Headsets: Birmingham / BSA Type

 

Having more or less finished the 1957 Schwinn Traveler, I've moved on to a very nice 1951 New Hudson Silver Arrow bicycle, produced by BSA. The Silver Arrow is a clubman style bike with 531 main tubes in the frame, 26 x 1-1/4 wheels and celluloid fenders.

I've done some preliminary cleaning, as well as cleaned and repacked the bottom bracket. There is nothing special about those jobs. It's a process I have covered many times before. The clean and re-pack process for the bottom bracket is the same as any run-of-the mill Raleigh Sports or similar English bike.

So let's get into something trickier: the BSA-style or "Birmingham" style headset. Whereas the common Raleigh headset takes 25x 5/32 inch loose bearing balls in each race, the Birmingham headset uses 30x 1/8 inch balls. The Birmingham headset also uses an upper race "insert". 

Let's take a closer look:

Above is a top view of the head tube. As you can see, the frame does not include an integral bearing race. Rather, the head tube has  "bowl" in it, which in turn houses a removable top race.

Above you can see the top race components. On the left is the insert that will sit in that "bowl" in the previous picture. At right is the top ring that screws down. 

 

 

Above are, again, the two top components. The insert for the "bowl" has grease and the 1/8 inch bearing balls in it. It will hold 31 balls, but tends to bind if it is completely filled. It will be smoother with 30 balls, which is full minus one ball. The top screw-down ring also has been greased.

Above is an illustration of how the two will go together. The insert will sit in the head tube "bowl" and the screw-down ring will ride on top.

Above is the insert with the balls sitting in the frame "bowl". I tried a full insert of 31 balls initially, but it went much better with 30x 1/8 balls (again, full minus a ball).

 

What about the bottom of the headset? Well, the bottom is conventional - the frame cup is pressed into the head tube as normal. However, keep in mind you're using 30x 1/8 balls,  not the usual "Raleigh" type 5/32. 

 

And above is the fork crown race, also conventional except that it takes the 1/8 inch balls.

 

Above are my crude notes drawn in Sharpie on a paper towel while working. This is as much to remind myself of how to set up this headset as it is any other purpose. I'm very accustomed to the Raleigh system of 25 balls at 5/32 apiece. I needed a note to myself that this Brimingham headset likes to run 30x balls at 1/8 inch apiece.

And a quit shot of the New Hudson head badge. Pretty cool...