Innovations & Ideas
Art of Engineering
From our Partners
New Bicycle - How to improve a bike
These articles are available in the standard RSS format for publication on your website:
How to improve bicycle
By A.E. KROPP, Professor, PhD.
The modern history of the bike has more than 200 years, although the image something like a bicycle found on the walls of the ruins of ancient Egypt, Babylon, Pompeii. According to Russian historians, the bicycle was invented by a Shamshurenkovym in 1752. This nugget lodged in the Senate draft «running by itself carriages», received for the project «fodder money to 10 kopeeks for the day», and indeed created something like a bicycle. However, the history of the bike with a count taken in 1791, when the Count de Sivrak built a wooden car with two wheels that are consistent, they were joined by beams, which were sitting. Wants to ride sat astride a timber and move, taking his feet from the ground (Figure 1). Since then, till today, not stop the process of improving the bike, a list of inventions relating to the bike, has more than 20 thousand items. Among these innovations are the most important: on the one given in the 1836 H. Dalzelem, while others - in 1839, K. Macmillan, invented the pedal (with the help of pedal levers give the rear wheel. The fare to get rid of the need to build on land with their feet), in 1868, the Paris company «Meyer & Co.» issued a bicycle with a chain drive to the rear wheel to the same time include the use of rolling bearings, the emergence of thin-spoke wheels with rubber upholstery and wheel rim. The speed with which improved bicycle, characterized by the following data: in 1892 in France, was granted 1000 patents related to a bicycle, in England - 2400, the United States - 4000. The last major invention, in our opinion, was the emergence in the mid-20 century, a chain transmission system with multiple lead and led by stars and the mechanism chain transfer from a pair of stars to another, so the opportunity to change the gear ratio of chain transfer and thus optimize the effort of the cyclist Depending on the profile of the road or for other reasons.
At the turn of century, 20 observed the first burst of fashion at the wheel. Thus, if in 1869 in Paris, there were 1300 cyclists, then to the beginning of a new century, there are 500 times more. In the United States in 1895 was produced 1.25 million bicycles. The second peak of popularity was in the 60th of 20th century. This boom was associated with the idea of preserving the environment and healthy lifestyles. A major role in the development of fashion on the bicycle belongs to the increasing oil prices. According to some data is currently in the world annually produces about 100 million of bicycles for different purposes.
The modern bicycle, for example, road, mountain, let alone racing, amazing perfection of each detail, using modern technologies and materials, high strength steel, aluminum, titanium is not uncommon in cycling. It seems that the ideas in this case has reached its limit, to improve the bike exhausted.
Yes, this is so, such opinion is very prevalent. It is no coincidence that a proverb «invent the wheel». It is used to characterize the long-known and implement the proposal. Nevertheless, we here intend to provide such a change in the design cycle, which substantially reduces the cost of the cyclist to ride, you will have an important new feature to the already known and a thorough study of the bicycle.
Among the important inventions relating to the bikes, we call a chain transmission system. This is, perhaps, the only widely used in the invention is now to optimize the efforts of a cyclist while driving. Note one feature of this optimization. When changing gear in the transmission of a bicycle chain is changing force that is required for movement, while changing speed. In this work force at the rate remained the same as before the change of gear, because the work force at speed is power, but it must be accepted as a constant value for the cyclist. Thus, for example, when driving uphill cyclist changing gear in the transmission chain to increase the force on the drive wheel of the bike needed to address the recovery, while simultaneously decreasing speed bicycle in such a way that the work force at the speed remains a constant value.
Our proposal, which we intend to describe here, is not related to the ratio of chain transfer, and refers to optimization of the cycling leg, acting on a pedal. The imperfections of the legs, we see a cyclist in the rotary motion of the pedals, while the direction of leg forces a cyclist to be in the first approximation to take a consistent direction, ie acting vertically down the pedal. With this rotational movement periodically appear pedal position when the line of force action passes through the center of rotation of the pedals. These provisions are referred to as «dead», because the moment of force in these regulations is equal to zero.
The force moment in mechanics is called the product of force value on the arm (distance) of the applied force, i.e. at the shortest distance from the center of rotation to the line of action of force. It currently performs the force moment in the rotational motion. If the moment of force is zero, then the work of force is zero too, although the force is not equal to zero. So, in the «dead» positions and close to the cycling, the leg’s forth does not commit the useful work, in which we see a fundamental lack of transmission of motion in the bicycle. It is a consequence of the rotation of the pedals. Therefore, the essence of our proposal is to replace the rotary motion of the pedals on their rocking motion, so that the pedal has never occupied the «dead» of or close to it.
