I am looking to buy an exercise bike... need help!!?

i know that the heavier the flywheel the better... but is a magnetic recumbent exercise bike with an 8kg flywheel bad because it is only 8kg? and if so what is a good weight for an average weight woman?

The flywheel weight is not responsible for the quality of your workout or the resistance of your workout. All that the flywheel accomplishes is to smooth the pulses of power out that you put to the pedals.

When you ride your bike on the road if you push really hard on the pedals the bike resists that change in speed because you are in contact with the road and your own body weight and momentum provide a flywheel effect. If you stop pedalling or reduce your pedaling force the bike will slow down gradually. It won't stop instantly because again your body weight and momentum provide a flywheel effect. So on a regular road bicycle your own body weight and momentum accomplish this flywheel effect this while on the stationary bike the flywheel weight simulates it because there is no road nor body generated momentum.

On a stationary bike with a lighter flywheel you will find it harder to pedal smoothly because your power pulses as you turn the cranks and your pedal speed goes up as you push on the down side and slows as you go across the bottom and top of the power stroke. This pulsing will obviously be exadurated if you were a large male rider who pumps away at the pedals with a lot of body mass and strength. If you are of slight build and turn the pedals over lightly and smoothly the lighter weight flywheel may be no problem at all. In a gym you can sometimes hear exercise bikes making a pulsating roar as riders pump away and this is the pulsing I refer to here.

As a side note from cycling history - One of the finest lady riders in the world was Rebecca Twigg. Rebecca could smoothly ride on her bicycle trainer at 200RPM of crank speed. No male rider that was ever able to accomplish this feat of smoothness.

So the exercise bike you propose to get is better than a bike with a lighter flywheel but not as good as one with a heavier one. If you are able to test ride it you should be able to tell in a few seconds if the pulsing will be an issue for you given your body weight and pedalling style. There is no fomula that I have seen that will help you on this as the gearing of the bike to the wheel and other factors will change how the flywheel dampens the pulsing.

The most important factor on stationary bikes is the resistance mechanism which will impact smoothness even more than flywheel weight. Electronic means are best but generally only comes on more complex stationary bikes. Wind resistance where fan blades are made as part of the flywheel are another approach or may be used to augment others means. A simple set of felt pads (similar to brake pads on a road bike) rubbing on the sides of the flywheel are probably the most common and low cost type.

There is an interaction between the quality of the resistance mechanism and the weight of the flywheel. If the bike has a lightweight flywheel and the resistance mechanism is not precise, the varying resistance can cause the pulse problem also. So again, heavier is better, because the flywheel will stabilize and tend to smooth out any problems with resistance mechanism caused pulsing.

Good luck on your purchase and happy pedaling.

Try Craigslist

two words:
WALLMART!

craigs list acadamy look for used ones at

Yes the 8kg is fine. Adjust the resistance as needed to increase the effort to your work out. If the machine has variable resistance, the weight of the flywheel is a mute point. The weight of the flywheel is for smoother running. You only have to get the mass spinning then it becomes easier. That is why they add a form of resistance -- to continue your effort.

Good luck with your workout.