CyclesMod

🏁 Works also with Grand Prix Circuit!

The Cycles - International Grand Prix Racing is a motorcycle simulation video game developed by Distinctive Software and published by Accolade.

Dating back to 1989, it was distributed for the most popular platforms of the time, from the Commodore 64 to the IBM PC (DOS), and is now easily available as Abandonware.

Nowadays it cannot be executed natively on modern operating systems, but it runs fine in DOSBox.

CyclesMod is a mod for the DOS version of this game, which allows to change the configurations of the bikes, which are normally not modifiable by the player:

The game allows to choose three different bikes: 125, 250 or 500cc. The motorcycle operating parameters are stored in the BIKES.INF binary file in the game directory. CyclesMod loads and interprets this file, and provides a graphical interface for inspecting and modifying the configuration of the bikes. On save, the program generates a new BIKES.INF containing the modified configuration.

Download

Download the latest release from the releases page.

Installation

• Windows: if you downloaded a ZIP package, simply unpack the archive; otherwise run the installer (EXE) to install the application.

  If the OS complains with a Windows protected your PC popup, you may need to click Run anyway to proceed with the installation.

  

  In order to enable the Run anyway button, you may need to open the Properties of the installer, tab General, section Security (if available), and tick the Unblock option.

  This workaround is required because the installer executables are not signed, and there are no free certificates I can use to sign them.

• Linux & macOS: unpack the archive.

This application requires Java SE Runtime Environment (JRE) v1.8 (or newer) to run.

Usage

The main application window has three tabs, one for each motorcycle category: 125, 250 and 500 cc. Each tab is divided into three groups:

• General Settings
• Gearbox
• Power curve

There is also a graph of the power/torque curve that is generated in real time from the engine power values present in the relevant group.

Each group has several fields with descriptive labels. Customized values are shown in bold typeface to highlight the fact that the value is different from the default one. Anyhow the default value of a field is always available as tooltip, just move the mouse over the field and wait for the suggestion to appear.

When CyclesMod is launched without arguments, all the fields are preloaded with the default values for all motorcycles.

Through the menu bar it is possible to:

• open an existing BIKES.INF file;
• save the current settings in a BIKES.INF file;
• restore the default settings for one or all bikes (any unsaved customization will be lost);
• modify or draw the power curve in a special dialog box;
• change the numeral system (decimal/hexadecimal);
• change the interface language;
• view CyclesMod version, license and acknowledgements.

After modifying the desired properties, simply use the Save or Save as... function (File menu) to save the BIKES.INF file in the game directory. The file will almost certainly already be there, so you will be prompted to overwrite it, so make sure you have a backup copy of the file you will overwrite. You can now run the game in a DOS emulator such as DOSBox. The configuration is reloaded every time you start a new race, so you don't need to completely restart the game.

Restoration of the original BIKES.INF file

If you want to restore the original configurations of all the bikes, simply use the Reset function (Edit menu), which will reset the settings like the original BIKES.INF file supplied with the game. After that, use the Save or Save as... function to re-create the original version of the BIKES.INF file.

Bike configuration

General settings

Each bike has eight general settings that determine the following characteristics:

• Gears count: the number of gears of the gearbox. Valid value range: 0-9.

• RPM redline: engine speed beyond which, after a variable time determined by the Overrev grace period setting and the difficulty level chosen, the engine breaks down. At difficulty levels 1 and 2 (the lowest), this value also determines the upshift speed. Valid value range: 8500-32767 RPM (values less than 8500 are considered equal to 8500).

• RPM limit: maximum speed that the engine can reach (limiter). Valid value range: 768-14335 RPM. Note that, once the limit is reached, the motorcycle continues to accelerate with the engine power set for the limit RPM, therefore, to effectively limit the speed to a certain value, it is necessary to set to zero the power values around this RPM limit.

• Overrev tolerance: grace period during which the engine does not fail despite running at a higher speed than the RPM redline; the value is expressed in a linear unit of measurement of time which varies according to the difficulty level. Valid value range: 0-32767. The following list can be useful to determine the value based on the desired tolerance in seconds, depending on the difficulty level:

  • Level 1/5 (Beg.): The engine never fails unless 0 is set.
  • Level 2/5: 1 sec. = 50 (automatic gearbox is still active).
  • Level 3/5: 1 sec. = 80.
  • Level 4/5: 1 sec. = 120.
  • Level 5/5 (Pro): 1 sec. = 160.

• Grip: skid threshold, that determines the speed at which corners can be tackled. Valid values between 0 (the bike skids immediately and does not turn at all) and 65535 (the bike never skids).

• Braking speed: determines the stopping time of the motorcycle. Valid values between 0 (the bike does not brake at all; on the contrary, friction and aerodynamic resistance are eliminated) and 65535 (the bike stops instantly on brake).

