CAIBI ASSESSMENT

OpenBike Rev4

CAIBI VERDICTWORTH CONSIDERING

An open wooden bicycle whose frame parts are CNC-cut locally, with additional printed parts and conventional bicycle components assembled into a usable physical vehicle.

See what the build involves Original source ↗

Build or buy?

Compare the documented build with the purchase reference.

Build it yourself

Build estimate£350–£800CAIBI estimate · low confidenceOne bicycle; standard components and modest CNC allowance

Time: Not currently published by the source
Difficulty: 4/5
Physical processes: CNC router · 3D printer · Mallet · Allen keys · Bicycle assembly tools · Measuring and inspection tools

See build requirements →

Purchase reference

Buy price referencePrice not checkedNo priced alternative recorded

Check the source for the exact model, availability and what is included.

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Purchase comparison not yet priced

What the prices cover

Broad planning allowance for plywood/CNC fabrication, printed parts and conventional bicycle components. Local CNC access and reused cycle parts can move the result far outside this range.

Includes: Frame sheet material; CNC fabrication allowance; Printed parts; Typical bicycle component allowance.

Not included: Owned workshop machinery; Premium drivetrain/wheels; Finishing labour and shipping.

Build evidence recorded 4 Sep 2026. Currency conversions are approximate.

The build cost changes dramatically with local CNC access, reused cycle components and specification. Comparing it with a mass-produced bicycle would mostly measure production scale rather than the project.

BUILD AT A GLANCE

Source view and main parts

Check the source ↗

OpenBike Rev4 source photograph · Arquimaña ↗

PHYSICAL BUILD11 key parts or groups

No.	Source specification
01	21 mm birch plywood for the main fabricated wooden structure
02	5 mm aluminium plate
03	TPU filament for printed parts
04	Carbon-fibre PLA filament as listed by the Rev4 source
05	Wood glue
06	BB86 press-fit bottom bracket
07	Single-speed crankset with 24 mm spindle and 50-tooth chainring
08	Chain and flat pedals
09	1 1/8 inch steering/headset components
10	20 inch front and coaster-brake rear wheels as specified by the current Rev4 source
11	18-tooth sprocket and required fasteners

Full source specifications

21 mm birch plywood for the main fabricated wooden structure
5 mm aluminium plate
TPU filament for printed parts
Carbon-fibre PLA filament as listed by the Rev4 source
Wood glue
BB86 press-fit bottom bracket
Single-speed crankset with 24 mm spindle and 50-tooth chainring
Chain and flat pedals
1 1/8 inch steering/headset components
20 inch front and coaster-brake rear wheels as specified by the current Rev4 source
18-tooth sprocket and required fasteners

TOOLS / PROCESSES6 involved

CNC router
3D printer
Mallet
Allen keys
Bicycle assembly tools
Measuring and inspection tools

The real-world work

YOU STILL HAVE TOThe real-world work

Source structurally suitable plywood, aluminium and bicycle components
Prepare and supervise CNC machining
3D print the required parts
Inspect every machined and printed component
Assemble and align the frame, fork, steering and drivetrain
Set up and verify brakes and wheels
Make the final safety and road-use decision

THE BUILD SEQUENCE

How it comes together

1Preparation

Choose Rev4 and obtain the source manufacturing package
Use the current OpenBike Rev4 source rather than mixing earlier revision files. Review the assembly manual and fabrication data before buying material or modifying geometry.
AI + YOU
Map the full material and bicycle-component requirement
Separate CNC sheet material, printed parts and conventional bicycle hardware. AI can help cross-check the list, but compatibility and structural suitability must be confirmed against the physical components.
AI + YOU
Prepare the CNC work from the supplied design data
Confirm material thickness, tool diameter, workholding, zero position and CAM interpretation before cutting. Do not casually alter load-bearing or steering geometry because a generated change looks plausible.
AI + YOU

