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Almost got hit by car, hit brakes hard= fell

Old 02-13-24, 06:12 PM
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Originally Posted by Maelochs
Based on Sellerz™ physics, it is safer to have no brakes and no shirt .... and based on his reading skills, we can see immediately that his advice is the best.


See, in Actual physics, it impossible to lift the back wheel without strongly applying the front brake. Locking up the rear brake causes fishtails …. Jamming hard on the front brake cause forward weight transfer, which force rotates around the front axle, lifting the rear of the bike in extreme cases.

Mr. Sellerz …. You claim to be a Scientist, working in a laboratory. Surely you have taken at least a high-school physics course?

Please explain how the back wheel lifts under braking if the front brake is not applied and applied very strongly.


Also … you do realize theat the OP is an Actual Human Being who actually crashed, right … not an internet fantasy? Giving totally crap advice to actual people who are actually riding in traffic could actually cause avoidable injury … and actual injury is bad, m,kay?

The OP understands that had she braked less, she likely would have hit the car …

Your “advice” is essentially, “Hit the car so the car helps absorb some of your momentum, thus shortening stopping distance.”

Dude, we know you are not stupid, and your persona here is just schtick … but maybe not All of us know that, and maybe be careful when giving people advice which could lead to extremely dangerous situations? What do you think?



Nah, just kidding … I think it was a perfect @LarrySellerzs post. I appreciate the humor, guy …
wow that’s a lot.

1) never claimed to be a scientist, I'm a technician.

2) you can get the back wheel to come off the ground in lots of ways, ever see a bunny hop?

3) I claimed that OP fell because she isn't used to making emergency stops. It sounds like she's used to relying on the back brake, and when she really needed to stop this training failed her.

4) I delivered food full time in traffic for years, it’s how I made money to live and eat

5) I'm serious that learning how to use the front brake is the key to stopping on the fly. If you undo the back brake, you are forced to learn how to use the front.

6) people in this thread are acting like falling off your bike when slamming the front brake is some unknown or unusual phenomenon. It’s what happens when you aren't emergency stopping correctly. It’s so engrained in me how to move my body when stopping like this that its hard to describe what I do, but I think I stand up and move my weight back behind the saddle when slamming the front.


my advice can be summed up by “learn how to use the front brake. You wouldn’t have crashed if you were adept with the front brake. You can force yourself to get better by taking the back brake off”

Last edited by LarrySellerz; 02-13-24 at 08:22 PM.
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Old 02-13-24, 06:49 PM
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Originally Posted by ScottCommutes
Bleeding away any energy via your brakes before a crash is always better. A slow crash beats a fast crash.
I heard more than one guy say about motorcycle accidents, "It's a good thing he laid it down when he did..."
and all I could think was, "Which decelerates faster? A motorcycle sliding on its aluminum crankcase, or a motorcycle with both brakes fully employed on rubber tires?"

I'm also a big fan of rear brakes. Yeah, the front brake can lift the rear wheel (I've done it on road bikes and on motorcycles), but we can shift our weight behind the seat and use that braking force. Even though our lives are riding around on little dime-sized contact patches with the porous asphalt, every little bit helps in an emergency.

Last edited by calamarichris; 02-14-24 at 02:55 AM.
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Old 02-13-24, 07:15 PM
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Any meaningful amount of braking force your rear provides in an emergency stop will just make you fishtail, IMO atleast. Provided you have a good front brake and are using it to its fullest

Last edited by LarrySellerz; 02-13-24 at 07:20 PM.
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Old 02-13-24, 11:06 PM
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Originally Posted by LarrySellerz
Any meaningful amount of braking force your rear provides in an emergency stop will just make you fishtail, IMO atleast. Provided you have a good front brake and are using it to its fullest
Fishtailing means you're still reducing your velocity. Your body slamming into a car at 15mph > slamming into a car at 20mph. It doesn't sound like much of a difference numerically, but it really is.

And whom among us can really say we're using the front brake to its optimum, short of the Turkish kid Razgatliagthu?

