BicycleCinema.org
Bike generator in the Low Tech Magazine living-room power setup
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Low-tech Magazine — Household Bike Generator

United Kingdom · Open plans

Historical last verified 2026-09 Published as an open build guide on 6 March 2022; the document and its schematics remain current. It describes a household generator, not a fielded cinema, and the sources located do not state where the publication is based, so the entry carries no map pin or city.
Topology not documented
1 bicycle (1950s exercise bike with flywheel, friction drive)Documented
  • Open manual source
  • Split from an aggregated directory row

Websitehttps://solar.lowtechmagazine.com/2022/03/how-to-build-a-practical-household-bike-generator/

No location documented — this entry has no map pin.

Low-tech Magazine published a measured, open build guide for a household bicycle generator on 6 March 2022. The same generator ran a video projector directly from its regulated 12-volt circuit, with no battery in between.

Key facts

  • Sustained output

    45–75 W1

    Measured

  • Burst output

    ~100 W1

    Measured

  • Peak generator efficiency

    75–78% (above 72 W)1

    Measured

  • Published

    6 March 20221

    Documented

“Our generator achieves its maximum efficiency (75-78%) at a power output of more than 6A (72W). Efficiency decreases when you produce less power: it drops to 60% at 3A and less than 45% at 2A.”

Low-tech Magazine, 'How to Build a Practical Household Bike Generator', 6 March 20221

The solar-powered publication on low-energy technology run by Kris De Decker compiled the loss-budget figures still cited across the field in a 2011 article, "Bike powered electricity generators are not sustainable" 3,2; the 2022 guide turned that reading into an instrumented build 1. A 1950s exercise bike with a flywheel turns a permanent-magnet DC motor through a friction drive, and a control panel of buck/boost circuits distributes the output to USB, battery-charging and inverter circuits 1. The guide is a household energy project, about lighting a home, boiling water and running small appliances from pedalling. It is in this directory because its output and efficiency were read at the generator with volt/ampere meters, and because, with the KLAK manual, the Bespoke Gear no-weld plans and the Cinebike build log, it is one of the four open manuals here from which a system can be built.

Specifications

What do these labels mean?

FieldValueConfidenceSources
Generator type12V/24V permanent-magnet brushed DC motor (Ampflow Pancake Motor P40-250)Documented1
Generator rated powerup to 250 W (150–250 W typical range recommended)Documented1
Control-panel outputs5 V USB, 12 V, 14.4 V battery charging and 220 V AC via inverter, plus one unregulated circuitBuck/boost converter circuits on the build's own control panel.Documented1
Sustained output (moderate effort)45–75 WMeasured1
Burst output (short, heavy effort)about 100 WMeasured1
Generator efficiency, above 72 W (6 A)75–78 %Measured1
Generator efficiency, at 36 W (3 A)60 %Measured1
Generator efficiency, at 24 W (2 A)below 45 %Measured1
Friction-drive coupling lossabout 15 % (average extra loss)Measured1
Pedal input needed for 100 W outputat least 150 W (accounting for generator and friction-drive losses)The authors' own derivation from their measured efficiencies, not a separately instrumented figure.Estimated1
Output after drivetrain cleaning/oilingdoubledPower production doubled after the bicycle's drivetrain was thoroughly cleaned and oiled.Measured1
2011 loss budget (chained AC architecture)42–67.5 % total electrical loss (32.5–58% net efficiency)Generator 10–20%, voltage regulator ~25%, battery 10–35%, converter 5–15%; a literature-sourced cascade, not this build's own measurement.Documented2,3

Technology

The guide specifies a brushed permanent-magnet motor because brushless types need too high a rotation speed 1. Efficiency falls steeply as the load drops, so a generator turned gently by several casual riders can sit at the worst point of its own curve 1.

Data card of the measured sustainable and burst outputs and the drivetrain-hygiene finding
45–75 W sustained, ~100 W short heavy effort (measured at the generator); output doubled after cleaning and oiling the drivetrain1,2 Image: BicycleCinema.org, drawn from the research corpus
Bike generator powering a 12 V air compressor at Low Tech Magazine
Photo: Low Tech Magazine (solar.lowtechmagazine.com) — via solar.lowtechmagazine.com
Line drawing of a friction-drive bicycle generator showing the blocking diode that stops the battery driving the pedals
Friction-drive household generator with Schottky blocking diode1,2 Image: BicycleCinema.org, drawn from the research corpus
Low Tech Magazine bike generator build detail
Photo: Low Tech Magazine (solar.lowtechmagazine.com) — via solar.lowtechmagazine.com

In their own words

"We obtained roughly 100 watts (12V, 8-9A) of power during a short and heavy workout. During a moderate effort – which we can sustain for a longer time – power production is between 45 and 75 watts." 1

Sources

  1. [1]Low-tech Magazine — How to Build a Practical Household Bike Generator (2022)solar.lowtechmagazine.com
  2. [2]Low-tech Magazine, 'Bike powered electricity generators are not sustainable'www.lowtechmagazine.com
  3. [3]Low-tech Magazine — Bike-powered electricity generators are not sustainable (2011)solar.lowtechmagazine.com

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