Here are the answers to your questions;
* The rotor was purchased through another prominent tandem manufacturer that offers 10" (255mm) discs. We will shortly be offering a rotor that has been optimized for lighter weight, cooling, rigidity, durability and "good looks". The chief characteristic that impresses us about this rotor [the 10"] is its size!
* We fabricated adapters for use with our disc brake dropouts and Avid mechanical disc brakes
* 10" disc clearance is a no charge option on Calfee tandems (we've been doing this by request for years). To create clearance, we remove additional material from the chainstay, add material inside the tube, and wrap with carbon to create the requisite strength.
* 203mm is the largest disc that will clear Calfee tandems that have not been made compatible with 10" rotors.
* We can modify/repair Calfee chainstays to achieve clearance for 10" rotors (I'll return with a price).
* In the last 3 years, we've had one customer strongly request 10" rotors. After speaking with him about this particular requirement, we agreed that he could benefit from the 10" rotor and moved to fabricate the appropriate adapter. Now, we are happy to offer this frame option as well as the supporting hardware.
* I'm generally sympathetic to Dave's point(s)
and we'll sell very few of these 255mm rotors. That said, if the customer does not care about cost, weight, and compatibility challenges and "feels" strongly that they contribute to an increase in performance and/or "peace of mind", then we stop pushing back and provide the solution. Ultimately, it is our position that some teams can benefit from this rotor size.