What an e-bike is made of
The frame is 6061 aluminium tube: extruded, drawn and butted, hydroformed, mitred, TIG-welded, heat-treated to T6 and powder coated. The fork is 4130 chromoly steel. The rear dropouts are investment-cast stainless, the crank arms are forged 6061 aluminium and the chainring is heat-treated 1045 steel.
The electric drive is where the money sits: a 36 V pack of 21700 lithium-ion cells with its battery management board, a 250 W hub motor with a die-cast housing, copper windings and NdFeB magnets, and a display and controller built on a printed circuit board assembly.
The process chain, part by part
Tap any part in the drawing to see its chain. A frame runs through tube extrusion, butting, hydroforming, mitre cutting, TIG welding, T6 heat treatment, alignment and powder coating. A crank arm goes from billet to hot forging, trimming, CNC machining and anodising. The motor combines high-pressure die casting, CNC machining of the bearing seats, stator winding and an IP test.
Where India is strongest
Ludhiana is India’s bicycle capital and forges cranks, chainrings and many bought-in parts. Rajkot casts and machines precision parts such as dropouts. Pune–Chakan brings forging and an automotive and EV supply base. Noida, Bengaluru and Chennai assemble electronics, which suits the display and controller. Cells and hub motors are usually imported, and the rest of the bill of materials can be split by strength.
What drives the cost
In our illustrative should-cost at 5,000 units a year, the battery pack and hub motor are more than half of the bike. After those, the frame is the next largest line: tube grade, weld time, heat treatment and finish decide its price. Volume, the number of frame sizes and colours, and the certification scope move the rest.
What we inspect
Weld quality and frame alignment in a jig, fatigue results to ISO 4210, EMC to EN 15194, battery transport testing to UN 38.3 and the labelling the EU Battery Regulation asks for. On the line we check torque, cable routing and a ride test, then run a pre-shipment inspection against an agreed AQL.
Example teardown for illustration. Standards named here are the ones we usually check against; your drawing and target market set the exact scope.