Mars presents a somewhat unique environment in many respects for people. With the Earth lost, it is one of the largest bodies in the solar system one can reasonably expect to travel on. While Titan has ground-roads and highways, they do not have the surface area and distance of Mars to cover, nor the population levels who utilize these roads. This leaves Mars as one of the few places in the Solar System where those who have appreciation for the "open road" or the "need for speed" to thrive and grow. Unfortunately, subculture development is somewhat limited by vehicle selection - groundcars are notoriously small and compact, though urban street racing (illegal as it subverts the traffic control grids) often utilizes modded ones, and while the Martian Buggy can get some speed going, the vehicles are not the most aesthetically pleasing - though "post-apoc" rigs of buggies with extraneous armor plates, spikes and chains are not uncommon in rebellious rednecks.
This means that the traditional cycle has some of the best availability and style for those who seek to feel the independence and power of owning a vehicle. In urban centers, you may find traditional bike clubs and authentics "retro-Mod" cultures who focus on riding and customizing cycles. These make great venues for recent immigrants or ex-Indentures within the hobby to socialize with others and get back into the swing of post-Fall life, and act as an element of a social network. While there are still some wider popcultural implications of a "cycle club", the ratio of the urban ones which engage in criminal activity is low - and in these cases they mostly act as a slightly more mobile street gang, engaged in vehicle theft, extortion and drug dealing to gain additional money for the members or the club and may clash with more established neighborhood gangs. However, the high presence of surveillance and traffic control makes these criminal actions harder.
It is outside the major cities, on the distant highways and their attached communities, where you find groups one can really call "motorcycle gangs". Many of these these resemble rebellious youth and racing subcultures, such as Japanese bosozoku or Maylay Mat Rempit. The backbone of these communities are in local youths, usually areas which have a concentration of similar ethnic cultures (though multicultural gangs exist in areas which are sufficiently diluted) and have little else to do, except perhaps help parents with work or attend virtual schooling. Far from Mars' urban centers, traffic controls get less strict, surveillance gets less comprehensive, and the ease of building a serviceable cycle or trike out of some fabs in a prefab garage gets much higher. This means that many bike gangs are also technically skilled, able to do basic subversion of DRM and licensing, and can handle their own maintenance and assembly of bikes - some gangs even take building your own ride as a bar to entry. While historically there may have been some element of gender separation or roles in bike gangs, the modern gangs rarely make anything of it including active members ("riders") of any gender identity - though some of the most established may comport themselves as a "brotherhood" or "sisterhood". Though, of course, bike gangs are often hotbeds for casual dating and sex in their communities, and it's not uncommon for a date (sometimes called a "bitch" or a "squeeze" usually not intended to be derogatory) of any gender who is not a member to ride with the gang.
Activities for these outback gangs are pretty standard. At their basis, they engage in running (usually friendly) races on highways and access roads, bike parades and other rabble rousing usually just for their own amusement. Particularly adventurous or skilled gangs will travel on major arterial highways, subverting the traffic grid or otherwise operating in manual to travel at high speeds interspersed with regular traffic (though this occasionally draw the attention of the Martian Rangers). Those who feel particularly strong or delinquent might engage in common youthful crimes such as vandalism, extortion or bullying of locals, petty thefts and even robberies. Others might engage in drug distribution and smuggling, illegal courier jobs or act as a hub for illegal fab operations. While sometimes this is selfishly for profit, mostly it is an act of youthful rebellion or a quest for more thrills - many of these gangs' members live ordinary lives otherwise and engage in activities for the adrenaline high. This is reflected in their outfitting; almost no-one uses an enclosed cabin on their cycle or trike, they only wear lightly shielded clothing or crash suits for protection, and the only people wearing helmets or masks are those who do not have respiration implants. This means that while often dangerous and violent, gangs are rarely consistent in their operations beyond the basics. Only the longest established and largest gangs tend to have steady operations which go hand-in-hand with various codes of conduct and strict membership rules.
While high-speed and danger seeking are critical to these cultures, so is rebellion. Gang colors and symbology are often drawn from their cultural or ethnic heritage (a subversion of the Consortium's insistence on Mars as the new home of humanity), others use anarchist symbols or rhetoric in how they operate and may even comport themselves as "lacking hierarchy". However, some gangs will focus on subverting their own cultural expectations operating like "Authentics" in Urban Mars modeled after cultures which are not their own - or deliberately anachronistic stylings such as American "cowboys" or late 20th century "cyberpunks". Some cyclists are brave enough even to chance the outskirts of the TQZ. Culturally, cycle gangs are split between cycles and trikes - with trikes being larger, more durable and better at rough terrain, but the cycle being faster and the lighter frame more customizable. Membership in these gangs is usually youths in their mid to late teens at the low end and early-mid 20s at the high (as opposed to urban cycle clubs, which have a broad age range). Some members naturally mature out of the club, or their older age and legal status makes the risks of the lifestyle less appealing. Those who engage in criminal activities may be recruited by local crime gangs, triads or militant Barsoomians as members. Others may pursue dangerous contract jobs such as PMC work, ego hunting or bodyguarding, or become professional athletes or X-casters engaging in other extreme sports. Very rarely, bikers will "go straight" and join government jobs with the Tharsis League doing infrastructure or surveying and some will even "betray" the gang by becoming Martian Rangers. Some don't ever properly grow out of it, remaining in the local culture to support new blood and keep the gang revitalized while going on with their own lives.
Occasionally, two gangs' territories will meet or abut. This is rare, as very few rural communities have a large enough population spread out to form multiple gangs - though rivalries and falling outs can cause a gang to split or fork. Typically, both being driven rebels, this will result in low-key gang warfare with brawls, vandalism, taunting and very rarely serious fighting over the contested area. This ends either when the local authorities have to step in, or one gang loses the will to hold the territory, causing them to fall back. Occasionally, gangs are mature enough to negotiate, and will split territory up, or one will pay concessions to the other for the space. Exceedingly rarely, gangs might merge to form a new gang with combined membership - this usually only happens if a third party (such as Rangers or local criminals) is present, or in the non-zero chance that gang leadership really just wants to bang and have a weird way of showing it. Combined gangs tend to be volatile, but much stronger and more daring.
Lastly, there are a couple ways gangs might settle things in event of a fight, or some other dispute. Races and related wagers are common, especially in gangs with younger membership who aren't dead set on fighting (and may not have access to weapons). But another common way is jousting, where a champion of each gang will engage in almost ritualized fighting utilizing simple shields (or no shields at all) and carefully crafted lances made with self-balancing materials to be easy to handle - and with smart material heads which can be blunt or sharp depending on the conflict.
Jousting Lance: Lance used in ritualized jousting of Martian Bike Gangs, and occasionally reenactors on horseback. Has a bluntable tip and powerful balance correction for high accuracy. It is designed to be used in motion, and thus has no penalty to make a Charge Attack, but all attacks while not charging takes a -20 penalty. Uses the Exotic Melee Weapon: Lance skill. [Low]
AP -3 1d10+3+DB DV (Half DV when blunted)