The Reynolds 520 series is normally a welded, cold-drawn version. Based on the 4130 Chrome-Moly steel with similar properties to our original 531 brand alloy which set Reynolds to be world renowned in the bicycle industry, with no fewer than 27 Tour de France champions crossing the finish line atop bicycles built with their tubing.

In cycling industry, Reynolds 520 steel tubes are mandrel butted for accurate profiles, and available in a wide range of shapes. This process makes Reynolds butted tubes uses less than a half material, compare to the other hi-ten steel tubes, but still enhances theirs strength, stiffness, toughness & brings an optimized frame weight.

On Tinman frames are manufactured with Reynolds 520 double butted 0.9-0.6-0.9 mm wall-thickness tube for toptube, downtube and seattube. Maybe those numbers sound not attractive, but in order to easily imagine, you can compare that thickness with the thickness of a paper !

The Reynolds “520” range uses the same alloy, made under license for us in Taiwan and subject to the same quality standards. It can be used for sports car chassis, suspension units, motorcycle race frames etc. in welded and fillet-brazed structures.

Thanks to the combination of chrome and molybdenum elements, Reynolds 520 steel frame is 300% stronger and stiffer than a 6061 aluminum alloy frame ( same size & geometry ). Beside that, they are rust-resistant.

Comparative values for UTS in MPa and Stiffness in GPa for metals used by Reynolds in previous applications to date including 6061-T6 Aluminium and 3Al-2.5V titanium.

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Reynolds Butting process in the UK uses a mandrel press

In a mandrel press, the tube is pushed through a die sinking it down onto the mandrel. The die determines the outside diameter and the profile of the tube, while the mandrel sets the inside diameters and defines the wall-thickness profile. After this process, the mandrel is trapped inside the tube in a conventional double-butted geometry, where the end wall thickness is greater than in the middle section. The mandrel is removed after reeling the tube between angled rotating rollers, which increases the diameter while having a negligible affect on the wall thickness. Finally, the outside diameter is sized by pushing the tube once again through a die.