Common sizes
This measurement typically refers to the length from the center of the bottom bracket spindle to the center of the pedal spindle.
165mm and 170mm are the most common sizes for one-piece Cranks. SUMLON Provides almost all other sizes, including 89mm, 102mm, 114mm, 127mm, 140mm, 152mm, 165mm, 170 mm, and 175mm.
The expected bicycle one-piece Cranks (OPC) sizes are standardized due to manufacturing efficiency and compatibility requirements. These one-piece cranks usually come in two sizes:
165mm: This size is standard for BMX, children’s bike, and cruiser models. The 165mm crank arm provides a shorter length, ideal for applications requiring mobility. They are often favored by riders who perform skill performances or ride in narrow spaces, such as in a skate park or an urban environment.
170mm: The 170mm crank arm is more common in adult bikes, including entry-level road bikes and some mountain bikes. This size is slightly longer than the 165mm version and may provide better stampede efficiency and power transfer. This is a versatile size for a variety of riding styles and terrain.
What are the One-Piece Cranks?
Each component plays a crucial role in a bicycle’s performance and function. The crank is one of the most basic components. Understanding its common size is critical.
The one-piece crank is a standard bike part that usually appears in entry-level or affordable bikes and some BMX bikes. As the name suggests, it was constructed as a separate bicycle part, usually made of steel. Different from crank arms, One-Piece Cranks consist of combined crank arms and spindles, and one-piece crank integrates these components into a single component, providing simplicity and durability.
Why do we need different sizes?
The sizes between the crank arms can significantly influence the bicycle cycling experience and performance. Here are some contributing factors to consider:
The sizes between the crank arms can significantly influence the bicycle cycling experience and performance. Here are some contributing factors to consider:
Comfort and suitability: The length of the crank arm affects the rider’s comfort and the bike’s suitability. Riders with shorter legs or who prefer more upright rides may feel the 165mm crank arm more comfortable, while taller riders or those seeking more aggressive rides may opt for the 170mm version.
Stepping efficiency: The length of the crank arm can affect the stepping efficiency and biomechanics. The more extended crank arm may provide a slightly more extensive range of motion, possibly allowing more power to be generated during each stampede movement. However, this advantage may be slight, depending on the physiology and preferences of the individual rider.
Pass and mobility: In the BMX bike and cruise models, the shorter 165mm crank arm provides better passage and mobility, ideal for skill, jumping and narrow turns. Riders focusing on agility and responsiveness may prefer bikes of this size.
Frame Compatibility: Framework compatibility is critical when replacing or upgrading crank components, including gaps for the length of the selected crank arms. While many bikes designed for a single block crank are compatible with 165mm and 170mm sizes, specific frameworks may have limitations depending on geometry and design.
To summarize, the standard sizes of a one-piece crank, namely 165mm and 170mm, cater to different rider preferences, bike types, and cycling styles. Whether riding on city streets, conquering rugged mountains or mastering BMX skills, choosing the right crank arm length is essential to optimizing comfort, performance and overall riding experience. Understanding the impact of crank size and choosing the right size for your needs can increase fun and efficiency for cycling.
