ALA CYCLES, focused on THE MTB bike, E SCOOTER BIKE, CARGO bike/tricycles, SINCE 2012.

add:Ningbo High Tech zone,Zhejiang.

No.756th,Chuangyuan Road,Ningbo High Tech zone,Zhejiang.

phone: +86 574 268 591 68

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The structure of MTB bike

  1. Transmission system

Schematic diagram of bicycle transmission system and travel speed control

(1) Chain

For the transmission bars of the transmission system, different systems have strict requirements on the width of the chain. When purchasing a chain, it is necessary to pay attention to whether it matches the speed change system of the bicycle.

I introduce the chain from four aspects. After reading it, I believe you will have a certain understanding.

  1. Dimensions of the chain:

Generally divided into three categories (represented by two numerical values, the axis distance is  X  inches):

① 1/2″ X 1/8″

② 1/2″ X 3/32″

③ 1/2″ X 11/128″

The meaning of the first value is the length of each link of the chain, which is generally 1/2″ for common bicycles.

The second value is the width of the chain. The 1/8″ chain is the widest and can be used on thicker chainrings, and the 11/128″ chain is the narrowest and can only be used on thin chainrings.

8-speed and below is usually 1/2″ X3/32″, 9-speed and above chains are usually 1/2″ X11/128″, and the size of the chain for sports shifting bicycles is basically 1/2″ X3/32″ and 1 /2″ X 11/128″.

Note: The 1/8″ chain is universal, that is, it can be used on other thin chainrings, but the 11/128″ chain must not be used on thick chainrings, many finely crafted chainrings will be marked on it The width of the chain is required.

Second, the speed change performance of the chain:

In fact, the speed change performance is to choose “how many speeds” (referring to the number of pieces of the rear sprocket, and the selection of the chain generally does not consider the front speed change), such as: common 7-speed, 8-speed, 9-speed, 10-speed.

The higher the speed rating of the chain, the greater the required twist angle of the chain. (When the chain works at the highest speed and the lowest speed of the rear chainring, the front and rear chainrings are not in a straight line, and the chain is working in a twisted state, which requires that each joint of the chain can have enough clearance to cope with this twist. .)

High-speed chains can be used at low speeds, but low-speed chains cannot be used at high speeds. For example, an 8-speed chain can be used on a 7-speed tower wheel. If a 7-speed chain is used on an 8-speed car, due to the twist angle of the 7-speed chain Small, when the speed change is adjusted to the highest speed and the lowest speed, the twist angle exceeds the bearing capacity of the chain, so the forcible work will cause great damage to the chain and the chainring, or even break the chain.

Another thing to note is that even if you choose the right chain, it does not mean that your car will have no problems. Assuming that the bottom axle of the 8-speed car is too long, the front chainring and the smallest chainring (outermost) of the rear tower wheel On a line, if you adjust to the lowest speed at this time (the innermost chainring with the largest chainring), the chain will be damaged by too much twist.

So the correct way is to align the large chainring with the chainring in the middle of the rear tower wheel, which can be achieved by choosing different lengths of the bottom bracket.

In addition, if the front derailleur has three large chainrings, it can only be considered as a compromise, or a higher-level chain can be considered.

Third, the length of the chain:

The length of the chain is expressed in knots. There are calculation methods and empirical methods for selecting the length of the chain. Here only the empirical method (from Baidu experience) is briefly introduced.

① The chain is not attached to the derailleur, and the chain surrounds the front and rear large plates, adding two sections to this length.

② The chain is hung on the derailleur, and the support arm of the rear derailleur is parallel to the ground when the front is small and the rear is small.

③ The chain is hung on the derailleur, in the case of small to small, the chain does not sag significantly.

Fourth, the appearance inspection skills of the chain

① Whether the inner/outer chain pieces are deformed, cracked or embroidered;

② Whether the pin is deformed or rotated, embroidered or corroded;

③ Whether the roller is cracked, damaged or excessively worn;

④ Whether the joint is loose and deformed;

⑤ Whether there is abnormal noise or abnormal vibration during operation, and whether the chain lubrication condition is good.

(2) Center axis

The device connecting two pedal cranks is divided into ball center shaft, bearing center shaft, etc.

Ball center shaft: low price, easy to replace than the bearing center shaft, and inconvenient to replace.

Bearing axis (Peilin axis): high price, high strength, not easy to damage, easy to replace.

(3) Flywheel

The driven gear on the rear axle of the bicycle.

Material: Common flywheels are made of steel or aluminum alloy.

High-end flywheels use expensive materials such as titanium alloys. And in pursuit of light weight and strength, hollowing is often used to reduce the weight of the vehicle.

At present, the maximum number is 12 pieces, and the shifting operation is completed by switching the chain to the flywheel with different tooth numbers through the rear derailleur. The size of each sprocket is different, and the number of teeth is also different, so that in the transmission, different gears (ie different gear ratios) can be achieved with the chainring.

(4) Crankset

The part where the bicycle bottom bracket and the crank are connected.

The crank is driven by pedaling, which in turn drives the rotation of the chainring, and finally drives the rear wheel to rotate through the chain and flywheel, providing power to complete the entire transmission chain of the bicycle.

