Wow. Lots of suggestions for this unfortunate fellow. Having lived in a violent city for 50+ years, I have some things to add to the education of people who live in peaceful communities and those who go through life without a care.

1. Guns on bikes don't work. I am a gun owner myself. I would love to protect myself with a firearm while bicycling. It does not work in most situations. The OP could not just shoot someone until the assault (smack in the face) took place. You can't just shoot someone because you think they might knock you off your bike. So how exactly would a gun help stuck in a backpack, pannier, or even a pocket? And you can't just carry a gun anywhere, so that limits your commute directly home from work (if you are allowed to have a firearm at work). Impracticable.

Once the attack takes place, you have to get your hands on the gun. Then what if you succeed? Just start spraying lead all over the hood? Maybe hit a kid or other innocent bystander. Certainly one or more of the attackers had guns on them (at least in my town). So instead of a beat-down, you are in a shootout and probably out-gunned. Death is not part of my short term plans.

2. Cops are no help. First thing a cop would tell the OP is "You should know better than to ride a bicycle in that neighborhood. Were you trying to buy drugs?" Cops are worthless in these matters in most cases.

3. As hard as I try to stay out of arms reach of strangers, I find it impossible. I have made U-turns in situations like the OP. I have had to make evasive maneuvers and narrowly missed getting clocked in the head. Friends of mine have been stopped and narrowly escaped with their bikes and health only because the attacker did not land a solid blow the first time.

4. Stay out of sketchy neighborhoods? Impossible in some cities. I can't tell you how many extra miles I bike each month to avoid the "worst" areas, only to settle for other areas of risk. In New Orleans, it is nearly impossible to get anywhere directly without passing through a high risk area.

The only advice I have for preventing such things (besides giving up cycling) is to ride fast (so hoodlums have less time to formulate plans); make a U-turn if the street ahead is blocked by a group of 2 or more people; don't stop for anything if you don't absolutely have to (red lights and stop signs). And don't advertise your presence with blinky bike lights up front. Get something as bright as a motorcycle light, or go stealth through the worst of the hood. I believe that fast and non-stop gives one the best chance of avoiding trouble. Stay off the edges of the street - ride right down the center line whenever you can. And if you get jumped anyway, scream for help. Get some witnesses looking out of their windows. Hoods are less likely to kill you in front of eyewitnesses who probably already know who they are.

That's all I got.