The Specialist Bicycle Development Unit (SBDU) Details of Fork Ends and Dropouts

Having a large collection of SBDU frames means that I’ve accumulated most of the various features that they built with. Fork ends are one such area of the frame design where I have an almost complete set, ranging from the earliest 531 frames produced at Ilkeston using Campagnolo 1010/A, through to frames produced at Raleigh’s Special Products Division using their own ‘RALEIGH’ stamped ends. 

But before I move on, I have to start with a definition. Is it a fork end or is it a dropout?

The area of the frame at the junction of the seat and chain stays which forms a slot for the wheel to sit is called a fork end. Some fork ends are horizontal and can release the wheel at the rear like a track bike, or forward like a typical road bike. Some fork ends can also be vertical or semi-horizontal. It’s only fork ends that release the wheel forward or vertically that are called dropouts, because the wheel can be dropped out of the frame without the need to derail the chain; a dropout is a ‘type’ of fork end. The end of a track frame shouldn’t be called a dropout because the wheel cannot simply be dropped from the frame without having to derail the chain. A track frame has an ‘end’, not a dropout.

Fork ends are often used to identify different types of SBDU frame, and sometimes used to attempt to identify different the type of Reynolds tubing. Using the fork end for frame identification can certainly help on some earlier SBDU frames built during the first few years at Ilkeston, but as things moved on it wasn’t always that clear.

Some fork ends have even become iconic… the mere sight of some of these can tell you pretty much everything you need to know about the type of frame! Unlike paint, frame transfers and braze on fittings which can all easily be replaced and updated, fork ends rarely get changed so they are great features for providing accurate date evidence.

The dropout below is probably one of the most iconic. It is a drilled Campagnolo 1010/B short fork end with the Portacatena fittings – the type of dropout, the paint colour, drillings and shape of the stay ends are so representative of an SBDU Ilkeston TI-Raleigh Team Pro Reynolds 753 Road frame built a few years either side of 1980.

The range of fork ends produced by Campagnolo were the preferred choice of the SBDU for most of the 1970s. However, this blog post isn’t a history of Campagnolo ends, I wish I knew enough to write a post like that, but I don’t, so I’m just looking at how the SBDU used some of them.

I’ve always found with Campagnolo that their parts identification can be a bit of a minefield. Depending on which Campagnolo catalogue you read, the long fork end can be listed as either a “Record” end or a “Gran Sport” end. There is sometimes a slight change in profile where the hanger meets the lower part of the slot. So for the sake of simplicity in this blog post, I’ll class any long Campagnolo end without eyelets as a 1010/A .

Early SBDU Reynolds 531 Road and Track

Starting at the beginning of the unit in 1974, the established choice for many builders, including the SBDU, was the Campagnolo 1010/A. This was rather a long fork end without eyelets.

Below is another 1010/A dropout from 1977 – you can see a slightly different profile compared to the two above where the hanger meets the lower part of the dropout.

The 1010/A was the default dropout on SBDU Reynolds 531 Road frames for the first few years from 1974 to 1978.

While Reynolds 531 SBDU Road frames were using the 1010/A dropout, the 531 SBDU Track frames used the 1053 fork end. There isn’t much I can say about the 1053 end, it’s been in production and used in frame building for so many years, it is simple, plain and strong.

Early SBDU Reynolds 753 Road and Track

Towards the end of 1975 Reynolds 753 was pushed into the public domain following development and testing between Raleigh and Reynolds. The new 753 tube required a different approach to frame building, and the choice of the frame components used to build with was important . Most of the frame parts used in the build of SBDU 531 frames were replaced for 753 frames. Lugs, bottom brackets, fork crown and seat stay ends all changed to accommodate the different diameter tubing, tighter tube fit tolerances and the need to use less heat. The dropout on Road frames also changed to a shorter Campagnolo end.

