Hoofddorp Barn, BSA folding Bicycle

[Alex van de Wetering]

Attached you will find some pictures of the repair work on the seat-frametube. The former owner forced a new seat post into the frame. Nothing wrong so far.....but remains of the original BSA seat post were still in the tube....in the end the frame tube was forced to expend which resulted in a crack.
I wasn't satisfied with the frame crack, especially when my intention was to actually drive the bike.
It was extremely difficult to get the seat post out, in order to repair the frame tube. In the end I even had to open the crack a little further, before the seat post could be removed. I than started cleaning up the tube, bending it in the right shape again, welding it and sanding down the welds with a powerfile.
I wasn't able to get all the remains of the original BSA seat post out of the frame, so I decided to leave it and make a "custom" seat post with a slightly smaller diameter at the bottom.

[Alex van de Wetering]

Here is a picture of my "custom" seatpost, which is essentially a seatpost with the correct "BSA" measurements, which I shortened. I than welded a new steel tube with a slightly smaller diameter into the seatpost.

Also pictured is the bolt for the steering wheel. I measured up an original BSA steering wheel and looked for a replacement. I found an old chromed example with nearly the same shape and measurements, so I decided to use this as a base. I drilled a hole trough the bolt and inserted a piece of rod which I bent into the "wingnut" shape. A few welds to secure it and to creat a slightly domed end to the bolt. I than cut the ends to the correct lenght and welded a little bit of material to the ends, creating the rounded ends.

Next up.....the BSA chainwheel, cranks and peddles.

Alex

[cliff]

looks like you will have a good example of the bike once you have finished Alex.

[Alex van de Wetering]

Thanks Cliff!
Since a few months I have been closely looking at a lot of preserved examples and I realised that a lot of them carry non-original parts, especially those here in Holland. It seems the bikes were extensively used after the war....(Holland being a typically "cyclist" country of course) and therefore a lot of them have the same worn parts replaced...like the chainwheel, seats and brakes (which according to some never worked anyway).

Alex

[Alex van de Wetering]

Work on the chainwheel and cranks.

My bike came with a non-original chainwheel and cranks whihc took a good amount of abuse during it's lifetime. A few friends of mine surprised me with a newly milled BSA chainwheel, spare crank and bushings, rods and washers to recreate the pedals. Initially I wanted to modify my current chainwheel by having letters "B, S, A" lasercut and wedling them into the existing chainwheel. But the crank was in the wrong orientation regarding the chainwheels as well. Anyway, the surprise parts were a great thing and saved me a lot of time.

Pictures below is the chainwheel and crank that came with the bike, the newly cut BSA chainwheel and a picture of three stages of crank modification to the appearance and measurement of the BSA ones.

The last picture of this post is the start of the chainwheel modification. The non-BSA one was seperated from the crank, which was a little harder than I anticipated. During production the crank was forged to the chainwheel, so I had to sand down the centre of the attachment until I saw the little tooth keeping the crank and chainwheel in the correct orientation. It took some serious hammering to get the two separated. In the picture the new BSA chainwheel is lossely positioned onto the crank.

[Alex van de Wetering]

Time for a new update. The chainwheel is done in the meantime. Here is a short description of the process:

There were two issues with the newly cut BSA chainwheel; it's is a few millimeters too big (while the centre is of the correct size) and it's completely flat, compared to an original chainwheel which is slighly pressed into shape, creating an edge to guide the chain onto the teeth.

To create the correct shape and size of the chainwheel I decided to use the cranks and the teeth of the stuff that came with my bike and the centre of the newly cut BSA toothwheel.
I fixed the newly cut wheel to the "modified" crank (rounded to the BSA shape) with two small welds. This way I could check if it was centered and straight, before securing it.
After checking, I made a ring of welds "filling" the gap between the hole in the chainwheel and the slightly smaller crank. After cleaning up the welds I welded some extra material to the centre to get it a flat surface in the centre.
A normal chainwheel has a boss near the centre, which is basically some material from the crank which is forged around the hole in the chainwheel. It also ensures the chainwheel positions good on the bike itself. I replicated this by welding a thick washer onto the chainwheel. Four holes were drilled to be able to weld it securely to the chainwheel.

[Alex van de Wetering]

I decided to use four extra welds along the edge to decrease the chance of failure while driving in the sun along the Normandy beaches

Than...cleaning up the welds and checking the chainwheel on the bike again.

Now......changing teeth! With a basic saw I removed the teeth from the chainwheels that came with the bike. I cleaned up the remains of the spokes from the "old" chainwheel and than used it as a template to draw onto the newly cut wheel. This way I knew where to cut it the teeth from the newly cut wheel. Then it was basically removing some material and testfitting....removing some more, testfitting again, until it fit perfectly. The last picture in this batch shows the pieces combined with a few welds.

Alex