Would it be better to study boxing or BJJ to give myself the best shot against a bear?

I've got some outdoorsy pals, but they are limp-wristed liberals who can never defend themselves, so if I do manage to come along on one of their camping trips and things turn south, I may the only hope.

Any ideas?

Great post TK! You really know your stuff.

Back home in Wisconsin you might see a bear up in the north woods, but nothing around any cities. Maybe a coyote as well.

But out here in Colorado they have everything. Bears, mountain lions, coyotes, rattlesnakes, you name it. I'm considering taking a self defense class this spring before hiking season starts. Any suggestions on what I should look for in a class? I've never trained in a martial art or with firearms. I really need to though.

(11-23-2016 12:04 PM)Il Bersagliere Wrote:  Would it be better to study boxing or BJJ to give myself the best shot against a bear?

I've got some outdoorsy pals, but they are limp-wristed liberals who can never defend themselves, so if I do manage to come along on one of their camping trips and things turn south, I may the only hope.

Any ideas?

Boxing vs a bear? LMAO! No amount of boxing can help against a bear, even a small black one. That would just piss him off and make him really want to eat you.

BJJ vs a bear is a life and death situation. Let me make this clear. If you are on the ground with any bear (Black, Brown, Asian, Grizzly, or Polar) The last 2 are going to kill you. Period. Even if The Mountain (A Worlds Strongest Man) was the opponent, it won't be enough. He could roll with the first three and push them off and get away. He's more than strong enough to do that. Anyone who can toss kegs or pull fire trucks could. Those men are also very few in number.

Asian black bears claws are the biggest problem. They will rip you open so badly, you won't survive in the end and will bleed out. They kill people from time to time. A old Japanese Karate master beat one up recently in Japan, but still. Their claws are longer than the other bears and is too risky.

The biggest drop off factor is the weight. Why are lions and gorillas the kings of the jungle? They weigh 400+ lbs! They also have very low body fat to muscle ratio (BMI). That's a metric ton fuck load of power. Bears and some tigers are in this same territory. You cannot fight something that is twice your weight and more than twice your muscle power, with claws and extreme bite force.

If you find yourself on the ground with a bear, that means you made several major mistakes before it happened.

Deterrence is key and only by respecting and not underestimating these beasts can you avoid getting killed. Our brains are the x factor. We have guns and enough intelligence to outwit them. That's the best way to deal with them.

(11-23-2016 12:36 PM)wi30 Wrote:  Great post TK! You really know your stuff.

Back home in Wisconsin you might see a bear up in the north woods, but nothing around any cities. Maybe a coyote as well.

But out here in Colorado they have everything. Bears, mountain lions, coyotes, rattlesnakes, you name it. I'm considering taking a self defense class this spring before hiking season starts. Any suggestions on what I should look for in a class? I've never trained in a martial art or with firearms. I really need to though.

Kinda of a big question. Gotta take multiple factors into account.

1. Level of threat to your safety.
2. Your age, health, and mobility.
3. Legality (can you carry a knife where you live? A gun? a stick?)
4. What threats are prevalent where you live. (chavs or hooligans? Asian gangsters with knives? Armed terrorists? etc.)
5. What kind of places do you frequent? (Night clubs? home and just work?)
6. What kind of transitional spaces are you frequently in and out of? (parking garages, hallways, alleys, bus stops, gas stations, etc. )
7. Availability. Can you train once a week? or up to 3 times?
8. What styles are available in your area?

As always I can help you find a place via PM. Don't post your location if you can help it.

In India, they wear masks on the back of their heads to ward off Bengal Tigers:





http://www.nytimes.com/1989/09/05/scienc...igers.html

I wonder if that shit works.


The hills where I grew up, there are signs warning of mountain lions everywhere. Never seen one.

Wikipedia only lists three attacks against adults in North America in the 2000's, and one was skiing, and one was riding a bike, that is, acting like prey.

https://en.wikipedia.org/wiki/List_of_fa...rica#2000s

I am pretty sure there are more sharks out there messing up guy's shit than mountain lions.

When I hike up in the hills, I am more worried about ticks, rattlers, and pissing off a wild turkey during mating season. I think feral pigs are out there too.

You can worry about what you want, but. . .

I was just thinking something simple that I could knock out over a couple weekends. I don't have time to pick up a new sport like BJJ or boxing.

I'm not worried too much about thugs or criminals, I almost got mugged a couple years ago but was able to fight them off. If they had any weapons I would've just handed over my wallet.

