This is the post I’ve been most looking forward to writing and also fearing with equal measure… Reynolds 753 was a tube set that took the bicycle world by storm. It had unrivaled strength while being ultra light and thin for a steel tube. It is probably the most mis-understood tube set and the one that has the most stories connected to it.
There is lots written about Reynolds 753 and like most things, this is sometimes good but often it’s just bad. Information can be found in various books, internet articles and forums. You need to search and look hard for good information. Once you find it, you have to figure out for yourself if it is reliable and accurate; has the author checked their facts or have they simply recited something that was already incorrect? Indeed, you will have to do the same with all my blog posts. Hopefully though, if you follow me regularly, you will know that I aim to only present facts, information direct from the source.
In this post I’ll be pulling together what I’ve found out in my research about this tube. It’s not a technical analysis of the metallurgy and strength of 753, or a discussion on how 753 performed in comparison to other materials. This post is going to be a simple, but hopefully interesting look, at how 753 came about together with some well researched facts about the tube.
A Brief History
The early 1970s was an era of innovation in bicycle technology, especially bicycle frames. Carbon, Aluminium and Titanium, all materials you would place very much in the present day, were all being experimented with at that time.
An article in “Motor Cycle and Cycle Trader” in July 1971 talked about the Raleigh-Carlton Carbon Fibre track bike, built using the “New light synthetic material”, coming in at a weight of approx 13 lbs. The tubes were held together by 2 part aluminium castings and set screws.
All of these materials had ‘issues’. Although the carbon tube was stiffer than steel, it had to be glued/epoxied together at the joint. But the joint was the problem. There wasn’t a suitably strong glue to maintain the stiffness of the carbon frame. Because of the weak joints, carbon frames were not as stiff as 531DB. Gerald O’Donovan had overcome problems with joining titanium and retaining stiffness but only by using oversize tubes. The larger tubes created a problem with lack of components to fit them. These issues meant that steel was still very much the material of choice.
By the time the New York Cycle Show came around in early 1975, “Ultra-Light” was definitely the topic for most manufacturers. These articles from ‘Bicycling’ in April 1975 describe the Miami and later New York shows.
The 10.5 lbs Panasonic came in at $4000. As you can see from those articles, there was no mention of Reynolds 753 at either of these shows…
So how did Reynolds 753 come about?
The Reynolds company had been interested in a Titanium frame built by another Birmingham company called Speedwell Gear Company. They were so interested that they even purchased a frame for testing. They found that although it was light, it had no stiffness. So the hunt was on for a tube, the remit was for something as light as Titanium but stronger than Reynolds 531.
It all came down to finding a cost effective material that could provide strength and lightness and a material that could be joined together successfully. In an article written by Fred DeLong for Bicycling in March 1976, he recalled visiting Carlton a few years earlier (pre SBDU), and talking to Gerald O’Donovan about Reynolds 753.
According to his article, “Reynolds had a high strength material used in Rocket casings and the problem at the time was finding a reliable method of joining the tubing without destroying its high strength”. Another story is that Reynolds tried several other materials but none were successful. They had another material, a heat treated steel tube used for making ejector seats that was similar to 531; so Reynolds heat treated some samples of 531 that were drawn slightly thinner. The research continued at the new SBDU. A method of joining the heat treated, thin walled tubing was needed; overheating this tube would cause it to lose it’s strength. The outcome of all the research and testing would become Reynolds 753.
Dave Lloyd had one of the first 753 frames and had amazing success straight away. Dave recorded a record in the 50 mile British Road Racing Association (RRA) in October 1974, setting a record of 1h 35m 45s – nearly 4s better than the previous best time.
At this time, late 1974/early 1975, Reynolds 753 was still in development, a secret essentially! Dave’s bike in the Cycling article is described as his “…special extra-light titanium equipped Team Raleigh…”. Following this, Raleigh had further success with Roy Schuiten and other members of the team in Paris-Nice, Lugano and the Grand Prix des Nations, with Roy Schuiten winning the World 5000m pursuit in Belgium in the autumn of 1975. It is said that while the team were riding these bikes, they were actually badged as “Reynolds 531”.
In an interview, Gerald O’Donovan described his freedom in developing Reynolds 753.
