Four 2in tube sections were welded to the chair creating the attachment points. Two on this side, two on the other.

Four 2in tube sections were welded to the chair creating the attachment points. Two on this side, two on the other.

Four 2in tube sections were welded to the chair creating the attachment points. Two on this side, two on the other.

View shows attachment points, with hand cycle attached. Very important that they do not interfere with regular function of the chair. This is my full time wheelchair, with or without the hand cycle attached.
Aluminum housing tube welded inside the bottom tube of a canondale mountain bike frame.