What can be done from bicycle parts. Homemade block of sprockets for a bicycle. Gear ratio of driving and driven stars
One of the problems with the bicycle pedal drive was and still is the need to change the torque to the drive wheel depending on the road conditions. And I must say that the designers solve it, but in different ways. They even created planetary drive bushings, but they are complex, and therefore not cheap. Therefore, most often a multi-stage transmission with several sprockets and mechanisms for transferring and compensating the length of the chain are installed on the rear wheel. This is the most developed and inexpensive option. But the number of stars (usually three, sometimes four) is sometimes not enough. Then, to increase the number of "speeds", the leading sprocket is also made two- and even three-stage.
The essence of such a device is that the drive sprocket is cut into four sectors, which, by means of a multi-stage cam, are simultaneously symmetrically moved apart in all directions (or shifted back), changing the gear ratio of the drive. But the problem here is that the sectors are covered not by a belt, but by a chain, and how to move them apart? Then, with the teeth, we leave only two opposite sectors to ensure the transmission of torque, and cut off the teeth of the other pair of sectors - they will only serve to support and guide the chain. Now, when one of the sectors with teeth is out of engagement, by manually turning the cam we move apart (shift) the sectors, changing the torque. But in practice it is possible to do without smooth reference sectors. Then the chain will cover the "quasi-elliptical" contour. Thus, the idea of an elliptical sprocket, which is known to significantly increase the efficiency of the drive, is also implemented here.
You can install such a two-sector sprocket on any bike instead of the standard one, by providing the chain drive with a simple spring-lever compensator near the driven sprocket.
So, the design of the device. First, we note that all of its parts are steel, and the flat ones are made of 3 mm sheet.
A guide disc with a diameter of 260 mm is welded to the inside of the bottom bracket head of the regular right crank. Two axes are rigidly mounted (welded) into the disk at a distance of 65 mm from the center, on each of which a lever is freely put on with a spacer washer (a little more than a cam thick). A nine-tooth sector cut from a standard 28-tooth drive sprocket is bolted to each lever through washers with two screws. children's bike. The screws located closer to the axes have grooves (pins) at the ends that come into contact with the ledges of a two-lobe multi-stage cam loosely put on the carriage shaft. To turn the cam, handles are welded to its last ledges. The screws with the pins of both levers (and hence the gear sectors) are pulled together by a normally compressed coil spring. The depth of the cam ledges in the process of pre-assembly and adjustment is adjusted with a file so that the first teeth of the sectors freely enter the chain links. For the same purpose (so that the chain does not suddenly jump off without hitting the first tooth), antennae - guides - are welded to it. So that at the maximum disclosure of the sectors, the antennae do not cling to the frame of the bicycle, they should not be made wide. In extreme cases, you can tweak the frame a little with a hammer.
To shift gears, you must first position the connecting rod so that one of the sectors is out of engagement with the chain. Bending over, cyclist right hand turns a multi-stage two-lobe cam with a handle into one or more ledges, thereby increasing (or decreasing) the torque transmitted by the drive.
Since the total difference between the chain links at the maximum separation of the gear sectors and at the minimum displacement is 16 pieces, the drive also requires a spring-roller compensator for changing the length of the chain. The compensator consists of a bracket rigidly fixed on the rear fork of the frame and a swing arm hinged (on the axis) suspended on it. At the ends of the lever, on their axes, there are two rollers made of ball bearings 201, "compressed" with washers to guide the chain. One end of the lever is connected to the frame by a spring brace.
It is, of course, better to use hand brakes here, but you can also use foot brakes. To do this, an additional bed catcher made of tin should be installed on the rear fork of the frame, which will prevent the sagging part of the chain from getting between the wheel and the frame. In this case, the compensator lever will rest against the fork feather and will return to its place after the end of braking under the action of the spring.
To ensure the operation of the device, it is necessary to lubricate all contact surfaces and links well.
Multi-speed drive sprocket:
1 - right connecting rod; 2 - guide disc; 3 - two-petal cam; 4 handle for turning the cam (wire 04, 2 pcs.); 5 - chain; 6 - normally compressed spring; 7 - gear sector (from the leading 28-tooth sprocket of a children's bicycle, 2 pcs.); 8 - lever (2 pcs.); 9 - a finger of fastening of the lever to a disk (2 pieces); 10 - carriage shaft; 11 - screw securing the sector to the lever (2 pcs.); 12 - screw securing the sector to the lever with a pin (2 pcs.); 13 - distance washer (2 pcs.)
Chain length compensation mechanism:
1 - right connecting rod; 2 - guide disc; 3 - handle for turning the two-lobe cam; 4 - chain; 5 - right feather of the rear fork; 6 - bed catcher (tin plate s0.5); 7 - spring (from an old expander); 8 - bracket (St3, sheet s3); 9 - rotary lever (St3, sheet s3); 10 - restrictive washer (4 pcs.); 11 - rear wheel drive sprocket; 12 - roller (bearing 201, 2 pcs.)
In order to make a drive star, it is not at all necessary to have a CNC or other special equipment.
