Gravis
A legacy reimagined. Innovation at its core.
Gravis is the perfect fusion of LUG's rich heritage and modern innovation. It combines the timeless elegance of LUG's classic craftsmanship with cutting-edge design and geometry, creating a folding bike that both honors tradition and leads the way into the future. While prioritizing lightweight and convenience, Gravis retains the warmth and depth of craftsmanship, allowing riders to still feel the elegant legacy of a century-old tradition.
Gravis-Steel Folding Bike
Your bike already arrives 95% built. We give you the tools. And simple instructions. No technical skills needed.
Free frame replacement for natural cracking under normal riding conditions (non-impact related).
FAQ:What is
LUG Housing?
LUG housing craft originated in Europe, with brands like Colnago, Bianchi, Cinelli, Pinarello, and De Rosa known for their LUG and steel frames, representing the peak of steel frame craftsmanship. In the U.S., Rivendell is famed for silver brazed LUGs and retro geometry. In Japan, TOEI, and in the UK, Mercian, are renowned for hand-carved LUGs and custom paint, making them highly coveted by collectors. Today, many brands are reviving these classic designs, solidifying LUGs as a symbol of high-end craftsmanship.
Compared to direct welding, the LUG housing process makes it easier to maintain consistency during frame production and allows for the use of lightweight steel tubes. LUG housing offers a larger contact area and precise angle control, making the frame connections more solid and reliable.
LUG Craftsmanship: Where Tradition Meets Modern Design
LUG craftsmanship blends tradition with modernity, elevating folding bicycles with its intricate design and artistic details. It preserves the elegance of classic steel frames while adding a timeless charm to urban cycling.
4130 High-Strength Steel
Made from 4130 steel (C0.28-0.33%, Cr0.8-1.1%, Mo0.15-0.25%, balance Fe), this low-to-medium carbon chromium-molybdenum alloy offers excellent strength and toughness. After heat treatment, its yield strength reaches 560-700 MPa and tensile strength can go up to 700-900 MPa, combining high strength with great durability.
Compared to aluminum alloys like 6061-T6 (tensile strength around 310 MPa), 4130 steel offers more stable performance under impact and fatigue loads. Its excellent weldability and machinability make it an ideal material for complex and precise frame structures, especially for high-end road and folding bike frames.
Stopping Power: CNC Machined Aluminum Hydraulic Disc Brakes
Precision-engineered for optimal performance, these CNC-machined aluminum hydraulic disc brakes offer superior stopping power and control. Built for durability and responsiveness, they ensure smooth braking even in demanding conditions, providing a safe and reliable riding experience.
HIGHER STRENGTHR
ACCOMMODATING SIZE
STABLE HANDLING
Bike Configuration List
Specification
| Item | Specification |
|---|---|
| Frame | 4130 Cr-Mo Steel Frame with LUG Construction |
| Folding Stem | One-Piece Forged Aluminum Folding Stem |
| Cockpit | 6061-T6 Forged Handlebar & Seatpost |
| Crankset | Forged Aluminum Lightweight 44T Single Chainring |
| Shifter | MicroShift Advent 1 X 9S |
| Cassette | Lightweight 9-Speed 11-34T |
| Brakes | Dual-Piston, Fully CNC-Machined Forged Aluminum Integrated Hydraulic Disc Brake System – 160mm Front / 140mm Rear |
| Wheelset | High-Polish Forged Aluminum Hub + Double-Wall Sleeve-Joint Aluminum Rim, 24 Spokes |
| Tires | 20*1.95 inch CST Mountain Bike Tires, Skinwall Color |
| Item | Specification |
|---|---|
| Frame | 4130 Cr-Mo Steel Frame with LUG Construction |
| Folding Stem | One-Piece Forged Aluminum Folding Stem |
| Cockpit | 6061-T6 Forged Handlebar & Seatpost |
| Crankset | Forged Aluminum Lightweight 44T Single Chainring |
| Shifter | MicroShift Advent 1 X 9S |
| Cassette | Lightweight 9-Speed 11-34T |
| Brakes | Dual-Piston, Fully CNC-Machined Forged Aluminum Integrated Hydraulic Disc Brake System – 160mm Front / 140mm Rear |
| Wheelset | High-Polish Forged Aluminum Hub + Double-Wall Sleeve-Joint Aluminum Rim, 24 Spokes |
| Tires | 20*1.95 inch CST Mountain Bike Tires, Skinwall Color |
Crafted for those who value artistry and innovation, the 4130 chromoly steel frame combines legendary toughness with advanced LUG copper brazing. Skilled artisans use molten copper to forge a bond of unmatched strength, leaving behind intricate, hand-crafted details that elevate the traditional road bike legacy to new heights in folding bike design.
Blog posts
How to Choose Bike Fenders for Spring Rain | Full vs Clip-On Mudguards Guide
This guide explains how to choose the right bike fenders for wet spring riding. It compares full-coverage vs clip-on mudguards, materials, installation, and real-world performance, helping riders s...
How to Choose a Waterproof Bicycle Bag: A Complete Guide to Waterproof Ratings and Ease of Cleaning
This guide explains how to choose the best waterproof bike bag based on waterproof levels, cleaning and maintenance, and installation tips, featuring ROCKBROS’ top options for city commuting and lo...
How to Choose a Bike Bell: Safety, Sound & Practical Tips
Bike bells may be small, but they play a big role in safe and polite city riding. This guide explains why bike bells matter, how different materials affect sound, and how to choose the right ROCKBR...