Last edited by calamarichris; 02-13-24 at 11:13 PM.
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Old 02-14-24, 12:48 AM
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Originally Posted by ScottCommutes
I know this is old thread, and I scanned some parts of it, but....

More important than learning to emergency brake is learning how to not use the brakes. Look first at the moving cars, then the stopped cars that might move, then the places the cars might appear from. If you've got all that, memorize the scene around you.

Bikes also avoid accidents differently than cars. My preferred path seems to often be straight ahead and to the left. Think about what might happen to you after the initial problem - don't get stuck in the middle of an intersection with an opposite light turning green and nobody expecting you there - especially if you are on the ground.

Sometimes speed helps, to match traffic. Other times speed kills.

You only need a couple feet of escape path.

Frequently update your mental "threat level". Green - no danger. Yellow - hands on brakes. Red - High danger identified.

Also treat every car like a giant metal safety barrier from other cars.

Bleeding away any energy via your brakes before a crash is always better. A slow crash beats a fast crash.
All good thoughts. From my past professional life for critical, failure-is-not-an-option stuff:

"Layers of protection. No single-point failure." (Failure of a single item in a system causing catastrophic failure.)

So, all of the above, AND learn good emergency braking and evasion.
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Old 02-14-24, 12:55 AM
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Originally Posted by calamarichris
Fishtailing means you're still reducing your velocity. Your body slamming into a car at 15mph > slamming into a car at 20mph. It doesn't sound like much of a difference numerically, but it really is.
Right on. Energy = (1/2)MV^2. Thus, 15^2/20^2 = 0.56, energy reduced by almost half.
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Old 02-14-24, 06:59 AM
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Originally Posted by LarrySellerz
wow that’s a lot.
Dude .... wow .....

1) never claimed to be a scientist, I'm a technician. Got a degree? Understand Scientific Method, as proposed by Francis Bacon of whoever, and subsequently developed into observation, hypothesis, experiment, analysis, theory??

[QUOTE=LarrySellerz;23156038]2) you can get the back wheel to come off the ground in lots of ways, ever see a bunny hop? {/quote] When speaking in public, it is wise to recall both the immediate situation and the larger context when replying (what might be called the "I can scroll up, did you?" principle) ... to save oneself a bit of embarrassment.

No one who has suffered through my tens of thousands of posts thinks I don't know what a bunny hop is. Are you saying that bunny-hopping is in some way relevant to this discussion? If so explain how, please?

Originally Posted by LarrySellerz
3) I claimed that OP fell because she isn't used to making emergency stops. It sounds like she's used to relying on the back brake, and when she really needed to stop this training failed her.
This is pure idioc... ridiculousne... a straight-up "reading should be Fundamental" moment. The lady fell because she locked he Front wheel after decelerating enough for the front wheel to grab hard under extreme braking. She flopped the front wheel. She panic-stopped badly and when she had slowed enough for the front wheel to lock she didn't modulate so she got dumped. She never mentions the back end sliding out. She mentions the back end Lifting.

She also doesn’t mention doing a bunny-hop.

Originally Posted by freckles
Just a mile from home and a car pulled out fast blindly from a driveway onto a one way "sharrow". I hit my BF brake's hard and … I think the back wheel lifted up a bit and while stopped, I tumbled a bit forward with my bike to the left side, landed below my knee and got a nice little road rash..
As has been mentioned repeatedly, the rear wheel lifts Only when the front brake is used with extreme force.

Use your technician training … analyze the evidence and compare it to known principals of physics, particularly as it applies to bike riding.

Originally Posted by LarrySellerz
4) I delivered food full time in traffic for years, it’s how I made money to live and eat
Did i mention relevance, above?

If you hasdd learned during those years, you should have learned that eh back wheel rides in a panic stop Only when the front brake is applied with great force. Even when delivering food … so the whoel “I delivered food” comment adds nothitgn but to make it look like somehow you were lucky enough to ride by instinct without understanding what you were doing. Nothing to so with this post.

