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Does it fit my bike?

Yes you can!

Customers ask us all the time, "Can I put the kit on my bike? Does it fit my bike?" Please read the following guide so you can be absolutely sure that the Unlimited eBike Kit will work on your bike. Spoiler! What you should be looking at is your bike Wheel Size.


Wheel Size

The most common wheel sizes for road and city bikes are 28", 27.5", 26", 24", 20" and 16". We offer these sizes as standard, but If you have a different wheel size just email us and we will help you right away!


How do I find my Wheel Size?

Find your wheel size from the online or retail store where you bought it

You can always reach out to where you bought the bike and ask for the specifications of your model including the exact Wheel Size. If you bought it recently and the bike details are still online, then just go find the link and check the specifications. There will be a “specifications” section, and inside the specs table there is usually information on the specific Wheel Size.

Find your Wheel Size by looking at the tire markings

Most bikes tell you the wheel size right there on the tire! If not, you can measure the rim diameter of the bike wheel, and that way you will know the exact size of the wheel.

Pay attention! the diameter of a bicycle rim is not the same as what the wheel is called. For example, if you have a 29″ bike wheel, the measurement 29″ equals to the outer diameter of the tire, not the rim.

To avoid all confusion and issues, ISO, the International Organization for Standardization has developed a universal tire and rim sizing system. This system was formerly known as the "ETRTO" system and is the main measure system to know your Wheel Size. Sheldon Brown has a cool blog post about this.

Wheel Size = tire diameter

Here is where to find the ETRTO measure in the tire: 

Tire Size Markings


These are the most common wheel sizes measured in mm (ISO / ETRTO):

 Whats My Wheel Size - Unlimited

Available wheel sizes

What's my weel size

Works with disc or rim brakes


Works with disc or rim brakes

Important note: 74 mm wide motors do not work with disc brakes. Disc brakes need to be ISO 6-bolt standard.



Battery Mount?

Our system uses the standard frame water bottle bosses to mount the quick release battery mounting plate. Make sure your frame has them or if not (e.g. Brompton bikes), we offer a mount adapter that can fit to many size tubes. They are available to buy post-campaign.

Battery Mount?



Compatible forks?

Your front wheel needs to be swapped for our motor wheel (comes with tire installed). In order to do that, the front forks (where the wheel is attached) has to accept a standard axle with open dropout. These axles come in quick-release (most common) or bolt-on (fixies, BMX, cruisers, older bikes). Only modern high-end mountain bikes or very modern road bikes use a through-axle that is not compatible yet.

Dropout width: the distance between the inner faces of the fork must be 74 mm or 100 mm. Please make sure our motors will work on your bike.


Compatible forks



Rear motor (optional)

If you are interested in a rear motor, frame and drivetrain requirements are as folows:

  • Dropout: 135 mm open width (not compatible with Brompton/folding or "track/fixie" bikes
  • Drivetrain: cassette (Shimano HG spline - usually 7-12 gears) or threaded freewheel (usually <7 gears or single speed)

Note that 11-speed road-specific cassettes are wider and not compatible.

For more details about rear hub dimensions and dropout spacing, visit these wonderful sites:?


Rear motor

Not sure? We've got your back!

Just email support@unlimitedev.com and send us some photos of your bike, we will help you. Also, you can send us a link to where you got it from and/or the name and model. We’ll be happy to help check what the wheel size is for you.

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