Helping someone who wants a Bafang Ultra Max drive. Since he can't weld this into a DIY aluminum frame, he's planning to bolt the mounting plate in the middle of a DIY steel recumbent frame as an intermediate drive. But that means he'll need an ISIS spider without a crankarm to attach to the Ultra Max to use as a timing sprocket to the front crank. Anybody know of any armless spiders? I know Maxarya has a similar spider since their bikes use a similar layout, but that one is square taper, not ISIS.