What are the characteristics of bicycle pulley transmission system and chain traditional system?

The pulley transmission system and chain transmission system of bicycles are two core transmission schemes, and there are significant differences in structural design, performance and applicable scenarios. The following is a detailed analysis from three dimensions: core characteristics, comparison of advantages and disadvantages and applicable scenarios to help clearly understand the differences:

First, the core features: the essential difference between the two transmission systems

1. Chain transmission system (traditional mainstream)

Chain transmission is the most classic transmission form of bicycles. Its core is to connect the tooth plate (crank side) and the flywheel (rear wheel side) through a metal chain, and use the "meshing" between the chain and the tooth plate to transmit power. When the tooth plate rotates, the chain links are clamped into the groove of the tooth plate to drive the flywheel to rotate synchronously, and finally drive the rear wheel. Its core features are:

Open structure: the chain, tooth plate and flywheel are completely exposed without closed protection;

Metal rigid transmission: depending on the rigid engagement of metal parts, the power transmission is direct and "toothed";

Strong adjustability: support multi-gear speed change (realized by changing the tooth plate/flywheel with different teeth numbers and matching the speed change derailleur), and can replace the wearing parts such as chain and tooth plate separately during maintenance.

2. Pulley transmission system (modern upgrade scheme)

Belt drive is a popular "chain-less drive" scheme in recent years. The core is to connect the toothed disc with the flywheel through a high-strength polyurethane/carbon fiber belt (reinforced with built-in aramid fiber, similar to an automobile belt), and use the "bite" of the teeth on the inner side of the belt to transmit power. Some high-end models will add a closed protective cover to the belt. Its core features are:

Structure closed/semi-closed: belts and pulleys are often covered (or partially blocked) to reduce external interference;

Flexible transmission: the belt itself is slightly elastic, and the power transmission is smoother, without the "frustration" of metal engagement;

Maintenance-free property: the belt has no metal parts, does not depend on lubricating oil, and is not easy to be contaminated with dust and sediment.

Second, the deep comparison of advantages and disadvantages: from experience to maintenance cost

In order to distinguish them more intuitively, compare their performance in key dimensions through tables:

Comparative dimension chain drive system pulley drive system

The power transmission efficiency is high (about 95%-98%), and there is no slippage in metal engagement. However, after long-term use, the wear and slack of the chain will lead to a high efficiency decline (about 94%-97%), and the belt has no slack problem, so the efficiency is more stable, and there is no chain "seizure" loss.

Ride comfort and noise are obvious (friction between chain and teeth, collision between chain links), and there may be "shifting frustration" when shifting, with almost no noise (flexible belt transmission, no metal impact), smoother power output and quieter riding experience.

Maintenance frequency and cost High-frequency maintenance: regular cleaning (removing silt) and lubricating oil (preventing rust/wear) are required, and the chain has an average life of 10,000-20,000 kilometers and needs to be replaced; Tooth plate/flywheel is easy to wear, so it needs to be replaced with low-frequency maintenance after 30,000-50,000 kilometers: no oiling is needed, only the dust on the belt surface needs to be wiped occasionally, the belt life is 30,000-50,000 kilometers, the pulley wear is slow (life is 50,000-80,000 kilometers), and the long-term maintenance cost is lower.

Poor anti-pollution ability: the chain is easy to get stuck with sediment and oil, so it needs to be cleaned immediately after riding in rainy days, otherwise it is easy to rust and accelerate wear; the surface of the belt is smooth and the sediment is not easy to attach, and the protective cover can isolate the rain, so it can be simply wiped after rainy days.

Heavy weight and compatibility (about 200-300g for conventional chains), extremely strong compatibility: it is suitable for all types of tooth plates/flywheels, and supports single speed, internal three speed and external speed change (such as 27 speed for mountain bikes and 11 speed for road bikes), light (about 100-150g for belts), and limited compatibility: it is only suitable for "toothed tooth plates/flywheels" (.

The price threshold is low: the basic chain is only a few tens of yuan, and the whole transmission system (chain+tooth plate+flywheel) can be done at a hundred yuan level. The entry belt needs 300-500 yuan, and the whole system with protective cover (belt+pulley) starts at a thousand yuan level, and the price of high-end models (such as carbon fiber belts) is higher.

Trouble shooting is easy to maintain: roadside repair shops can change the chain and adjust the tightness. After the chain is broken, it can be temporarily spliced with "magic buckle". It is difficult to maintain: the belt has no "temporary repair" scheme, and the whole belt needs to be replaced after the belt is broken, and special tools are needed to adjust the pulley position, which is difficult for ordinary repair shops to handle.

Third, the applicable scenario: choose chain or belt? See demand matching

1. Chain transmission is preferred:

Mountain bike, road bike, long-distance station wagon: it needs multi-gear speed change (to adapt to complex road conditions), and it may ride in muddy and dusty environment, so the "strong compatibility+easy maintenance" of the chain is more practical;

Limited budget and pursuit of cost performance: daily commuter cars, student cars, etc., the chain system has low cost and convenient maintenance, so there is no need to worry about "special accessories";

I like DIY modification: it is necessary to change the tooth plate/flywheel frequently to adjust the tooth ratio (such as climbing to change the small flywheel and racing to change the big tooth plate), and the openness of the chain is easier to operate.

2. Preferred pulley drive:

Urban commuter cars and retro leisure cars: the daily riding conditions are clean (mainly asphalt roads), and there is no need for multi-gear speed change, pursuing "quietness and worry-free". The "maintenance-free+low noise" of the belt can greatly enhance the experience;

High requirements for cleanliness: I hate chain oil stains on pants, or I don't want to clean and maintain them frequently (such as office workers and lazy cyclists), and the characteristics of belt "no oil and no dust" are more suitable;

High-end exercise bike and folding bike: the pursuit of lightweight (folding bike needs to lose weight) and riding texture, the smoothness and low noise of the belt are suitable for indoor fitness or short-distance exquisite riding.

Summary: the core differences are summarized in one sentence.

Chain drive is a "pragmatic choice"-wide compatibility, low cost and easy maintenance, but it needs frequent maintenance; Belt drive is "exquisite experience choice"-maintenance-free, low noise, high texture, but high cost and limited compatibility.

You don't have to worry about "who is better" when choosing, but you can match it according to your riding scene (road conditions/speed change demand), budget and maintenance willingness: choose a belt for daily commuting, and choose a chain for mountain cross-country/pursuit of cost performance.