This clearance is determined solely by the frame design. A well-designed frame requires tires of a certain width (depending on the purpose of the frame) and, of course, requires some distance to the fender to avoid friction.
Historically, all track bikes have been built with minimum clearances, as this uses the smoothest, narrowest slick possible. In the 1980s, road bikes began to adopt the basic design principles of track bikes, and as a result, most "racing" bikes ended up with unnecessarily little clearance. The reason for this was just a blind desire for stylization. At one time, when this design disease was at its peak, the bike industry as a whole began to acquire a painful tendency to produce rather strange bicycles and parts. On a bike with a minimum clearance, you can install a caliper brake with only the shortest levers. In this regard, many manufacturers of brake systems completely switched to the production of short-lever brakes, and normal brake systems simply disappeared from the market. Frame and fork manufacturers, in turn, picked up the trend and continued to produce products with a minimum clearance.
The only person who worked at Rivendell, Grant Petersen, noticed an unhealthy trend and was able to influence the return to production of brake systems with longer levers.
A frame with a minimum clearance cannot be repaired. Somehow you can try to solve the problem only by installing wheels of a smaller diameter.
Pedal distance in turn
At the moment when the cyclist enters the turn and leans to the side, there is a high probability of catching the pedal on the road surface. This gap depends on several parameters:
- Carriage height
- Crank length
- Pedal length
The combination of all of these values determines how much lean can be in a turn, without eliminating the possibility of pedaling.
This distance is especially important for bikes with a fixed drive, since such systems do not have free play, and the pedals are constantly spinning. In addition, when you hit the pedal on the ground on a fix, rear wheel immediately jumps up, which can lead to a fall.
Distance from toe
There is another important gap on a bicycle from the toe of the cyclist to the front wheel or fender.
Bicycle frame geometry is a parameter that determines the behavior of your two-wheeled bike, its essence, character, level of compliance with your height and your own capabilities. The geometry of bicycle frames consists of the angles at which the frame tubes are welded and the length of these tubes. In their combination, they form a different height of the bottom bracket assembly (if it’s very rough, then the height of your feet from the ground), can vary the rider’s mass distribution along the bike axles, create different angles of the steering column, changing the sharpness and control features, create different lengths of the base, front and rear triangle, vary the height of the bike.
Each of these parameters has a direct impact on everything, and when choosing a bike, riders are often puzzled by what frame geometry they should choose. We will summarize the main geometric characteristics of velorams, try to explain what and how each feature of the geometry directly affects, and explain why it is impossible to build a universal bicycle with ideal characteristics.
Components of frame geometry
Frame size tied to pipe length seatpost. Sizes M, L, XL, 17, 19, 21 inches all come from her size, but if the manufacturer of the bike is serious and smart about designing geometry, then changing the size will affect other geometric characteristics. In a good frame, every detail is tightly interconnected.
What does growth affect? If the bike is too big for you, then you will rest your crotch against the top tube in the place of the frame standover (see diagram), if the size is small, then you will have to unnecessarily pull out the seatpost, and the frame will often turn out to be also short (you will touch the steering wheel with your knees) .
But everything is not limited to this. A small size makes the bike more comfortable for performing many tricks, and in the case of a trial, the minimum size of the seat tube allows you to carry out the maximum possible preload of the bike under you, followed by jumping on obstacles.
The essence of the size of trial geometry in one frame
Effective frame length- a value dependent on the length of the front triangle and the inclination of the seatpost, measured from the top of the head tube to the seatpost (in the horizontal plane). If this value is small, then the bike will feel good on technical winding paths. Often this geometry is correlated with short feathers and eventually develops into a very interesting "short man" for technical skating with a maximum degree of freedom in movement. Longer bikes, when achieved not by shifting the rider's mass rearward but by increasing the length of the front triangle's top tube, make for a comfortable fit for maintaining high speeds and handling uphill sections.
Short frame for dirt jumping
Steering angle- one of the explicit destination classifiers modern bicycle.
On bikes for downhill and fierce freeride, the corner often collapses - the fork, like a bulldog's jaw, begins to bulge forward relative to the frame. Steering loses its sharpness, making taxiing more stable and prone to straight paths. And this is important when downhill. Also, when the angle of the steering column is littered, the fork turns out to be a turned movable part of the shock absorber towards the encountered obstacles, and as a result, the shock absorber begins to effectively work out any irregularities encountered. And the reverse side of the coin is the loss of controllability and the placement of the fork that dampens the efficiency. The latter is especially seriously felt on the rise - the bike seems to rest against the wheel of every encountered stone.