The number of gears on the chainring: there are three types: single, 2, and 3. There are almost no four, because it is technically difficult and meaningless in practical use.

(5) Hub

It is named after the shape like a musical instrument “hub”.

The inside of the “hub” is the bearing, which is connected to the rim through the car bar to form a complete wheel set.


①Iron hub/aluminum hub.

②Quick release hub/solid axle hub.

③Card fly hub/spin fly hub. Kafei hub, that is, the flywheel he is equipped with is a cassette, the hub has no tooth pattern, only the freewheel, while the spin fly hub has a tooth pattern, and the flywheel is screwed up. It is used more for flying;

④V brake hub and disc brake hub. The finger hub does not have a disc brake seat, and the brakes used in the car are caliper brakes, while the disc brake hub is equipped with a disc brake seat, which can be equipped with disc brakes. At present, both of these are very commonly used in the market!

  1. Transmission system

(1) What is the number of gears/stages of bicycle shifting?
Bicycle gear position = the number of front large plate gear pieces x the number of rear flywheel gear pieces

Mountain bikes generally have a front flywheel with 3 large plates and a rear flywheel with 6, 7, 8, 9, and 10 speeds. The shifting gears are: 18, 21, 24, 27, 30 shifts.

Road bikes are special, with only 14, 16, 18, 20, and 22 shifts.

Generally speaking, those with a large number of segments can adapt to a variety of road conditions, but most of the high-end cranksets use a single speed, the simpler it is, the less likely it is to make mistakes.

(2) Transmission system brands and ranking

In the mainstream market, most mid-to-high-end bicycles use Shimano and SRAM brands, which are very reliable in terms of performance and quality.

(1) Brand introduction
Shimano is a Japanese brand, occupying more than 50% of the domestic transmission accessories market, and its products cover a wide range of low, medium and high-end products.

In the world’s high-end sports bicycles, Shimano’s components maintain the world’s first share with an absolute advantage. Shimano’s products cover shifting, transmission and braking systems, and have their own unique style. Naming rules.

(2) Kit level and introduction
Shimano kit levels are ranked from high to low: XTR, DEORE XT, DEORE LX, DEORE, ALIVIO, ACERA, ALTUS, TOURNEY, TourneyTZ, SIS, MF, zee, Saint, etc.

(①) Competition level (top, sub-top)
Competition grade: XTR, DEORE XT

XTR: It is the most top-level competition parts. In order to pursue extreme lightness, XTR uses more lightweight materials. The pursuit is extreme lightness and precision, and the price is also “top”.

Deore XT: This is the second top series, the DEORE XT is as accurate and easy to use as the XTR, but slightly heavier than the XTR. There are more metal materials in the XT, which is relatively more dependable.

(②) Advanced
Premium accessories for mountain trails: Deore LX, Deore

Deore LX and Deore: More economical choices, the performance is slightly inferior to that of the competition-level XTR and DEORE XT, but they are still above a higher level. They are common accessories for high-end vehicles. These two products are also very durable.

Deore and above (XTR, DEORE XT, DEORE LX, DEORE) are all high-level accessories, all of which are sufficient for real mountain off-road activities.

(③) Intermediate
Intermediate accessories for mountain off-road: advanced ALTUS, Acera, Alivio for XC (cross-country mountain bike)

Acera and Alivio: 24-speed entry-level accessories for mountain sports, which can correspond to low-intensity mountain sports and entertainment. For vehicles with a level of around 2500, manufacturers generally use Alivio the most.

ALTUS: 21-speed entry-level accessories, suitable for urban commuting entertainment or mild mountain wilderness, but don’t! ! ! Don’t challenge the road conditions that are too “exciting”. 1500 or so the vehicle, generally the most common is ALTUS.

(④) low level
Urban recreational vehicle and low-end XC: Tourney, TourneyTZ.

Tourney, TourneyTZ: 21-speed civilian-grade accessories, suitable for walking and leisure in the city.

After all, the performance and price of the Tourney series are here, so don’t make it difficult for it to accompany you to meet higher demands!

(⑤) Civilian
Ordinary civilian categories: SIS, MF

SIS: Shimano 18-speed low-end accessories. Many people may have started with SIS when they first saw Shimano. At that time, it was a symbol of good things, but now the domestic bicycle market has changed, and SIS has gradually faded out. The sight of attention will only appear in the models of the major manufacturers under $150.

SIS shouldn’t be in a complete vehicle over $150.

(⑥) Others
Zee (between XT and SLX for heavy duty XC and AM)

Saint (between XTR and XT, for DH and FR)

DXR, Capreo: for BMX.

(3) How to judge?
In order to reduce costs and prices and meet the needs of the domestic market, bicycle manufacturers generally do not use complete kits, but select a few main components for use, such as gear shifters, front and rear derailleurs.

Because the transmission system has the highest technical content and users are more concerned, other transmission and braking systems such as cranksets, cranks, hubs, brakes, etc. are generally replaced by Taiwanese manufacturers such as Giant and Merida.

