There’s a lot of good engineering on modern BMX, but some things, to my mind, are still as dumb as chips.
Top hat spacers. A way of ensuring a sprocket can be used on a variety of spindle diameters. Make a sprocket 24mm then provide a 22mm and a 19mm top hat, and everyone is happy.
Almost eveybody states that the top hat goes in to the back/inside of the sprocket. So the rim part of the hat sits between the sprocket and the BB cover NOT between the sprocket outer face and the crank arm.
But why does this adaption require a sprocket to be pushed 1mm further out by the hat rim? If you have a 19mm sprocket and a 19mm crankset, it won’t be 1mm further away, it will be flush. If you have 22mm on 22mm, there’s no top hat, so no rim, so no 1mm offset.
Why aren’t top hat spacers just ring shims that sit inside the sprocket hole? Why the lip (hat rim)?
Tell me what I’m not understanding about top hat spacers…
by Awkward_Importance49