It happens that it is not always possible to find and buy a star with the right number of teeth for a bicycle, moped or motorcycle. I offer a simple and affordable way self-manufacturing desired star.
The technology is simple - in the Sprocket program
Download file:
(downloads: 2073) .zip
It is necessary to make a star with the right number of teeth for a specific chain, the program is simple and does not require special knowledge. We open the downloaded archive with the program, in which, in addition to the program, there is an instruction on how to use it.
The chain parameters indicated in the photo with a red arrow can be taken from this site, and for those who do not understand how to do this, see the manufacture of a star from beginning to end in the video.
After the star has been printed out, the sheets must be joined together along the line and glued to the metal of the desired thickness. I made a star for a moped chain, and took metal 5.5 mm thick.
I cut off the excess metal so that it does not interfere.
In order for all the teeth to be cut in the same way, I fix the star and the grinder on the same rail, and I look at the angle at which I need to cut on the factory star with any number of teeth.
The grinder is on a hinge, which allows it to be raised and lowered. After cutting on one side, I turn the star over to the other side and also cut off the excess.
After that, we need to trim the height of the teeth, which I measure according to the factory sprocket, for this I fix the grinder.
After all the teeth are aligned in height, I trim them a little on the grinder.
In fact, absolutely anything can be made from bicycle parts. This is not always appropriate, it is not always practical, the result does not always look great, but with free time and materials, everything is really possible.
Let's look at the main categories of such crafts:
-
Desire to surprise
Urgency;
Art;
Disposal;
In our article, we looked at various categories, and also wrote an approximate list of parts that would be required to reproduce an idea.
Which of the ideas belongs to which category, we are sure you can guess.
Chandelier
What details will be required:
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Ratchet;
Wiring.
It is difficult to call this example a craft, it is more like art. Chandelier diameter 48 inches. You can read more at the link.
Desk lamp
What details will be required:
-
Wiring.
One of the many table lamps made from scrap bike parts. We liked this one more than others.
Table
What details will be required:
Rim with spokes;
Rims without spokes;
Tables made from bicycle wheels are perhaps the most organic looking furniture in our article.
Armchair
What details will be required:
Rim with spokes;
Rims without spokes;
This chair looks quite comfortable and sturdy. I'm not sure if it's worth reproducing the idea with old rusty rims and burst tubes - it might not turn out so aesthetically.
Shop
What details will be required:
To make a bench, you will need the same set of parts as for the chair in the example above: rims, cameras and some stars.
Probably, slicks are more suitable for a shop than embossed tires.
Chair
What details will be required:
-
Flask holder.
A situation where you can not think about the geometry of the frame and even welcome the so-called "sofa", that is, soft imposing saddles. Such a chair is quite simple to manufacture, but it certainly will not leave anyone indifferent.
Shelf
What details will be required:
We are sure that for such a shelf, some camera defects are quite acceptable and will not affect the performance. The idea looks extremely simple to implement.
What details will be required:
-
Wood.
Very nice trophies from Andres Scheiger (his website). The idea is quite simple: from a steering wheel, a saddle and a small piece of wood, you can make a holder for a bicycle or other items.
The color, type and shape of the steering wheel or saddle almost does not play a role.
Mirror
What details will be required:
Of course, a completely old bent wheel with a shabby tire is not very suitable for a mirror in the bathroom, but for a garage or a hallway it is. For the bedroom and living room, feel free to write off the wheel a little ahead of time and make a nice piece of furniture out of it.
Watch
What details will be required:
Stars (optional);
Clockwork.
As we wrote in one adjacent article, wheels are one of essential parts bike. And outside of the bike, they can do a lot of good: in addition to furniture, mirrors, shelves and much more, they can be made into very stylish watches.
In fact, almost any round (and not only round) part is suitable for watches: crafts from stars and cassettes are very popular.
Fence
What details will be required:
Most likely, such a fence will give you the former owner of the bike shop, otherwise where do you get so many unnecessary bikes.
As for exactly how to make a fence out of a bicycle, there are no exact recommendations - as you can see in the examples above, you can turn on your imagination to the fullest and you will succeed.
Decorations
What details will be required:
Wire;
The main thing in jewelry is to maintain balance and not go into excessive brutality.
Most often, chain links are used to create jewelry. On sites like Etsy, you can easily find a lot of artisans focused on this type of jewelry.
And if you want exactly the same as in the picture, then they are in our store at a very affordable price.
Bicycle parking
The world of bicycles has its own reincarnation - after a while, bicycles that have served their purpose may again find themselves in the world they are used to. For example, in the form of bike racks made from old bicycle frames.
Backpacks and bags
Not quite handmade, but fits perfectly into our review. Vaho is a company based in Barcelona that manufactures backpacks and bags from old tires. On their website, they tell and show how they came to this and what comes of it.
Not only bags and backpacks are obtained from old cameras, but also wallets and travel bags. Another example of competent processing of materials from the Australians.
We hope we managed to inspire you and the next time you buy a gift for a friend or choose furniture for your home, you will think that you can do it yourself from unnecessary parts of a bicycle.
