The Fat Tube RSD frame is designed to accommodate for the latest extreme wide rear tires, such as Avon's 300 and 330. Frame accepts stock and aftermarket Evolution style Big Twin engines, when used in conjunction with ZPN236889 motor mount adapter it will also accept a Twin CamA style engine. Must be used with Right Side Drive transmission. The Right Side Drive frame allows for central mounting of the 330 tire in the frame and keeping a perfect balance in the bike. The frame features massive 35mm down tubes and 28mm swing arm tube size. In addition we increased the frame side plate thickness from 12 into 15mm, providing Fat looks that are in balance with the wide rear tire. These side plates are stepped at the seat mounting area, allowing the use of an Evolution Softail style seat, such as our Le Pera Bare Bone seat. Frame takes up to 12 1/2" wide RSD rear fenders. The steering head is raked to 38 degrees, this requires a 4" to 6" overstock fork (depending on the front wheel and tire size used). Mounts for side stand and forward controls are welded in place. The frame also features a Twin Cam style oil drain system. Frame is fully TIG welded for superior strength and takes 1987 thru 1999 Softail style shock absorbers, Evolution Big Twin oil tank, Flat Side gas tank, Evolution Softail style forward controls, Big Twin style steering head bearing cups, and Custom rear brake calipers with Y-bracket.