I'm more worried about animals when hiking or camping in the mountains. Easy mistakes to avoid and things like that.

(11-23-2016 02:10 PM)debeguiled Wrote:  In India, they wear masks on the back of their heads to ward off Bengal Tigers:





http://www.nytimes.com/1989/09/05/scienc...igers.html

I wonder if that shit works.


The hills where I grew up, there are signs warning of mountain lions everywhere. Never seen one.

Wikipedia only lists three attacks against adults in North America in the 2000's, and one was skiing, and one was riding a bike, that is, acting like prey.

https://en.wikipedia.org/wiki/List_of_fa...rica#2000s

I am pretty sure there are more sharks out there messing up guy's shit than mountain lions.

When I hike up in the hills, I am more worried about ticks, rattlers, and pissing off a wild turkey during mating season. I think feral pigs are out there too.

You can worry about what you want, but. . .

That's the thing. They see you waaaay before you see them. You may never see one in your life, but that does not mean you were not stalked 10 different times by one, in your lifetime.

I went fishing once with an old hunting buddy in a small boat on a little lake surrounded by forest. We heard a cougar growl/gruff into a miniature scream. Boy did we pucker up. It sounded close as fuck. We pulled our guns but saw no movement. There were these little islands of brush and trees in this lake like area. A cougar can jump 40 feet. He steered the boat out towards more water and away from that brush area, and I didn't have to tell him. He knew better. That would have been a mess having a cougar jump on you from brush into a pontoon boat. That little lake was 70 feet deep with tall dead trees in it.

Thinking back on that situation, perhaps that was a mother with a cub laying low in that brush, but our boat got too close to the shore of that brush area. No idea, just my best guess. Alligators do the same shit. Get too close to their nests in those little marsh islands, and they will growl or hiss super loud and smash the water with their tails.

I've never seen a cougar in the wild, but I know for a fact I was seen by at least 3. The droppings, noises, and tree scratches (broken branches told the truth). I don't live in bear country, and hogs don't do that shit either, so that was not hard to figure out. The game wardens around where I live don't like to admit it, but a few will tell you if they are honest or work that portion of the service, that there are 1-5 of them in the area. They just don't want folks scared, but most of them know they are around. Some are even tagged and radioed for university research and also for reasons they know immediately, if an attack happens, which cougar did it.

If you have healthy deer populations, they shouldn't ever bother anyone. Really young juveniles make the news because they show themselves out of curiosity or other stupid reasons. California has issues because they build and make jogging trails in their territory too much. They don't always have enough good deer or food for them out there either. Gee I wonder why.....

(11-23-2016 02:14 PM)wi30 Wrote:  I was just thinking something simple that I could knock out over a couple weekends. I don't have time to pick up a new sport like BJJ or boxing.

I'm not worried too much about thugs or criminals, I almost got mugged a couple years ago but was able to fight them off. If they had any weapons I would've just handed over my wallet.

I'm more worried about animals when hiking or camping in the mountains. Easy mistakes to avoid and things like that.

Then I wouldn't bother with it. Get a good deterrent device, like a retractable baton, or get a concealed handgun license, if that is possible where you live. In fact, if that is an option, that is your best option.

After you get your license, take a weekend seminar class for active shooter self defense. It's worth the money and makes you much much better at responding to threats. This kind of CQC stuff is great for weekends whenever you get the time.

(11-23-2016 02:44 PM)TravelerKai Wrote:  That's the thing. They see you waaaay before you see them. You may never see one in your life, but that does not mean you were not stalked 10 different times by one, in your lifetime.

Of course you're right, although technically, I didn't say they never saw me. I'm just saying getting attacked, as an adult, by one of these bad boys is unlikely.

It is the fact that they sneak up on you and go for the neck that gives us the visceral willies, not the likelihood of attack.

Quote:If you have healthy deer populations, they shouldn't ever bother anyone. Really young juveniles make the news because they show themselves out of curiosity or other stupid reasons. California has issues because they build and make jogging trails in their territory too much. They don't always have enough good deer or food for them out there either. Gee I wonder why.....

This might have been how it was in my case, because I went running for years in those dry California hills crisscrossed with jogging trails, watershed land, you could avoid roads for a hundred miles if you wanted, and only forty minutes from a city.

Deer for days though.

I think I once saw 25 deer on one run, so maybe the cats were full.

Anyway, I am not pretending that strategizing about how to beat a puma hand to hand is not a worthwhile activity, and fun too, more fun than figuring out how to take down a tick, anway.

