S&M Mid School Guard Sprocket (25, 28, 30, 33, 36, 39T)

This CNC-machined guard-style sprocket features an integrated bashguard design originally released in 2005 and reissued in 2024 with modern updates. Built from 6061-T6 aluminum with offset teeth for improved chain alignment, widened crank clearance cuts, and modern tooth profile. Made in the USA and available in six tooth count options with multiple color choices including matte purple.

Key Features

• Integrated bashguard design – Extended outer ring protects sprocket teeth and chainring from impacts during grinds, pedal stalls, and obstacle contact
• Four mounting positions – Multiple bolt hole orientations allow precise chain alignment adjustment and accommodate different crankset bolt patterns
• Offset teeth for improved chain alignment – Teeth positioned for optimal chain tracking reduces wear and improves drivetrain efficiency
• Widened crank clearance cuts – Updated cutouts provide better clearance for modern crankarms compared to original 2005 design
• Modern tooth profile – Updated tooth geometry improves chain retention and engagement compared to mid-school era profiles
• CNC-machined 6061-T6 aluminum – Precision machining with T6 heat treatment maximizes strength while maintaining weight advantage over steel sprockets
• 15/16" (24mm) center bore with included adapters – Universal bore fits 19mm, 22mm, and 24mm crank spindles using provided steel hat washers

Technical Specifications

• Material: CNC-machined 6061-T6 aluminum
• Tooth width: 1/8"
• Center bore: 15/16" (24mm)
• Spindle compatibility: 19mm, 22mm, 24mm (with included adapters)
• Mounting: Four positions
• Available tooth counts: 25T, 28T, 30T, 33T, 36T, 39T
• Weight: 4.5 oz (25T), 5.5 oz (28T), 6.4 oz (30T), 7.7 oz (33T), 8.9 oz (36T), 10.1 oz (39T)
• Included hardware: 19mm and 22mm steel hat washers
• Made in: USA

Compatibility and Ideal Use Cases

Works with all three-piece cranks using 19mm, 22mm, or 24mm spindles and standard 1/8" BMX chains. The integrated bashguard design suits street and park riders who frequently grind on their sprocket side or perform tricks where the sprocket contacts obstacles. Four mounting positions allow fine-tuning of chain alignment for optimal drivetrain performance. Smaller tooth counts (25T-30T) provide quick acceleration for technical street riding, mid-range counts (33T-36T) balance acceleration with reasonable top speed, and larger count (39T) offers higher top speed for riders prioritizing momentum. The guard design adds protection at the cost of slightly increased weight compared to non-guard sprockets.