On road bikes, the fork tilt is minimal (the steering column is practically not littered), the head tilt is slightly more on cyclocross bikes. In cross-country geometries, the lean is still negligible, but allows you to harmoniously combine decent rolling and climbing comfort with at least some bike control on descents. The AllMountain geometry has more headroom which makes the bike more interesting on descents with a loss of speed on flats and uphill sections of the course, on DH bikes climbing uphill will require a huge waste of energy, but on the descents themselves the control will be at its best. . In trial geometries, headstrap allows for a longer wheelbase for easy tackling obstacles, but tricks through the front wheel, as well as overall bike control, will be reduced.
Head angle is not always enough for a cross-country bike, making the descent completely dependent on the exact miscalculation of the trajectory down, as can be seen in this photo.
Seatpost Angle- an important element in the distribution of the mass of the rider along the axes of the bicycle. The seatpost tucked back takes the weight of the body with it, partially unloading the front wheel. As a result, in combination with a short wheelbase, this allows for a direct “comfort” level fit, and in combination with almost everything else, it improves the ease of yanking the bike. The latter is important in the extreme disciplines of cycling.
If the angle of the seatpost is not littered, then the mass is distributed along the axes of the bike more evenly, and as a bonus, the rider receives optimal body placement relative to the bottom bracket assembly (it becomes easier to pedal for a long time).
Carriage height is not just the clearance of your bike, but the height of the center of gravity, which affects the control over the horse. Almost everywhere, except for the trial, manufacturers tend to lower the bottom bracket (in the trial, a high bottom bracket improves the stability of the bike in the rack on the rear wheel and simplifies the process of performing most tricks).
On freeride bikes, the bottom bracket height relative to the axles often tends to zero, on country bikes the height is negative. Low-mounted pedals are easier to turn uphill, while the zero height relative to the axis gives the range of the fork to go through obstacles.
In bikes for street and park, the situation with the bottom bracket is ambiguous. The low bottom bracket improves flight stability, and is generally viable for dirt and park AIR riding. On the other hand, it is impossible to use pegs and perform some street tricks on a low carriage. Zero carriage is a popular option in the street.
The high bottom bracket adds stability in trials when standing on the rear wheel.
Rear chainstay length- the most important parameter of the geometry of the bicycle frame. Excessively short chainstays make it difficult to ride a bike uphill and the strength of the whole structure (more loads end up on the head tube), but they give good handling and freedom in performing many tricks. Long and moderately long chainstays provide manufacturers with an unprecedented field for the most complex bicycle engineering. In them, you can lay the bike's rolling moments when handling obstacles, reduce the negative stiffness of the frame, improving its comfort and rolling performance. A good XC bike will never have too short chainstays, just like a serious downhill bike. And never will a modern fan-riding and stunt bike have long frame stays.
Feathers are the most complex component of a bicycle. A well-engineered rear triangle is only found on a decent level of frame.
But I still want a versatile bike!
The golden mean of the cycling world is All Mountain bikes. Their geometries are the most balanced and such bikes, with proper skills, allow you to enjoy riding in almost any situation. But it should be understood that All Mountain will give way in all more specialized options.
Universal bicycle frame geometries exist, but there is no perfect solution for all disciplines.
From the geometry of the bicycle (bike) - from the dimensions and angles - many parameters of the behavior of the bicycle depend. It depends on handling, stability, acceleration dynamics, cross-country ability (in a positive sense), braking efficiency, uphill and downhill climbing, the ability to engage in extreme driving and take sharp turns. Since ancient times, the geometry of a bicycle has been unambiguously and rigidly determined by the geometry of the frame.
Today, this is no longer true. There were suspension, rear and front. And, therefore, the geometry and behavior of the bike is largely dependent on the characteristics of the suspension (damping, stiffness, travel) and on their settings. In order not to delve into the wilds, but, just to look at this dense forest with the casual gaze of a connoisseur, let's move on to reviewing the main points.
WHAT SHOULD BE THE TILT AND ANGLES OF THE BIKE, CHOOSE THE RIGHT GEOMETRY OF THE BIKE
For the most part, it sets the rider's position and determines the comfort of pedaling. If the pipe is vertical and the bottom bracket is located directly under the saddle, then pedaling is inconvenient, there is nowhere for the hips to go. Another parameter determined by the inclination of the seat tube is the weight distribution of the bike, in other words, the distribution of the load between the rear and front wheels. The smaller the angle of inclination (it is measured from the horizon line) and the higher the position of the cyclist, the less load falls on the front wheel and more on the rear.