Speaking of using martial arts to defend against animal attack, is this advice strictly for land based applications or could it apply to aquatic environments as well?

Such as facing off against a small to medium sized sharks, squid, etc.

Having lived inland my entire life, I'm eager to try living on the edge of the ocean as soon as I become location independent, but I have a certain amount of anxiety about a possible water creature attack.

It would be nice to know that one can actively increase ones chances by training for these situations.

(11-28-2016 11:38 PM)Suits Wrote:  Speaking of using martial arts to defend against animal attack, is this advice strictly for land based applications or could it apply to aquatic environments as well?

Such as facing off against a small to medium sized sharks, squid, etc.

Having lived inland my entire life, I'm eager to try living on the edge of the ocean as soon as I become location independent, but I have a certain amount of anxiety about a possible water creature attack.

It would be nice to know that one can actively increase ones chances by training for these situations.

I caught my first shark last summer. Never in my life have I been pulled so hard. Not even NCAA 300 pound offensive linemen, can yank my ass that hard. But a Black Tip Shark under 100 pounds did.

Their power is insane.

Dolphins punch them in the gills and kill them. They have a weak spot there. Can a human hit that in the middle of an attack? Doesn't seem like it. The bigger the shark, the less likely it seems.

I would recommend that shark knife that has that freezing gas inside it. If I recall correctly, you stab the attacking shark with it, and it forces them to surface instantly, getting them off you.

This reminds me. I forgot to show Scotian a picture of my shark. LOL

(11-28-2016 11:38 PM)Suits Wrote:  Speaking of using martial arts to defend against animal attack, is this advice strictly for land based applications or could it apply to aquatic environments as well?

Such as facing off against a small to medium sized sharks, squid, etc.

Having lived inland my entire life, I'm eager to try living on the edge of the ocean as soon as I become location independent, but I have a certain amount of anxiety about a possible water creature attack.

It would be nice to know that one can actively increase ones chances by training for these situations.

When the seals get out of the water, you get out of the water.

I had always heard it was best to punch them in the nose or try to gouge an eye, assuming you didn't have the forethought to get out of the water when the fins started circling.

^Would that tactic be effective on a freshwater threat like the American Alligator as well? Or would it be better to neutralize the target by holding it's mouth shut?

^ You could try reasoning with it

(11-29-2016 03:43 PM)wi30 Wrote:  ^Would that tactic be effective on a freshwater threat like the American Alligator as well? Or would it be better to neutralize the target by holding it's mouth shut?

According to this, eyes and windpipe.

http://www.wikihow.com/Survive-an-Encoun...-Alligator

Crocs and Alligators are just one of those beasts that if you end up being bitten by, you made alot of mistakes before that happened.

From my personal experience with Alligators, the only ones that seem to be bold enough to approach me, were the 10ft plus ones. Smaller ones usually mind their own business.

During the mating season which is pretty much all summer, stay away from the nest areas. The females get uber bitch rage if you even come within 20 ft. If they are there, they will warn you every time. They will hiss loud and open their mouths. Their tempers are super bad at that time, so just stay away. Often times, you will run into a male in the perimeter area before you see the nests, because the females don't really like them being too close either, unless they are the area's alpha which is usually a 12+ footer.

Unless you are a lard ass, you should be able to run away from one. Just don't torque your ankle so badly that you sprain your foot trying to get away, due to fear.

If you fall in the water, God help you. I have no advice for that other than get back in the boat.

Most guys that are in these kinds of areas know what to do and don't need my advice. For you European cats, do not do what that tourist from Europe did this year, and go swimming in an alligator pond at night. That was utterly ridiculous to die over. If the gators are not bad enough, any place in America where gators live, we also have 2-3 species of venomous snakes that live in the same water. If that doesn't scare you, we have Alligator Gar fish, Snapping Turtles, and the occasional Tiger Sharks that swim up rivers.

I'm sorry if the answer to this has been said before in this thread, and I'm pretty sure it's been extensively discussed.

But, how big would a guy have to be, so that his physical power it's so big that an martial artist would not be able to take him down/have a really hard time doing it. You guys were talking about wrestling a bear and that tought came to my mind.

