The hours I spend browsing the online classifieds does pay off occasionally. Sometimes you see something that isn’t quite what it seems to be.

I’ve bought mis-represented Raleigh SBDU frames before. Sometimes they can be just advertised as “Raleigh”, with Raleigh decals, and sometimes they are hidden under the guise and decals of another builder or manufacturer. The new arrival today is the 11th SBDU frame I’ve owned and it is the 5th frame that I’ve found that wasn’t sold or known to be from the SBDU. It is now the 10th member of my current SBDU collection.

SB5377 SBDU Ilkeston 753 TI-Raleigh 1982
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982

Under the Barron Cycles head badge, is actually a Raleigh SBDU frame built in 1982. Barron decals on fork blades and frame tubes can’t hide the very clear features of an early 80s Ilkeston built frame. It doesn’t take the Reynolds 753 “Renovated” decal to tell me that this has had a change of appearance at some point in its 34 year life. The style of Reynolds 753 decal that it has fitted, started in 1989, so it had its face lift at some point in the  last 27 years.

I asked the seller for the frame number and as soon as they told me “SB5377”, it just confirmed that the features of the frame that gained my attention, were definitely from the SBDU. A few days later, and the frame was on my work bench! There is a growing market for these frames with more and more people seeking them out, so if one comes along, you need to snap it up.

SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Frame Numbers
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Frame Numbers

I wanted this to be a quick post just to show a few images of my new frame before I get into my usual ‘investigation’ mode. I was going to write a second, more comprehensive post once I had done my research, but I can’t help feeling my ability to ramble on about anything and everything to do with the SBDU starting to take over, and this is probably going to turn into an epic…

SB5377 puts this frame at a production date of 1982, and at that point in the SBDU production timeline, some things were starting to change. Up to this point, SBDU built with the Metric version of Reynolds 753. Metric 753 had different tube sizes and was typically lighter than the 753 which replaced it. Metric tubes were later replaced with Imperial tubes.

Metric 753 frames of this period generally used ‘RGF’ bottom bracket shells – as you can see from the image above showing the frame number, this is clearly a ‘Cinelli’ bottom bracket shell. So my first question about this frame, is… “is this Metric or Imperial tubing”. I covered a lot about this topic when I bought my first frame back in 2011, SB4059. If you want to have a quick recap of 753 tubes then click here to have a read. After a bit of a measure with the digital calipers, the results tell me that this is a Metric tubed 753 frame. The 3 main measurements that tell me this are…

  • Top tube outside diameter measures 26.3 mm (an unpainted Metric top tube should be 26.0 mm – Imperial is 25.4 mm (1″). So 26.3 is good for a 26.0 mm tube + paint)
  • Seat tube outside diameter measures 28.13 mm (an unpainted Metric seat tube should be 28.0 mm – Imperial is 28.6 mm (1 1/8″). So 28.13 is good for a 28.0 mm tube + paint)
  • The seat pin required for this frame is 27.0 mm (a Metric 753 frame in 57 cm should take a 27.0 mm seat pin – Imperial in this frame same size is larger)

Measurements don’t lie. I also popped the frame and forks onto the scales. Metric 753 in this size is approx 1650-1700 grams with forks at approx 650 grams. Imperial will be close to 1750-1780 and 650-680 respectively. Braze ons, lugs and fork crowns have an impact on overall weight, so no 2 frames will be the same.

SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Fork Weight
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Fork Weight
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Frame Weight
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Frame Weight

Both those weights, but specifically the measurements of the tubes, confirm this as a Metric Reynolds 753 frame.

The Cinelli BB shell used on this frame is a very early appearance of Cinelli BBs in SBDU production. The collective knowledge of the TI-Raleigh Yahoo group, and specifically the work done by Hilary Stone, who has created the foundation of a timeline of known frame numbers and frame features, puts the earliest known Cinelli BB shell at least 50 frames later than mine.

Not everything is straightforward though. Indeed, not everything with the SBDU is straightforward, or even known. Facts about the SBDU are few and far between. Not everything they did slotted nicely into a known design or formula. You also cannot control what someone does with a frame once it leaves the factory. Chrome was something that the SBDU just did not do on 753 frames. They used chrome, and they used it beautifully on Reynolds 531 and Reynolds 531 Professional tubing, but never on 753.