The timeline for the introduction, progression and design of the Campagnolo 1010/B, or “Nuovo Record Short Fork End” is a bit of a mystery. Catalogue 17 dated 1974 only shows the 1010/A. This is the same for catalogue 17a dated 1975. I haven’t seen the 1010/B listed until the 17a supplement catalogue which was circa 1978. The 1010/B in that 17a supplement was shown with a Portacatena fitting. But it’s clear from the SBDU frames I’ve seen that there were at least two iterations of the short 1010/B end before the Portacatena type shown in the catalogue 17a supplement.

There is a tantalising entry on the Velo-Retro Campagnolo Timeline of a 1974 ‘Special Catalogue’. This was listed as everything in catalogue 17 with the addition of a short Nuovo Record dropout. It also listed the never released black anodised parts of the Super Record group. I’ve never seen this catalogue in full, just an image of the front cover, so at least I do know it existed and it was published.

I just can’t explain why this special catalogue listed a short Nuovo Record short end but it didn’t appear in the later catalogue 17a from 1975. The mysteries of Campagnolo!

Back to the SBDU!

The first SBDU Reynolds 753 frames built in 1975 and released to the public with an SB frame number used a short Nuovo Record dropout. Maybe it was the type listed in the special catalogue above?

The dropout in the image above is from SB664 and according to dating evidence of other SB frames in the timeline, this frame is probably from Easter 1976. The dropout has been drilled by the SBDU and this early style of drilling had 8 holes, and each hole was drilled all the way through the dropout. Other characteristics of this style was the large diameter adjuster hole at the rear of the dropout that the adjuster screw head fitted into. There was very little metal around the lower edge leading from the adjuster to the gear hanger. The three sides of the window cut out are very similar lengths. This very early design of 1010/B seemed to disappear from SBDU production sometime between SB900 and SB1000 (late 1976/Early 1977).

It was replaced with what appeared to be a forerunner of the Portacatena end. The replacement had a longer triangular window (a much longer bottom edge to the cut out) and a longer horizontal slot. It also had much more metal on the bottom curved edge. The adjuster screw hole was now a simple M3 threaded hole with the adjuster head fitted from the inside of the dropout. It also seemed to have areas forged into the end that would later become the Portacatena fittings, but in this particular type they were blanked off.

The first type of 1010/B had 8 drillings but the replacement reduced that number down to 7, and if you look at it closely the rear 2 holes near the adjuster are blanked off with only 5 of the 7 holes drilled all the way through.

I first noticed this type of end on SBDU Reynolds 753 frames dating from approx SB1000 and it lasted until approx SB1500 (start to mid 1977). It may have been introduced earlier but the gap in my data between SB900 and SB1000 means this is as accurate as I can be at the moment. Just like the first type of 1010/B, the use of this 2nd type was relatively short lived, it is one of a couple of SBDU fork ends that I don’t currently have an example of, so the image above is a mock up using my Photoshop skills to show the features that I’ve seen on SB 753 frames in this period.

Campagnolo then released the 1010/B short end with the Portacatena (Chain Holder) fitting part way through 1977; this was now the 3rd type of 1010/B used by the SBDU. This is probably the type of dropout that most will know about and recognise. The SBDU adopted it on their 753 frames straight away. I’ve got the Portacatena type end documented on SB 753 frames dating from approx SB1600. The SBDU continued the feature of drilling the dropout.

Apart from the obvious holes for the Portacatena, the drillings applied by the SBDU changed again. Both the 2nd the 3rd type ends appear to have 7 holes from the outside of the dropout, but the 2nd type has 2 blanked holes with 5 complete drillings and the Portacatena type has 3 blanked holes with only 4 complete drillings.

The comparison below gives you a very clear example of how the 1010/B progressed from the 1st type to the 3rd type. The size, shape, drillings and end adjuster fittings are very different on the 1st 1010/B.

