When I add a traditional horizontal top tube SBDU bike to my collection it can sometimes take a few careful measurements and a little bit of knowledge of the bike’s history to figure out something as subtle as whether it was built for road racing or time trials. The obvious style of SB8790 leaves me with no doubt about it’s intended purpose – I’m still going to measure and document it because that’s my process, but the 24″ front wheel and the top tube that slopes dramatically to meet the fork tells me all I need to know!

SB8790 1987 SBDU Nottingham 531c Lo Pro Road Frame 55cm
SB8790 1987 SBDU Nottingham 531c Lo Pro Road Frame 55cm

This style of frame was not standard. Even though they were still just a lugged steel frame, those lugs needed to be modified to meet the extreme angles required to get that wonderful geometry.

I can hear you all saying… “but what about fillet brazing, that method would have meant that special lugs weren’t required?”

That’s very true and fillet brazing would allow for a lugless design so that the weird and wonderful mitred angles could be achieved, and indeed, many builders used that method to build this style of frame. I can see that it would have been a possible option on a Reynolds 531 frame but may have been ruled out for Reynolds 753. Although frames like the 753 Ovoid tubed Dynaflite demonstrated that with great skill, a 753 frame could be joined without a lug and just using Silver alone, the limited quantity of these rare fillet brazed 753 Dynaflite frames probably tells a story of how that method possibly wasn’t a commercially acceptable way to produce 753 lo pro fillet brazed frames in any viable quantity.

Gerald O’Donovan claimed  to be the first with the 24″ front wheel design, and early ‘Specials’ of a type of 24″ wheel frame design could be seen in use towards the end of the TI-Raleigh era.

… I’ve made a lot of specialised frames in my time, I was the first person to make 24in front wheel, low profile bikes… 

Face to Face With Gerald O’Donovan Cycling Plus Interview

If there were early 24″ wheel ‘specials’ towards the end of the TI team era, when did the first SB numbered 24″ wheel frame appear? There was no mention of this type of frame in the 1983 update info published in June 1983, the first mention was in the 1984 frameset brochure – here is a snippet from it, simply listed under a heading of “Specials”.

SBDU Ilkeston 1984 Specials Including 24in Front Wheel Low Profile
SBDU Ilkeston 1984 Specials Including 24in Front Wheel Low Profile

Therefore, if my thinking is correct, a 24″ wheel frame could possibly have existed in the second half of 1983, sometime between the June 1983 update and the start of 1984.

1984 started at approx SB6300’ish but the first (unconfirmed) SB numbered 24″ wheel model I have been sent info on is SB5724, which is an early 1983 frame number? I say unconfirmed because I haven’t been sent an image of the SB number for that frame, I’ve only seen one side view image of the frame, and as I’ve done successfully in the past, I’ve questioned the SB number as it doesn’t fit in with it’s frame features. The image I’ve been sent looks very much like a 1984 frame based on a couple of frame features.

The first (confirmed) SB numbered 24″ wheel model that I have seen evidence of is from the start of the SB6000s – its SB number is bang on for the second part of 1983.

By 1986, the ‘Lo-Pro’ had moved on and they now had their own model types and descriptions – the 1986 brochure was the last one for the SBDU based at Ilkeston. * Note the mention below of “own hand made lugs and bottom brackets” – as I mentioned earlier, these were needed to get the required tube angles.

SBDU Ilkeston 1986 Lo-Pro Road and Track
SBDU Ilkeston 1986 Lo-Pro Road and Track Definition

My frame is from 1987 so to get the correct model classification I really need the 1987 SBDU frame information. By this time, the SBDU had relocated to Nottingham and the SBDU frame info could be found listed in the “Raleigh Specialist Lightweight Dealer” brochure.

SB8790 1987 SBDU Nottingham 531c Lo Pro Road Frameset and Box
SB8790 1987 SBDU Nottingham 531c Lo Pro Road Frameset
SBDU Nottingham 1987 Gerald O Donovan
SBDU Nottingham 1987 Gerald O’Donovan

This brochure has another mention of the first design of 24″ wheel lo-pro bikes…

Nothing has altered with the move to Nottingham. If we miss the fun, excitement and perhaps pain of our long connection with Peter Post, the doyen of team managers, his equally great and gifted riders, and the comradeship, help and advice of his chief mechanic, Jan Le Grand, we have other consolations.

We have George Shaw and our team in the UK, as well as a host of friends and customers at all levels of cycling to keep us on our toes and to keep up the pace of development. It may be history that we were the first with 753, the first with 24″ wheel lo-pros, that we tried the then illegal disc wheel in 1975, but we see our history as lying in what we can go on to achieve in the future.

Gerald O’Donovan (SBDU Nottingham) Raleigh Specialist Lightweight Dealer Brochure

A description of each model number and frame then follows on, defining all the 1987 SBDU frameset types. This is a snippet describing the low profile range.

SBDU Nottingham 1987 Low Profile Model Classification
SBDU Nottingham 1987 Low Profile Model Classification

Based on that definition, my 1987 SB8790 frame has the model number 8726.

SB8790 SBDU 531c Low-Profile Road 8726 Individual or Team Time Trial Details
SB8790 SBDU 531c Low-Profile Road 8726 Individual or Team Time Trial Details
SB8790 SBDU 531c Low-Profile Road 8726 Individual or Team Time Trial
SB8790 SBDU 531c Low-Profile Road SBDU Model 8726 Individual or Team Time Trial

It’s always good to tie up any loose ends and it’s good to put an SBDU definition to my frame, SB8790 is defined as: Low Profile – SBDU Model 8726 (Reynolds 531c); “Individual and Team Time Trials on the Road”


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