Although it is difficult to see a complete set of kits in domestically sold brand vehicles, in the level of less than 3,000 yuan, it is generally more accurate to judge the grade of the whole vehicle by looking at the level of the transmission system.

②Quick Link (SRAM)
(①) SRAM brand introduction
SRAM (English: SRAM Corporation, referred to as SRAM) is a privately-owned bicycle parts manufacturer headquartered in Chicago, founded in 1987. The company has acquired through mergers and acquisitions to become one of the world’s largest premium bicycle parts brands, sold under the brands SRAM, Avid, RockShox, Truvativ, Quarq and Zipp. Its components are primarily manufactured in-house at its in-house plants in Portugal, Taiwan, China and the United States, and are distributed and sold as original equipment manufacturer (OEM) equipment and aftermarket components for the global premium market.

SRAM is an American brand and has always been a rival to the SHIMANO brand. SHIMANO has occupied the Chinese market for many years, and SRAM is slightly better in terms of cost performance. For example, the SRAM-7.0 shifting system is designed for Shimano-XT, but the price is much cheaper.

SRAM company has SRAM derailleur series, ROCK SHOX front fork series, AVID disc brake series, etc.

SRAM company is the founder of the handlebars, and is the leader in the production of handlebars. The change ratio of the handlebar is 1:1. Since the rear puller cable ratio is 1:1, the tension of the chain is greater than that of Shimano, and the requirements for the wire tube are relatively low, which can tolerate greater wire tube wear. It has high speed change efficiency and strong durability!

(②) SRAM kit level
The SRAM kits are ranked from high to low (in descending order of product positioning, performance and price):

Statement 1:

XX1 (XX1 Eagle AXS, XX1 Eagle, XX1)

X01 (X01 Eagle AXS, X01 Eagle, X01)


GX (GX Eagle AXS, GX Eagle , GX , GX DH)

NX (NX, NX Eagle)

SX (SX Eagle)

(3) Dial
Installed on the handlebar, it is usually divided into one-piece dial and split dial, the difference is whether it is integrated with the brake handle.

(4) Front dial
The device that controls the front derailleur, controls the chain and crankset, and a single-speed mountain bike does not have a front derailleur.

(5) Rear dial
The device that controls the rear derailleur, controls the chain and the flywheel.

  1. Support system
    (1) Front fork
    The upper end of the front fork is connected to the handlebar, and the lower end cooperates with the front axle component to form the guide system of the bicycle.

①Front fork shock absorber stroke

The red part in the picture is the suspension travel of the front fork
By mountain bike category:

(①) XC off-road~~80-120mm (80~100mm is hardtail, 80mm is urban leisure/mild off-road, 100mm is standard hardtail; 80~120 is mostly soft tail)

(②) Trial forest road 120~140mm (hard tail~

~120-130mm, soft tail ~120mm-140mm)

(③) AM all-terrain 130~160mm (hard tail130-140mm, soft tail140mm-160mm)

(④) FR free riding 160~180mm

(⑤) One of the branches of FR: 4X four-player competition~~100mm

(⑥) One of the branches of FR: DJ dirt slope mountain bike~~80~100mm

(⑦) One of the branches of FR: ST street car~~80~100mm

(⑧) One of the branches of FR: SS fancy downhill~~160mm

(⑨) DH downhill/falling type ~ ~200mm double shoulder front fork

(⑩) Enduro all-terrain long-range endurance120~180mm (hard tail120~160mm, soft tail~~160-180mm)

② Category
Air front fork: Suspension is achieved through positive and negative air pressure. (The air is light, and the use of air as the spring should be the most suitable for mountain bikes, and if different hardness is required, there is no need to replace the spring, just increase or decrease the air pressure to achieve)

Advantages: Lightweight.

Disadvantage: Due to the physical properties of air, the linear function of the shock cannot be guaranteed.

Oil spring front fork: On the basis of the spring fork, damping is added, mainly using oil as the damping, among which the lockable front fork is divided into wire locking and shoulder locking.

Advantages: The rebound speed can be adjusted, the shock absorber is linear, the price is moderate, and the riding comfort is high.

Disadvantages: heavy, it is more troublesome to adjust the elasticity.

Oil-air hybrid front fork: gas is used as the rebound medium, oil is used as the damping, and it has the function of locking.

Advantages: relatively lightweight.

Disadvantage: Linear rebound effect cannot be guaranteed.

Spring front fork: The structure is relatively simple. There are springs on both sides or on one side, which can compress the springs to realize the softness and hardness of the shock absorber. It is generally used for low-end vehicles.

(The hardness of the spring, the so-called spring rate, represents the ratio of the force to the degree of deformation. Under the principle of not exceeding the load, the spring rate of a simple coil spring is fixed in different states of force, and will not be affected by The effects of ambient temperature, and then painted or lubricated, are very stable and durable. More advanced forks have begun to use lighter weight but more expensive titanium alloy springs.)

Resistance rubber front fork: Using resistance rubber as the medium, without damping, it will age, and the lifespan is short. It has to be replaced in two years, and has now withdrawn from the mainstream market.