The 4 significant features of the 1st early style 1010/B are…

1. The window cutout measures a little over 16mm
2. The distance from the rear of the dropout to the front is approx 33mm
3. The rounded edge running from the end adjuster hole to the hanger has very little metal
4. The external end adjuster hole is large diameter and the slotted adjuster screw head is fitted from the outside edge

Here is the Portacatena style 1010/B that was used from later in 1977

1. The window cutout is longer with the bottom measuring slightly over 22mm
2. The distance from the rear of the dropout to the front is approx 39mm
3. The rounded edge running from the end adjuster hole to the hanger has more metal, it is much thicker
4. The end adjuster hole is smaller and threaded and the adjuster head is fitted from the inside

So the original ‘short’ 1010/B was shorter by approx 6mm than the later ‘short’ 1010/B end.

The 3 different styles of 1010/B in this relatively short period of time (late 1975 to late 1977) had 3 different styles of drilling…

• 1st style – 8 holes drilled completely through the dropout
• 2nd style – 7 holes drilled (2 blanked off & 5 fully drilled)
• 3rd style – 7 holes drilled (3 blanked off & 4 fully drilled)

The image below shows the inner surfaces of the early 1st style 1010/B (SB664 on the left) and later 3rd style (SB3505 on the right). Only 4 of the 7 holes on the later end are fully drilled.

While I’m waffling on about the 1010/B, here is another little SBDU feature. I read an article from the period that mentioned how the SBDU would profile the leading edge of the lower part of the dropout, to shorten it and make it easier to fit and remove a wheel. There is clear evidence in the frames I have that show this modified feature.

The 2 dropouts at the top of the image are from 1981 and 1982 and the bottom image is from 1985. The 2 earlier dropouts definately show a flatter modified leading edge on the lower part of the dropout slot, just above the hanger. The lower image is the later end and it has the original intact Campagnolo shape. The excerpt below is from the 17a supplement showing the correct profile.

The drilling of fork ends by the SBDU also extended to their 753 Track frames. The same Campagnolo 1053 end used on the 531 Track frame was drilled, with all the holes drilled fully through. The end on SH377T is an excellent example of a drilled 753 track end dating from 1977.

But I do have an earlier 753 Track frame from the SBDU. SB632 is so far the earliest known SB numbered 753 Track frame and the ends are slightly different because they are thinner. SB632 dates to Easter 1976.

I had to do a lot of work to repair the ends on SB632, but during the renovation I didn’t notice and Campagnolo stamping, I didn’t see the words ‘BREV CAMPAGNOLO’ stamped around the end of the slot. This end is much thinner than a 1053 end and I don’t know if this is a modified 1053 or a custom cut end using the 1053 as a template. You can see a clear difference in the comparison images below, SB632 (1976 753 Track) on the left with SH377T (1977 753 Track) on the right with the standard drilled Campagnolo 1053.

Early Time Trial (TT) Frames

SBDU Reynolds 753 TT frames are normally associated with drilled vertical Campagnolo fork ends. I don’t have much data on the earliest of these frames but what I do have shows that most of the first 753 TT frames used the 1st type, short 1010/B horizontal drilled end. My own SB664 is an example, it measures up as a TT frame and has the 1010/B end; other TT frames I’ve seen from the same period show the same 1st type 1010/B end.

I then have a big gap in my data for TT frames and the next 753 TT is SB1500. This is the first frame I have documented with the Campagnolo 1060 ends. The large curve at the rear of these dropouts allowed the SBDU to drill progressively larger holes from the bottom to the top. Depending on the Campagnolo catalogue you read, these will either be called Corsa, Serie Corsa or Racing Set. These ends have appeared in Campagnolo catalogues dating as far back as catalogue 15 dated 1967, and maybe earlier.

The 1060 was a thin stamped dropout, so the SBDU brazed washers to the inner surface to increase their thickness to that of the forged 1010 ends.

1979 – 1984

It wasn’t long after the SBDU adopted the 1010/B Portacatena fitting on their 753 frames, that they also fitted the 1010/B to their 531 frames. From approx SB2800 (start of 1979), the 1010/B became a regular feature on 531 SB frames with both the 1010/B and 1010/A offered on the Team 531. From the data I have, most Reynolds 531 SB frames took the 1010/B option from this point on and although the Reynolds 753 frames continued with their drillings, the 531 frames were left with plain undrilled ends.

