Steel – the different types of steel in bike frames

I was and still am slightly confused – there is a lot of steel out there, chromoly 4130, reynolds from 501 to 953, columbus thron to spirit – so I have googled, pilfered, condensed and accumulated some of the findings. I am no expert – for more info click on links. They follow after explanation roughly in order of strength, rarity and of course price

What is Steel?

Steel is an iron/carbon alloy that, with the addition of several elements such as chrome, nickel, manganese, molybdenum, vanadium, etc., develops specific characteristics such as tenacity, fatigue resistance, workability and insensitivity to overheating.

Al vs Steel vs Ti

Why choose steel?

Steel ensures high performance at really low weights. The new alloys give a weight close to that of the aluminum alloys, together with a perfectly balancable elastic response, that is appreciated in particular on long rides. Unlike aluminum, steel is substantially stable over time, not requiring onerous maintenance cycles. If properly rust-treated, under normal conditions of use, it has almost unlimited fatigue resistance.
It allows frames to be built with excellent performances, rigid yet comfortable, suitable for any type of use.

Reynolds 953  STAINLESS STEEL

Reynold’ latest innovation takes steel alloys into a new league. By utilising a specially developed martensitic-aging stainless steel alloy that can achieve tensile strength in excess of 2000 MPa, with a strength-to-weight ratio that can take on the best in the world. The resilient ride of steel, very high impact strength (similar to armour plating) and fatigue resistance combine to provide an extraordinary material that can now be used for tubing.

Reynolds work with directly with fabricators to provide recommended production techniques, so that the challenges inherent in using an extremely hard metal can be overcome.

Why it works:

UTS: 1750-2050 MPa

Columbus XCR

In cooperation with Trafiltubi ed Aubert & Duval, the new Columbus seamless tube set in stainless steel named XCr, is created. Starting form a specific request of the military industry, looking for a valid substitute for cadmium plated temper hardening steels which could no longer be produced because of their highly polluting manufacturing process, a new martensitic stainless steel with high content of Chromium and Molybdenum and Nickel as alloy elements which increase the mechanical and weldability characteristics, was created. The martensitic main structure contains traces of austenite that reduces the possibility of crack formation especially during the welding process.
The great weldability properties of the new XCr stainless steel, together with its high fatigue resistance and its extraordinary geometrical stability at high temperatures, make this material the natural element for welded structures, such as bicycle frames. Thanks to the high stiffness/weight and UTS/weight ratios (better than titanium and aluminium alloys) together with the elevated characteristics of corrosion resistance, it is possible to manufacture triple butted tubes to build extremely light and indestructible frames.

Why it works:

Mechanical characteristics  UTS = 1250-1350 MPa.

NOTE: It’s the most expensive steel tubeset in the world, but it’s also the only seamless stainless steel tubeset available; Reynolds’ 953 is a welded tube.

 

 

Reynolds 853

SEAMLESS AIR-HARDENING HEAT-TREATED STEEL

The benefits of air-hardening steels are particularly noticeable in the weld area where, unlike conventional steel alloys, strength can actually increase after cooling in air immediately after welding. 853 is heat-treated to give high strength and damage resistance, and the steel properties allow thin walls to be used, so that lower weight but fatigue-resistant structures can be made.

Why it works:

UTS: 1250-1400 MPa, density 7.78 gm/cc
Favourite Quote – a high end Reynolds 853 with SRAM red and/or dura ace for the person with money who wants a non carbon racing bike option 

 

NOTE The main advantage of Reynolds 853 is its ability to air harden after joining, a characteristic not shown by other chrome molybdenum / manganese molybdenum materials presently on the market. When building frames using either TIG welding or high temperature brazing, above 1600 degrees, the joints increase in strength as the frame cools to room temperature.

 LUG CONSTRUCTION IS THE PREFERRED METHOD OF JOINING 853. It allows a much larger area to be heated than tig welding which concentrates the heat to a very small area at the weld. This completely goes against the “AIR HARDENING” building philosophy of the material and adds nothing to the strength of the joint. It is however a much cheaper joining method, requiring less time and skill to perform.

Due to the superior mechanical properties of 853 tubing, there are several benefits which will translate directly to the cyclist. The wall thickness of 853 has been reduced to 0.4 mm, a full 0.1 mm thinner than Reynolds other top of the line 753 tubing. This translates into a frame weight of under 3 pounds 5 ounces for a 56 cm frame. The final significant advantage is the increased stiffness of the frame and its ability to transmit all of the cyclist power into forward motion.