2Build and assembly

Machine and inspect the plywood and aluminium parts
Cut the source parts on suitable CNC equipment, then inspect dimensions, edge condition, hole fit and any damaged or weak material before assembly.
YOU
Print the required polymer parts
Print the Rev4 polymer components using the source material route. Check orientation, layer integrity and fit on the actual mating parts rather than accepting a successful print as proof of suitability.
YOU
Assemble frame, fork and steering interfaces
Follow the source manual carefully around the steering and frame interfaces. Independent fablab experience shows that steering-axis fit can become a real iterative fabrication problem rather than a simple bolt-together step.
YOU

3Configure and test

Install wheels, drivetrain and controls
Fit the wheels, bottom bracket, crank, chain, sprocket, pedals and all steering/braking hardware. Verify alignment, free movement, fastener security and braking function mechanically.
YOU
Inspect before any riding load is applied
Check frame joints, steering play, wheel retention, brake operation, tyre condition and component clearances. Any first ride should only follow a competent real-world inspection; AI cannot certify the finished vehicle.
YOU

Benchmark this project

Use the OpenBike Rev4 prompt. Compare what different models deliver, then add what happened when you tried it.

Try this benchmark

View the project prompt

CAIBI adaptation · Prompt 1.0 · Project source

Prompt for OpenBike Rev4

CAIBI project benchmark: OpenBike Rev4
Prompt version 1.0

Help me build OpenBike Rev4 using the existing creator project at https://openbike.cc/download/. This is a CAIBI benchmark adaptation of the project build brief, not a claim about how the creator used AI.

Project context:
- An open wooden bicycle whose frame parts are CNC-cut locally, with additional printed parts and conventional bicycle components assembled into a usable physical vehicle.
- Build context: 21 mm birch plywood for the main fabricated wooden structure; 5 mm aluminium plate; TPU filament for printed parts; Carbon-fibre PLA filament as listed by the Rev4 source; Wood glue; BB86 press-fit bottom bracket; Single-speed crankset with 24 mm spindle and 50-tooth chainring; Chain and flat pedals; 1 1/8 inch steering/headset components; 20 inch front and coaster-brake rear wheels as specified by the current Rev4 source; 18-tooth sprocket and required fasteners.
- Where AI helps: Explain the source BOM and fabrication sequence, Help map source dimensions into CNC/CAM preparation, Compare reusable bicycle components with source requirements, Help reason through non-safety-critical customisation before cutting, Troubleshoot assembly observations against the documented geometry.
- Physical work: Source structurally suitable plywood, aluminium and bicycle components, Prepare and supervise CNC machining, 3D print the required parts, Inspect every machined and printed component, Assemble and align the frame, fork, steering and drivetrain, Set up and verify brakes and wheels, Make the final safety and road-use decision.
- Main limitation: A downloadable bicycle design is not proof of a safe finished bicycle. Steering fit, frame joints, material quality, wheel alignment, braking and every load-bearing interface must be verified on the real build. CAIBI has not road-tested Rev4 and does not infer roadworthiness from the files.

Read the source first. Use its published design, files, dimensions and parts as the baseline; do not redesign it unless a missing detail requires a clearly labelled proposal. If you cannot access a source or verify a revision, say so.

Provide one practical build package:
1. Design and files: explain the source design, link the original editable files, and identify missing files or modifications.
2. Parts and fabrication: give quantities, exact variants and compatibility, plus a cutting or printing list where applicable. Preserve source dimensions; flag anything unconfirmed.
3. UK and US purchasing: direct product links, checked dates, stock, pack sizes, taxes, delivery and regional costs. Mark unverifiable details as unknown; do not invent links, prices or availability.
4. Assembly: an ordered guide covering fabrication, fitting, wiring or software as applicable, setup, checks and troubleshooting.
5. Cost and time: separate parts, fabrication, delivery, hands-on time and machine time, with assumptions and exclusions.
6. Function and ease: a test plan for the project's stated purpose, likely difficulties, required skills and any corrections or limitations.

Keep source facts, your proposals and items needing physical verification distinct. An estimate is not a measured build result. Do not claim to have built or tested hardware. Include failed attempts and omissions. If a section does not apply, say why.

Use the source as accessed during this run and record its revision or access date. The prompt is fixed; the linked source can change.