The first objection is that we hear from our opponents, is that the alleged rotational movement of pedals is commonplace and even the most natural. We agree that, indeed, is the usual rotation of the pedals, but we cannot accept that it is a natural. Nowhere in nature, there is no rotation of the extremities of animals. Here we should pay attention not to the motion of the pedals or on the movement of pedal levers, these details are part of the device, which created by a man. The natural movement of the feet of the cyclist - is rocking movement: walking the thigh and shin make rocking motion, at the foot of the traffic, which is driven by the foot pedal, foot just moves along with the pedal in a circle. Therefore, we argue that it is a natural rocking motion of the feet, especially evident during human movement up the ladder. Thus, the changing of rotation of the pedals on their agility in terms of physiology does not introduce anything new. As far as pedal habitually, we can say today habitually rotated pedal, but tomorrow they will become accustomed to rock, if that is convenient and saves power while driving.
Another objection of our opponents is as follows. Indeed, they say, in the «dead» positions there is not transfer motion to the wheel, and in the provisions that are close to the «dead», the human force use is not very efficient. But an experienced (professional) cyclist, knowing or feeling it in the «dead» positions and the positions of the pedals which are closed to them, is not hard on the pedal and thus does not spend unnecessary force.
At this assertion, we disagree as follows. First, such savings forces is only for experienced cyclists, the majority of cyclists are not so experienced and so this method of saving them is not available.
Secondly, and this is more significant, this force saving is equivalent to the reduction of speed, as well as reducing the angle of rotation of the pedal, at which force is transmitted to the wheel, is equivalent to the reduction on the driving wheel of “job” (energy), as long as the reduced quantity of “job”, it means decrease in speed, because speed of movement between the bike and the realized “job” of the cyclist has a strict line. Thus, saving power, cyclist loses speed. If the drop speed is not desirable, the cyclist at the «dead» and close to it positions, will force pressure on the pedal, but the effect of this will be closed to zero.
The third objection of our opponents is that our assumption that the strength of leg cycling always directed vertically downward, it is wrong. They say that turning the feet can be avoided «dead» provisions. Indeed, this is so, but this method is available only to experienced cyclists. But even an experienced cyclist using this method could not be sure that it does by the best way.
You should now determine the portion of the cyclist, he irrevocably loses while driving on a modern bike, or in other words, should identify what benefits accrue to the replacement of the cyclist's pedal revolving on their rocking.
Assuming that the force P, which acts on the pedal cyclist leverage, is constant and always strictly directed vertically downward and angular velocity of rotation of pedal lever is also constant, the dependence of torque M = P*S from the corner of rotating of the pedal lever and time t for regular bike, there will be introduced on the graph (Fig.2) as a sinusoid 1, which takes zero value in the «dead» positions pedal lever (S – arm of force P; «dead» in this review will be upright pedal lever). Sinusoids cyclically repeated in accordance with the movement of the feet of the cyclist. You can calculate the average value per cycle torque M*; Its value in Figure 2 depicts the line 2, parallel to the axis of abscissa, the ordinate of this line is equal to 0.64 Mmax, where Mmax - the maximum value of the moment M.
If the force of biker’s leg P would be always perpendicular to pedal lever, the dependence M would depict in Fig. 2 as a line 3, ordinate which is constant and equal to Mmax. Line 3 shows a constant and the maximum value of torque, which can be obtained at the most favorable direction of force P on the pedal lever. Line 3 can be considered to be a perfect representation of torque in the sense of the possibility of P in the creation of torque.
Then the curve 1 shows the actual situation with the creation of torque in the normal cycle, and line 2 shows how the ideal situation (a line 3) differs from reality. Provided fairness assumptions can be made to argue that the conversion of passenger traffic during the rotation of the legs pedal lever used in the modern bicycle has an organic deficiency, which lost 36% of useless work force P. If you put it in line with the above that the rotation of pedal arm replaced its Kachanov, with pedal swing arm will be in both sides of the situation, the corresponding Mmax., i.e. the horizontal position of pedal lever, for example, at an angle of 60º, then calculated the average moment of force, P, takes the value 0.83 Mmax. (line 4 in figure 2) Thus, the gains of the cyclist in this case is 30% (ratio of 0.83 to 0.64) compared with the normal cycle.
