What the weldments are made of
Carbon steel precision tube (E235 to EN 10305) for the bent frames, chromoly (SCM435) for the fork blades and steerer, and stainless 304 for the steering tube, its machined bush and its laser-cut plate. The brackets, dropouts, lock plates and mounting plates are S235, S355 or cold-rolled DC01 sheet and plate, fibre-laser cut and press-brake formed. Bosses and bushes are turned from bar, with threads and bearing seats to tight tolerances such as h6.
The process chain
Tube laser cutting, CNC bending and coping come first, alongside laser cutting and forming of the plates and turning of the bosses. Every part is located in a welding jig, tacked and then welded: MAG (process 135) fillets on carbon steel, TIG (141 and 142) on stainless. A weld sequence that balances heat limits distortion, and straightening or post-weld reaming brings seats and bores back into tolerance.
Finishing follows: degreasing and zinc phosphating, then cathodic e-coat (KTL) and powder where specified, with threads, seats and paint-free zones masked. Stainless parts are pickled and passivated to remove heat tint instead.
Where India is strongest
Ludhiana has the deepest base of tube bending and MAG welding, grown on bicycles and their parts. Pune–Chakan and Chennai–Hosur add robotic welding cells, automotive-grade KTL lines and machining for bosses. Faridabad adds sheet-metal fabrication, and Rajkot builds the welding jigs and check fixtures that everything else depends on.
What drives the cost
Tube grade and wall, the number of bends and bend tools, arc-on time per part, manual versus robotic welding, and straightening labour. Jig and fixture cost is spread over volume. Coating route matters too: phosphate and KTL, powder, or both, plus masking time. Distortion scrap and rework are the hidden cost that good jigs and weld sequences remove.
What we inspect
The jig first: every locator measured against the drawing on a CMM before the first weld. Then weld penetration on a cut-and-etch macro of the first article, visual weld quality to ISO 5817 (size, undercut, porosity and spatter), fixture-to-drawing alignment, head-tube parallelism and dropout alignment. On the coating: dry-film thickness, cross-hatch adhesion to ISO 2409 and salt-spray hours to ISO 9227 on test panels.
Example teardown for illustration. Standards named here are the ones we usually check against; your drawing and target market set the exact scope.