Reynolds started making nails and then went on to making tubes for aircraft frames before making cycle frame tubing‘. Prior to the famous ‘531‘ tubing the names indicated their origins as the ‘Special Aircraft High Manganese Tubing’ mension in Holdsworth first catalogue in 1934.
There are several histories on the company written already so here are the main ones and below that a summary of the various steel cycle tubing with ‘531‘ in bold.
Steel
SMS – Plain gauge (0.8mm) drawn tubeset in high tensile steel.[8] Replaced 531 plain gauge in 1980,
replaced by 453.
453 – cromoly steel alloy. Reynolds produced only the 3 main tubes in this alloy and they were single
butted, replaced by 500 series.
500 – A chromium-molybdenum (CrMo) steel, seamed, plain gauge tubeset of 3 main triangle tubes
500ATB – Mountain, All terrain, Off-road
500 Magnum – Same use as ATB
501 – Reynolds 501 was a chromium-molybdenum (CrMo) steel, seamed, butted 3-tubes tubeset that
made its debut about 1983 and was available in two different thicknesses.
501ATB – Mountain, All terrain, Off-road
501 Magnum – Same use as ATB
501SB – Single Butted
501SL – Special lightweight (SL) tubeset
K2 – Reynolds K2 was a chromium-molybdenum (CrMo) steel similar to 501, seamed, butted tubeset, with
eight laterally aligned ribs on the butt section, designed and produced exclusively for Raleigh between
about 1993 and 1995[9]
Optima – A chromium-molybdenum (CrMo) steel, seamed, butted tubeset designed and produced
exclusively for Raleigh from 1995. Similar to 501 but tweaked for tig welding.[9]
525 – Cold worked AISI-4130 (CrMo). Yield Strength / Ultimate Tensile Strength (YS/UTS): 700/900 MPa,
density 7.78 g/cm3 8 tube set
525-Triathlon – almost identical to 525, with the only differences being seat stays are 0.1mm thinner,
and chainstays are 0.1mm thicker, than standard 525
520 – is the same as 525, made under license in Taiwan, to the same specs and qc standards as for 525 – For proximity to manufacturing in South-East Asia.
531 – Manganese/Molybdenum. YS/UTS: 695/803 MPa (45-52 Tsi, 100-130 ksi) (number quoted are for
after (lower) and before (higher) brazing), density 7.85 g/cm3 Starting in about 1980 tubesets of different
gauges were named as follows.
531ATB – Designed for Mountain, All terrain, Off-road
531Competition/531C – Competition Racing tubeset. Road racing, track, time trial and cyclo-cross.
main tubes were 8/5/8 double butted
531CS – Club Sport. Double butted 531 main tubes, 501 forks and stays.
531Magnum – Oversize, heavy gauge tubeset for use in ATB’s.
531OS – Oversize tubeset
531Professional – Superseded 531SL, thinner and 150g lighter than 531Competition.
531SL – Special lightweight (SL) tubeset, comprising 531 main tubes drawn thinner than standard 531.
Later named 531Pro.
531 Speed Stream – 531SL Oval shaped aerodynamic tube. 50g heavier than 531C but 100g lighter
than 531ST.
531ST – Special Touring tubeset[10]
531 Super Tourist – Superseded ST.
531DS Designer select tubing. Alternative 531 tubes with differing gauges and profiles were available
to the specialist builder.
631 – Seamless air-hardened. UTS: 800-900 MPa, density 7.78 g/cm3
631OS – Oversize tubeset
653 – Was a mixed tubeset with a non-heat treated 753 main triangle. Stays used 753r and fork blades
were borrowed from the 531c tube set.
708 – 708 was a tube set in Reynolds’ range in the 1990s. It has main tubes with special section. These
were not butted, but had 8 flats running along the length of the tube. The rear stays would be 753.
725 – Heat-Treated 525; AISI4130 (CrMo), with strength placing it just above 921 and below 931; UTS:
1080-1280 MPa, density 7.78 g/cm3
725os – Oversize version of the 725 tubeset
731OS – Oversize tubeset introduced in 1992 double butted oversized tubes with laterally aligned
stiffening ribs on the but sections to maximize stiffness and torsional rigidity. Tubeset: Strength steering
tube and fork 802N/mm2, top, down and seat tube 925N/mm2 and rear triangle 1315N/mm2.[11]
753 – Heat-Treated Manganese-Molybdenum. Essentially 531 made with reduced wall thickness and heat
treated to increase tensile strength. UTS: 1080-1280 MPa (70-83 Tsi, 157-186 ksi) Complete tube set of
11 tubes (Frame 8, Fork 3). 753 can only be lugged and fillet-brazed with an alloy of 56% silver below 700
degrees Celsius and sale is restricted only to approved builders certified by Reynolds
753ATB – Mountain, All terrain, Off-road
753R – Road tubeset
753T – Thinner tube gauges for time trial framesets
753OS – Oversize tubeset
853 – Seamless air-hardening heat-treated. UTS: 1250-1400 MPa, density 7.78 g/cm3
853OS – Oversize tubeset
921 – Cold-work stainless steel
931 – Precipitation hardening stainless steel. Tubing introduced in 2012. Can be used with 953 to reduce
overall frame costs.
953 – Maraging stainless steel. Introduced in 2005. UTS: 1750-2050 MPa, density 7.8 g/cm3 No longer
being sold.