Originally Posted by
queerpunk
i think that either it does or it doesn't needs to. it sits on the inside and the 144 ring mounts to the outside of it, so it mounts the chainring in a good spot - further inboard than an outer ring would sit, and further outboard than the inner ring would sit. i recall bergstrom talking about it sitting at 42.5mm for proper chainline.
Exactly. Chainline on a double crank is measured to the middle of the spider, so if you set a chainring in the middle of a typical road double, you would in theory be sitting at 43.5mm chainline. However, this doesn't take into account chainring thickness, so you're closer to ~44mm.
Long story short, it's a flat plate, no different - but much more expensive - than the bdop adapter. And the counterbores are too big for serrated track nuts to bite in.
Long story even shorter: I think it's a massive rip-off, but I'll gladly sell mine to whoever wants one.