Buying a Used ONYX

Buying a used ONYX is not only about inspecting the bike.

You are also evaluating the listing, seller, ownership history, battery, modifications, asking price, and claims being made about the bike.

You do not need to be an ONYX expert to buy a good used bike. You need to collect the right information, verify what you can, ask for help with what you cannot, and be willing to walk away before you pay.

Do not buy the story. Buy the bike you actually inspected.

This guide covers:

• ONYX 72V
• ONYX 80V
• ONYX CTY2

Many expensive problems can be discovered before purchase, but some require BMS data, testing under load, documentation, or help from somebody familiar with the bike.

If you verify only one major component, make it the battery.

• ONYX Aftermarket Caution

Before You Go See the Bike

Do as much verification as possible before traveling.

• Save the original listing and photographs
• Screenshot the asking price
• Confirm what is included
• Ask what currently does not work
• Ask what has been modified
• Ask about ownership history
• Request current photographs
• Ask the ONYX community whether anyone recognizes the bike

Marketplace listings can disappear after a sale. Save the information before meeting the seller.

Get Current Photos

Do not assume the listing photographs show the bike’s current condition.

Ask the seller to take new photographs, preferably using the camera flash for detailed areas.

Request:

• Both sides of the bike
• Battery
• Battery compartment
• Display powered on
• Odometer
• Motor
• Controller if accessible
• Wiring
• Charger
• Existing damage

Flash can expose scratches, corrosion, wiring problems, residue, repairs, and other details that may be difficult to see in low-light photographs.

If you are traveling a significant distance, ask for a current video.

You can also request a photograph that would be difficult to have prepared in advance, such as the powered-on bike next to a piece of paper showing today’s date.

The goal is simple: verify that the seller currently has the bike and that its present condition resembles the advertisement.

Ask the ONYX Community

ONYX bikes have a social owner community, and individual bikes are sometimes recognized by other owners.

Before buying, consider posting the listing in:

• ONYX AF
• The official ONYX Facebook group

Ask:

• Does anyone recognize this bike?
• Does anyone know its history?
• Has anyone worked on it?
• Has it been listed before?
• Does the asking price make sense?
• Does anyone recognize the modifications?
• Is anything unusual visible in the photographs?

Someone may remember the bike from a previous owner, ride, repair, shop, or older Marketplace listing.

Community information is useful, but it is still information to verify.

Contact Me

You can also contact me before buying a used ONYX.

Send me the listing, photographs, asking price, configuration, and whatever information the seller provided.

You can ask whether I recognize the bike, have worked on it, know anything about its history, recognize the modifications, or see something worth investigating before you buy it.

I work on and repair ONYX bikes and know these platforms well. Everything ONYX is a passion project for me, and I have spent a lot of time helping owners with these bikes.

I stay busy, so I cannot promise immediate help with every request, but it is worth reaching out. More often than not, I can at least help point you in the right direction.

The same applies if you already purchased the bike and discovered a problem.

Make Sure It Is the Bike That Was Advertised

When you arrive, compare the physical bike directly against the listing you saved.

Check:

• Battery
• Motor
• Controller
• Wheels
• Tires
• Seat
• Suspension
• Brakes
• Lighting
• Accessories
• Mileage
• Damage
• Overall condition

Make sure it is actually the same bike.

A seller may be using older photographs. The bike may also have changed since those photographs were taken.

If an advertised battery, controller, motor, charger, accessory, or other expensive component is missing or different, the transaction has changed.

The same applies to price.

Be cautious if you arrive and suddenly hear:

• “That price doesn’t include the battery.”
• “The charger is extra.”
• “Those parts aren’t included anymore.”
• “Someone offered me more, so I need another $500.”

You already traveling to see the bike is not a reason to accept a different deal.

Evaluate the bike and transaction that exist in front of you.

A Real Used ONYX Example

A buyer contacted me after purchasing a 72V ONYX RCR through a Facebook Marketplace listing in Asbury Park, New Jersey.

