Sturmey Archer Quadrant Shifters - Making a Replacement Flat Spring

Sturmey Archer quadrant shifters are a defining characteristic of many of the older three speed bikes dating back to the 1910s-40s. The quadrant is one of the signature parts of these vintage bikes, often sitting prominently alongside the top tube of the frame.

 

Sometimes you get a quadrant shifter with a limp lever - one that won't "click into" the pegholes on the shifter body. This is often due to a weak or corroded flat spring inside the shifter. 

So why not make a new one? They are not hard to make with a little attention to detail...

(1) Start with with a large hose clamp from the hardware store. These clamps are made of a reasonably thick, springy metal. In this case, I have a stainless steel clamp. The width on many of these clamps is also fairly close to what you need for the spring. The first step is to clip the clamp so you have just a solid section of metal. Place the old spring atop the section of metal and trace the outline of the eyelet. The location of the eyelet will determine how you shape everything thereafter. Take the metal to the drillpress or use a hand drill to drill the eyelet in your metal.

(2) Now that you have the eyelet drilled, you can layout the shape of the spring on the hose clamp metal. I place the old spring over the metal and trace the outline of the spring using a fine Sharpie. You can also etch the line using a file tip. Either way, you want something durable so you can work the metal without having the outline rub off. If it begins to rub off, refresh your lines and continue working. When you trace the outline, make sure you make your outline extra long. The reason is that the spring will need a little bent tooth at the end to engage the shifter lever notch. Leaving a little extra length will ensure you have enough material when you go to make that tooth.

(3) Now that you have your outline, take some aviation shears and snip the metal down to a workable size. Don't go too close to the lines. Just get it roughed out so you can reasonably file or sand the metal down to the lines.

(4) Use a sander, grinding wheel, file, Dremel, or other tool to work the piece down to the correct size. It should still be somewhat long. Take the extra length and place it in a vise or pair of pliers. Bend the end on a 90-degree angle to make the tooth that will engage the shifter lever notch. Then sand/grind/file down the tooth until it is a size that will fit in the shifter notch. Periodically check your work against the original spring you are using as a model.

(5) During the course of work, the clamp metal may have flattened a little bit. Take a mandrel or the handle of a screw driver and carefully re-bend the metal. The old spring likely has also become somewhat flat with age. Your new part should have a bit more bend to it than the old one.

(6) De-burr and polish your new spring. You want the edges and the surfaces to be smooth and not sharp, that way it will move smoothly along the surface of the shifter when you install it.