Editing the project

Pressing the Edit button on the right top part of the project window drops down the edit grid.
The parameters are grouped into sections –Titles, General, Points, Shock, Fork, Wheels.

Most of the changes take place after pressing the Apply button, but some of them appear instantly or after pressing the Enter key on the keyboard.

Let’s see the fields that behave specially or require further explanation.


“BB attached to” – set this to change the bottom bracket placement. For example – attaching the BB to the swingarm will make a URT (unified rear triangle) system bike. Keep in mind that this does not affect the force calculations since rider mass is not involved in the calculations yet.
There are some fields requring more explanations:

The original author field can not be modified, it is the name of the user who originally created the file. The "modified by" field changes as you make changes to the project and save it.

The "Protection" field can only be set by the original author of the file. You can't make modify other users' files protection level. Old version files (whose author is unknown) also can't be made protected. See more about protection levels in the web library section.


Changing point positions is possible by entering numerical values or by dragging them with mouse. Dragging is available after pressing the icon above the bike image. For numerical input, consider that the values are always relative to the current reference point, which can be changed on the top of the project window. The values are interpreted in the current measure unit, which can be changed in the settings dialog of the main window. Measure unit can be meter, cm, mm (default) and inch.

You can define a chain-guide point. Thus, the bike can have an additional roller wheel that drives the chain. The roller can be attached to any frame element. Using a chain guide may effectively reduce chain lengthening and pedal-kickback. An example for this is the "Balfa BB 7" bike.

Shock parameters

Length – the eye-to-eye length of the shock unit. If you change this directly, the program will recalculate the results according to the new situation. To change this value indirectly, move the endpoints of the shock.

Type – can be “coil” and several air configurations. Coil springs are linear-rate by default, and have a spring rate. You can define an other-than-linear behavior by giving an exponent other than one. For example the value of 2 will result in a parabolical spring curve.
Air shocks have a progressive curve by default and require larger forces for their initial movement. The dual-air (preloaded by a negative spring) shocks are more sensitive in their low travel range.
The exponent parameter is avaliable coil shock configurations, a value larger than one makes a progressive curve.

Pull-shock – set this if your shock uses a shock that’s endpoint are extending instead of compressing. Some of the designs that use this setup: GT Lobo, Scott Genius etc.

Shock attachment – you can connect the shock to any linkage element, or the main frame. This can be altered any time.

Air shock parameters – A dual-air air shock is modeled in Linkage. There are separate initial pressure values for both positive and negative chambers. Their initial volume can also be set with the parameters. Please visit the program website for more detailed description. Though if you are familiar with dual-air mtb shocks, you'll find out each value's meaning.

Fork parameters

See the fork parameters section for a graphical explanation of the values.
The axle-to-crown length can be set two ways. Pressing the “set” button will set the value directly, not affecting the head angle, while the “change” button will notice the difference between the current and the new value, and correcting the head angle and wheelbase accordingly.


You can choose between common tyre sizes and they will be graphically shown, as well as affecting the geometry of the whole bike.