whatever hills are around one's home, one can simulate any size and steepness. One triathlon coach estimates that three hours of indoor training can be as effective as four hours of outdoor training. Trainers provide better preparation for racing than stationary bicycles. Trainers require better technique than stationary bicycles, and they provide a more realistic-feeling ride. The geometry and resulting body position of a stationary bicycle may be significantly different from a racing bike; of course, if one uses the racing bike itself in an indoor trainer, the body position is identical.
However, indoor training is extremely monotonous. Some people find the tedium unbearable. Others distract themselves with music, television or videos.
Some trainers are equipped with sensors that monitor the rider's performance. Power output, cadence, virtual speed and heart rate are among the metrics that can be transmitted electronically. Analyzing these figures can help to fine-tune the athlete's training.
Rollers are a similar device, but they do not support the bicycle. Balancing the bicycle without flying off the rollers is an extra challenge for the rider. Some find that this helps them focus on the workout, while others prefer the stability of a trainer.
Contents |
[edit] Types of Trainers
Bicycle trainers are categorized by how the unit provides resistance.
- Wind - the unit uses a fan powered by the cyclist's legpower to provide resistance on the rear tire. Pros: Resistance progresses with cyclist's speed, creating a realistic feeling of cycling on a road. Cons: Noise, limited resistance.
- Magnetic - a magnetic flywheel creates resistance on the rear wheel. Pros: Nearly silent operation. Cons: Resistance has an upper limit, prone to break. A notable exception may be the CycleOps 2006 Magneto, which is advertised as the first "magnetic trainer with progressive resistance."
- Fluid - combines magnetic flywheel with fluid resistance chambers. Pros: Nearly silent magnetic operation with added progressive resistance. Cons - Repeated friction heating and consequential expansion and contraction of the fluid can result in seal leaks.
Usually all trainers can be adjusted for most sizes of road and mountain bikes. However, knobby mountain bike tires can cause vibration and noise, defeating the purpose of noiseless units.
[edit] Turbo Trainers
A turbo trainer is any device used to convert a road bicycle to a stationary exercise bicycle, by mounting the cycle in a rigid framework. This distinguishes turbo trainers from rollers which likewise permit a bicycle to be used without moving, but which allow the cycle to sway in a similar manner to when moving on a road. Turbo trainers all provide a framework which makes the bicycle stable to sit on and pedal while stationary and some sort of mechanism to provide resistance to pedalling. More sophisticated examples provide a greater degree of control and precision to the user and a variety of feedback, particularly in modern computerised devices.
[edit] Turbo trainer resistance mechanisms
Turbo trainers apply several different physical principles to produce rolling resistance comparable to the total resistance to the motion of a cycle on the road (which is mainly due to air resistance and slope).
The simplest examples use an adjustable frictional resistance, which may be a robust band, which may be tightened by the user prior to exercise, pressing against a cylinder rotated by the back wheel of the bicycle. Other examples use a gearing mechanism to drive a large fan which takes a considerable amount of power to turn at speed, and which can be used to provide useful cooling for the user to replace the movement through air on the road. Some modern turbo trainers drive a small fan in an enclosed fluid, which provides a large and quite precise resistance to rotation in a compact device. Others use a magnetic resistance system, based on the dynamo effect. These have the advantage of allowing electrical calibration and a wide range of precise control through increasing the current passing through one of the coils.
[edit] Input and output
Most turbo trainers provide a mechanism for adjusting resistance, although in the simpler devices this may only be adjusted prior to a session. However, in the large majority of designs, the resistance changes as the gears are changed on the bicycle, which allows a high degree of user control of resistance during a session.
Some modern turbo trainers incorporate a simple built-in computer which caters for a variety of user input and output. These may provide calibration of the resistance, control of resistance to emulate hills (under the control of the user or a pre-programmed schedule), measurements of mechanical power, inferred speed, pedalling cadence, heart rate (via a radio interface from a chest band) and even torque on the most sophisticated models. In addition derived statistics including integrals and averages of these statistics are commonly available. Some designs provide an interface to a standard personal computer, which allows more sophisticated processing and graphing of data.
[edit] Applications
Turbo trainers are used as a training aid by many competitive cyclists, allowing precisely controlled and monitored exercise regardless of weather and road conditions. With the wide availability of increasingly economical and sophisticated devices, turbo trainers are beginning to become a more popular exercise device for cyclists at all levels, including those who do not participate in road races. One advantage of turbo trainers over exercise bicycles is that the device itself is compact and easily stored, and a road cycle can be mounted in it for an indoor exercise session or removed for use on the road in a matter of seconds.