  1. The status of FOX can be said to be deeply rooted in China. Today, it can be said to be one of the most popular and most used SHOCK brands. Whether it is XC, DH, or AM, it can be seen, but the price is slightly higher.
  2. ROCK SHOX (front fork/rear SHOCK): SRAM’s shock absorber brand (which is said to be the founder of contemporary shock forks) was acquired by SRAM in 2002. It also has a very high status among Chinese mountain bike enthusiasts. Its SID BOXXER series are not uncommon in world-class competitions and become classics. Large-stroke and high-strength forks such as TOTOM, which were added in 2007, are also popular. Many of this brand’s products are made in Taiwan.
  3. MANITOU (front fork/rear SHOCK): This one needs no introduction. The deeply rooted design of the rear fork bridge can be recognized at a glance. There are many CBs using its XC fork R7 series, and then SHOCK is also common on large-travel vehicles such as DH. Main technology: SPV TPC, etc.
  4. CANNONDALE (front fork LEFTY/HEAD SHOCK/frame): They are all very special and distinctive left-handed forks, which are also deeply rooted in the hearts of the people in China. The main business of this brand is to make complete vehicles, and the shock absorber is in his complete vehicle. As a sideline, at the end of 2007, the company was acquired by American Pacific Motors. LEFTY is divided into two series, SPEED and MAX, which are gas and spring forks respectively. In cooperation with many big manufacturers such as FOX and MANITOU, the LEFTY with TPC SPV smart lock function was born, plus the special 4 internal locks. The lubrication system can be regarded as a very good fork, but unfortunately because of the special head tube, it can only be used on C’s own car in most cases, unless there is an adapter. HEAD SHOCK is the head tube shock absorber. It is an old product before LEFTY appeared. The shock absorber system is built in the head tube, so that the fork can be very sensitive and light (usually about 1200 grams), but it is a pity because The head tube is special, only a large head tube rack can be used, and it cannot be transferred.
  5. 5TH ELEMENT/Post-SHOCK) The fifth element: DH or FR should all know a very good manufacturer, used a lot in world competitions, and was later acquired by MANITOU
  6. ROMIC (post-SHOCK): It is also made in the United States for large-scale use. It is very durable and used a lot by foreigners.
  7. AVALANCHE (front fork/rear SHOCK): a big job ~ handmade fork and rear shock The large number of CNC parts are impressive, the performance is naturally uncompromising, but the price is also beautiful…
  8. MAVERICK (front fork/rear SHOCK/shelf): very impressive brand, 2 inverted forks, a single shoulder (SC32) and a double shoulder (DUC32), all handmade in the United States, the shoulders can be made To 1400 grams, it is indeed shocking. Since then, SHOCK is not well known by domestic players because it can only be used on its own shelf.
  9. FOES (front fork/rear SHOCK/shelf): an absolutely shocking brand, the super thick TI spring rear SHOCK and its Foes XTD F1 front fork are even seen on some off-road motorcycles because they are extremely thick, of course the price Definitely not cheap
  10. WHITE BROTHERS (front fork): White Brothers, a brand I don’t know very well, it seems that there are some forks used for big work
  11. SPECIALIZED (front fork/rear shock/frame): In 2007, Lightning dug some engineers from FOX to make their own forks and rear shocks for 07’s ENDURO SW and S-WORKS EPIC CARBON and other models.
  12. SCOTT (rear SHOCK/shelf): SCOTT and DT SWISS have cooperated to develop their own rear SHOCK for a long time, especially the 07 NUDE TC rear SHOCK used in its own lightweight off-road vehicle SPARK LIMITED attracts attention.


  1. Marzocchi Marzocchi: It has a high status among domestic riders, and it can be said to be the first brand of SHOCK in Europe. Its classic 888 66 marathon and other series have been deeply rooted in the hearts of the people. Less (this has been gradually eased in recent styles) ROCO and other post-SHOCKs are also used in many excellent post-SHOCKs for DH, but they are hardly seen in China.
  2. FRM (front fork/frame): It is an Italian lightweight brand. The appearance of the fork is similar to the old one. besides. It is also the same rear fork bridge as MANITOU.


  1. MAGURA: This brand of brakes has a high status in China, especially MARTA SL used to be the lightest oil disc (now replaced by the highest-end HOPE). Its vertical cylinder design has also been followed by many manufacturers, but its shock absorber system is not well known to domestic players. MAGURA’s forks have gone through almost 4 or 5 generations of development. In the past, the evaluation of its forks was not very good, or even very poor (I am using its 05 RONIN 80 XC forks, which are average but not so bad. , but not as outstanding as FOX and other manufacturers). However, in the past two years, especially since 2007, it has improved slightly. It independently developed the front and rear two-way fork bridge design. It has the vertical high rigidity like MANITOU and also obtained the lateral rigidity that MANITOU lacks (a friend told me that using The V-brake will be soft, obviously soft). Another feature of MAGURA’s forks is that there are many adjustments, and its WOTAN forks even have bilateral wire controls. MAGURA is a developing SHOCK manufacturer and is slowly making progress. I hope it can learn from the experience of other manufacturers and develop a better SHOCK system. After all, Rome was not created in a day. To create a truly excellent SHOCK, it still needs to work hard (Its 2007 WOTAN has won high praise in German authoritative magazines. Anyway, we can indeed see that it is improving a little bit.) Of course, it takes time, such as letting MARZOCCHI do the brakes, and it is also a day or two. not doing well~
  2. AFORK (front fork): A FORK is an abbreviation. The full name is unclear. Small German manufacturers and workshops use a unique connecting rod front fork shock absorber system, which can make the fork very light (the lightest CARBON model). Only a little over 1100 grams). There is also a German backwashed shoulder fork, and the brand of carbon outer tube is also A FORK. I don’t know if it is one. Official website: I can’t find 3 VOTEC (front fork/frame). I feel that many of these brands need to use shoulders for a little stroke. I don’t know if it is the Germans’ infinite pursuit of strength or some other reason.


