Anatomy of the new Kirk Frameworks cyclocross frame
Part One – Frame design, fork and seatstays
Proceed to Part two - mitering of the main tubes and prepping the lugs
When I build a frameset I do it in more or less a specific order and in every case I start by creating the design for the frame and the rider. The frame design provides all the rider-specific numbers like top tube length and also has the dimensions needed to cut the tubes to the right length and to properly set the jig for the construction. The JK Cross uses the same tubeset as the JK Special and has geometry suited to cross racing in a variery of conditions. The JK Cross has a level top tube for ease of shouldering the bike and uses lugs to allow for that.
When the design is complete the raw materials are gathered and a quality control check is made of every piece. Once that is done I start into the “subassemblies.” This means doing all the prep work of joining dropouts to chainstays and capping and shaping the seat stay tops. Once complete these subassemblies are set aside until needed later. I also build and finish the fork at this stage.
Computer image of complete bike including all jig and cut dimensions.
All major raw materials laid out and ready to cut –
Lugs – Sachs Singer
Dropouts – Breeze Hood Style
Top tube – Reynolds 953
Down tube – Reynolds 953
Seat tube – True Temper S3
Chainstay – proprietary Reynolds
Seat stay – proprietary Reynolds
Fork Crown – Sachs
Fork Blades – Reynolds lightweight
Steerer – Reynolds butted lightweight
Freshly brazed cantilever brake studs
“H” tools used to make front dropout faces parallel and concentric
Stamping serial number
Fork ready for alignment
Finished fork tips
“Full deck” blade reinforcements
Completed fork
Chainstays and dropouts ready to be joined
Chainstays mitered for dropouts
Dropouts and chainstays in jig, covered with flux and ready to braze
Preliminary brazing of dropouts
Freshly laid fillet on dropout still hot and covered with flux
One dropout cleaned up and one to go
Marking for chainstay to bottom bracket miter
Rough cut for chainstay/BB miter
Tire clearance dents made with arbor press
Seatstay Caps
This type of cap is labor intensive so it’s seldom done now but it’s also the lightest and strongest type. Most caps are solid cast steel plugs that are brazed into the end of the stay. The inverted tube type I make are hollow to the very end.
Rough cut on top of seat stays in preparation for caps
One of the stays mitered for cap and one rough
Both stays mitered and caps cut
Freshly brazed tubular stay cap
| Pair of finished stay caps curved to match the curve of the seat lug where they will join. |
| One finished and one rough cut cap. The concave surface of the cap is the inside of the tube that was brazed on. |