On a steep uphill, if the cyclist is sitting in the saddle, the load on the front wheel of the bike may completely disappear and contact with the road will be lost. And the cyclist, at this time, runs the risk of falling on his back. On steep descents, the process is reversed. The front wheel is being loaded, and than more bike the rear is shifted back, the more stable the bike is, and thus the chance of falling over the handlebars is reduced.
It is generally accepted that if the angle with which the seat tube is tilted is 73 ° (with an error of 1 ° ... 2 °), the cyclist is provided with a correct, comfortable fit and his weight is correctly distributed. This statement is valid for an ideal cyclist with a hip length of 813mm (32 inches). To further adjust this angle and fit the bike to the actual dimensions of the cyclist (length of legs and arms, height ...), you can replace the straight seatpost with a curved one (Thomson). Or you can move the saddle back or forward, which is even easier. If the saddle is installed correctly, in the lowest position of the pedal, the leg should be almost completely straightened.
WHAT SHOULD THE CARRIAGE BE GREAT
This parameter determines the clearance of the bike - the distance between the road and the pedal at the moment when it is in the lowest position. If the clearance is too low, then this will not allow you to tilt the bike much, then during high-speed cornering, it is likely that you will catch the pedal on a root, bump, stone, accelerating when exiting the turn.
For this reason, bicycles designed for different ways skiing, the height of the carriage above the ground has a different value. For example, for freeride and DH, the carriage is raised much higher than in road builders (approximately 34 ... 36 cm). As an illustrative example, Table No. 1 is given (which Alexey Majuga was kindly provided for this article), which, using the example of KONA bikes, demonstrates the change in geometric dimensions depending on the style of riding and the purpose of the bike.
Note: Due to the fact that there is clear progress in the design and operation of rear shock absorbers, suspension forks, as well as the creation of stable platforms, shock absorber travel in last years has increased significantly and it is likely that, over time, it will increase even more.
In addition, if the carriage is located high, the saddle must also be raised higher, respectively, the height of the bicycle increases and the center of gravity of the “bike + cyclist” mobile system rises. There is no doubt that this affects handling and stability. On a high bike, it is easier to keep balance, and when performing a turn, the angle of inclination, which is designed to compensate with the help of gravity that occurs during roundabout(on the radius) centrifugal force, will be smaller than low bottom bracket bike.
This follows from the school geometry course. Accordingly, a bike with a high seating position is much easier to ride on forest singletracks and easier to fit into sharp turns. This means, once again, to pass the turn at a given speed and along a fixed radius, low bike you need to tilt it to the side at a more than high angle. However, when descending and braking, everything looks quite the opposite. During steep ascents, descents and during instantaneous braking using front brake, on a bike with a high seating position, the chances of losing balance, falling backwards, or rolling over the handlebars are greatly increased. To minimize this unpleasant effect, they try to increase the wheelbase of the bike - the length from the front wheel axle to the rear axle.
At the same time, a greater smoothness and softness of the ride is achieved, the bike bounces less on bumps, potholes and roots. But a bike with a long wheelbase has greater directional stability and is less likely to enter sharp turns, which, again, can be understood thanks to a school geometry course. To improve maneuverability and controllability, you have to “twist” the angle of inclination of the steering tube and make Trail (removal of the front wheel) less.
HOW THE GEOMETRY OF THE BIKE WILL CHANGE WHEN THE FORK IS REPLACED
It is worth noting the following point. The greater the value of this angle, the closer to the vertical plane are the feathers of the fork, the higher the acceleration speed of the bike, and the more efficiently the fork works out all sorts of small bumps and bumps on the road. And, accordingly, if the angle decreases, the fork feathers will become flatter in relation to the surface (sharper), as a result, handling and dynamics deteriorate, but at the same time, the fork begins to more easily tolerate large bumps and potholes, and they, in to a lesser extent, affect the movement of the bike.
For cross-country bicycles, the steering angle is most often from 71 to 69 degrees, and the distance between the axles of the wheels is from 100 to 107 cm, and in DH the angle is approximately 64 ... 65 degrees, and the wheelbase length is 110 ... 117 cm (See Fig. Table No. 1). The low tilt of the front fork paired with long feathers, which is quite often used in bicycle choppers, leads to a significant deterioration in the bike's maneuverability, sharpness (efficiency) of control, an increase in the minimum possible turn radius and makes the steering wheel turn to a higher angle.