  1. PACE (front fork/frame): It is estimated that some people know that small British manufacturers are enthusiastic and sponsor the SPECIALIED team. The carbon outer tube fork is eye-catching, and the rear fork is very light. Its hard forks are also very famous and are made very light and light.
  2. USE (front fork): USE’s SUB fork is a British LEFTY left boy, not to mention its shock absorption effect, the advertised handmade and more exaggerated link structure than C mark are impressive. The inner tube anti-slip system adopts a link type to make the shock absorption effect more sensitive, but it is also heavier and less adjustable~


  1. DT SWISS (post-SHOCK): Its wheel system and parts are popular in China, but many people don’t know that it still does SHOCK. In fact, according to those who have used it, it is still good, and there are many advanced technologies. It is often seen on some big-name cars in Europe, such as NICOLAI BMC, and MERIDA cars are also useful. The most impressive thing is its CARBON shell post-SHOCK, what a crazy light top supplement!


  1. KOWA (front fork/rear shock) can be said to be the only shock in Asia that can compete with European and American manufacturers, but because it is basically not exported, I don’t know much about it, and it is said that the shock of this brand is expensive.


  1. SR SUNTOUR: The company was first established in Japan. It has only started producing shock absorbers in 1995, mainly at low-end prices. It has developed rapidly in recent years, and there are many terminals, but it still feels relatively bad. In addition, this brand seems to be acquired by Taiwan, so it should be considered as Taiwan.
  2. RST: It is the front fork brand of Dah Ken Industrial Company. It was established in 1972. At first, it mainly produced automobile and motorcycle parts. Until 1990 the company decided to switch to bicycle front suspension forks. After nearly 20 years of development, the RST brand has been widely used at low prices and in the global bicycle market, changing the status quo that shock absorbers can only belong to high-priced luxury goods.

Weight is an important point for many XC players. The front fork with a weight of 1.3kg is the limit. In terms of materials, aluminum alloy fork heads and inner tubes are often used, and high-end mountain bikes even use titanium alloys.

(However, the weight data on many mountain bike spec sheets is not necessarily accurate, and the manufacturer may show a “nice figure” by shortening the fork head or leaving out the weight of the suspension or oil.)

⑤ Rigidity
When the rigidity is insufficient, in high-speed riding or bumpy road conditions, the riding will feel uncontrolled and floating. If your weight is too heavy, you should try to avoid using a fork that is too light. resulting in insufficient rigidity.

Generally speaking, Downhill races and Double slalons require higher rigidity, and will use a fork with a thicker inner tube, while XC players generally only focus on weight.

⑥Sensitivity (smoothness)
A high-performance suspension front fork needs to have “smoothness”. The so-called smoothness means that the front fork is never under stress, compressed, compressed to the end, and then returned to the uncompressed state without any stuttering, or without any friction. feel.

The new front fork will be a little tighter, but after a period of running in, it should be smooth in principle. After the front fork is used for a long time, debris such as mud and sand may enter the pads between the inner and outer tubes, and there will be a feeling of discomfort.

(2) Handlebar
Generally speaking, there are two kinds of handlebars for mountain bikes, straight handlebars and swallow handlebars.

① Straight handle
Advantages: light, low wind resistance

Cons: slightly less maneuverable

② goose handle
Advantages: good maneuverability

Disadvantage: heavier than a straight handle

③Handlebar material
Titanium alloy

Titanium alloy is an aerospace material with low density and high strength. Titanium alloy handlebars have both strength and light weight, and are expensive.

carbon fiber

Carbon fiber is light in weight, strong in toughness, low in stiffness and not durable.

Carbon fiber materials have relatively high process requirements during production. When welding, the skeleton needs to be wrapped first, and then a layer of carbon is wrapped on the outside. Carbon fiber is very expensive and is generally used in high-end and professional-level races and models.

Aluminum alloy

Aluminum alloy is widely used and the price is relatively low.

There are many kinds of aluminum alloy materials, the best is 7075 aluminum, but most of them are 6061 aluminum used on handlebars, and the strength is average.

Some aluminum alloy handlebars can also catch up with carbon handlebars, but the price is not cheap.


The handlebars on low-end bikes are mostly high carbon steel.

The high carbon steel handlebar is easy to rust and its heavy weight is its biggest weakness.

(3) Handlebar
The main parts of the handlebar are mostly round tube shapes, and the sizes are mostly 31.8mm and 25.4mm.