My forks ends on this frame have been chromed – almost certainly at the point of renovation. The drop outs wouldn’t have left the SBDU like this. The SBDU and Reynolds worked together during the development of 753. Building with Reynolds 753 took certified builders who had submitted either test frames or test sub assemblies to Reynolds for inspection – this was due to the brazing temperatures and tube/lug tolerances needed to join the very thin and heat treated 753 steel with silver solder.

SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Rear Dropouts
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Rear Dropouts

All the usual features of an SBDU 753 frame from 1982 are there, including the drilled drop outs with Campagnolo Portacatena fittings. The feature that shouldn’t be there is the chrome plating. So why is chrome on 753 not recommended by the SBDU? After all, lots of builders, even some massive frame manufacturers like Peugeot, used chrome a lot on 753 frames such as the Perthus Pro. Lots of renovators also add chrome, as in this case.

The plating process to create the chrome introduces Hydrogen into the steel. The process is called Hydrogen Embrittlement. Lots of articles exist on the internet about this process so I’m not going to go into detail. I’m also not a chemist so I’ll not try and get too far into what happens. This following description comes from the American National Metal Finishing Resource Center…

“Hydrogen embrittlement – (definition) … is a metallurgical phenomenon that occurs in many different metals, however, high strength steel by far seems to have the highest sensitivity to embrittlement. In high strength alloys, the presence of hydrogen tends to block ductility. (definition)…Ductility can be more commonly understood as the ability of metals to deform under stress. We know there is a predictable relationship between stress/load and ductility/ elongation. Hydrogen is absorbed into the steel structure during some electroplating processes, especially hexavalent chrome plating. (fact: hydrogen gas is liberated at the cathode during electroplating)

Hydrogen inhibits the metals ability to deform, and the result is, the metal can break or fracture at a much lower load or stress than anticipated. The affects of hydrogen embrittlement on metals is a serious problem, especially in aircraft & aerospace component manufacturing.”

So have I bought a dud…? Not really…, I don’t think so… I knew it was chromed when I bought it. Lots of 753 gets chromed and lots of these 753 frames are still around – there is actually a large following for the Peugeot Perthus and Perthus Pro; I’ve had one myself, I rode it and then used it as a donor bike for parts for an SBDU build, SB7219. The Hydrogen Embrittlement raises the chance of failure but doesn’t necessarily mean that failure will happen. In a perfect world, I wouldn’t want the chrome, but it is there and there isn’t much I can do about it. When I eventually come to renovate this frame, I’ll remove the chrome and paint over – that won’t unfortunately undo the damage caused by the plating process.

SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Oversized Seat Stay Caps
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Oversized Seat Stay Caps

I still think the over sized seat stay caps are one of the best features on any make of frame. They are also a signature feature of the SBDU and when you see these on a frame, the first thing you should think of, is … “is this an SBDU”. Those caps together with several other features around the frame and forks will always help identification.

One feature that has me puzzled and which doesn’t fit into the typical look of one of these frames are the head lugs.

SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Head Lug
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Head Lug

Lugs often have cut-outs. This lug has a cut-out shape cut into the top lug point. Infact, some builders spend more time crafting and cutting shapes and designs into lugs than actually assembling and building the frame. Lug design is one part of a frame build where a builder can stamp their design and creativity on the finished product. The thing I haven’t seen on an SBDU lug is the hole drilled through the lug towards the top face of the lug. There is a matching hole on the other side and matching holes in the bottom head lug.

It’s not unheard of for the SBDU to produce something different, and as I’ve said, SBDU were probably going through a phase of change with Metric and Imperial tubes. The SBDU also used a range of different lug types, BB types and seat stay caps at different points of its existence. But after seeing literally hundreds of these frames, I’ve not seen this design before.

So there it is, a rather longer than intended introduction to my new frame. I’ll still write a 2nd post once I’ve done more research, especially on the lug design. But that is all for now.

SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Features and Detail
SB5377 SBDU Ilkeston 753 TI-Raleigh 1982 Features and Detail
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About the Author Neil McGowran

Blogger of all things to do with the Specialist Bicycle Development Unit (SBDU) and TI-Raleigh Ilkeston.

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