“…we took a clean sheet of paper – Reynolds and ourselves found a material, found a way of putting it together between us and then designed the tubes from scratch. And it really was from scratch – what lengths they would be, the thickness of the butts… and they were designed purely from in service testing… bikes with strain gauges all over them… we got the material right between us but there were enormous problems with heat treating thin sections of tube and putting them together…”
Reynolds 753 Introduction
After a period of development, after overcoming problems with joining, after proving the strength of the tube, after breaking time trial records, after a season of secret testing with the TI-Raleigh team and even with World Championship success, Reynolds 753 was finally revealed to the world at the Paris Cycle Show in October 1975.
Reynolds 753 Frame Transfers 1975 – 1976…
In 1975 Reynolds was part of the larger Tube Investments (TI) group but had still not adopted the name of ‘TI’ or the ‘TI’ circular logo. The Reynolds company name was still “Reynolds Tube Company Limited”. Up until this point, all Reynolds 531 frame transfers used that name – Manufactured by Reynolds Tube Co Ltd.
Reynolds 753, and Reynolds 531 Special Lightweight (which was released at the same time), marked a small change in frame transfer design. They were the first Reynolds frame transfer to show the ‘TI’ circular logo. However, the company name remained the same Reynolds Tube Co Ltd
These documents show the new logo for Reynolds 753 and 531SL. The first is Reynolds own publication for the Technical data for 753. The second is their advertising leaflet for the 1976 New York show.
I guess most people have heard the story of how Reynolds 753 got its name and how the purple colour was selected for the transfer, but for those who haven’t heard, here it is… the following is from the Raleigh book written by Tony Hadland – see Recommended reading below…
Terry Bill was the Commercial Manager and recalled a meeting to discuss marketing of the new tube. Top of the agenda was a name! It had to be a higher number than 531 and couldn’t be the same colour. The year was 1975 and the ultimate tensile strength of the new tube was 75 tonnes. It was also the 3rd material tested and was drawn to 0.3mm in the centre of the tube – so 75 & 3 seemed appropriate (it was also higher than 531).
The purple colour was apparently the colour of the tea cosy used to serve their afternoon tea at the meeting. They combined the purple with the existing gold on Reynolds transfers.
A purple and gold transfer with the number 753 – that is the story… direct from Reynolds!
Reynolds Frame Tubes, Blades and Stays 1975 – 1976…
When it was introduced, Reynolds 753 had Metric external dimensions and several internal dimensions, or tube gauge. As the interview with Gerald O’Donovan explained, he had free rein to design whatever tube spec they wanted.
Sadly, there aren’t many technical documents available for early Reynolds 753 from this period. There were however at least 4 different sets, each set having a different wall thickness or gauge.
Seat Pin Size – not such a straightforward subject!
It’s often said that the SBDU used two gauges of early 753 tube depending on the frame size, these were 801 & 803 (although 802 and 804 also existed). I’ve written about 801 and 803 in earlier blog posts. It’s believed that there was a “change-over” frame size, somewhere in the region of 58-59cm; smaller frames would get the lighter gauge (801) and larger frames would get the heavier gauge (803). This difference in tube gauge meant that different size seatpins were used depending on frame size. The smaller 801 gauge frames would be 27.0mm and the larger 803 frames would be 26.8mm.
This pattern of “Seat Pin Size to Frame Size” worked in most cases. However, some SB owners say that they have something different, a 753 801 with a 26.8mm when a 27.0mm pin would be expected or vice-versa, or even a 27.2mm pin. The arguments rage on whenever seat pin size is mentioned…
I have three Metric tubed SBDU 753 frames, one x 56cm and two x 57cm, all three are under the accepted frame “change-over” size so should all be 801 gauge – I have seat pins for all of these frames and they all take a 27.0mm seatpin perfectly – they all fit the expected ‘pattern’.
So why do some owners report differences? There are probably a couple of reasons for this.
Reason One – Tolerances (or even just incorrect measuring/fitting)…
Everything that is built, no matter what it is, is built to a tolerance. A tolerance is a size over or under “+/-” a given measurement. Even components considered to be the highest quality are built to a tolerance. I’ve had Campagnolo seatpins that aren’t quite the size they are meant to be. My 27.2mm 2 bolt Record seatpin comes in with a different measurement depending on where I measure it.
Reynolds butted tubing also has a tolerance. In some technical documentation the tolerance is given as +0.03mm/-0.13mm and other documentation it is given as +0.02mm/-0.13mm.