Of course, the picture provided by the feet of the biker (in the rotation of the wheel) is slightly idealized. This idealization relates primarily to assumptions about the direction of force P. In fact, this force is not always the vertical direction and this force is not always constant in size. Therefore, the validity of gains in the force P may be less than the reported value of 30%, but even if the gains would be 20% ... 25%, and then it is essential, since the gain refers to savings in power cycling.
However, to implement the law required only the use of swinging motion instead of rotation is not enough. Reducing the angle of rotation pedal arm at an angle of 180º, which is the normal cycle in the transfer of forces to the corner swinging, for example, the angle 120º, there is a decrease of 1.5 times (the ratio of 180 º to 120 º) road, which passes pedal lever, which means at the same speeds in both legs compared cases, a path that will take place in the swinging pedals a bicycle on the corner of 120 º would be 1.5 times less than in the ordinary bicycle. So, and the speed of the bike from swaying pedal will be lower than in 1,5 times. To compare the speed of a bike would be the same, should the proposed bicycle in the 1.5-fold increase in the speed of his feet, which means a corresponding increase in the frequency of oscillation pedal lever in 1,5 times. This increase in the frequency of oscillation negating all the advantages of the drive, as well as increasing the frequency of oscillation requires a corresponding increase in the cost of job.
The correct solution is to install between the pedal arm and the leading star of chain transfer in the accelerating transmission gear ratio equal to 1.5. Then at the same speeds of leg cycling in both cases the speed of bicycles will also be the same. In view of accelerating the transfer of the desired law of motion to depict in Fig. 2 curve 5.
And that's not all. Now - about the length of pedal levers in this example. The leg’s force of P in both compared bicycles should be the same, as should be the same a “job” of these forces. Then, the force P in the normal bike for one cycle of the leg revolving:
A = P*l, where l - length of pedal lever.
The work of the force P in the proposed drive: A = P1*L, where L - length of pedal lever in the proposed drive. In our example P1 = 2/3. Equated to the expressions, we get L = 1,5 l, it means, a pedal lever, in the proposed bike, must be 1.5 times longer than in the ordinary bicycle.
Now we must turn to the construction of the proposed bicycle. Just note that all changes made by us in a normal bike cover only drive.
Figure 3 presents the suggested bike part which is adjacent to the pedal sleeve. Fig. 3 are designated:
1 - part of the frame of a bicycle;
4 - leading star of the transmission chain;
5 - footswitch socket of the bike frame;
7 - movement transducer, the body of which is fixed to the body of frame (mounting not shown in Fig.3);
17 and 18 - pedal levers.
Attention should be drawn in - first, that the center of rocking pedal levers is at the point O1, which belongs to the transducer shaft. The second, leading star 4 of the chain transmission is on the shaft, which is located in the pedal sleeve (the O2). Thus, the axle shafts O1 and O2 are interlinked by gear. Note that in the normal cycling points O1 and O2 are combined, i.e. the pedal levers and the leading star of chain transmission are on the same shaft. The fact that the proposal is they are divided and connected by gear, is the hallmark of the proposed drive.
Fig. 4 shows a section 2 -2 Fig.3 of the movement converter. The figure marked:
6 - shaft;
7 - gear that is engaged in with the pedal to the wheel hub 5;
8 - body;
9 and 10 internal magazines of overtaking sleeves;
11 and 12 sleeves, on which the right and left pedal levers (positions 17 and 18)are established;
13 - screw;
14 - statement magazines of overtaking sleeves;
15 - conical wheels;
16 - conical wheel, which is engaged with the wheels 15;
The drive works as follows. The pedals 17 and 18 are moving from time to time under the biker leg movements. Suppose that at this point in time the biker leg force acts on the pedal 18. This pedal results the rotation of sleeve 12 and further, a detail 14 of the overtaking clutch. Then, clutch shims, and transmits rotation to the part 10 and then to the shaft 6, from the shaft 6 to the crown wheel 7 and the further – to the star 4 (Fig.3). From star 4 the chain is forced and provides a further rotation of the rear wheel of the bike.
At the same time by the right conical wheel 15,the wheel 16 is rotated and then - wheel 15 on the left, but it rotates in the opposite direction. That is why the left overtaking sleeve, formed by parts 14, 9, does not shim. The rotation is provided to the pedal 17 through a part 11. Thus pedals are moving in opposite directions: the pedal 18 moves down, and pedal 17 - up. When the force acting on the pedal 17, the movement occurs similarly, but only the left pedal 17 moves downwards, while the right - up.