TRAIL (FRONT WHEEL STAND) AND BIKE FRONT FORK PARAMETERS
A small experiment. If you put a bike of the correct configuration vertically on two wheels, take it by the frame and tilt it to the side, then the steering wheel should also turn in the same direction. The reason for this phenomenon lies in the geometry of the steering column and front fork. It is these details that determine the location of a pair of important points between themselves. Points A are the points of contact between the road and the front wheel, and points B are the points of intersection of the axis passing through steering column, and roads. The mutual arrangement of these points determines not only the direction of the steering wheel while the bike is tilted, but also its handling, directional stability, stability during turns, strictness of control, and much more. Bikes can be divided into two types: AB and BA. An AB-type bike is one in which the point of contact between the front wheel and the road is located in front of point B (Figure 2a). A BA-type bike is one in which point A is behind point B (Figure No. 2b).
If you tilt an AB bike to one side, the handlebars will turn in the opposite direction and, for obvious reasons, point A, where the friction force is applied, will be closer than the axis of the head tube (point B). The bike, if turned without hands, will fold in half like a book and fall to the ground with a thud. The front wheel and handlebars of a BA-type bike react completely differently to the tilt of the bike - they will lean towards the tilt of the bike themselves and without the help of hands.
And with balanced angles and dimensions, the bike will return to the vertical position exactly as if its handlebars were turned by hand, the handlebars only need a little help, to correct it in the right direction, and everything will turn out just fine! For this reason, AB-type bikes cannot be found in stores.
NOW A LITTLE ABOUT THE GEOMETRY OF THE FRONT FORK.
The executions that are shown in Figure 3, a) and b), will give us an excessively large distance from point A to point B, which causes the effect of over-stability of the bike. The longer the distance from one of these points to the other, the higher the moment of force that turns the front wheel and, of course, the steering wheel in the same direction as the bike is tilted. The result is clear, vertical and directional stability are quite good, and handling is nowhere worse. For this reason, in order to reduce the distance between these points, the fork on bikes is bent forward, Figure No. 3, c).
However, even if the bike is equipped with a straight fork, its inclination changes with respect to the axis passing through the steering column, or the cocks to which the front wheel is mounted are shifted forward. Figure No. 4. The distance from the axis passing through the front wheel hub to the axis of the steering column has different names, and Fork Offset, and Rake, and with us you can sometimes stumble upon run-out, displacement or offset of the fork. The value of the fork offset R, most often, fits in the value from 30 to 50 millimeters.
If the offset of the fork, the angle of the axis passing through the steering column, and the actual diameter (taking into account the thickness and deformation of the tire) of the wheel are known, then it is easy to calculate the distance between points B and A. This distance is called Trail or rollout (runout) front wheel, it happens that it can be found in catalogs. As a result, with the known Trail-e, it is possible to calculate the handling (stability) coefficient (Ku), which is equal to: Trail-y (T), divided by the sum of the same Trail-a and the length of the bicycle wheelbase (G), the result of the operations performed multiplied by 100%. Let's look at the formula: Ku \u003d (T /) * 100% (1), there is nothing complicated. For modern bicycle models, Ku is in the range of 5 ... 7.5%, and the value closest to the stability limit is usually chosen. The reason for this is quite simple - a bike of this design is easier to manage.
HOW THE GEOMETRY OF THE BIKE CHANGES DURING THE WORK OF SHOCK ABSORBERS
At the moment when braking occurs and the bike nods during the compression of the suspension fork, the wheelbase decreases, but at the same time, the Trail decreases even more, and therefore the Ku becomes smaller. It turns out that during braking, the handling of bicycles becomes greater, but stability decreases. The same situation is observed when pedaling while standing, at the moment when the cyclist brings the body closer to the steering wheel and during the descent from the hill, especially if intensive braking is carried out by the front wheel.
Now, if you load the trunk with a heavy load ( beautiful girl) or make less travel of the rear shock absorber (install a shorter shock absorber) for a full suspension, then the position will change to the exact opposite. The trail will get bigger, the Ku will rise, the bike will be more stable, but it will become harder to control. This is no doubt familiar to most cyclists. With a tightly loaded trunk, the bike rides confidently like a tank, especially if the acceleration is good. But to make a turn or drive along a winding path at a low speed, oh, how difficult.
