I have a couple of these gears but have never been able to get them working properly. They are a little heavier and clumsier than the Sturmey T/TF 2-speed gear which can be used in either fixed or freewheel form but to change from fixed to free the sprocket needs to be removed and replaced with a special splined freewheel. The internals of the Sturmey 2-speed are very simple with almost nothing to go wrong but many are these days totally worn out - the bearing surfaces will eventually pit very deeply and I have seen a couple where the bearing surfaces on the sprocket carrier/right hand ball cup have worn completely worn through. This just shows how popular the T/TF series of hubs were with riders - I certainly would never part with the two I have in my collection. To get back to the BSA DP. It is very much more complicated internally and the problem with mine appeared to do with the numerous springs. I have a parts diagram - unfortunately it's not an exploded diagram of the hub and I have never seen a any service material relating to it. It is certainly very rare and recently I bought another one which is for sale at $65 - the end cover plate is missing some screws and comes with no guarantee.
Hilary Stone, Bristol, England
Russ Fitzgerald wrote:
The chapter on derailleurs has an interesting quirk - buried within it is a small section on the B.S.A. "D-P" gear - a two-speed gear that allowed fixed-gear or freewheel operation in both gears. The fixed/free control was a cable-operated unit mounted to the bars, the gear selector was fitted to the top tube. A cool-looking epicyclic (sp?) unit, and I wonder how many were made. Hilary? Ray? Mick?
Mike Butler added:
> Russ Fitzgerald was asking about this particular hub gear it really is a rare
> bird my father used to ride on one of these gears and said it was the greatest
> thing since sliced bread. He was a fixed wheelman and swore by them for
> general riding and touring, so much more convenient than swapping your rear
> wheel around to freewheel and descend in hilly areas. They came out in 1936
> and were very expensive.To my knowledge they were only manufactured for three
> years 1936 to 39. The BSA factory was extensively bombed during the war and
> all drawing etc. were lost. When BSA got back into normal production after the
> war they fitted their remaining stock to there top lightweights(Gold Series)
> as an extra but the craze for derailleur's had already taken off. This was a
> superb gear, although always a rarity I have only ever seen three and I have
> been ridig since !958.The Hobbs marque enthusiast for the VCC owns one of
> these gears. F.J.Camm also wrote about model steam railway locomotives.