As far as the "dog bones" go:
RSR cranks, as shown, milled backs; one spider arm is in line with the crank arm. Need to use the chainring bolt in the wrong way round to do it up.
CBR, non milled (or "fluted") arm, the spider was in the conventional configuration.
The spider is located with a bolt and then hammer drive rivets. If you press the spider off, you'll either bend it trying to pull the rivets out, or you need to machine the rivets out to gracefully lift the spider off. Just then you can't replace it exactly until you re-machine and extract the redundant rivet portion. . .
I don't see how spider orientation would affect a purchace choice. Or removability, if its the right bolt circle, go for it. You'll never find a separate spider if you want to change the PCD. E-crank was the first with the proper interchangable spiders.
RSR cranks, as shown, milled backs; one spider arm is in line with the crank arm. Need to use the chainring bolt in the wrong way round to do it up.
CBR, non milled (or "fluted") arm, the spider was in the conventional configuration.
The spider is located with a bolt and then hammer drive rivets. If you press the spider off, you'll either bend it trying to pull the rivets out, or you need to machine the rivets out to gracefully lift the spider off. Just then you can't replace it exactly until you re-machine and extract the redundant rivet portion. . .
I don't see how spider orientation would affect a purchace choice. Or removability, if its the right bolt circle, go for it. You'll never find a separate spider if you want to change the PCD. E-crank was the first with the proper interchangable spiders.