Reynolds 753 – MANGANESE-MOLY heat-treated steel:

The 753 tubeset was the first heat-treated tubeset in the race bicycle industry, based on the same alloy as 531. Used mainly in lugged and fillet-brazed framesets, Reynolds implemented a Certfication procedure for builders who wished to use the tubing, as it helped builders understand the requirement to avoid overheating the thin wall tubes. Most builders used silver-brazing for the fabrication of frames, due to the low melting point, so that 753 tubing was not annealed inadvertantly. All 753 tubes are now available in the same dimensions within the Reynolds 725 brand tubing.

753 is now only available to special order and subject to a high minimum quantity due to raw material constraints.

Why it works:

UTS: 1100-1340 MPa
Favourite Quote –   “your back just doesn’t get sore on this bike”

NOTE This was the benchmark by which all high performance bicycle frames have been judged for the last 20 years. 753 is among the strongest tubes currently available for the manufacture of high performance, light weight, ultra responsive road frames. This tubing uniquely combines terrific power transmission ability, lively ride, responsiveness and a high degree of comfort, while producing some of the lightest frames available.

Unfortunately 753 frames will never be seen in great numbers. Frame builders having access to this material is closely controlled.  Builders must be certified as to their proficiency in low temperature silver brazing 753 by Reynolds. Only after having passed a structural test on their work will they be certified and sold these tubesets. Another drawback is the cost of silver brazing material as compared to that of brass, approximately $150.00 per pound compared to $9.00. Having to keep the area to be joined at a maximum of  1200 degrees, tig welders are immediately ruled out, along with their ability to mass produce 753 frames. It is primarily for these reasons that 753 frames are not offered by the bicycle giants. Highly skilled labor and time consuming hand work are not the direction large companies wish to move in.

Reynolds 725 -HEAT-TREATED CHROME-MOLY STEEL

Using an industry standard alloy with mechanical properties similar to our famous 753 brand, Reynolds mandrel butt and heat-treat this alloy so that thinner walls can be used compared to non-heat-treated steels. 725 can be TIG welded and used within our “Designer Select” combinations including 853 and 631 tubes.

Why it works:

UTS: 1080-1280 MPa

Based on a 0.3% carbon steel alloy which has been heat-treated and back-tempered for increased ductility. The chromium content promotes hardenability and resistance to oxidation. The molybdenum works in conjunction with the chrome to stabilize the alloy and maintain strength after heat-treatment and in use.

Columbus Spirit – Heat treated

NIOBIUM is a special steel with manganese, chrome, nickel, molybdenum and niobium. Columbus’s special chemical composition, the combined effect of strengthening for precipitation and reducing the alloy grain size are incredibly enhanced compared to standard steels. Niobium proves more effective than Vanadium as an alloy-strengthening agent. After specific processes of progressive drawing and forming, NIOBIUM undergoes a special heat treatment that gives the steel its final characteristics. It is a steel designed to provide superior mechanical characteristics and higher resistance to environmental effects than conventional carbon steels. A serious choice for a competition or top-of-the-line frame, where lightweight and reliability are essential.

Why it works:

UTS = 1050 ÷ 1250 MPa
Favourite Quotes – “Spirit” cromoly from Columbus. Well at least that’s what my Pegoretti is made from and I think it rides the best of my steel bikes. I’m fully aware it’s not just the tubing though. 

 

Columbus Life

NIOBIUM is a special steel with manganese,chrome,nickel,molybdenum and niobium.Columbus’s special chemical composition,the combined effect of strengthening for precipitation and reducing the alloy grain size are incredibly enhanced compared to standard steels.

Why it works:
UTS: 1000-1150 MPa

An all-purpose, high performance tubeset, manufactured in Cyclex steel, a top quality chrome molybdenum steel which has been cold worked to increase its strength.
These tubes in this set have short butts and are super finished to remove any surface defects. A wide range of tube diameters and shapes allow us to build frames to the customer’s exact requirements.
Why it works:
UTS: 830-965 MPa

Progetto Zona: custom, competitive road, and MTB frames

• Nivacrom for Zona: Nivacrom is patented by Columbus. This is a steel alloy in which vanadium and niobium – precipitating in the metal matrix – block the grain growth during the elevated overheating of the welding containing the decline in the mechanical characteristics even at temperatures above 1000°C. The material developed for the Zona series, is subjected to a series of operations and treatments that, after drawing, homogenize the mechanical characteristics of the tube, making them uniform along the Iongitudinal axis. As a result, the fatigue behaviour is excellent.