According to the buyer, he paid $3,500 for the bike.

He told me that parts of the transaction felt off, but he was excited about finally getting the bike and completed the purchase.

He also told me that the seller specifically warned him not to listen to John Angel or ONYX Motors and claimed they knew how to do the bikes better.

The unusual part was that the buyer did not know who I was.

Mentioning my name caused him to look me up.

About two weeks later, the bike began shutting off and the buyer reached out to me.

I inspected the bike and found a problem involving cell group 18 in the ONYX 41Ah battery.

The Bluetooth BMS name itself also indicated that the battery had previously been identified as bad.

After the buyer contacted the seller about the battery problem, the seller agreed to refund $1,000 toward replacing the battery.

A replacement battery now costs roughly $1,000.

The important lesson is not that every buyer needs to understand how to repair cell group 18.

The buyer needed a process that could have identified the battery problem before paying for the bike.

Attacking another source also did not establish anything about the condition of the bike.

If a seller tells you not to listen to John Angel, ONYX Motors, another shop, or another owner, investigate the actual technical claim yourself.

Seller and Ownership

Do not let the seller rush the inspection.

Ask:

• What does not work correctly right now?
• What has been modified?
• Has the bike or battery ever unexpectedly shut down or had an intermittent problem?
• Who performed the repairs or modifications?
• Why are you selling it?

“I don’t know” can be a legitimate answer.

A confident answer that cannot be supported is not necessarily more useful.

Ownership

Make sure the person selling the bike can reasonably demonstrate the right to sell it.

Useful records can include:

If documentation is missing:

• Ask the seller to search email
• Request available purchase confirmation
• Contact ONYX for post-2025 records where appropriate

If the seller says the bike belongs to a friend, relative, or somebody else, slow down and verify the situation.

The person selling the bike, the claimed owner, and the person receiving payment should make sense together.

Bill of Sale

Get a bill of sale that identifies the actual bike and transaction.

Where appropriate, document:

• Seller
• Buyer
• Date
• Bike identification
• Price
• Battery
• Charger
• Major included components

Do not rely on a document that identifies the transaction only as “electric bike.”

Quick Used Bike Inspection

Start with checks that anyone can perform.

If something does not make sense, slow down.

If you do not understand something, take a clear photo or screenshot and ask before paying.

Basic Bike Inspection

Frame and Rust

Rust inside electrical areas deserves additional investigation.

Look for physical evidence that contradicts the seller’s description.

If the seller says the bike was never exposed to rain but electrical areas show significant corrosion, ask why.

If the seller says the bike was never modified but the wiring has clearly been changed, investigate further.

Harness and Internal Wiring Inspection

• ONYX 72V / ONYX 80V: remove side panels
• ONYX CTY2: remove battery tray

Good Signs

• Uniform routing
• Appropriate connectors
• Appropriate terminals and crimps
• Correct insulation
• Proper strain relief
• No obvious heat damage

Warning Signs

• Large unexplained tape bundles
• Exposed copper
• Poor crimps
• Improvised twisted connections
• Mixed or questionable wire gauges
• Melted insulation
• Burned connectors
• Loose terminals
• Poor routing
• Abrasion damage

A crimped connection is not automatically bad. Proper crimping is a standard electrical connection method.

The issue is workmanship.

If wiring has been modified, ask who performed the work and why.

Check the Battery

The battery is one of the most important and expensive components on a used ONYX.

A bike can look excellent while having a battery problem that substantially changes its real value.

BMS Apps

Install the appropriate app before you arrive.

You should normally be able to connect to the battery before buying.

If the seller cannot provide BMS access, treat the battery as an unknown until you can verify it.

What to Check

Depending on the battery and BMS, look at:

• Total pack voltage
• Individual cell-group voltages
• Highest and lowest cell groups
• Protection or error information
• Temperature information
• State of charge
• Current
• Behavior under load

You do not need to understand every number.

Look for something obviously abnormal and take screenshots.

