Motorcycle industry
Overview of Rolling Bearings Used in Motorcycles
The bearing configuration of motorcycles varies depending on the model, engine type, and design requirements. Since motorcycles under 250cc account for approximately 90% of the market—and most of them use single-cylinder engines—we summarize the common bearing arrangements in fuel-powered motorcycles below 250cc.
1. Engine System
Motorcycle engines integrate the crankcase, clutch, and transmission into a compact structure. Despite their relatively small size, a single engine can contain more than a dozen bearings, including crankshaft main bearings, connecting rod bearings, camshaft bearings, shift shaft bearings, rocker arm bearings, and clutch bearings.
1.1 Crankshaft Main Bearings
Typically use deep groove ball bearings or cylindrical roller bearings.
• Deep groove ball bearings are suitable for general loads and speeds.
• Cylindrical roller bearings can withstand higher radial loads and shock.
1.2 Balance Shaft Bearings
Single-cylinder engines often use a balance shaft to reduce vibration caused by imbalance. These bearings are usually deep groove ball bearings or cylindrical roller bearings.
1.3 Connecting Rod Bearings
Mostly use needle roller bearings due to their compact structure, making them suitable for high-speed rotation of the small end of the connecting rod in limited space.
1.4 Camshaft Bearings
Commonly use needle roller bearings or ball bearings.
• Needle bearings are suitable for space-constrained camshaft designs.
• Ball bearings are used where higher precision and stability are required.
1.5 Valve Rocker Arm Bearings
Typically designed without rolling bearings, though some designs may use needle roller bearings.
1.6 Clutch Bearings
The clutch release bearing is located at the center of the clutch, at the front end of the push rod. It supports axial loads during clutch disengagement and typically uses thrust bearings.
1.7 Magneto bearings
The magneto supplies power to the entire vehicle. It usually does not have independent bearings and is supported by the crankshaft's left main bearing.
1.8 Starter Motor Bearings
Some motorcycles do not have electric starters and instead use kick-start mechanisms. Where present, starter motors generally use two miniature thin-section deep groove ball bearings.
1.9 Oil Pump Bearings
The oil pump circulates engine oil throughout the system. Most motorcycle oil pumps are gear pumps or rotor pumps.
The pump shaft is typically supported by thin-section needle roller bearings or miniature deep groove ball bearings.
1.10 Main and auxiliary shift shaft bearings
These shafts are mainly supported by deep groove ball bearings.
Some engines use CVT systems, in which case there are no main or countershaft gear shafts.
2. Final Drive System
Common types of motorcycle final drive systems include:
1. Chain + sprocket (or toothed belt + pulley)
2. Belt + variator (CVT)
3. Shaft drive
The final drive connects the transmission to the wheel axle, ensuring engine power is delivered to the rear wheel.
2.1 CVT (Continuously Variable Transmission)
The CVT system consists of:
• Drive pulley (variator assembly)
• V-belt
• Driven pulley + clutch assembly
• Reduction gearbox
The drive pulley connects to the engine output shaft, while the driven pulley connects to the rear wheel via the reduction gears.
2.2 Chain and Sprocket Drive
The chain drive system is one of the most common forms of power transmission in motorcycles, widely used in standard motorcycles and underbone models. Its core function is to flexibly transmit the engine’s output power to the rear wheel via the chain.
The drive sprocket is mounted on the transmission countershaft and operates in conjunction with the engine crankshaft. The driven sprocket is installed on the rear wheel hub and is connected via dampers to absorb shocks.
2.3 Shaft Drive (Universal Joint Transmission)
The shaft drive system consists of multiple precision components, including the main shaft housing, sliding sleeve, universal joint, bevel gears, oil seals, bearings, and brackets. During operation, the universal joint generates lateral torque, resulting in relatively higher power loss. Additionally, due to higher manufacturing costs, shaft drive systems are less commonly used in motorcycles.
3. Running System
Wheel Hub Bearings:
Deep groove ball bearings or tapered roller bearings are typically used. Deep groove ball bearings are suitable for general road conditions, while tapered roller bearings can withstand greater radial and axial loads, making them suitable for heavy-duty or off-road motorcycles.
4. Steering System
Upper and Lower Steering Head Bearings:
Angular contact ball bearings or tapered roller bearings are generally used, providing high rigidity and low friction to ensure precise and stable steering.
Our Expertise
With extensive experience in motorcycle bearing applications, we provide reliable and performance-driven solutions for a wide range of motorcycle products.
1. Full-system bearing integration support
From engine systems to final drive and chassis, we offer complete bearing selection and matching solutions.
2. Application-driven design optimization
We optimize bearing types based on real operating conditions such as load, speed, temperature, and space constraints.
3. Cost-performance balance
We help customers achieve the optimal balance between durability and cost efficiency.
4. Strict quality control
Our products comply with ISO international quality standards, ensuring stable performance and long service life.
Engineered solutions
Rolling bearings are fundamental to motorcycle performance, durability, and riding experience. With deep application knowledge and proven project experience, we not only supply bearings—but also deliver engineered solutions tailored to real-world motorcycle applications.
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