Dear members of the forum,
My original question was:
I am looking for information about rollers and trainer for
Advantages and disadvantages.
-Rollers vs. trainers.
-Magnetic vs. fluid.
-Feasibility for training.
If you are user of this equipment, personal opinion will be welcome.
This is the summary of the different opinions and comments that I received
from two forums: Biomech and Sports Enigeering. Thanks to all.
If you have more opinions or comments, I will complete the summary
in the future
Advantages of rollers

 Good for warming up

develop good co-ordination

You will also have found your natural cadence, which you can then use on
the road to tell you when to change gears

 On rollers is where I really learned bike control

Disadvantages of rollers

can offer little resistance

require skill and attention when riding

is as boring as watching cement set

the newer grooved aluminium rollers, use touring tires- those things eat
racing tires for lunch

too much resistance and the bike/rider would ride off the front of the

Advantages of trainers

More stable ride

several types of resistance (fan, constant magnet, variable magnet, fluid
in order from cheaper)

Expensive models can be connected to a PC to run a simulated program of
variable resistance, race against an imaginary opponent or even connect
to the internet

Trainers are easier to learn

probably safer

they are smaller and more portable.

Disadvantages of trainers

is as boring as watching cement set


Fluid supposed to be better than magnets which supposed to be better than

to simulate actual road cycling you need a flywheel that has equivalent
rotational inertia as the linear inertia of a cyclist. i.e. 60-80kg. The
cheap units are hardly ever heavy enough to do that

The air resistance needs to be simulated as well. Air resistance is cubic
in nature as is water. i.e. the faster you want to go the force required
increases cubically not linearly. This is normally done with air turbine
fans (but rarely is it done correctly. i.e. pedal speed at a given gear
offers the right resistance). This is not simulated by magnetic or belt
brakes or electrical brakes ( gym equipment), which tend to be linear in

Fluid trainers are smoother and resistance increases exponentially. 
Most magnetic trainers give the sensation of "pulses" coming from the rear
wheel.  Fan assemblies are also popular, but are noisy.  As in
fluid trainers, the resistance increases as velocity increases.

Wind resistance is used with both trainers and some rollers. It is loud
yet can be used to create a cooling breeze very desirable when in a sealed
room. No different resistance settings yet accurate exponential increase
in resistance with speed. Same speed/resistance relationship as outdoors.

magnetic resistance has variable resistance but it's not speed dependant.
Much quieter than wind

fluid resistance is quiet has variable resistance as well as speed dependant
resistance. Supposedly the cadillac of trainers but I don't think there
too much better than mag trainers.

fans generate a lot of noise

the noise that may be created by the fans or the magnetic unit are in my
opinion not a big deal

ROLLERS: also I wanted to get aluminum and not PVC drums

Juan V. Durá - Instituto de Biomecánica de Valencia
Tel. +34 - 961366032       Fax. +34 -

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