Today, many extreme bikes are equipped with long chainstay dropouts, which allow for a wide range of rear axle shift or a wheel that has a smaller diameter, instead of 26 - 24 inches. No one will be surprised by the fact that during this, the handling and stability of the bike changes.
There are already the first trail bikes on sale, the geometry of which changes directly during the ride, and over a wide range. For example, the novelty of the season, the BIONICON EDISON bicycle. With the help of an industrial valve used in pneumatic lines and pneumoautomatic devices, it is possible to change the frame geometry by 6 degrees! Head tube angle from 67.5° to 73.5°. Seat tube angle from 71° to 77°. The front shock absorber travel is from 69 to 147 mm, the rear shock absorber travel is 142 mm, taking into account the wheelbase of 1056 mm. Now, on one bike, you can effectively move down a steep slope, and roll in the style of cross-country.
Tuning a bike or how to improve the ride quality of a bike Replacing the rear shock absorber and front suspension fork with shorter or longer ones affects the handling and stability of the bike. This must be taken into account.
The length of the top tube is the distance from the center of the seatpost to the center of the head tube. This distance, together with the length of the stem, for the most part, determines the fit of the cyclist. In addition, the size of the top tube significantly affects the weight distribution of the bike. A long pipe allows you to unload the front wheel, which can cause slippage during turns. A shorter top tube can cause your knees to catch on the handlebars while pedaling in a dancer style. People who prefer to ride cross-country usually opt for a longer, longer stem tube (100mm to 130mm) to get a low, stretched fit.
This makes it difficult to navigate tight turns and overcome difficult sections, however, the main struggle, most often, occurs during climbs. Freeride and downhill use a combination of a slightly shorter top tube and short stem. Due to this, on the slope, the cyclist transfers his weight far back, thereby ensuring the correct distribution of the load on each wheel. In addition, the additional loading of the front wheel, when moving the cyclist slightly forward, will help to overcome technically difficult sections.
BIKE TOP TUBE ANGLE
First of all, it determines the height of the standover - the distance from the top tube bicycle frame to the vital organs of the cyclist. This setting is very important for extreme species sports.
In addition, the construction height of the bicycle frame becomes smaller, as a result of which, its strength and rigidity are even greater, which is important for jumping disciplines and hard freeride. IN Lately it has become fashionable to use a lowered top tube in motocross and road bikes. This makes it possible to reduce the size of the produced frames and their weight.
LENGTH OF LOWER BIKE SEATS
The length of the chainstay is determined by a line parallel to the horizon, from the axis of the rear hub to the axis of the bottom bracket, the length of which affects the dynamics of the bike and its weight distribution. Moreover, it does not matter whether the cyclist is in a sitting or standing position, this is the difference between the influence of the length of the lower feathers on the weight distribution and the influence exerted by the inclination of the seat tube. Because when the cyclist gets off the saddle, the angle of the seat tube ceases to affect the distribution of weight between the wheels.
Short chainstays increase the load on the rear wheel and help increase its grip on the road, and at the same time make the rear triangle more compact, stiff and preloaded. The bike rides uphill more easily, overcomes corners more quickly and accelerates faster. For touring and touring bikes, the base is most often increased and the rear triangle is stretched. This makes the dynamics worse and forces you to apply more energy to climb the mountain. But these sacrifices have to be made in order to place a voluminous and heavy cycling backpack on the trunk and not cling to it with your heels while pedaling.
And a few more words about the difference in the geometry of bicycles in accordance with different styles skating.
The more geared for downhill and hard freeride, the longer the shock travel, the sharper head tube angle, the higher bottom bracket position and the longer the wheelbase. A dirt bike stands out with a shorter seat tube, lower standover (the distance from the center of the seat tube to the ground) and a short stem. This ensures the safety and comfort of the cyclist during tricks and jumps, and a higher strength of the bicycle frame.
Thanks to the "marketing wars", over the past few years, a huge number of different bottom bracket standards have poured onto the market. Fortunately, this mainly applies only to expensive bikes, and in the budget and average price range, everything is more or less clear.
Carriage selection algorithm
The algorithm for choosing any caret looks like this:
1. First of all, when choosing a bottom bracket, you need to figure out the type of connecting rod mounting. Compatibility here happens only within the framework of one standard.
Cotter Pin - a familiar standard from the Soviet past. Such a carriage was the standard for carriages on bicycles from the times of the USSR. The connecting rod was fixed on the carriage directly with the help of a pin (we called it a “finger”), which was threaded through the connecting rod and passed through a cutout in the axis of the carriage, hence the name. Due to dynamic loads, the pins were always spinning, and the connecting rods were pretty dangling.
