It’s time to figure out the correct SBDU frame number for my frame stamped as SB4522. Is that number correct? Is it SB5422, indicated on the fork column? Once again, being able to read the SBDU frame details should give me the answer to this mystery.
Here is that suspect frame number.
There are a few areas of SBDU frame design that I can look at to help me solve this. I can also compare each design feature to a database containing hundreds of other SBDU frames.
Looking at the details… attempting to establish the SBDU frame number
If this frame is indeed SB4522 it would be a 1981 frame. The implication of that 1981 date would alter what I believe to be the originality of this frame. If this was indeed 1981 then this must be a repaint – or at least it would be a frame with updated transfers. The Reynolds frame and fork transfers are the wrong period and type for 1981.
I do believe the paint is SBDU paint. It’s quality and finish is everything I would expect to see from the SBDU. The transfers are correct for 1982. It carries the later style Reynolds 753R frame transfer. Reynolds updated their range of tubing late in 1982 and the SBDU started to use the new transfers on some frames. So the 753R frame transfer could match the SB5422 SBDU frame number perfectly. The earliest I have seen an original 753R frame transfer is SB5550, and SB5422 is very close to that period.
>> Paint Conclusion
The paint appears to be original. The transfers also appear to be original and they also fit in with the period of the introduction of the new Reynolds range. It’s not conclusive, but the paint and transfers do point more to 1982 (SB5422) rather than 1981 (SB4522).
Braze on Front Derailleur
It is just a small piece of metal that connects the front derailleur to the frame, but this type of fitting can be dated.
The earliest I have seen an original SBDU paint frame with a braze on front derailleur is approx SB4900 – mid way between the two frame numbers I’m checking. So if this was SB4522 the braze on fitting would likely be an addition. However, if it was SB5422 then it could be an original fitting.
>> Front Derailleur Braze On Conclusion
Again, I can’t be conclusive because of the lack of certainty regarding original paint and available frames. If the paint is original then the braze on fitting is period correct and SB5422 could be correct.
Shimano Vertical Drilled Frame Ends
Here is a little known fact… Shimano vertical ends on earlier 753 frames had seven drillings. Later Shimano ends on 753 frames only had five. Here is SB4409 from 1981 showing the seven holes…
…and here is SB6398 from 1984 with five holes…
So the question is, where in the range from SB4409 to SB6398, did the number of drillings transition from seven to five. My new frame has five!
There are only 113 frames between SB4409 (seven holes) and the suspect SB4522 (five holes) – was it possible for the change to happen in that very short window of time?
What can the frames in my data tell me?
Sadly, after looking through relevant frame types, I can’t narrow down the change any earlier than SB4522. The next frame to have only five holes is SB4686.
>> Shimano Vertical Drilled Frame End Conclusion
After looking at this frame feature, it is still difficult to have a positive opinion on which frame number is correct.
Recap – SBDU Frame Number Investigation
So far I’m not much further forward. If this frame is SB4522, it falls in the middle of several feature changes and there isn’t enough data to support either number being the genuine.
Brake Bridge Supports
Believe it or not, these small, often never noticed details, can help to date an SBDU frame. My frame is in the image below. It has a specific support where the lower point is longer than the upper point. It includes a small cut out window in that longer, lower support.
Over the years, I feel the SBDU had a “love-hate” relationship with these little brake bridge details. So many SBDU frames don’t have them. And when they were in use, there were a few different styles.
This feature presented one of the many problems I had when I bought SB4059 all those years ago. There was an absence of a significant source of information at that time, and I worried because SB4059 did not have them. The internet chatter at the time said that SB frames without supports were repaired frames following a failure. That, as I later discovered through my own research, wasn’t the case.
This is where I might have some evidence to define this frame. I have frames in my database that show a different type of brake bridge support in use at the time that differs from from the image above. Frames built at the time of SB4522 appear to have a bridge support which had equal length points above and below the bridge – with no cut out window. My frame has a different support so the SB4522 number stamped on the BB shell does not fit with this style.
>> Brake Bridge Support Conclusion
As ever, the SBDU can throw up the odd ‘one-off’ frame that can add some small doubt to anything I write. But here is a frame detail that can be traced and verified with a high degree of confidence that supports the fact that this frame could indeed be SB5422 rather than SB4522. The brake bridge in use on this frame was not (according to my date) in use at the time when SB4522 would have been built.
Bottom Bracket Gear Cable Guides
One frame detail that certainly changed over time was the management of gear cables and the route they took as they navigated the bottom bracket shell. I detailed this evolution in a post I wrote about the renovation date of SB1995.
SBDU gear cables were first routed on top of the BB. The main method used was braze on Campagnolo cable ferrules (tunnels) 626/b and 663. There was an occasional and random use of a metal cable clip, Campagnolo’s 626/a twin gear cable clip is an example. The bottom of the BB shell at this time was either plain on earlier frames or with 4 slots milled into the BB slightly later. Here is a selection from SB664, SB1500, SB1861 and SB2692. SB1500 is the gold frame (bottom LH corner) requiring the cable clip, you can see the mark on the paintwork at the bottom of the down tube from the band of the clip.
Things moved on and gear cables moved to underneath the BB shell. Two slots were cut into the BB shell and the cables sat in the slots. Sometimes either bare cable, sometimes protected with a plastic sheath. This is a 1980 frame, SB3505.
The grooves on SB3505 are clear and well defined and cut. A little later the grooves became less well defined, especially when Cinelli BB shells came along. Here is SB4933 from late 1981/early 1982. Note the difference in the definition of the slot. The lack of definition and depth in the cut was pronounced on Cinelli BBs. Cinelli typically had a very shallow groove. Some team frames even used a small brazed on loop to ensure the cable stayed in the shallow groove.
At approx SB5000, things changed, and the very first SBDU plastic cable guide appeared on SB numbered frames. Branded as VITUS, it was a press fit into a large hole on the underside of the BB shell. This is the Cinelli BB on SB5377 – the frame is no longer in original paint but it does still with original guide fitted.
And here is the RGF BB on SB5464, this frame is still original and has the original VITUS guide fitted.
As a plastic cable guide is being used, the BB is no longer grooved.
This means that for SB4522 to be the correct number, it should have the two groove system… but it doesn’t… This is the BB shell I’m investigating.
It has a large drilled hole, no grooves and the VITUS cable guide.
>> Bottom Bracket Gear Cable Guides Conclusion
The cable routing on this frame only came into use from approx SB5000 – this frame cannot be SB4522. It must be SB5422.
Summary: SBDU Frame Number
The gaps in my data due to the small number of known and well photographed SBDU frames, mean some features like the drilled Shimano vertical ends cannot be used to date this frame and cannot help to prove the true frame number.
However, the BB cable guide routing is accurate and can be proved through data and frame evidence.
This frame is SB5422. The BB shell stamp of SB4522 is wrong. The ‘5’ and ‘4’ are mixed up. The number on the fork is the correct number. SB5422 is a 1982 frame. It dates to the latter part of 1982 when tubing and transfers were changing within Reynolds and the SBDU.
This also means that I am happy to call this original paint and transfers, and I’m happy that the front derailleur braze on is original and not a later addition.
This is SB5422 (stamped SB4522)
Sometimes the SBDU did get it wrong!