S&M ATF Frame (20" Wheels)

Product Overview

The S&M ATF (All Terrain Frame) is a versatile chromoly frame with balanced geometry for street, park, and dirt riding. Serves as the foundation for multiple S&M signature models and features butted Thermal-X tubing with an integrated head tube and seat clamp. Made in the USA with 100% chromoly construction. Available in four colorways.

Key Features

• Adjustable rear end (13.4–13.875") – Rearward dropout slots allow chainstay length adjustment to fine-tune wheelbase for stability on transitions or tighter balance point for manuals and nose tricks
• Butted Thermal-X tubeset – Variable wall thickness chromoly tubing strategically removes weight from low-stress areas while maintaining strength in critical impact zones
• Integrated seat clamp – Built-in clamp design eliminates external hardware and removes a common failure point caused by overtightened separate clamps
• 4Q-Baked dropouts – Heat-treated 14mm slot dropouts increase hardness and tensile strength to resist flex and cracking under pedaling torque and landing impacts
• Mid BB height (11.7") – Balanced bottom bracket position provides stable platform without excessive risk of pedal strikes during grinds or technical obstacles
• 75° head tube angle – Steeper geometry delivers responsive steering input while maintaining predictable handling at speed
• Thread-on 990 brake mounts – Removable U-brake bosses keep frame clean when running brakeless, sold separately for riders who need stopping power
• 8.5" standover height – Lower than XL models for riders under 6'1" who need proper clearance without excessive height

Technical Specifications

• Top Tube Lengths: 20.5", 20.75", 21"
• Rear End Length: 13.4–13.875" (adjustable)
• Head Tube Angle: 75°
• Head Tube Style: Integrated (45°/45°, 41.8mm internal diameter)
• Seat Tube Angle: 71°
• Seat Clamp: Integrated
• Seat Post Size: 1" (25.4mm)
• Bottom Bracket Height: 11.7"
• Bottom Bracket Style: Mid
• Standover Height: 8.5"
• Brake Mounts: Thread-on 990 (mounts sold separately)
• Dropouts: 14mm slot, 4Q-Baked
• Gyro Tabs: None
• Weight: 4.65 lb (2.12 kg)
• Tubeset: Butted Thermal-X chromoly tubing
• Available Colors: Four options

Compatibility and Ideal Use Cases

This frame is designed for standard 20" BMX wheels and suits riders approximately 5'6" to 6'0" tall. Requires forks with integrated race systems (45°/45° angular contact bearings with 41.8mm crown race diameter). The integrated seat clamp accepts 1" (25.4mm) diameter seat posts only. 14mm slot dropouts accommodate 14mm bolt-on axles or 3/8" axles using adapter sleeves. Thread-on 990 brake mounts must be purchased separately if running brakes. No gyro tabs means this frame supports brakeless or direct-cable brake setups only. The adjustable rear end allows riders to dial in chainstay length: shorter settings (13.4") improve maneuverability and manual balance, while longer settings (13.875") increase stability for transitions and high-speed riding. Best suited for riders who need one frame capable of handling multiple terrain types without geometry compromises.