Connecting to the BMS proves that you connected to the BMS. It does not prove the battery is healthy.

Before and After the Test Ride

Take useful BMS screenshots before riding.

Test the bike under meaningful load.

Check the BMS again afterward.

Look for:

• Shutdown
• Reset
• Sudden power loss
• Protection events
• Abnormal cell-group behavior
• Abnormal heat

A full charge can hide some problems. Battery behavior under load matters.

When practical, testing between 30% and 70% can provide more useful information than looking only at a freshly charged battery.

Voltage Reference

Battery Identification

• 72V and 80V use metal battery cases
• CTY2 does not

If the expected battery or enclosure is missing, assume the system has been modified and inspect further.

Ask whether the battery has ever been:

• Opened
• Repaired
• Rebuilt
• Recelled
• Modified
• Had the BMS replaced
• Had connectors changed

An externally stock-looking battery may not be internally stock.

Also look at the Bluetooth device name.

A Bluetooth name does not establish battery health by itself, but if the battery has been deliberately labeled “bad,” “failed,” or something similar, stop and find out why.

Electrical System

Controls

Brakes

Suspension

Wheels and Spokes

Tires

ONYX 72V and ONYX CTY2

Check:

• Even wear
• Cracking
• Damage
• Rubbing
• Overall condition

ONYX 80V

Check:

• Correct size
• No clearance issues
• Even wear
• Cracking
• Damage

A tire can have remaining tread and still need replacement because of age or condition.

Motor

Bring a motor tester when buying used equipment if you know how to use one.

Otherwise, photograph anything you do not recognize and ask for help.

Controller

If the controller is not stock, continue to the modified-bike section before deciding what the bike is worth.

Charger

Do not assume a charger is correct simply because the connector fits.

Verify that it is appropriate for the actual battery.

Test Ride

Do not test ride a bike that already appears unsafe.

If the frame, brakes, wheels, wiring, or another critical system presents an obvious problem, investigate that first.

For a bike that appears safe to ride:

A 30-second parking-lot ride may not reveal an intermittent electrical problem.

Ride long enough to meaningfully load the battery and evaluate the bike.

After the ride:

• Check the BMS again
• Check battery behavior
• Check connectors
• Check wiring
• Check motor
• Check controller
• Check brakes
• Check for abnormal heat

Odometer Check

1. Hold SET 10 seconds
2. Release
3. Hold again

Mileage is useful information, but condition matters more than a low odometer number.

A low-mileage bike can still have a degraded battery, poor storage history, water exposure, crash damage, or bad modifications.

Buying a Modified or Performance ONYX

A modified bike is not automatically a performance bike.

A bike can have an aftermarket battery, controller, motor, harness, and a higher claimed top speed while still being poorly planned as a complete system.

Start with one question:

Is this bike stock or modified?

If modified, determine what changed.

At minimum, identify:

• Battery
• BMS
• Main harness
• Main battery connector
• Controller
• Motor
• Charger
• Major supporting modifications

Think about the electrical system as a complete path:

Battery -> connector -> harness -> controller -> motor

Expensive individual parts do not prove that the complete system is well designed.

Ask About the Build Plan

Ask what the builder was trying to accomplish.

Was the goal:

• Acceleration
• Top speed
• Range
• Reliability
• Sustained performance
• Racing
• General street use

Then ask why the battery, controller, motor, and harness were selected for that goal.

I regularly encounter modified ONYX bikes where the battery, controller, motor, harness, or settings were not planned as one complete system.

Parts may have been selected from several unrelated recommendations without verifying how everything works together.

Post the Plan

A much better habit in the ONYX community is to post a proposed build before buying all the parts.

Use ONYX AF or the official ONYX Facebook group and explain:

• What you want the bike to do
• Battery you plan to use
• Controller
• Motor
• Harness/connectors
• Other major changes

Other owners can identify obvious compatibility problems, missing considerations, unrealistic expectations, or better combinations before the money is spent.