Let us turn now to the characteristics of this design.
Easy to see, the main contribution of the weight of the proposed actuator is determined by weight converter site traffic. As evidenced by our experience, the converter motion weighs about one kilogram, i.e. additive weight of conventional bicycle by the application of the proposed drive is no more than 7%.
The proposed drive can be installed in such a way that the body of its units made in conjunction with the bike frame, but much more interesting to mount this drive on the existing conventional bicycle frame, i.e. without any changes in its design of the bike. This possibility is existed. Then, the proposed actuator can be sold separately and installed on a conventional bike according to request of his potential owner. This increases the market potential of the proposed drive.
In the previous example, the swing amplitude of pedal levers is adopted 120º: 60º in both sides of a middle position. In this example, the angle of oscillation was considered as the maximum. From the description of design it is obvious that cycling with the proposal is possible with a much smaller swing amplitude of pedal levers. Of course, that this will decrease the speed, but it is not essential for a certain category of users of the bike with the proposed drive. This category of users covers patients after orthopedic operations on the knee or hip joints, people with impaired health and mobility of defects in the joints of the feet. Normal bicycle, in which the angular displacement of knee joint is more than 90º, does not apply to this category of users. Thus, you can specify the following specific areas of application of the bike with the proposed drive.
Rehabilitation. After the injury, or after surgery for knee or hip joint, you can use the device to restore load capacity and mobility of the damaged joint. Funds, which are available to medicine today for these purposes, are very limited and refer to either manual therapy or the use of a mechanical rolling device (Continuous Passive Motion - CPM). This is a passive device, characterized by the fact that moves the joint while the patient lies on his bed and not making any muscular effort. Among the very small amount of physiotherapy devices are only those that belong to major medical institutions. Among them, a device which enables the active participation of the knee joint with a controlled angle of bending the knee, but it is very expensive and not used in all rehabilitation offices. Using a bicycle with reciprocating pedals allows the loading of active knee after injury or operation, with the frequency and amplitude, which may be changed as the patient recovers. In fact, today there is no device that would provide this function without having to when it was engaged all the weight load. The only device, that device close to the functional and cost, it is walking (Stepper), which operates both a full weight load of the patient, which is very often not the opportunities in the process of postoperative rehabilitation, or after injury.
Means of movement. Bike is an ideal low-cost means of transportation. It is energy efficient, always ready for action, it is very mobile, does not lead to pollution of the environment and provides a useful exercise and recreation users. For the older age group or postoperative sick and wounded, when a significant loss of mobility of the knee joint, using the normal bicycle is impossible. The new device, according to its description, will allow this group of sick or injured to return to the use of bicycles as a means of transportation within the city or settlement, as well as sporting and tourist resort, which today are interested in many populations.
Sports halls. Using this popular as a trainer bike in sports halls today, it is impossible for people who have problems with the knee joint. In particular, bending the knee on a bike depends on the height adjustable seats, seat location and size of the pedal and can be up to 130º. This is inherent in conventional bicycles can not use them in the sports halls of those who have limitations on bending the knee or hip joint. Using the new simulator will help these people to use bikes to improve their fitness.
Ergometers and the study of health status. Older people and athletes of all ages must often undergo the study load for a comprehensive picture of health in the case of heart disease, the diagnosis of cardiovascular disease, or rehabilitation after cardio event. Older people are often in conjunction with cardiovascular disease have breaches of the mobility of the knee and hip joints. As noted above, the violation of the ability of knee flexion or hip joint makes it impossible for them to check the passage of a standard bicycle ergo-meter, and the characteristics of their physical condition. While bike-ergo-meter parameters are widely used in medical practice. The use of a bicycle with reciprocating pedals allow for verification of the physical condition of athletes, and patients undergoing rehabilitation, for which such verification is necessary.
Thus, in conclusion, it can be noted two areas of application of the proposed drive.
1. The proposed actuator is used to save work, spent the cyclist while driving. This cost can be reduced by 30% to the cost of the ordinary bicycle.
2. The proposed drive pedals allow the use of bicycles for the part of the population, which is damage to the knee or hip joints of different origin, as injuries and operations.
Creation date : 08/10/2009 @ 12:34
Reactions to this article