This makes me think about the 1010, which was Campagnolo’s long horizontal end with eyelets. I haven’t really mentioned it yet even though there are plenty of SBDU frames with long ends and eyelets. But you can see in the paragraph above that the Campagnolo 1010 (long end with eyelets) isn’t mentioned; instead, either the 1010/B or 1010/A can be fitted with mudguard eyes. In fact, the 1010 doesn’t get a mention in any of the information I have available to me. The documents I have always refer to the fact that eyelets can be fitted to existing ends.

I have two randonneur frames from the end of 1985, and both have long ends and both have eyelets, they actually have two eyelets. I’ve always used one for mudguards and the other for a rack.

But are these 1010 ends or modified 1010/A ends?

My best guess is that they are modified 1010/A which fits in with the SBDU descriptions. The black dropout is on my 753R randonneur and the top eyelet appears to be larger than the lower eyelet so could that be a 1010 with an additional but slightly smaller eyelet? The red dropout is from my 531c randonneur and both eyelets appear to be the same size. These two frames are only 3 SB numbers apart (SB7657 & SB7660) which means that these ends were almost certainly prepped at the same time, so I can’t really think that they would use a 1010 on one frame and a modified 1010/A on the other to create similar ends on similar frames. I therefore think that these are both modified 1010/A.

Up until 1980, unless there was a one-off that I haven’t seen, every fork end used by the SBDU was Campagnolo, but moving into the 1980s there was a change as the first Shimano fork end appeared. Here is the Shimano SFR vertical dropout.

The Shimano SFR took over from the Campagnolo 1060 on TT frames during 1980. The SFR started to appear at the beginning of that year. The SBDU were still drilling the ends on 753 frames which meant that the SFR was also drilled. But instead of the progressively larger holes you see running up the back of the Campagnolo 1060, the SFR received standard, regular size drillings, drilled through the face of the end. Some of the first drilled SFR ends had 7 holes but this was soon reduced down to 5.

Nothing much else changed in the first part of the 1980s. Everything I’ve written so far is quite straightforward and tended to follow a pattern…

• 531 frames continued with the 1010/B Portacatena
• 753 frames continued with the same end but with their trademark drillings.
• TT frames continued to use the Shimano SFR
• Track frames continued with the 1053 track end

But because the SBDU were a custom frame building unit, I have to assume that any fork end could be requested on any build, so although there were obvious patterns there is no reason why a 753 Road frame could not have a long 1010 (with eyelets), and there is no reason why any Road frame could not have a vertical SFR. Likewise, there is no reason why a TT frame could not be specified with a horizontal 1010/B.

This is where I would warn potential buyers of these frames that the type of fork end on an SBDU frame does not always tell you what type of frame you are buying. Just because an SB frame has a vertical dropout does not make it a TT frame. It was undoubtedly much easier in the earlier part of the 1970s to identify frame type and tubing by the type of fork end and frame features, but the early 1980s really did mix things up.

Here are some snippets from the 1983 SBDU frameset information…

The 1985 frameset information also lists the option of Campag (horizontal) or vertical on both road and TT frames…

This is the fork end from SB6398, a 753R frame… looking at a drilled vertical end like this on a 753 frame would make most people wrongly assume that this is a TT frame… but it isn’t, it is 100% a road frame, just with an optional vertical dropout. (Notice the reduced number of 5 drillings).

So never make an assumption about what you are seeing or buying. The only way to work out what you have with an SB frame is to look at the frame as a whole; you need to look at the type of lugs and seat stay arrangement, type of BB and most importantly frame geometry. I do this with every frame that I add to my collection. By the end of 1984, the SBDU had come full circle, and instead of the early years when they gave visual clues to what a frame might be, they ended up hiding the detail away in the measurements of their later frames.

Getting back to fork ends!