(4) Handle Stem
The parts connecting the handlebar and the front fork are the most commonly held positions when one-handed carts. The lengths are generally 60mm, 70mm, 80mm, 90mm, and 100mm.

(5) Vice handle

“Secondary handlebars” are also called “ox horns” or “sheep horns” (except road bike rest handlebars and TT handlebars). Generally long and curved are called horns, short and relatively

The straight ones are called horns.

The role of the vice handle

①Make more postures and body angles in riding.

②It is more convenient to pull the car to exert force when climbing a slope.

③ Play a certain protective role in the event of an accidental fall.

The installation angle of the vice bar varies from person to person, but it is usually the angle where the bar end is forward and upward. The auxiliary handle was originally mainly used for mountain bikes, and was installed at both ends of the straight handle of the mountain bike.

(6) Handle Grip
A protective device between the hand and handlebar for shock absorption, increased friction, and better control of MTB handlebars with grips.

(7) Seat tube
Also called the seat post, the part that connects the seat and the frame, the load-bearing tube under the bicycle seat cushion.

The seat tube diameter of a bicycle is mainly determined by the inner diameter of the seat tube of the bicycle frame. Seat tubes of different diameters are generally equipped with seat tube clips of the corresponding size. For models with low-intensity riding environments, a relatively small tube diameter will be used. seat tube.

Common pipe diameter specifications are mainly 27.2mm, 28.6mm, 30.9mm, 31.6mm, and 34.9mm.

Seat tube length specifications are mainly 300mm, 330mm, 350mm, 580mm, and 600mm.

Seat tube classification:

①Ordinary seat post
Ordinary seat tube has a simple structure and high cost performance, and is the most common seat tube.

From the material point of view, it is divided into steel, aluminum alloy and carbon fiber material.

Steel seatposts are generally less expensive and have better shock absorption, but are also heavier.

Aluminum seatposts are moderately priced and slightly lighter, but not as comfortable as steel ones.

Carbon fiber seatposts are lightweight and comfortable, but are also more expensive.

In addition to ordinary seatposts, there are also functional seatposts for specific usage environments.

They are wire-controlled adjustable seatposts for AM (all-terrain mountain bikes)

②Wire-controlled adjustable seatpost

③Shock absorber seat tube
Suspension seatpost for long travel and other uses

(8) Frame

The frame determines the type of car (XC? AM? DH? etc.)

The frame directly or indirectly affects the performance of all aspects of the car (handling, stability, comfort, etc.)

The size of the frame also determines whether the car is suitable for you. Even if the type of frame is selected correctly, the performance is not bad, but if the size of the frame is not suitable, not only will it not be able to exercise the body, but it may also cause sports injuries and even bring physical safety hazards.

Whether a mountain bike is comfortable to ride, whether it is light and easy to control, how strong it can withstand, how long it can be used, whether it can be upgraded, etc., the frame accounts for a large factor.

Therefore: the frame is the soul of the mountain bike, the core part of the mountain bike.

①Frame material
Note: Part of the content of the frame material is referenced from Baidu Encyclopedia. If there is any inappropriateness, please correct me.

The materials that can be used to manufacture bicycle frames mainly include the following: steel, aluminum alloy, titanium alloy, magnesium alloy, scandium alloy, carbon fiber, etc. The frames that appear in the general market mainly include steel, aluminum alloy, titanium alloy, and carbon fiber.

Scandium alloys and magnesium alloys are emerging materials in recent years, which are rare.

Distinguish frame material from appearance:
From the appearance, we can easily distinguish the frames of these materials.

Rugged in style and wild in shape is the aluminum frame.

The tube body is slender, and the skinny is the steel frame.

And there is no coating, the titanium frame exudes a metallic luster.

The surface of carbon fiber is covered with various 3D cloth surfaces, which is very modern.

To understand the properties of these materials, it is necessary to know some basic concepts and parameters:

  1. Weight (WEIGHT)

Weight is fairly slightly affected by the alloy composition of the material.

Even if your frame is labeled “Lite Steel TM” (lightweight steel), in fact, all steels are nearly equal in weight.

Here are some properties of several common materials:

Coefficient of elasticity (rigidity) ~~ strength (yield point) ~~ weight (kg/m3)

Steel 30-46~~16-27~~800-8200

Aluminum alloy 10-11~~11-59 (after annealing at 4-22) ~~2700-3200

Titanium alloy 15-16.5~~40-120~~4500—4700


Assuming that the weight hanging on the other end of the metal rod is heavy enough to permanently deform the metal rod, that is, when the weight is removed, the metal rod is still bent and cannot be completely restored to its original shape, which is called yielding. .

The force that brings a material to yield varies from material to material, and this is called strength.

Strength is related to frame durability but not ride quality.

Strength is determined by the yield strength of the material.

The yield strength has a considerable relationship with the quality of the frame tube, the heat treatment process and the alloy composition (some brand types).

  1. Stiffness (STIFFNESS)

Suppose one end of a metal rod is fixed on the fixture, and a certain weight is added to the other end to temporarily bend the metal rod. When the weight is removed, the metal rod immediately returns to its original shape.

