Blog Reynolds 753 Ovoid SB4409 SBDU Ilkeston SBDU Specials Time Trial

SBDU Ilkeston SB4409 1981 753 Dynaflite – New Arrival

It’s not often I write a quick blog post, but this is just too exciting to wait for a full and detailed review – so here is a short teaser of what just landed in the workshop! This is a really amazing and rare SBDU frame – there will be more to write on this one in a little while, but for now, I’d like you to meet SB4409, a 1981 753 Dynaflite.

SBDU Ilkeston 753 Dynaflite 1981 SB4409 753 Aero Tubing
SBDU Ilkeston 753 Dynaflite 1981 SB4409 753 Aero Tubing

Never heard of the Dynaflite? I’m not surprised, there weren’t that many built. The word ‘Rare‘ is often commonplace when talking about classic bikes and bike parts; some bikes are described as rare because only a few hundred or few thousand exist of the many tens of thousands that were made, but with the 753 Dynaflite, the word ‘Rare‘ takes on another meaning altogether, it takes the meaning of ‘Rare‘ to a completely different and altogether higher level! It’s thought that no more than 25 of these SBDU Specials were ever built. So from those reputed 25 frames, how many still exist? I’ve seen a picture of one other Dynaflite and heard a story about a second and then there is this one, the third, that is all, three known frames. Now that is what ‘Rare‘ means!

Why was the Dynaflite rare? There are a few reasons. First, they were a special build, they weren’t a standard model of road or time trial frame. Second, they were fillet brazed, so there is no seat lug or head lugs or standard bottom bracket shell. Third, not only were they fillet brazed, they were 753 tubes which many think could not be fillet brazed. And finally, the tubing was Reynolds 753 Aero, where each tube is shaped specifically for it’s purpose in the frame. These frames took incredible technique and skill to build.

SBDU Ilkeston 753 Dynaflite 1981 SB4409 753 Aero Detail
SBDU Ilkeston 753 Dynaflite 1981 SB4409 753 Aero Detail

I said it would be a short post and that is where I’m leaving it for now. I really want to write lots but I’ll save it till later. I just wanted to get this frame out there and published onto the blog. In the next post I’ll expand on some of these features with lots more images and look at the frame geometry, build process and the amazing details of this special frame.


  1. I have a 753 Aero Team track bike. Photos are at Since it doesn’t need to accommodate a rear brake, it looks like the builder used a section of seat stay to make an aero bridge. The only 753 designation is in the top tube decal (I have a Raleigh USA road bike that also lacks the 753 decal, except in this location). From the photos, the tubes look similar, but perhaps even thinner on mine. The track lacks an aero top tube, but when you think about it, there’s no aerodynamic reason why that tube should be ovalized. All three of these frames (yours, Hilary’s and mine) share some similar details, such as the seat cluster, but the track frame lacks the gussets and isn’t in the same class in terms of workmanship. The road frame I have, with very similar decals, dates to 1987, and so was built after Ilkeston was disbanded and production moved to Worksop. There’s quite a gap between 1981 and 1987! The track frame lacks any serial number or stampings.

    My theory, totally unencumbered by facts, is that an unused set of Dynaflite tubing was obtained by Raleigh USA in the turmoil that Raleigh England was going through at the time. This tubeset was handed off to some US builder who was tasked with building up a frame for some special event. The frame is small, so it may have been for a female rider, possibly for some record attempt. Whether the job was rushed, the builder inexperienced in fillet brazing, wasn’t sure he was going to get paid, or perhaps just knew the frame was for a one-and-done event, no extra work to make the brazing pretty was invested. One would not expect even Raleigh USA to hand 753 to an inexperienced builder to fillet braze, so that explanation is a bit of a stretch, and the frame is dead-straight. Likely, its origin will always remain a mystery, as will the anachronistic first generation Dura Ace track group that it wore when I got it. Was the entire bike hanging around and then repainted in ’87 in Raleigh USA colors?

    1. Hi Steve, I’ve seen your frame in the Yahoo group before and it always intrigued me. That frame and mine seem to be similar but different. The rear stays look to have had the same ‘flattened’ treatment, but the front triangle is where you see the differences. The seat tube and the need to cut the seat pin to suit the rider, the round top tube and the way that the back of the head tube has been created. The fork crown too doesn’t look like an SBDU item so maybe fits in with your theory that it was built elsewhere.

      I think the Dynaflite and the need to build in oval tubing was relatively short lived for time trial and pursuit. If the dynaflite started in 1981, I believe that by 1983, the SBDU were committing to the 24″ front wheel ‘lo-pro’ for road and track. They still weren’t easy frames to build as each lug needed to be cut and re-welded to a different angle to achieve the geometry.

      The Raleigh frames I like the best are those that have that little bit of mystery to them!


  2. Congratulations Neil!

    This couldn’t have gone to a better home – you were really quick to snap it up from Hilary.

    You disappointed quite a few I’m sure but saved money for many of us too!


    1. Thank you Malik – I did actually sit and ponder for a good few days and thought someone else would snap it up in the meantime. It is a rather special frame and I’m very happy to have it.

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