SQR - square (from English square). The most common standard for budget solutions in this moment. Previously, during the heyday of MTB, it was the main standard for bottom brackets. It becomes a little more difficult to kill the cranks on such a bottom bracket than the previous version, however, a loose bottom bracket bolt can quickly “fix” this.
Octalink - splined standard exclusively for Shimano cranks. So that consumers do not seem small, there were two versions of Octalink v1 and Octalink v2 with 5mm and 9mm slots, respectively.
ISIS Drive - (from the English International Spline Interface Standard or the International Connecting Rod Interface Standard) due to the large splines and the large diameter of the axle of the carriage, the contact area of the connecting rod with the axis increases, this makes the carriage practically unkillable. The axle itself is hollow inside, which saves weight. The standard was proposed back in 1999 and was very breakthrough at that time. It was used by Truvativ, Chris King, Race Face and FSA.
Howitzer - splined standard from Truvativ (now SRAM), which followed ISIS. The first standard, in which, for the sake of increasing the size of the bearings, they were made “remote”. There were also carriages in the usual version with bearings inside the carriage.
Hollowtech II Shimano's latest standard for cranksets with a built-in 24mm axle. The carriage itself is just cups with bearings. On such a carriage, you can install any connecting rods with an axis of 24mm.
Giga X Pipe( GXP) - an analogue of Hollowtech II and the development of ISIS Drive now from SRAM. The only difference is the boot of the driven (left) cup, which, despite the same axle diameter in the cranks (24mm), will not allow you to install this bottom bracket and any other non-SRAM cranks.
2. With the type of attachment of the carriage in the frame, things are a little easier. If you have MTV, then with a high probability we can say that you have a BSA standard. However, it will be possible to find out for sure after dismantling the carriage.
Threaded carriages- These are carriages that are screwed directly into the frame. All carriages above are threaded. Called ISO/English/BSC or BSA. Landing diameter 34.6 - 34.9mm. Be careful! The MTV uses the English version, where the leading (right) cup has a left-hand thread . The variant with the same thread is called Italian and is used in BMX.
Press-Fit carriages- do not have a thread and are pressed into the frame. This standard looks logical in carbon frames, where there is no metal “insert” with a thread in the bottom brackets.
However, thanks to the kind marketing uncles, these carriages also appeared on aluminum frames. For example, the 2011 aluminum Specialized Demo was equipped with this bottom bracket assembly. Moreover, there were no carriages themselves at the time of release, and the frame was equipped with a plastic (!) Adapter for carriages BSA. And if the owners of the completes were worried about the presence of a plastic adapter between the carriage and the frame purely theoretically, then the buyers of the frames were given such an adapter as an appendage. Do I need to say that the adapter requires precise alignment and is pressed in with a special tool and cannot be repressed?
There are as many as 8 pieces of carriage standards for pressing in, and the devil himself will break his leg in them. BB90/BB95, PF86/92, BB30, BB30A, PF30, BBright, BB386 EVO and T47. The latest standard, by the way, uses the seat of the PF30 standard bottom bracket, but is pressed during installation itself, thanks to the thread inside the bottom bracket. Why and Press-Fit go hand in hand.
Fortunately, all of them are quite rare in MTV, so we will not focus our attention on them.
3. Finding the right bottom bracket width is easy. Measure the width of the bottom bracket on your frame.
Carriages 68/73mm wide - Fits on most MTB bikes. The carriages themselves are absolutely no different. To use a 73mm bottom bracket on a frame with a 68mm bottom bracket, you will normally need to install 3 spacer rings (unless the bottom bracket instructions say otherwise), 2 on the drive side and 1 on the driven side.. The 73mm bottom bracket is fitted with one spacer ring on the drive side.
Carriages 83mm wide - are usually installed in bikes for downhill and freeride, that is, where greater structural rigidity is needed. 83mm bottom bracket is not compatible with 68/73mm frames.
4 . The simplest Cotter Pin and SQR bottom brackets often differ in the length of the bottom bracket shaft. They come in 110mm, 113mm, 118.5mm, 122.5mm and 128mm. In order not to miscalculate with the size - just measure the length of the bottom bracket shaft on your bike.
5. Even if you had a carriage on bulk bearings, it is better to change it not to the same one, but to a carriage with industrial bearings. They are not whimsical and will allow you not to bother about the condition of the carriage assembly.
