I have just sent an email to Mike at Bike Specialties asking for some details on this item. I have a ref:175 Professionel Adapteur and doubt that this is the item referenced. See:
http://www.blackbirdsf.org/
While I didn't measure offset when mounting only a single Criterium pattern ring on the inboard shelf, it doesn't seem to be an elegant solution in that one would then need to suspend an inner chainring solely via the spacers and bolts (no shelf). The outer chainring position with the ref:175 is the same distance from the crankarm as the conventional outer chainring I'll echo any answers received from Mike to the CR and iBOB lists.
Charlie Young
Honeybrook, PA
>
> Yes it is just to let you use the arms from the TA 5 bolt
> tourist with the 6 arm rings. I remember seeing some on
> cyclecross bikes years ago. I was told this was stiffer.
> Steven Willis
> 1778 East Second Street
> Scotch Plains NJ 07076
> 908-322-9022
> http://www.thebikestand.com