The main thing in this business is a little skill and a sense of taste: we have already seen enough of swans from car tires in the yards :)
Stars - transmission units for the chain transmission of forces from the cyclist's legs to rear wheel. Asterisks for a bicycle play a paramount role - without them, he simply will not go. Single-speed models are supplied with a pair - leading and driven stars. Bicycles with multi-speed transmission are equipped with speed dials in front (system) and rear - ratchet or cassette.
The number and size of the sprockets determine the bike's flexibility in various road conditions. Thanks to the correct gear ratio, you can significantly reduce the energy consumption for a trip and move at a comfortable speed. The durability of the parts depends on the quality of the material, the style of riding and the quality of service - with proper care, even "initial" stars will last longer than professional, but neglected ones.
Gear ratio of driving and driven stars
Stars on speed bikes located on the right connecting rod (drivers) and the rear wheel hub (driven). Through the chain is the transmission of forces from the front gears to the rear. Interestingly, the rear wheel, on the contrary, is leading, and the front wheel is driven.
gear ratio- the difference between the size and number of teeth on the stars. This parameter directly affects the speed of movement and transmission power. A high gear ratio is provided by a large drive and small driven gears, a low gear ratio, on the contrary, is provided by a small front and large rear sprocket. Accordingly, the gears on a classic transmission in the first case are 3 x 8, and in the second 1 x 1.
The larger the chainring, the higher the speed. For example, the front has 44 teeth for chain engagement, the back has 11 teeth. For one revolution of the pedals, the rear gear will do 4 revolutions. If we take a gear of 22 to 11, then only 2 revolutions of the wheel will be made in one revolution of the pedals. In low gears, the opposite situation is observed: the chain is on a 22-toothed gear in front, and 32 on the back. The gear ratio is less than 1, that is, for 1 revolution of the pedals, the wheels do not have time to spin completely.
High gears are designed for fast movement on a flat road. On hills, in headwinds and in poor road conditions, lower gears are used - the speed of the bike is lower, but more power and less energy consumption. Often, gears with an average star ratio are used, for example, 2 x 5 and 2 x 6.
Each star in the system has its own range on the cassette. It can "float", that is, the same reverse gear applies to two stars of the system at once, but, in principle, the pattern is as follows:
Scheme of the optimal ratio of gears for different driving modes
- collapsible on a single drum with separators;
- on a spider;
- on blocks (several spiders);
- Open slide;
- X-Dome.
The first type of cassette is the simplest - all stars are installed on a single slotted drum. They are separated from each other by partitions - spacers. The disadvantage is the constant load on the drum. But the undeniable advantage is that they are easy to disassemble and change one sprocket. They are easy to clean, but the components get dirty more often.
Spider - a light version of a collapsible cassette. The load on the drum is not so big - here it does not come from every star, but only from the slotted spider mount. These cassettes are lighter and less likely to get dirty.
The design on several spiders includes several pairs plus small stars separately attached to the drum. The model is very convenient because it is easy to pick up a new block and, unlike a collapsible analogue, you do not have to fiddle with spacers for a long time and lay out the entire cassette. The development of this piece belongs to the Japanese parts manufacturer Shimano.
Open Glide is a one piece set that fits over the largest gear. Unpretentious model: thanks to high-quality material less wear, long service life, low weight. True, it is problematic to clean a heavily soiled cassette.
One-Piece SRAM X-Dome Gear Set
A similar design is represented by the X-Dome system. Here both large and small stars are in contact with the drum. A whole-milled block of 7–8 stars is mounted on them. Both Open-Glide and X-Dome are owned by SRAM.
How to clean and lubricate sprockets
Friction mechanisms require periodic lubrication and cleaning from dirt. This will improve ride quality and extend the life of the transmission. Classic single-speed models often include chain guards. It is recommended to leave it. It also keeps the front sprocket free of dirt.
Already after several rides through the forests, crossroads and off-road Mountain bike overgrown with dirt. And if it is clearly visible on the wheels and frame, then it is not always in the mechanisms. Therefore, you need to inspect your two-wheeled horse more often and take action in time.
Cleaning the bike cassette:
1. Release the rim brake (remove the caliper on the disc brake), remove the rear wheel.
2. Check for dirt. If everything is very bad, you will have to remove and disassemble the cassette. With minor contamination, you can clean directly on the wheel.
3. Special narrow brushes are better used for cleaning. They allow you to get into the deep gaps between the gears and find a lot of interesting things there. Yes, and much more convenient than climbing into the gaps with a rag.
4. You can clean the teeth with an old toothbrush or wipe off the abrasive with a soft cloth.
5. After that, wipe the surfaces with kerosene, allow to dry and apply lubricant to the teeth and pits. It is recommended to clean and lubricate the chain at the same time as the cassette. Only in this way will it be achieved desired result.
Cleaning the system is done by analogy. Everything is simpler here: you don’t need to remove the wheel, just a few stars. True, you need to work carefully so as not to damage or upset the switch.
Asterisks are the most important components of the transmission, without which movement is impossible in principle. Correct selection gears, periodic cleaning and timely replacement of worn components will avoid unpleasant surprises on the road, and, indeed, will be high-speed, and not drive in only one gear.
