1948 BSA twist grip shifter

[TR6SC]

A friend just found this 26 inch small framed beauty. Looks like a good find for a BSA motorcycle guy, which he is. He was told it is a 1948. Anyone have any thoughts or input? There's no date on the hub, and I've never seen a twist shift before.

 

[dweenk]

I have not seen that type of grip shifter mechanism before. Do the detents in the shifter's metal sleeve lock in the gear selection?

 

[SirMike1983]

That could well be a 1948 - looks like a model #604DC Streamlight Sports Roadster with the optional chain guard in the 21 inch frame size. They made the same bike with rod brakes as the #604D (the additional "C" stood for cable brake model). The 1950 BSA catalog actually shows the twist grip shifter of that era.

http://veterancycleclublibrary.org.uk/ncl/pics/BSA catalogue 1950 (V-CC Library).pdf

(see page 2)

I'm not sure how reliable they proved to be compared to the quadrant of the earlier era and the flicker shift on the handle bars of the later era. You see more quadrants and flick shifters on the bikes today than this twist shifter. It's neat how the cable enters the handlebars themselves to connect.

 

[RidgeWalker]

Right. The twist grip was available as an option from 50-56, when BSA was assimilated into TI/Raleigh.
Did you have any specific questions?

 

[RidgeWalker]

Another point of interest on the BSA hub/shifter is that they work "opposite" of contemporary Sturmey Archer equipment. What I mean is that when the cable is under maximum tension on a Sturmey Archer set the hub is in Low gear while with BSA equipment the hub would be in High gear when the cable is under maximum tension.