Ronstan RF20101 Single Loop Head Pulley 20mm – Series 20 Ball Bearing Block

The Ronstan RF20101 Single Loop Head Ball Bearing Pulley (20mm) is a compact, high-performance Series 20 block designed for smooth and efficient control line handling on modern sailing boats.

Engineered with a 20mm acetal sheave running on precision stainless steel or Torlon® ball bearings, this block delivers exceptionally low friction and reliable performance under load, making it ideal for dynamic sailing applications.

The loop head attachment provides a simple and flexible rigging option, allowing easy connection via rope, lashing, or soft shackles—perfect for lightweight, performance-oriented setups.

Constructed from UV-stabilised acetal, fibre-reinforced nylon, and 316 stainless steel load components, the RF20101 is designed to withstand harsh marine environments while remaining lightweight and durable.

With a maximum working load of around 250kg and breaking load of 550kg, this compact pulley offers excellent strength-to-weight performance, making it a go-to solution for dinghies, skiffs, and small keelboats.

Key Features

• 20mm ball bearing sheave – smooth, low-friction operation
• Loop head attachment – flexible rigging options
• High load capacity (250kg MWL / 550kg BL)
• Lightweight (~14–16g) – ideal for performance sailing
• UV-stabilised acetal sheave – durable and low maintenance
• 316 stainless steel components – corrosion-resistant
• Compact design – ideal for tight rigging setups

Specifications

• Brand: Ronstan
• Model: RF20101
• Series: 20 Ball Bearing
• Product Type: Single pulley block (loop head)
• Sheave Diameter: 20mm
• Max Rope Diameter: 6mm
• Maximum Working Load: 250–275kg
• Breaking Load: 550kg
• Weight: ~14–16g
• Materials:
  • UV-stabilised acetal sheave
  • Stainless steel / Torlon® ball bearings
  • 316 stainless steel load strap
  • Fibre-reinforced nylon cheeks

Ideal Applications

• Vang systems
• Cunningham and outhaul controls
• Traveller systems
• Dinghy and skiff rigging
• General-purpose control lines

This block is ideal where you need a simple, lightweight, and efficient pulley for everyday sailing applications.

Why Buy from Barton Marine NZ?

• Trusted NZ Ronstan supplier
• Fast nationwide delivery
• Genuine marine-grade hardware
• Ideal for NZ sailing and coastal conditions

Pro Tip 

• Use loop head blocks for lightweight, flexible rigging setups
• Pair with soft shackles or Dyneema lashings for reduced weight
• Ideal upgrade from older fixed or plastic pulleys