There is also the internet chatter and gossip… I hear about people or mechanics who just didn’t understand or know that the new 753 tubing required a different size seat pin. By far the most common size at the time for other frames was 27.2mm (butted 531 frames typically take a 27.2mm pin).
Whatever the scenario, either poor fitting or a mixture of slack and tight tolerances, this may answer why some owners have seatpins that don’t appear to fit the pattern. Personally, I’m not too convinced on this theory.
Reason Two – Custom Spec’d Tubing…
This is what I actually think explains discrepancies in expected seatpin sizes. I simply don’t think it was ever that clear cut about the “change-over” size, I just don’t think it was correct that every frame under or over a specific frame size had the same gauge tube. These were custom frames built to suit a rider and their requirements.
After reading a large amount of SBDU documents, the same phrase, sometimes written and worded slightly differently, appears over and over again… “Built in the appropriate gauge of 753 for rider and programme of races”, “lighter gauge can be used where suitable”, “the tubing used is 753 to the appropriate gauge for the size and weight of the rider and the severity of courses to be ridden”
This means that it is feasible for a small but heavy rider, riding a mixed set of races, to require a heavier gauge of tube. Some people have different riding styles, some are smooth, some are very hard on their frames… I think the whole picture of rider size, rider style and race requirements were taken into account when specifying tube gauge.
I’ve seen SBDU documentation that uses terms such as 753 light/med/heavy – the different gauges of 753? From what I’ve read, small frames were definately spec’d and built with heavier gauge tubing and large frames were definately spec’d and built with lighter and thinner gauge tubing.
Most frames did fit the seat pin size pattern for 753 but it can’t be relied upon. It’s clear from what I’ve read that 753 tube gauge, as well as frame geometry, was certainly part of the spec depending on rider and race programme. Therefore, seat pin size will vary!
** UPDATE 1 ** I recently wrote another blog post on the subject of Metric 753 seat pin size which confirms Reason Two. That post can be seen here, “SBDU Ilkeston Metric Reynolds 753 Seat Pin Size – The Truth“.
** UPDATE 2 ** There was also a rare, early Imperial version of Reynolds 753 tubing which took a 27.2 mm seat pin, that post can be seen here, “The Mysterious Carlton Capella Lugged Early Ilkeston SBDU Imperial Tube Reynolds 753 Frames“.
Reynolds 753 Frame Tubing Dimensions
The first Reynolds 753 had Metric dimensions. Here is a comparison of Metric and Imperial tubing diameter.
Frame Tubes
Most of the available literature about early 753 only lists one spec of tubing – this is 801 gauge.
TT - 26 diameter | 0.7/0.3 thickness | 22/28 gauge | double butted DT - 28 diameter | 0.8/0.5 thickness | 21/24 gauge | double butted ST - 28 diameter | 0.7/0.3 thickness | 22/28 gauge | single butted HT - 32 diameter | 0.9 thickness | 20 gauge | plain gauge
Reynolds 753 Gauge 804 was listed with the same TT, ST and HT but with a slightly lighter gauge down tube.
DT - 28 diameter | 0.7/0.46 thickness | 22/26 gauge | double butted
Seat Stays
753 seat stays had a similar profile to period Reynolds 531, a taper from the top (seat lug end) down to the bottom (drop out) – a ‘single taper’.
Top diameter 16 Tip diameter 10 0.46 thickness | 26 gauge | plain gauge
Chain Stays
Chain stays followed a Round – Oval – Round (ROR) pattern. The dimensions in the period literature are given as…
BB diameter 22 Tip diameter 11 0.6 thickness | 23 gauge | plain gauge
Fork Blades
Reynolds 753 was introduced with the New Continental Oval (Wide Oval) shape. A taper gauge tube with an oval to round pattern
Blade diameter at crown 27.5 x 20 NC Oval Blade diameter at tip 12 Round Blade thickness 1.0/0.5 | 19/24 gauge | single butted taper gauge
Metric 753 and 531 Double Butted Tubing Comparison
I thought it would be interesting to show just how different early Metric 753 tubing was in comparison to the existing Imperial Reynolds 531 DB tubing.
Note* this comparison is with 531 Double Butted and not the later 531c.
753 wasn’t just a redesign of the main frame tubes… chain stays, seat stays and fork blades were all very different.
Early SBDU 753 Frame Features
Apart from a small amount of frames, all early 1975/1976 SBDU 753 road frames used Campagnolo 1010/B ‘short’ drilled rear ends. Seat stays were finished with a plain, flat end cap that fitted flush with the edges to the stay.