This is community peer review, not engineering certification.

Before building an ONYX, post the plan. Before buying somebody else’s modified ONYX, reconstruct the plan.

If the seller cannot explain why the components were selected, treat the build as something you need to evaluate rather than automatically paying a premium for the modifications.

Aftermarket Controllers

If the stock controller has been replaced, identify the manufacturer and model.

If available, document important configuration information.

You do not need to understand every controller setting while standing next to the bike.

Take screenshots or photographs and ask someone familiar with the controller.

Do not accept “professionally tuned” as a complete technical explanation.

Ask who configured it and what the tune was intended to accomplish.

Top Speed Is Not Performance

A seller saying:

“It does 70 mph.”

does not establish that the bike is a good performance build.

Acceleration, battery behavior, heat, repeatability, braking, reliability, and behavior as the battery discharges also matter.

Performance is not one peak number.

A well-developed performance bike should behave like a complete system, not simply produce an impressive number once.

Supporting Hardware

More electrical power also affects:

• Brakes
• Tires
• Wheels
• Spokes
• Axle retention
• Suspension
• Chassis

A faster electrical system does not automatically make the complete bike better.

Determine the Real Cost

Do not value a used ONYX based only on the seller’s asking price.

Use:

Purchase price + immediate repairs + missing parts + necessary safety work = actual acquisition cost

A $3,500 bike that immediately needs a roughly $1,000 battery is not the same purchase as a healthy $3,500 bike.

The same applies to:

• Tires
• Brakes
• Charger
• Wiring repairs
• Controller
• Motor
• Missing components

A seller may say:

“I have $8,000 into this bike.”

That does not automatically establish its current value.

Some modifications add value.

Some add little value.

Some reduce value.

Some cost money to correct.

You are buying the bike’s current condition, not reimbursing the seller for everything they ever spent on it.

Project Bikes vs Complete Bikes

A broken ONYX is not a cheap ONYX.

Buying a non-running or incomplete bike is not automatically a shortcut to owning one inexpensively.

Common problems include:

• Missing or incorrect parts
• Unknown electrical work
• Time spent sourcing parts
• Repeated troubleshooting
• Previous modifications that need to be corrected

What matters:

• 72V parts can be harder to source
• Electrical systems are not automatically plug-and-play
• Battery, controller, wiring, and motor need to work together

If you do not understand the system, you may depend on somebody else to finish it.

Price the missing or failed components before buying.

You are not only buying parts.

You are buying the previous work and the problems that come with it.

Maintenance History

Recent repairs are not automatically a warning.

They are part of the history you should understand.

Be Willing to Walk Away

Decide before you arrive what will cause you to stop the transaction.

Examples:

• Bike materially differs from the listing
• Ownership does not make sense
• Seller refuses reasonable inspection
• Seller refuses battery/BMS access without a reasonable explanation
• Bike unexpectedly shuts down
• Major damage was not disclosed
• Expensive claimed components cannot be identified
• Deal changes substantially after you arrive

Do not let travel expenses change your decision.

Gas, tolls, train fare, or two hours of driving are already spent.

They do not make a questionable bike a better purchase.

The same applies to urgency.

Maybe another buyer really is coming with cash.

That does not change the condition of the battery.

You do not need to prove that the seller did something wrong.

You can simply say:

“This isn’t the bike for me.”

Then leave.

Final Check

Before paying:

• Does the bike match the listing?
• Can the seller reasonably establish ownership?
• Did you inspect the battery and BMS?
• Did you test the bike under load?
• Did anything shut down, reset, or behave incorrectly?
• Do you understand the major modifications?
• Does the price still make sense after necessary repairs?
• Is there anything you should ask the ONYX community about before buying?

If something feels off, do not ignore it.

If you do not understand something, take a picture or screenshot and ask.

You do not need to know everything about an ONYX to buy a good used one.

You need to know when you have enough information to proceed and when you do not.

Inspect first. Decide second. Pay last.