Reynolds 631

SEAMLESS AIR-HARDENING HEAT-TREATED STEEL

Utilising the same chemistry as 853, this product is cold-worked and also has the advantages of air-hardening after welding. The alloy is a development on our famous 531 range with 10% higher strength. For cycling use, this provides tough, durable and comfortable frames particularly suitable for long distance riding, MTB and BMX . It has recently become available for touring and race fork blades.

In most applications, it should not be necessary to stress-relieve the weld zone.

Why it works:

UTS: 800-900 MPa
Favourite Quote – Reynolds 631 with Shimano 105 and a wider tire option for a person with a $1,000 to $1200 limit and who wants more of a real century bike in steel 

NOTE As 853 in composition but tube strength results from the extensive cold-working of the seamless billet without a final heat-treatment. The TIG welded part of the tube still benefits from the air-hardening feature that results in a fine grain structure within the heat-affected zone.

Reynolds 631 Air Hardened tubing is a tubeset based on their 853 Air Hardened technology. This tubeset has replaced 531 as the basic material used to construct Bob Jackson frames. The primary difference between 853 and 631 is the lack of heat treating applied to the an 853 tubeset, thus producing 631 tubing.  Tig welding is possible, however to bring 631 to its optimal strength level, brazing and the much larger heated area produced can greatly increase the finished joints ultimate strength.

 

 

Columbus Thron

An all-purpose, high performance tubeset. The formation of carbides prevents the grain enlargement, so the steel maintains it’s properties during brazing and welding, and even in the cold malleable raw state it features excellent mechanical characteristics.

Why it works:

UTS: 800 MPa

Reynolds 525 COLD-WORKED CHROME-MOLY STEEL

With similar properties to our original 531 brand alloy. For cycling, these are mandrel butted for accurate profiles, and available in a wide range of shapes. Weight savings from butting provide competitively priced, light framesets. The Reynolds “520” range uses the same alloy, made under license for us in Taiwan and subject to the same quality standards.

Why it works:

UTS: 700-900 MPa

The same 0.30% carbon steel chemistry as the 725 range but without the heat-treatment process. The strength and ductility can be varied by cold-working and normalizing if required. Reynolds 525 non heat treated chrome moly has been in Reynolds inventory of bicycle tubes for many years. Since 1998 it has been reconfigured and up graded to a strength level very similar to that of Reynolds legendary 531 tubing. The primary reason for it existence is its ability to be tig welded, thus producing lower cost and lower quality frames. It has no advantage over 531 except for this singular feature.

 

 

Reynolds 520 – CHROME-MOLY cold-worked steel:

With similar properties to our original 531 brand alloy. For cycling, these are mandrel butted for accurate profiles, and available in a wide range of shapes. Weight savings from butting provide competitively priced, light framesets. The Reynolds “520” range uses the same alloy, made under license for us in Taiwan and subject to the same quality standards.

Why it works:

UTS: 700-900 MPa

The same 0.30% carbon steel chemistry as our 725 range but without the heat-treatment process. The strength and ductility can be varied by cold-working and normalizing if required.

Reynolds 531 – MANGANESE-MOLY cold-worked steel:

In its 110th year, Reynolds re-launched a limited edition set of 531 tubes for brazed bike frame use. A long-running product and used in many Tour De France wins, 531 was first used in the “Aeronautics” industry from 1935

 Favourite Quote – Reynolds 531 double butted,because of it’s long history,used on many of the finest vintage bikes ever made.

531, 531c, 531OS No longer produced by Reynolds, due to its inability to be tig welded.

 

 

 Reynolds broken down - 
Reynolds 953 – maraging stainless steel
Reynolds 853 – heat-treated air-hardening steel
Reynolds 725 – heat-treated Chrome-molybdenum steel
Reynolds 631 – cold-drawn air-hardening steel
Reynolds 525 - cold-drawn chrome-molybdenum steel

some older columbus steel

columbus stickers

IS THIS ANY CLEARER

I thought not? Tell me what your favourite steel is.

my fav poster of steel

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