Crupi Pro 36h 20" & 24" Wheels

Quad Hub Wheelset with Rhythm Section Pro Rims

The Quad Hub wheelset features a high-performance spring and pawl engagement system with 150 ratchet teeth that engage every 2.4 degrees, delivering near-instant power transfer for BMX racing and aggressive riding. Laced with 14-gauge spokes and alloy nipples to 36-hole Rhythm Section Pro rims extruded from 6061-T6 aluminum, this wheelset balances strength, durability, and responsive engagement. Includes a 16T chromoly cog, four cog spacers for precise chain alignment, and rim tape.

Key Features

• 150-Tooth Ratchet Engagement (2.4° Engagement) – Near-instant engagement minimizes the dead zone between pedal input and wheel rotation, providing immediate power transfer for gate starts, sprints, and technical riding where pedal timing matters
• Fixed Independent Leaf Spring/Pawl System – Multiple pawls engage simultaneously when loaded, distributing engagement force evenly across the ratchet ring; reduces wear on individual components and creates smoother hub rotation with less internal resistance
• Adjustable Cog Positioning – Four included cog spacers allow precise chainline adjustment to optimize drivetrain efficiency and reduce chain wear; works with any Shimano-compatible cog (16T chromoly cog included)
• Rhythm Section Pro Rims (6061-T6 Aluminum) – Single-wall extruded rims provide strength and impact resistance for racing and street use; 36-hole drilling offers strong spoke triangulation for better load distribution
• 10mm or 20mm Front Hub Options – Choose between standard 10mm front hub or 20mm thru-axle hub depending on fork compatibility; 20mm version includes extra spacers for both carbon and chromoly forks
• No Rider Weight Limit – Hub construction and engagement system are designed to handle riders of all sizes without compromising performance or durability

Technical Specifications

• Rear Hub: Quad Hub with 150-tooth ratchet, 2.4° engagement
• Engagement System: Fixed independent leaf spring/pawl
• Rims: Rhythm Section Pro, 6061-T6 aluminum extrusion, 36-hole
• Spokes: 14-gauge
• Nipples: Alloy
• Front Hub Options: 10mm or 20mm (specify at purchase)
• Included: 16T chromoly cog, 4 cog spacers, rim tape
• Cog Compatibility: Shimano-compatible (cassette-style)
• Recommended Tool: Park FR-5.2 lock ring tool for cog removal
• Weight:
  • 20″ × 1.75″: 3 lbs 13 oz
  • 24″ × 1.75″: 4 lbs 1 oz
• Color Options:
  • Black: Black rims and black spokes
  • Red or Blue: Matching colored hubs and nipples with standard rims

Compatibility and Ideal Use Cases

This wheelset is designed for BMX race bikes and requires a frame/fork compatible with the selected hub sizes. The 10mm front hub fits standard BMX forks with 10mm dropouts, while the 20mm front hub requires a 20mm thru-axle fork (carbon or chromoly). The rear hub uses a Shimano-compatible cassette system, so it will not work with freewheel-threaded hubs. Best suited for competitive racers who need fast engagement for explosive starts and sprints, or aggressive riders who demand immediate power transfer for technical tricks and hard accelerations. The adjustable cog spacing makes this wheelset ideal for riders who want to fine-tune their drivetrain for optimal chain alignment and efficiency. Note that the 20mm front hub is only compatible with 20mm forks—verify fork compatibility before ordering.