When the same weight is applied to different materials, it will produce different degrees of bending, which is rigidity.

Rigidity affects the ride quality of the frame, because the frame is most afraid of deformation during normal riding.

Rigidity is determined by the modulus of elasticity of the material, and it is quite important that the modulus of elasticity has nothing to do with the quality of the metal and the composition of its alloys. For example, all types of steel have basically the same modulus of elasticity.

(①) Steel
Today, most low-end economy mountain bikes use steel as the frame material. Steel is a material with a long history, from the most common civilian bicycles to high-end competition-level vehicles, more or less steel is used.

Advantage: low cost

In addition to the improvement of smelting technology, steel also has advantages that cannot be replaced by other materials:

  1. Good processing performance, chrome-molybdenum steel is the oldest bicycle material, and its research time is also the longest, so its processing technology has developed to a fairly stable level.
  2. High strength. From the above, we can see that the strength of steel under the same volume is much greater than that of aluminum alloy and titanium alloy, so the strength of qualified steel frames can be reassuring.
  3. The riding feeling is comfortable. Steel is a kind of metal with good elasticity. The frame made of steel can absorb the vibration brought by the riding process. Therefore, the steel frame will not feel as uncomfortable as the aluminum frame, and it is especially suitable for use as a touring frame.
  4. The metal fatigue resistance of steel is much stronger than that of aluminum (as we can see from the experiments above), so under the same conditions of use, the life of steel frames will be much longer than that of aluminum frames.

(But nowadays, the magic cars of several hundred yuan are all over the market. In pursuit of low prices and sales, the materials have been greatly discounted!!!!!!!!!!)

Disadvantages: heavy weight, easy to rust

Of course, the steel frame also has its insurmountable shortcomings:

  1. Weight, in today’s extreme pursuit of lightweight equipment, the quality of steel makes everyone shy away from him. Although it is possible to use lightweight steel and use the pipe drawing technique to draw extremely thin walls, it is still difficult to reduce the weight of the steel frame to less than 1600 grams. And many aluminum frames weigh only about 1400 grams. That’s why steel frames are rarely seen in race-level frames.
  2. Rust, compared with other materials, steel is easier to rust. Rusting will greatly reduce the strength of the steel and reduce the service life. Therefore, various measures must be taken to prevent the steel from rusting. Therefore, if you are not pursuing the weight of the competition level and considering the durability of the frame, the steel frame is undoubtedly a good choice.

However, it should be pointed out that domestic good steel frames are harder to find than good aluminum frames.

First of all, a good steel frame is not cheap. For example, the high-grade steel frame of the Renault 853 series costs several thousand, while the steel frame of the Italian Konago costs tens of thousands. In addition, due to people’s preference for aluminum frames, steel frames are difficult to sell.

(2) Aluminum alloy
Aluminum alloy frames are the most commonly used frames.

Advantages: lighter weight than steel frame, strong corrosion resistance, strong rust resistance, low cost

Aluminum is low in stiffness and strength, but aluminum can make up for this by adding more material per unit volume, while still not being heavy.

In addition, the price of aluminum is very low compared to other high-grade materials for sports bikes. Aluminum used in high-grade aluminum frame (6000 series, 7000 series) are high-grade aluminum used in aerospace. Compared with ordinary aluminum materials, these aluminum materials have a significant improvement in strength and rigidity. Moreover, in order to ensure the strength, manufacturers have adopted the practice of using thicker pipes and increasing the cross-sectional area, so most aluminum frames look rough.

The appearance of aluminum does not change much over a long period of time. Aluminum itself is a metal that is easily corroded. There is almost no unoxidized aluminum in the air. When placed in the air, it is immediately oxidized to form a thin oxide film. Why not rust? The reason is that when the oxide film reaches a certain level, it prevents rust from continuing to form a dense oxide film (aluminum oxide). The oxide film is almost colorless so it is not easy to see changes (sometimes whitish) in appearance).

Disadvantages: low rigidity, poor toughness, poor shock absorption

The metal fatigue resistance of aluminum is very poor. The Achilles heel of a bicycle frame made of aluminum is that when riding a bicycle made of this material, the more times you ride, the more times the stress occurs, and the strength also changes significantly. Recently, in order to achieve light weight, many frames are made of thin materials (the degree of thinness has reached its limit). These are made of aluminum alloys with no fatigue limit, which is why an aluminum frame can only support 2-3 years under professional use strength.

Aluminum is inelastic and cannot absorb the shocks of riding. A hardtail frame made of aluminum transmits most of the shock directly to the rider’s body. This makes the aluminum frame quite bumpy to ride, and ride comfort is poor.

Because of these two deficiencies of aluminum, it is not suitable for general hardtail frames.

However, most of the XC off-road frames used in competition use aluminum alloys. This is because the weight of aluminum can be very light, and the strength can also be obtained through heat treatment and butting technology, which makes the aluminum frame very competitive. Good (race performance of course does not take into account the comfort level of the players and the service life of the product).

The full shock absorber car does not have these scruples. The lack of elasticity of aluminum is completely neutralized by having a completely independent shock-absorbing structure for absorbing shocks, plus a thicker and softer rubber and seat cushion.