Towards the end of 1983, a Simplex fork end was introduced to fit in with the Raleigh Weinmann team bikes. These bikes were equipped with a mix of Simplex, EDCO, Weinmann and Maillard. There aren’t many of these Simplex examples and from the data I have the majority appeared on frames dating to early 1985. Most of the frames I’ve seen with this specific end also came with the Simplex specific front derailleur fitting.

1984 was a significant year. It was the year that saw the departure of drilled ends on 753 frames and the end of the Portacatena style 1010/B. By the start of 1985, both of these features had gone.

1985 to 1987

Over the years the SBDU went through a series of steps to simplify their frame production. I’ve written before about the contrasting paint detail that the SBDU would add to lug cutouts in my blog post TI-Raleigh paint and transfer scheme, this post showed that the SBDU eventually dropped all lug detailing after a few years. They did the same with the prep work on fork ends. By 1985, they had already dropped the 1060 end with the requirement to braze a washer to the inside face, they had stopped drilling fork ends and they also stopped the profiling to the front edge of the 1010/B. SBDU fork ends now simply consisted of the stock 1010/B, Shimano SFR or 1053 Track ends. The Simplex and 1010/A long ends remained as options along with the choice of additional eyelets.

The absence of the Portacatena fittings meant that this was now the 4th style of 1010/B used by the SBDU. The image below shows no Portacatena, no SBDU drilling, no profiling and re-shaping, it is just the 1010/B in original Campagnolo form. This 1010/B is from SB7121, a 1985 TT frame.

Everything remained constant for the next couple of years until the end of Ilkeston and the relocation of the SBDU to Nottingham.

1987 Onward

The actual period that the SBDU relocated to Nottingham is open to some speculation. But it is generally accepted to be sometime near the end of 1986/start of 1987. According to my timeline, the Nottingham SBDU frame numbers started at approx SB84xx. But just before this relocation, the SBDU introduced a different track end.

Traditionally they had used the Campagnolo 1053. The 1053 was a great track end, standard on SB Reynolds 531 frames and drilled on SB Reynolds 753 up until 1984. The new track end was the Shimano UFP 10.

This switch to Shimano didn’t appear to be a total swap as there seems to be a good mix of frames with both Shimano and Campagnolo track ends in the high SB8000s (post Ilkeston). There also doesn’t appear to have been any differentiation between 531 and 753 frames as the UFP 10 was used on both types.

The Shimano SFR received a very small ‘face lift’. The 1st SFR used by the SBDU, which I referenced earlier had the wording ‘Shimano SFR’ pressed into the face of the end.

The later Shimano SF had a slight cosmetic change where the ‘Shimano’ wording was placed around the rear of the end with the ‘SF’ type number remaining on the dropout face.

Sitting alongside the redesigned Shimano SF and the Shimano UFP 10, the SBDU continued the use of the 4th type of Campagnolo 1010/B – this is the end from SB8868, my 1988 753R.

The graphic below displays an approximate representation of when the various fork ends were in use by the SBDU at both of their locations.

You might notice that I’ve stopped the 1010/A at the relocation point of 86/87 because I have no evidence of it’s use past this date. There is nothing in the SBDU documentation that shows or mentions it, the SBDU details from Nottingham just mention either a Campagnolo or Shimano fork end. I also have images of Road frames that have been sent to me showing lots of post Ilkeston frames and they only show the short Campagnolo or vertical Shimano dropouts.

Following the end of the SBDU and the creation of Raleigh’s Special Products Division, I’ve recorded details of both Campagnolo and Gipiemme horizontal ends and ‘Raleigh’ vertical ends on the SB stamped frames that they produced.

Because of the custom nature of their work, if anyone has something different on an SBDU frame then please get in touch as I would love to see some details.

One last point related to the SBDU and connected with fork ends, is the style of finish applied to the ends of the stays and blades. No matter what frame the SBDU were building, regardless of it being the lightest pursuit frame, road frame, track frame, touring frame, ATB or a frame built for the most aggressive of TI-Raleigh riders on the toughest of courses, they cut the stays into their same signature style!