Most of the known exercise bicycles are made with a drive system with roller chain and a freewheel bearing from a common bicycle which often implies disturbing noise problems. Besides, prior art exercise bicycles have problems with unbalance and wobble, especially with loading a plate-shaped freewheel by means of friction brake.

On this background, the invention has the purpose of indicating an improved exercise bicycle which is distinguished by the said problems being countered by means of simple measures.

The exercise bicycle according to the invention is characterised in that said flywheel is designed with spokes between a peripheral, annular part and a hub part, that said fly- wheel is enclosed by means of a double-sided covering, and that between said hub bearing and the flywheel there is arranged a free-wheel. Hereby is achieved an im- proved exercise bicycle by which the above problems are countered effectively, i. e. the prior noisy and imprecise rotational movement of the freewheel of the exercise bicycle is replaced by a noiseless and completely vibration free rotational movement of the freewheel by the exercise bicycle according to the invention.

Suitably, the exercise bicycle according to the invention is thus designed so that said freeewheel consists of a one-way bearing and a support bearing.

The exercise bicycle according to the invention is furthermore designed in such a way that said covering preferably consists of stainless steel plate and comprises integrated guard screens for said drive pulley, drive belt, and pulley.

With the intent of achieving a special optical effect, the exercise bicycle according to the invention is designed so that said covering opposite to the spokes of the flywheel

is designed with cut-outs covered by transparent plate material, e. g. Plexiglas or poly- carbonate.

The exercise bicycle according to the invention is furthermore designed so that the drive belt is constituted by a Kevlar drive belt, preferably of the poly-v-belt type.

The invention is described more closely in the following in connection with the drawing on which: Fig. 1 shows a so-called exploded view of an embodiment of an exercise bicycle according to the invention, Fig. 2 shows a sectional view of a preferred embodiment of a bearing arrangement for a flywheel in an exercise bicycle according to the invention, and Fig. 3 shows a side view of an exercise bicycle according to the invention for illus- trating a preferred and simple method for tightening the drive belt of the ex- ercise bicycle.

The exercise bicycle 2 shown in Fig. 1 comprises a frame 4 which is made up of quad- rangular tubes as the frame 4 consists of a forward inclining handlebar tube 6 and a likewise inclining saddle tube 8 spaced apart therefrom, which is in two parts, as the saddle tube 8 itself consists of a short quadrangular tube opening downward and fas- tened rearwards on a support tube 10 being parallel with the saddle tube 8 and extend- ing between an upper frame tube 12 and a lower, horizontal frame tube 14, which is connected at the rear with the saddle tube 8 by means of a rear support tube 16. This and the handlebar tube 6 are connected with horizontal foot tubes 20 and 22 by means of angle bars 18, of which a front foot tube is provided with wheels 24 so that the ex- ercise bicycle 2 is easy to move.

Between the support tube 10 and the handlebar tube 6 there is fastened a throughgoing bearing plate 26. A secondary bearing plate 28 is also fastened to the handlebar tube 6 but has a shorter dimension for accommodating a pedal driven drive pulley 30 sus- pended in the support tube 10. At the free end of the secondary bearing plate 28 there

is formed a slit 32 in which a tension pulley 34 for a drive belt 35 is mounted. Be- tween the bearing plates 26 and 28. is mounted a flywheel 38 on a horizontal axle 36, the fly wheel 38 being designed with spokes 44 between a central hub part 40 and a peripheral annular part 42.

The bearing arrangement for the flywheel 38 is shown in Fig. 2 where a pulley 46, besides forming a hub bearing 48, is suspended on the axle 36 by means of four ball bearings 50 while a hub part 52 of the flywheel 38 is suspended externally on the hub bearing 48 by means of a special one-way bearing 54 and a support bearing 56.

This bearing arrangement allows that the flywheel 38 may be driven about in a usual way by means of the pedal driven drive pulley 30, the drive belt and the pulley 46, and that the flywheel 38 may continue rotating freely when the exerciser stops active pedalling. In that connection is to be mentioned that the support bearing 56 is very important as in practice it has appeared to be very difficult to achieve a stable function of the one-way bearing 54 without the support bearing 56. Furthermore, it is important that the one-way bearing 54 and the support bearing 56 are mounted with mutual spacing.

It is to be mentioned that the exercise bicycle 2 according to the invention easily may be modified further to a completely different way of exercise, particularly used by racing cyclists, namely so-called spinning, by a very simple mechanical intervention.

By spinning, the flywheel 38 is connected rotationally directly with the pedal drive, i. e. where the special one-way bearing 54 is put out of action, for example, by arrest- ing the freewheel between the pulley 46 and the flywheel 38 with a direct mechanical connection which furthermore may be remote controlled without difficulty.

In Fig. 3 is shown how a loose saddle pin 57 may be used as moment arm for use in tightening the drive belt 35. For this purpose, a container 58 for accommodating a bolt 60 is disposed upon the lower frame tube 14, the bolt 60 intended-as shown-for connecting a free end of the saddle pin 57 to the secondary bearing plate and a tension block 62. The container 58 is normally hidden between covering plates 64 of stainless

steel (Fig. 1) which are designed with integrated guards for bearing plates and drive belt system. The covering plates 64 opposite to the spokes 44 are designed with a number of circular cut-outs 66 that are internally covered by means of transparent plate material 68 (Plexiglas or polycarbonate) for reasons of safe handling.