Calculations

How to Calculate Bicycle and E-Bike Production Metrics: 5 Core Formulas

Worked formulas for the five calculations that run a bike or e-bike line: frame weld yield, battery pack energy, test station capacity, wheel build standard time, and final road test energy load.

An e-bike assembly line runs on five numbers: weld yield, pack energy, test station capacity, wheel build labor time, and end of line energy load. Get any one wrong and the plan falls apart. If you schedule 300 bikes per day against a frame line that actually yields 91 percent, you are 27 frames short every shift. This guide works each formula step by step with real units and worked examples, and points to the calculator that automates it. Pricing and benchmark targets are covered in separate guides; here the goal is doing the math correctly.

Start with frame weld yield. First pass yield at one station is good frames divided by frames started, so 194 good frames from 200 welded is FPY = 194 / 200 = 0.97. Frames pass through multiple operations, so multiply station yields to get rolled throughput yield: RTY = 0.97 x 0.98 x 0.95 = 0.903 across tacking, final weld, and alignment. To hit 300 shippable frames you must start 300 / 0.903 = 333. Pull the good and started counts from end of line inspection and rework logs, not from operator memory. The Frame Weld Yield calculator chains the stations for you and flags the worst one.

Battery pack energy comes from the cell configuration. Pack voltage equals cells in series times nominal cell voltage, and capacity equals parallel groups times cell amp hours. A 13s4p pack built from 5.0 Ah, 3.6 V nominal 21700 cells gives 13 x 3.6 = 46.8 V and 4 x 5.0 = 20 Ah, so energy is 46.8 x 20 = 936 Wh. Range follows from consumption: at 12 Wh per km on assist level two, 936 / 12 = 78 km. Cell voltage and amp hours come from the cell datasheet at a stated discharge rate; use the 0.2C rating, not the peak. Cost per pack is a separate question, covered in the cost guide.

Test station capacity is available time times stations times uptime, divided by cycle time. A motor dyno with a 4.5 minute cycle, two stations, a 450 minute shift, and 90 percent uptime delivers 450 x 2 x 0.90 / 4.5 = 180 motors per shift. The Motor Test Capacity calculator runs this with changeover allowances built in. Firmware follows the same logic with gang programming: an 8 port fixture flashing controllers in 3.0 minutes moves 8 x 450 x 0.95 / 3.0 = 1,140 units per shift, so one fixture covers several assembly lines. Use the Firmware Flashing Throughput calculator when flash time varies by controller model.

Wheel build standard time is the sum of measured elements: lacing, tensioning, truing, and dish check. Time each element with a stopwatch over 10 cycles and add a personal, fatigue, and delay allowance of 12 to 15 percent. A hand built 36 spoke wheel typically breaks down as 8 minutes lacing, 10 minutes tensioning and truing, 3 minutes dishing and final check, so standard time = (8 + 10 + 3) x 1.13 = 23.7 minutes. Machine lacing with robotic tensioning cuts that to 6 to 8 minutes. The Wheel Build Labor calculator converts standard time into builds per shift, and the Brake Adjustment Time calculator applies the identical element method to caliper setup.

Every finished e-bike burns energy in final road test, and it adds up at volume. Energy per bike equals average power draw times test duration: a 6 minute dynamic test at 250 W average consumes 250 x 0.1 h = 25 Wh. Add the recharge to shipping state of charge: topping a 936 Wh pack from 55 to 60 percent through a charger at 90 percent efficiency takes 936 x 0.05 / 0.90 = 52 Wh. At 100 bikes per day that is 7.7 kWh of test related demand. The Final Road Test Energy Load calculator sizes the charging bank and the circuit so test does not become the bottleneck.

Tie the five calculations together with takt time. Takt = available production time / customer demand, so a 450 minute shift producing 300 bikes gives 450 x 60 / 300 = 90 seconds per bike. Now check every result against 90 seconds: 180 motors per shift on the dyno equals 150 seconds per motor, so motor test, not welding, caps the line at 180 units unless you add a station. Rerun the numbers whenever demand, cycle time, or yield moves more than 5 percent. For what these operations cost per unit, see the cost estimation guide; for target ranges, see the KPI benchmarks guide.

Published 2026-07-02.