Bulk bearings - are used in the most budget carriages. Concurrently, the most problematic, as they require constant inspection and maintenance. Otherwise, they quickly begin to backlash and fall apart. Usually these are carriages from no-name manufacturers. Made to standards Cotter Pin And SQR .
Cartridge bearings - a set of two or more industrial bearings. They live a long time and are extremely unpretentious in use. Produced by all and sundry, from Neco to Shimano. Made to standards SQR , Octalink And ISIS Drive .
Remote bearings - industrial bearing of increased diameter, hidden inside the remote cup of the carriage. Made to standards howitzer, Hollowtech II , And Giga X Pipe( GXP) . It is currently the most widely used standard.
Compatibility
Please note that in 99.9% of cases, except for the standards Cotter Pin And SQR , even despite the external similarity of the splines, the various connecting rods are absolutely incompatible with each other . If you want to replace one bad connecting rod, then do it within the framework of a suitable standard, but rather replace both.
Results
Due to the dominance of patent wars and marketing battles, a whole bunch of standards have appeared on the market. Try to use carriages on industrial bearings, they are much more durable and easy to install. Purchase only bottom brackets compatible with your bottom bracket. I hope our article will allow you to deal with your carriage and not miscalculate when buying new pieces of iron!
Sergey Kryuchkov
Fishing... Going out into the countryside... We take a car, load our luggage - and go ahead! Which? And the bike!
The advantages of a bicycle are its sportiness, accessibility and relative simplicity of design. Cycling develops endurance, trains the muscular and respiratory apparatus of the rider, which is important in our generally sedentary life. Manage such vehicle allowed at any age.
And another important advantage is mobility and maneuverability. It is not always possible to drive along a lake or a river by car, but almost always by bike.
But in order for the ride to be enjoyable, you need to do right choice technology. Here are the main recommendations.
Bicycle type
Bicycles are divided into several classes: road, mountain, tourist, hybrid, road.
Road vehicles have a design that is unsuitable for movement outside asphalt roads. Usually they have steel frame, most often one gear, but they are a fairly comfortable means of transportation.
Mountain, as the name implies, is designed for driving in the mountains and off-road. But, nevertheless, it can be used for many other purposes, including movement on asphalt roads. This bike has a large number of gears, as a rule - from 18 to 27. And the equipment in most cases is designed for simply terrible conditions: puddles, mud, sand, bumps ...
The distance from the ground to the pedal is from 29 to 33 cm, which increases the permeability. The steering wheel protrudes a little forward, is straight in itself, and it is much easier to control it off-road compared to a curved one. Wheels with a diameter of about 560 mm (26 inches), wide tires (2.0 inches and above), which also has a positive effect on cross-country ability.
As a rule, there is a shock absorber: front (almost always) and rear (less often). They are necessary not only to ensure riding comfort, but also to create a better grip, for example when downhill. This type of bike can be successfully operated on highways.
A touring bike is designed for long trips with a load, mainly on highways. The wheels are narrower (1.9-2.2 inches), having a "road" tread pattern, without side lugs. The frame is longer (wheelbase), so they roll more.
Elongated compared to road bike base (up to 1150 mm)
and a more gentle slope of the fork (71-72 degrees; road - 72-74 degrees) add directional stability (it is easier to ride on such a bike without hands). This geometry provides a more comfortable ride (shakes less), but pays for the elongatedthe base will have a slight decrease in maneuverability, which is not of great importance for tourism.
But for touring bikes, the base extension is mainly due to the rear triangle, and this leads to a loss of “acceleration”, the bike goes uphill worse, and more pedaling effort is simply needed. The extended rear fork allows you to install a large backpack-pants on the trunk without touching it with your heels. The main elements of these bikes are hard-surfaced roads and groomed country roads.
Highway. Their main purpose is high-speed driving (including competitions) on asphalt roads. Wheels of large diameter (28 inches) and narrow (1.5-2.0 inches) have a purely sporty tread pattern with its minimum rolling resistance. Steering wheel in the form of "ram's horns".
Hybrid. Many cyclists unfairly neglect such bikes in favor of the latest "fancy" mountain bikes, when in fact most cyclists ride in such a way that for them, most likely, a hybrid bike would be the best choice.
Rideable almost anywhere but the heaviest off-road, the hybrid bike inherits from mountain bike most of the features while having a higher riding position, slightly heavier frame, 700C (622 mm or 27-28") wheels with 38-40 mm tires, making it more suitable for road riding than mountain riding. They have large drive ratios for smooth highway driving, while maintaining low gearing for mountain and off-road driving.