I'm 6ft and had my fair share of street fights, some against 3-5 dudes, I don't get intimidated easily. I have 2 years of boxing/1.5 year of muay thai (I know i'm a noob, and can get my ass kicked by pretty much everyone one of you guys posting on this thread) and I fooled around with BJJ for a few months and learned to defend myself against it because my cousin was crazy about it and would attack me when I was playing video games,walking on the street, basically he would try to choke me, get a kimura, etc.. ramdomly, so I got relatively good at avoiding getting caught.

Nevertheless on a street situation I can't help but feel intimidated if a guy is above 6'5 ~220 lbs.

Have any of you guys ever had to fight a much larger opponent ? How did you handle it ?

(11-30-2016 10:08 AM)Mjölnir Wrote:  I'm sorry if the answer to this has been said before in this thread, and I'm pretty sure it's been extensively discussed.

But, how big would a guy have to be, so that his physical power it's so big that an martial artist would not be able to take him down/have a really hard time doing it. You guys were talking about wrestling a bear and that tought came to my mind.

I'm 6ft and had my fair share of street fights, some against 3-5 dudes, I don't get intimidated easily. I have 2 years of boxing/1.5 year of muay thai (I know i'm a noob, and can get my ass kicked by pretty much everyone one of you guys posting on this thread) and I fooled around with BJJ for a few months and learned to defend myself against it because my cousin was crazy about it and would attack me when I was playing video games,walking on the street, basically he would try to choke me, get a kimura, etc.. ramdomly, so I got relatively good at avoiding getting caught.

Nevertheless on a street situation I can't help but feel intimidated if a guy is above 6'5 ~220 lbs.

Have any of you guys ever had to fight a much larger opponent ? How did you handle it ?

(11-30-2016 10:08 AM)Mjölnir Wrote:  I'm sorry if the answer to this has been said before in this thread, and I'm pretty sure it's been extensively discussed.

But, how big would a guy have to be, so that his physical power it's so big that an martial artist would not be able to take him down/have a really hard time doing it. You guys were talking about wrestling a bear and that tought came to my mind.

I'm 6ft and had my fair share of street fights, some against 3-5 dudes, I don't get intimidated easily. I have 2 years of boxing/1.5 year of muay thai (I know i'm a noob, and can get my ass kicked by pretty much everyone one of you guys posting on this thread) and I fooled around with BJJ for a few months and learned to defend myself against it because my cousin was crazy about it and would attack me when I was playing video games,walking on the street, basically he would try to choke me, get a kimura, etc.. ramdomly, so I got relatively good at avoiding getting caught.

Nevertheless on a street situation I can't help but feel intimidated if a guy is above 6'5 ~220 lbs.

Have any of you guys ever had to fight a much larger opponent ? How did you handle it ?

And on the 8th day God invented force multipliers.

(11-30-2016 10:08 AM)Mjölnir Wrote:  I'm sorry if the answer to this has been said before in this thread, and I'm pretty sure it's been extensively discussed.

But, how big would a guy have to be, so that his physical power it's so big that an martial artist would not be able to take him down/have a really hard time doing it. You guys were talking about wrestling a bear and that tought came to my mind.

I'm 6ft and had my fair share of street fights, some against 3-5 dudes, I don't get intimidated easily. I have 2 years of boxing/1.5 year of muay thai (I know i'm a noob, and can get my ass kicked by pretty much everyone one of you guys posting on this thread) and I fooled around with BJJ for a few months and learned to defend myself against it because my cousin was crazy about it and would attack me when I was playing video games,walking on the street, basically he would try to choke me, get a kimura, etc.. ramdomly, so I got relatively good at avoiding getting caught.

Nevertheless on a street situation I can't help but feel intimidated if a guy is above 6'5 ~220 lbs.

Have any of you guys ever had to fight a much larger opponent ? How did you handle it ?

No, this has not been asked before. This is a good question.

It just varies. If I am walking around @ 230 and I have above average strength for someone at my weight, regardless of height, I would be a problem to deal with for any man under 260 with similar strength. My heavyweights around that size or higher were often too hard to roll with once they got passed blue belt, typically. Back then I usually was around 180lbs though.

Taller guys are not as much of an issue for anyone with grappling or SJM (Small Joint Manipulation) skills. Just don't see a 6'5" threat that is taking a boxing stance and think you should try and out box him (if you notice your reach is better and your weights are similar, it's okay), if it would be more reasonable to pick his ankle for a fast single leg takedown. If his ass is on the ground, none of that height will help him at all. If he kicks at you from down there, just don't let him kick your kneecaps. Stomp his groin, his ankle, Muay Thai kick his legs, only jump stomp his face or head, if he is hurt or gassed out. Just don't let him get back on his feet. If he tries, roundhouse his face or trip sweep him again.