Forks used a Vagner semi sloping crown; a few special builds used Haden. At this point in SBDU production, they were applying chrome plating to Reynolds 531 fork blades. However, Reynolds and the SBDU did not recommend any chrome plating for 753 tubing. Read more about Hydrogen Embrittlement here. 753 fork blades followed the Columbus pattern and Reynolds introduced the New Continental or Wide Oval fork blade.
Lugs were also different to the existing SBDU 531 frames. The first listed SB numbered 753 frame, SB498, used Bocama Super-Professional R3. 753 frames in this period then went on to be built with Prugnat S4 ‘cut out window’ lugs.
How strong was Reynolds 753?
Every piece of period 753 literature I’ve read has said the same thing… Reynolds 753 is 50% stronger than other materials, even 531. Reynolds also claimed better torsional rigidity than either Titanium, Carbon Fibre and Aluminium. The following figures are from Reynolds own Technical Data Sheet produced in 1976.
That is 75 tons Ultimate Tensile Strength (pre brazing). This figure changed to 65 tons post brazing. The simple definition of tensile strength is the resistance of a material to breaking under tension.
In Richard Jow’s Bicycling article in December 1977, he described witnessing a test at the SBDU. A 753 frame was loaded laterally across the frame starting at 200 lbs and increasing by 200 lbs each time. It took up to 800 lbs until the frame was not able to return to original alignment. He went on to say that these loads would have collapsed a 531 frame of a similar size.
A ‘Cycling’ article in November 1982 described an SBDU quality test on completed 753 frames. A force of 50 lbs per square inch was applied at a one foot centre to the BB deflecting it about 0.6″, the frame had to return to the exact centre after deflection.
Who could build with Reynolds 753?
Only frame builders approved by Reynolds could build with 753. Why was that..?
“The walls of 753 were so thin that the design of the frame, choice of lug, joining techniques and other aspects were critical.”
The significant difference between building with Reynolds 531 and 753 is the heat required and the filler material used to join the tubes and lugs. Reynolds 531 was joined by brass brazing. Brass has a melting point of approx 850°c which is great for a non-heat treated material such as 531. Brass is also more forgiving in that it allows for wider tolerances in the gaps between lug and tube or tube mitres by filling those gaps.
Reynolds 753 was a heat treated tube which meant that if it was heated to the temperature required to melt the brass filler, the tube would become annealed and lose any strength from the heat treating process. Silver filler was the answer to this problem as it has a lower melting point, approx 600°c. Silver however, introduces its own issues. Silver requires perfectly mitred tubes and a very close fit between lug and tube. Heat had to be evenly concentrated on the lug using a soft flame and the joint brazed quickly. Brazing is a process where a filler (in this case Silver) flows by being drawn between two metals by capillary action using a suitable flux. The builders skill had to be high to be able to prepare the close fitting tubes and then use a low heat while still getting excellent penetration of the filler to make a strong joint without over heating the tube.
Reynolds were so concerned about the skills and techniques required for building with 753 that they introduced their approval process. Reynolds would only supply 753 to builders who had been approved. The approval process at this time involved builders submitting a complete frame to Reynolds for testing. Only if the frame passed the test would the builder be approved and be supplied with the tubes.
If you have got this far through the post then thank you, you’ve reached the end! That is it, the ‘basics’ of early Reynolds 753 covered… were it came from, when it was introduced, what it was, how strong it was and who could build with it; and I think that is really only scratching the surface of this material.
So far, my Timeline posts have covered early 531DB and early Metric 753. Next up is a combined post for both tube sets taking the SBDU up to 1982.
Information Sources
www.velo-pages.com Veteran Cycle Club Library Other documents and articles credited where used.
Recommended Reading
Raleigh Past and Presence of an Iconic Bicycle Brand by Tony Hadland The Custom Bicycle by Kolin and De la Rosa
Other posts in my Timeline series
SBDU Frame Number and Frame Detail Timeline 1974 - 1975 Reynolds 531 Tubing Creating an SBDU Date Timeline for TI-Raleigh Ilkeston
Just a quick note, Neil…when I did my 753 test, in the early 90s, it wasn’t a whole frame supplied. A BB shell with 2x chainstays and a length of 28.6 downtube to be cut in half and fitted to the DT & ST sockets.
I have a picture, if you want.