Such bicycles always have fasteners not only for a flask, but also for trunks (always rear and almost always front), fenders, pump, etc., which allows you to set the mass additional equipment and accessories for tourism. But I would recommend either mountain or touring bike type.
Bicycle design
Frame. The main structural element that bears the maximum load during movement. Its classic and correct geometry: front and rear triangles, connected together on the seat tube and not having any reinforcing "kerchiefs", unnatural bends and other anomalies of engineering. The materials from which they are made: steel, more often - chromium-molybdenum alloys, aluminum and its alloys, titanium, carbon.
The most preferred aluminum, more precisely, alloys based on it. Due to their properties, the frames are light, strong enough, cheap enough, and do not corrode. The disadvantages include the complexity of repair in the field and high fragility in severe frosts.
Steel and its alloys are heavier than the above material, but they are also widely used in the manufacture of a bicycle. Titanium and carbon are intended mainly for sports, heavy duty applications. They have a high price and are practically not subject to repair in the field, but only in specialized workshops.
Shock absorbers, suspension. There are 4 types: without them; front wheel only (hardtail); both wheels (double suspension) and depreciation due to the geometry of the frame. Depreciation is needed not so much for a comfortable ride, but for tight contact of the wheel with the road - both with and without a hard surface.
Therefore, a hardtail is the most preferred option, especially if with the ability to adjust the damping force in the fork, up to its complete blocking.
"Two-suspension" is more convenient for unpaved roads, and the full advantage is manifested in high-speed movement on them (various disciplines of cyclocross).
The remaining 2 types of suspension are similar and involve short trips on densedirt or asphalt roads.
Brakes. Although they say that "brakes were invented by cowards", they are still needed. Types of brakes: rim (vi-break) and disc (hydraulic or mechanical). The most effective disc, and the simplest rim.
Braking is carried out either by the wheel rim (vi-break) or by a specially installed brake disc. Since the disc is located closer to the center of the wheel and is less exposed to mud, snow and water, it brakes better on paved or unpaved roads.
Tires. Depending on the season, they are used in winter and summer. Based on the operating conditions - highway, universal and mud (all-terrain). Each type provides the best performance "in its environment".
For example, a "road" tire has better speed performance than a mud tire, but it is useless in off-road conditions. It should be noted that in stores, as a rule, they are equipped with tires with a universal (all-terrain) type of tread pattern.
Trunk, fenders. About the purpose of the wings, I think, it is not necessary to tell. I will only say that the best protection from dirt is the so-called "full", covering almost half the length of the wheel (it is appropriate to recall Soviet technology).
The trunk can be of two types of fastening to the bike: standard (in the corresponding holes located near the rear "stars" and in the upper "feathers" of the rear triangle of the frame) and for the seat tube. If the first type allows you to carry up to 25 kilograms of cargo, then the second - no more than 5-7. You can, of course, do without the trunk. But when using a backpack, the back will sweat a lot, and you won’t put much in such a backpack ... And if you caught a trophy for five kilos? Where to put it?
What else do we bring with us? In addition to the fishing set of fishing rods, we take with us: a bicycle chamber, a pump, a bicycle first-aid kit, a medical first-aid kit. This is if we go for a day, in case of a longer trip, we additionally take tourist equipment, not forgetting the compactness and weight of the cargo. For fishing accessories, I used a cut plastic canister, which I installed on the trunk.
Tips for beginners
It is best to buy a bike at the end of the season (autumn) or early spring next year. During these seasons, prices for bicycles are usually the lowest, however, the choice is small, and the model you need may not be in stock. It is not recommended to buy a bicycle in chain stores. The models presented in them have a bright and catchy appearance, low price, but extremely low reliability of components and assemblies. This technique is not suitable for fishing trips.
Bicycle, according to the rules traffic, is a vehicle driven by the muscular power of the rider. It equally creates inconvenience for other road users: pedestrians and cars. To better attract attention to yourself on the road, you need to "turn" into a kind of Christmas tree -
just as bright and colorful. Bright and contrasting colors are welcome in clothes and on a bicycle. In the dark or fog, the use of front and rear lights is mandatory.
A very useful safety item is a bicycle helmet. In addition to the main function of protecting the head in case of a fall, it also has additional ones: thermal insulation in hot weather and at least some protection from rain. Usually it is acquired after the first serious fall, but it is better to do it in advance.