If you have enough BJJ skills, it's pretty self explanatory. Ankle lock, Achilles lock, toe holds, heel hooks, and any other leg submission (Russian Leg Sambo stuff), is better. Breaking or snapping those ligaments (MCL, ACL, etc.) will take him out of a fight completely. 1 vs 1, BJJ is awesome no doubt. Especially against people that do not know it. I would imagine that street fighting in Brazil (something very dangerous in general), gives you little advantages because lots of others can fight in these styles as well. Many also have guns and knives. I personally do not think you can know enough martial arts in Brazil and it be enough for all situations.

Anyway, when someone is 20 pounds more than you with similar strength levels, the more likely leverage fighting styles, will be your better bet. Leverage styles are just about anything grappling/SJM (JJ, Aikido, Judo, BJJ, Sambo, Wrestling). If they have back up, stick to standard multiple opponent defense.

The only time striking a very large guy makes sense is if that is:

1. Your only skillset.
2. You are faster and know it.
3. You have enough room for footwork and moving around. (small cramped spaces is a no go)
4. He grabs you and you have no choice but to clinch fight. (Yet another reason why all style of kickboxers need good clinch game)
5. There are multiple opponents and you cannot find a wall for a backstop or on two sides.
6. You can hit his weak spots well and know how (temple on the head, groin, MCL on knee, palm strike at Nose, knee/uppercut to chin, hook/elbow to the side of the eye socket, etc.)
7. You have a force multiplier (A baseball bat, baton/stick, brass knuckles, knife, a rock, etc.)

Avoid at all costs fighting people 50 pounds heavier with equal or more strength.

True story that happened not too long ago. I was in deep East Texas traveling through. A roided out skinhead was walking down the street talking to himself kinda loud. I was trying to get some gas for my car. As he got closer, I could see he probably was about 265-275 with maybe a bodyfat around 17% or so, if I had to take a wild guess. Dude started mugging me and started grinning very big. I had not started to pump the gas yet, so I put everything back and got back in the car and left.

Real talk, that guy was so yoked out, I knew 100% for a fact, I would not be able to even armbar him. He would have just lifted his arm and tossed me off him. Anytime a guy looks like he can bench press you into the air, respect that power and just leave the area if he is acting like an asshole. My family was with me as well and there are plenty other places to get gas. That area has bad racial history and skinhead WN gangs are common there, unlike Houston area proper. If that guy was high on painkillers or meth, forget it. 10 police officers would not be able to hold him down. A taser might not faze him much either. As I left, I saw him watching me leave, and he was nodding his head, like he was a laughing. You think I cared?

The best fights are always the ones you avoid.

^ Great post TK.

@Mjolnir: Fundamentally, if you want to be sure of ending a fight, you need to stop the circulatory system, respiratory system, or the nervous system. If you're big enough and trained enough, you can do this unarmed on the vast majority of people. TK has already given excellent guidelines on what you need to know to do this, and when to accept that someone is just too big to tangle with unarmed.

A major, and unpalatable part of real world violence is understanding what lengths you're prepared to go to. The answer to your specific question, 'if you HAVE to' fight someone much bigger, is that you must do catastrophic damage to one of the systems mentioned, which is likely to prove fatal to your opponent.

Taking TK's roided out guy as an example - you beat a guy like that by severing arteries, puncturing the heart, severing the spinal cord, collapsing the windpipe, etc etc. That's why you walk away from fights with people like that - not because it is impossible to win, but because the cost of doing so is unacceptably high in all but the most extreme circumstances - those very rare occasions where you HAVE to fight. You've got to make a lot of mistakes before you find yourself in that situation.

Thanks for your replies and great advice gentleman. I've never have faced myself against a much larger oponent. And even if the chances are small, I probably should get into some BJJ classes again.

I agree about force multipliers, but I'm little hesitant to use them, when I was younger what saved me from multiple oponents was a very heavy brass knuckle I always had with me. But one time I threw a hook with it at the guy who was closer and the dude just blacked out, fell on the ground like a rock. The second guy i hit the ribs and he crunches and fall back, the other guy that was with them just started running at the other direction (thugs ain't got no honor) and the second one followed him, while this happened the guy I hit with the hook was still on the ground, i gave him a little kick to see if he was awake but he didn't move, I proceeded to get the fuck out of there as fast as I could, he wasn't dead but best case scenario he would have a week long headache. But to be honest I got lucky many times, as I only got jumped from behind once, and they missed the brick they threw at me

This type of shit wouldn't put me in jail at that time, but since now I have legal age to go to prison i'd like to avoid cases like that. Submission through small joints it's probably the best bet against one big opponent withouth causing him likely lethal damage, if you can't avoid it fighting, like you guys said.