Open and copy prompt →

Benchmark results 0

No reviewed results yet for OpenBike Rev4. Add the first result →

AI IN THIS PROJECT

Get AI help on this build

CAIBI · AI CAN HELP

AI can help with

Explain the source BOM and fabrication sequence
Help map source dimensions into CNC/CAM preparation
Compare reusable bicycle components with source requirements
Help reason through non-safety-critical customisation before cutting
Troubleshoot assembly observations against the documented geometry

CAIBI · AI CAN'T DO

You still need to

Source structurally suitable plywood, aluminium and bicycle components
Prepare and supervise CNC machining
3D print the required parts
Inspect every machined and printed component
Assemble and align the frame, fork, steering and drivetrain
Set up and verify brakes and wheels
Make the final safety and road-use decision

Original source AI use and prompts

SOURCEThe original project does not publish an AI prompt

The prompts below are CAIBI helpers for this build. They are not presented as instructions from the creator.

CAIBI STARTING PROMPTS

Copy a prompt for this build

Each prompt tells AI to keep the original project source as the reference and to flag anything you must verify on the real build.

Ways to take it further

AFTER THE FIRST BUILD

Ways to take it further

Rev1, Rev2 and Rev3 historical OpenBike variantsLocal material and finish choices within source constraintsReuse of compatible donor bicycle componentsCargo-rack use on Rev4Cosmetic and non-safety-critical personalisation

More routes and resources

OTHER WAYS TO GET THERE

You do not have to follow one route.

ORIGINAL BUILDFollow the creator route

Use the published files and instructions as the baseline.

OUTSOURCE A PROCESSGet specialist fabrication done

You do not necessarily need to own every capability used here: CNC router, 3D printer, Mallet, Allen keys, Bicycle assembly tools, Measuring and inspection tools.

ALTERNATIVE PROJECTImageGenCam

A buildable Raspberry Pi camera designed around a Codex-assisted hardware and software workflow.

REVIEWED RESOURCES

Useful places beyond the main source

DOCSOpenBike manufacturing files and build route

Primary Arquimaña source for the Rev4 materials, CNC and 3D-print fabrication route, reused bicycle components, downloadable files and assembly-manual access.

DOCSOpenBike project background

Primary project context from Arquimaña covering distributed local manufacturing, maker culture and the project history.

COMMUNITYKonkarlab Woody Bike build log

Independent fablab build log documenting real steering-axis fit work, temporary 3D-printed adaptation and repeated CNC machining while resolving the physical assembly.

COMMUNITYGoogle Arts & Culture OpenBike exhibit

Independent institutional description of the OpenBike as a hand-assembled wooden bicycle fabricated locally from shared CNC and 3D-print data.

COMMUNITY3Dnatives OpenBike overview

Independent additive-manufacturing coverage confirming the mixed CNC/3D-print route and the progression through multiple OpenBike revisions.

SOURCE · CAIBI · BUILDERS

What supports the verdict

SOURCEArquimaña / OpenBike

The current OpenBike site still publishes the Rev4 route, materials, tools and downloadable manufacturing/assembly access. Independent coverage confirms the distributed CNC/3D-print concept, and a fablab build log documents real fit and steering work on an OpenBike-family build. CAIBI has not independently road-tested Rev4, so structural and roadworthiness claims remain outside the verified layer.

Open source ↗

CAIBIWORTH CONSIDERING

OpenBike is a strong example of data becoming a large, useful physical object without a conventional factory supply chain. AI can help inspect fabrication files, explain assembly, adapt non-safety-critical geometry and reason through sourcing. The main reason to build is local fabrication, learning, repairability and design control, not a guaranteed saving over buying a bicycle.

Evidence: Moderate

BUILDERSNo published reports yet

Actual time, cost, changes and outcomes appear here after submitted builds are reviewed.

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HAVE YOU MADE THIS?

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First-hand evidence improves the assessment

What we want to know

What happened when you actually tried to make it.

Did it work?
Actual time and cost
What did you change?
What was harder than the source suggested?
Would you build it again?