This SE Bikes one-piece alloy chainring and spider set is built for BMX and cruiser bikes that use traditional one-piece (Ashtabula-style) cranks. It combines a larger 39-tooth ring with a matching spider for a classic look and reliable single-speed performance.
This setup is commonly used on vintage-inspired builds or restorations where one-piece crank compatibility is required and a taller gear is preferred.
Key Features
• One-piece style chainring and spider set
• Alloy construction for reduced weight
• CNC-machined silver tooth faces on black chainring
• Anodized spider with ED gold bolts
• Standard tooth profile for consistent chain engagement
Compatibility & Use Notes
• 39-tooth chainring
• Compatible with 1/2" x 1/8" chains
• Mount compatibility: one-piece crank only
• Designed for single-speed use
• Not compatible with three-piece or spider-based crank systems
• Available in multiple color combinations
Service / Ownership Context
Larger chainrings increase gear ratio and pedal load, which should be matched to rider strength and riding style. Proper chainline and correct chain tension are important on one-piece crank systems to prevent premature wear and noise.
Fit & Use Signals
• Good fit for BMX or cruiser bikes with one-piece cranks
• Good fit if you want a taller 39T single-speed gear
• Good fit for 1/2" x 1/8" chain drivetrains
• Not a fit for three-piece crank systems
• Not a fit for multi-speed drivetrains