In addition, the lighter mass of aluminum allows for larger cross-section areas and local reinforcement where strength is required. Therefore, aluminum is a more mature and reliable material, and it has an advantage when making a full-shock frame.

(③) Titanium alloy
Titanium alloy is generally the material of choice for top lightweight frames, and its strength and weight are better than aluminum alloys. Titanium is an emerging metal, this new material has very superior properties.

Advantages: low specific gravity, good rigidity, wear resistance, light weight, corrosion resistance, long life, strong shock absorption

  1. Titanium alloys can make frames with light weight and high strength. As can be seen from the above table, the strength of titanium is similar to that of steel, but the weight is only a little more than half of steel, so the same strength of titanium alloy frames Will be much lighter than a steel frame.
  2. Titanium alloy has very good elasticity, which makes it indispensable in absorbing riding vibration. The frame made of titanium alloy has very good comfort, and titanium is a metal with memory, which has almost unlimited service life within its own deformation range, that is to say, buying a titanium alloy frame is a kind of A once-and-for-all approach.

Generally speaking, under professional use conditions, the service life of an aluminum alloy frame is 2 years, a steel frame is 8 years, and a titanium frame can reach about 20 years.

  1. Under normal conditions, titanium will hardly corrode.

Disadvantages: expensive, complex processing technology

There are advantages and disadvantages, and titanium alloys also have their inevitable disadvantages. The most headache is one word: expensive! !

In terms of metal content, titanium is actually not a rare metal. However, titanium in its natural state generally exists in the form of titanium dioxide. The refining and processing process is complicated, the technical requirements are high, and the time and cost are high.

In addition, the welding process is extremely difficult, because the affinity of titanium and oxygen is very strong, and it will become titanium dioxide immediately after contact with air, and titanium dioxide is hard and brittle, and the strength of this part will continue to decline. Welding must be done carefully with inert gas.

The so-called Tig welding is: (Tig: abbreviation for tungsten, inert gas) arc welding with tungsten electrode and argon gas.

Welding of titanium must be carried out under the isolation of air.

Titanium frames are expensive for these reasons.

Generally, the price of domestically produced air wheels and Baoti titanium alloy frames is about 3,000 yuan, and if the price of titanium frames like AIRBONE or LITESPEED is even tens of thousands. But if you consider the life of the titanium frame, the price will not feel so outrageous.

(④) Carbon fiber
The manufacturing process is very complicated, and it is generally used for high-end bikes or professional racing mountain bikes.

Carbon fiber has been used in bicycles as a high-tech material for the last ten years.

Strictly speaking, carbon fiber is not a simple carbon element, but a mixture of carbon elements that are woven and reinforced with epoxy resin.

For technical reasons, the early carbon fibers used epoxy resins that even decomposed in sunlight. With the advancement of technology, the shortcomings of this excellent material are gradually being overcome. For example, the K frame in Germany uses high-grade 16K carbon fiber, which is even stronger than steel and has a quality commitment with a lifetime warranty.

Advantages: very lightweight, strong rigidity, strong shock absorption ability

  1. Extremely light weight: Carbon fiber road frames of around 1200 grams have been seen everywhere. Since the mass of carbon is only 1.6 g/cm3, making a frame of around 1 kg is no longer an illusion.
  2. Good shock absorption performance. Carbon fiber can effectively absorb shock and maintain good rigidity. This feature makes it a great competition-grade material.
  3. Frames of various shapes can be made. Different from the manufacturing process of general metal frames, carbon fiber frames are generally first made of molds, then put carbon fiber sheets on the molds, and finally cemented with epoxy resin. This manufacturing process can use aerodynamics to create a frame with minimal wind resistance.

Disadvantages: expensive, not durable, brittle body, easy to damage

  1. Complex stress calculation. composition carbon fiber

The frame is made of carbon fiber, which is characterized by strong tensile strength, but weak shear strength. Complex stress calculations (longitudinal rigidity and transverse rigidity) are required during processing, and carbon fiber sheets are overlapped and formed according to the calculation.

Generally speaking, the impact resistance of carbon fiber surface is quite good, but the puncture resistance is very poor. That is to say, it doesn’t matter if you fall horizontally and vertically, but you are afraid that you will encounter one or two sharp small stones during the horizontal falling and vertical shooting.

  1. The price is expensive. Compared with titanium alloy, the price of carbon fiber frame is even more expensive. The price of the top carbon fiber frame is tens of thousands, and the price of Konago’s C40 and C50 is even more than 20,000. Yuan. This is mainly because the production process of carbon fiber frames requires a lot of manual work, and the scrap rate is very high, resulting in a substantial increase in cost.

②Frame size

15/16 inch (XS)~~Suitable for 155-165cm height.

17/18 inch (S)~~Suitable for 165-175cm height.

19/20 inch (M) ~ suitable for 175-185cm height.

21/22 inch (L)~~Suitable for 180-195cm height.


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Stevenford, the General Manager of ALA CYCLES, professional on the MTB,E scooters bike, cargo bikes for more than 15 years tll now.

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