Thanks again !

(12-01-2016 07:58 AM)Mjölnir Wrote:  Thanks for your replies and great advice gentleman. I've never have faced myself against a much larger oponent. And even if the chances are small, I probably should get into some BJJ classes again.

I agree about force multipliers, but I'm little hesitant to use them, when I was younger what saved me from multiple oponents was a very heavy brass knuckle I always had with me. But one time I threw a hook with it at the guy who was closer and the dude just blacked out, fell on the ground like a rock. The second guy i hit the ribs and he crunches and fall back, the other guy that was with them just started running at the other direction (thugs ain't got no honor) and the second one followed him, while this happened the guy I hit with the hook was still on the ground, i gave him a little kick to see if he was awake but he didn't move, I proceeded to get the fuck out of there as fast as I could, he wasn't dead but best case scenario he would have a week long headache. But to be honest I got lucky many times, as I only got jumped from behind once, and they missed the brick they threw at me

This type of shit wouldn't put me in jail at that time, but since now I have legal age to go to prison i'd like to avoid cases like that. Submission through small joints it's probably the best bet against one big opponent withouth causing him likely lethal damage, if you can't avoid it fighting, like you guys said.

Thanks again !

Defending yourself cannot be easy in Brazil. For a place as violent as Brazil, I read that you guys have a hard time legally defending yourselves against violent thugs. The fact that only off duty cops and criminals have all the guns, makes defense difficult. Even Californians don't commonly have thugs waiting outside your garage door with guns, for you to come home so they can rape/rob your whole family.

No matter where anyone lives, self defense will ultimately always be your responsibility. Never your country, never anyone else's.

(12-01-2016 07:58 AM)Mjölnir Wrote:  Thanks for your replies and great advice gentleman. I've never have faced myself against a much larger oponent. And even if the chances are small, I probably should get into some BJJ classes again.

I agree about force multipliers, but I'm little hesitant to use them, when I was younger what saved me from multiple oponents was a very heavy brass knuckle I always had with me. But one time I threw a hook with it at the guy who was closer and the dude just blacked out, fell on the ground like a rock. The second guy i hit the ribs and he crunches and fall back, the other guy that was with them just started running at the other direction (thugs ain't got no honor) and the second one followed him, while this happened the guy I hit with the hook was still on the ground, i gave him a little kick to see if he was awake but he didn't move, I proceeded to get the fuck out of there as fast as I could, he wasn't dead but best case scenario he would have a week long headache. But to be honest I got lucky many times, as I only got jumped from behind once, and they missed the brick they threw at me

This type of shit wouldn't put me in jail at that time, but since now I have legal age to go to prison i'd like to avoid cases like that. Submission through small joints it's probably the best bet against one big opponent withouth causing him likely lethal damage, if you can't avoid it fighting, like you guys said.

Thanks again !

I take a slightly different view these days. I'm of an age where I'm not going to get into fights gratuitously. If I have to walk away, so be it, I'm not fussed. Therefore I am very confident that if I do find myself in trouble, I will have done everything possible to avoid it - in which case I'm up against a serious predator, and the use of lethal force (and its means of production) becomes a much easier calculation to make.

@Mjolnir: Fundamentally, if you want to be sure of ending a fight, you need to stop the circulatory system, respiratory system, or the nervous system. If you're big enough and trained enough, you can do this unarmed on the vast majority of people. TK has already given excellent guidelines on what you need to know to do this, and when to accept that someone is just too big to tangle with unarmed.

I believe this the primary reason why some eastern martial arts have been watered down in the west.
I've been in one situation when the attacker had a significant size/strength advantage on me. He wasn't going to stop the attack even though i crossed to the other side of the street. At the time i carried around a knife. Once the attack began i used the knife to cause severe injuries that would be life altering.

I never reported it to the police but i followed the story on the news. The guy lived. For a few weeks i kept expecting to see the cops waiting in front of my place for me.
In the moment i felt kinda bad using the movements i did because i knew the rest of his life would be "uncomfortable", but after a few nights i thought if he attacked my gf or my mom i wouldn't have hesitated for a second.