DIY Spoke Nipple Washers
You may be asking what are nipple washers used for? Despite what you might be thinking it’s not kinky in the least.
On conventional bikes, it’s written that they increase the strength of the rim and reduce friction. That may or may not be true, I don’t know. I use washers because I ride aluminum motocross rims and the spoke holes are too large for 12ga nipples. You can’t simply use flat washers because the shape of hole in the rim is concave, you need a concave washer. I spent quite a bit of time searching and found nothing available.
On the front wheel, you will likely use a standard downhill hub, that should fit 12ga spokes without any drilling. I have seen them drilled to fit 10ga spokes, but it doesn’t leave very much meat on the hub flange. I prefer to use 12ga spokes with washers on the nipple side. I’ve ridden 2 bikes a few thousand kilometers with no issues. Never broke a spoke and never had a flat. I won’t get into the why run motocross rims and tubes, except to say that getting a flat would be rare. I think it’s the perfect rim for high power eBikes.
On the rear wheel, if you have high power motor, 10ga spokes really are the way to go. On the other hand if you have a lower power motor, you can use 12ga spokes just fine. Careful not to over tighten them or you will get broken spokes.
The first thing you’ll need is a bunch of washer. I used 10 x 5 x 1mm stainless washers. The outside diameter is 10mm, the hole is 5.4mm and the thickness is about 1mm. These seem to work really well. I have used both 316 and 304 stainless washers with good results. You can probably use regular washers, but the cost difference for me was minimal so I tend to use stainless hardware whenever possible.
Next we need a forming tool and a die. You can make do with just a drill and an angle grinder (or bench grinder), but if you have a drill press and a lathe, they are a bit easier.
First we will make the die. We need some sort of concave hole in a piece of steel. First drill a small hole through the steel plate. 5mm should be big enough. This gives clearance for the tip of the punch. Next use a coutersink to deeply counter sink the hole. You want the outside diameter to be slightly larger than the washer. 12mm should be about right. If you don’t have a counter sink, you can use a 12mm drill bit. The angle isn’t quite the same, but it will work OK.
Now we need a punch. I had this punch around. I think I turned it up to find the center of a hole on the mill. Just cut a 12mm, or larger, piece of round stock with a 90 degree point. If you don’t have a lathe, you can make the same kind of thing with a grinder or bench grinder. Just keep turning the bar and keep checking to make sure you are keeping it relatively round. You will probably want a jug of water nearby to keep cooling the part. Grinding gets things hot quick!
You’d think it would be hard to grind this by hand, but surprisingly it’s not. Very little of the punch contacts the die. As long as it’s approximately round, you should have good results.
Now we just need to make the washers. Place a washer in the recess in the steel block. Set the punch in the hole and hit it smartly with a hammer. You don’t need much force, they form very easily. Take out the formed washer and repeat as many times as needed. Here is a close-up of the washer installed on a spoke nipple.
Don’t worry too much about the angle, there is very little contact area between parts. As long as it has the approximate shape, it will work fine.
Good luck and happy riding!