• Spin threshold: ease with which the bike spins while skidding around a corner. Valid values between 0 (the bike spins at the first hint of skidding) and 32767 (the bike never spins).

• RPM downshift: significant only for difficulty levels 1 and 2 that involve automatic transmission; it determines the speed below which the automatic transmission engages a lower gear, if available. Valid values between 0 (never downshifts) and 32767 RPM (downshifts continuously, in fact it makes shifting impossible).

There are also three unused values related to a pit stop feature that was never implemented in this game, but that is present in its ancestor: Grand Prix Circuit.

Gearbox

Gear ratios can be configured for each individual gear. Higher values correspond to shorter ratios. Permitted values are between 0 and 65535 for gears 1 to 9, while for N (neutral) the value is irrelevant.

Power curve

The engine power curve is constructed from the values present in this group. Each value represents the engine power in hp (or something similar) at a given engine speed indicated on the label associated with the field containing the value. Allowed values are between 0 and 255. The resulting curve is graphically represented in a dedicated frame.

It is also possibile to draw and modify the curve using the pointing device from the Power Graph window, reachable from the Edit menu or simply double clicking on the graph in the main window.

Grand Prix Circuit

Grand Prix Circuit is a car racing game developed by Distinctive Software and published by Accolade like The Cycles, and in fact it is its ancestor, since it came out the previous year (1988).

The cars featured in Grand Prix Circuit and the bikes featured in The Cycles share the very same configuration scheme; there's only one biggest difference: the car settings of Grand Prix Circuit are stored inside the game executable files instead of an external file, therefore the only way to edit them is to patch the executable itself. CyclesMod is able to do this.

Simply Open your favorite original executable file of Grand Prix Circuit (e.g. GPEGA.EXE) and start modifying the car configurations. When you are satisfied and want to try your setup on a circuit, issue the Save command and choose a new name for your patched executable (e.g. GPEGAX.EXE) and eventually launch the game using this new EXE. Like The Cycles, Grand Prix Circuit is also compatible with DOSBox.

Note that CyclesMod is able to open only the original executables of Grand Prix Circuit, it cannot open patched versions, so the only way to save the settings in order to work on them later is to Export them as a CFG file using the appropriate functionality. This way, you can resume your work by reopening an original executable, and then importing the previously exported CFG file.

unEXEPACK

The original executables of Grand Prix Circuit are compressed with Microsoft EXEPACK and must be unpacked before they can be loaded and patched by CyclesMod. In order to automate this process, a suitable unpacker had to be incorporated into CyclesMod.

Although many unpackers were freely available in various languages like C and Rust, I couldn't find any in pure Java, so I decided to translate the C code written by @w4kfu to Java.

This unpacker is available also as a standalone executable and as Java library on Maven Central.

Command line version

If you prefer to operate without a graphical interface, an almost full-featured command line version of CyclesMod is available. It can be executed using the following executables:

• Windows: CyclesMod.exe
• Linux: cyclesmod.sh
• macOS: cyclesmod.command

Once executed, the program checks if a text file called BIKES.CFG exists; if not, it creates a default one mapping the original BIKES.INF binary file. The BIKES.CFG file is basically a plain text translation of the BIKES.INF file; opening it with a text editor, you can directly access the motorcycle parameters, which are quite self-explanatory and divided into the usual three groups: settings, gearbox and power. Thus, initially the BIKES.CFG file will contain the game defaults derived directly from the original BIKES.INF file.

Next, the program reads the BIKES.CFG file contents and eventually produces a new BIKES.INF file, making a backup of the existing one, if any. At this point you can copy the generated BIKES.INF file into the game directory. Starting the game you will then be able to experiment with the changes made to the configuration.

To make further changes to the bikes, simply open the BIKES.CFG file, modify the parameters of interest, save the file and re-run CyclesMod. The program will detect the existence of the BIKES.CFG file and will produce a new BIKES.INF containing the changes made. In case of errors, appropriate console messages will be displayed.

If you want to restore the original BIKES.INF file shipped with the game, simply delete the BIKES.CFG file and run the program with no arguments: it will automatically generate default BIKES.CFG and BIKES.INF files.

Acknowledgements

Icon designed by Everaldo Coelho.

This application uses or includes portions of the following third party software:

Component	Author	License	Home page
Eclipse Platform & SWT	Eclipse Foundation	License	Home page
Inno Setup	Jordan Russell	License	Home page
Launch4j	Grzegorz Kowal	License	Home page
Picocli	Remko Popma	License	Home page
Reflections	ronmamo	License	Home page
universalJavaApplicationStub	Tobias Fischer	License	Home page