[QUOTE=LarrySellerz;23156038]5) I'm serious that learning how to use the front brake is the key to stopping on the fly. If you undo the back brake, you are forced to learn how to use the front. [/back] And peopel who actually know how to ride bikes know that using Both brakes properly is actually the key to minimum stopping distances. Sorry to be blunt ....

But I do agree her issue here was not using her brakes properly .... she hit the front too hard. However, given the situation (as car came out of a driveway too close for her to stop safely given her skill level) she did at least manage to stop the bike before she hit the car, and her injuries were minor. if she had practiced panic-stopping, maybe she would have sued Both brakes to their limits and stopped and not fallen.

However there are endless hypotheticals .... Like a world in which Stephen Colbert is as smart Stephen Hawking, or a world in which Stephen Colbert is funny .... or even a backward-physics world in which locking up the front brake makes the ear wheel hop ... but it not this world.

Originally Posted by LarrySellerz
6) people in this thread are acting like falling off your bike when slamming the front brake is some unknown or unusual phenomenon.
Care to point out the posts showing this please? And then explain why they matter in this discussion?

Originally Posted by LarrySellerz
It’s what happens when you aren't emergency stopping correctly.
Yes …. Agreed ….. it is what happened here. Nothing to do with the rear brake at all, as you seem yoto understand … sometimes.

Originally Posted by LarrySellerz
It’s so engrained in me how to move my body when stopping like this that its hard to describe what I do, but I think I stand up and move my weight back behind the saddle when slamming the front.
So now you seem to realize that the reason she crashed is that she over-applied the Front brake, not the rear? Progress.

Originally Posted by LarrySellerz
my advice can be summed up by “learn how to use the front brake. You wouldn’t have crashed if you were adept with the front brake. You can force yourself to get better by taking the back brake off”
You cannot learn to use the front brake by not using it. You can learn to use Both brakes by using them---which is why so many people recommend practicing panic stops where we learn to stop our bikes in the minimum distance without crashing.

And you later post this gem:
Originally Posted by LarrySellerz
Any meaningful amount of braking force your rear provides in an emergency stop will just make you fishtail, IMO atleast. Provided you have a good front brake and are using it to its fullest
Let me brake it down for you (bad pun intended):

First, if you are fishtailing you are over-applying the rear brake. Learn how to to use the rear brake---Both brakes---before trying to educate others.

Second---you claim that the rear brake locks (causing the fishtail) only if the front brake is locked. This is nondsens. Since weight transfers forward when you stop, you can lock the rear brake even if all you have is a rear brake Ref: the classic coaster-brake brake slide done by pre-teen riders everywhere …. Chewing up the cback tire on a bike with only a coaster brake by jamming it on when approaching friend to do the “cool” brake slide/ controlled fishtail.

You might have delivered a lot of food but you didn’t learn much about riding.

Third---yeah, ebven you recommend using Both brakes for minimum stopping diastances.

Dude …. Sorry you are just wrong.
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Old 02-14-24, 07:03 AM
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Originally Posted by LarrySellerz
my advice can be summed up by “learn how to use the front brake. You wouldn’t have crashed if you were adept with the front brake. You can force yourself to get better by taking the back brake off”
Originally Posted by LarrySellerz
3) I claimed that OP fell because she isn't used to making emergency stops. It sounds like she's used to relying on the back brake, and when she really needed to stop this training failed her.
Originally Posted by LarrySellerz
6) people in this thread are acting like falling off your bike when slamming the front brake is some unknown or unusual phenomenon.
What is "cognitive dissonance?" Something about logically opposed ideas juxtaposed? I will look it up later .... somethign about ideas clashing ... I don't know ....
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Old 02-14-24, 07:06 AM
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Originally Posted by calamarichris
Fishtailing means you're still reducing your velocity. Your body slamming into a car at 15mph > slamming into a car at 20mph. It doesn't sound like much of a difference numerically, but it really is.

And whom among us can really say we're using the front brake to its optimum, short of the Turkish kid Razgatliagthu?
He is overbraking the front and wasting available rear traction.

I love bike-racing (motorbike racing.) The things those guys do .... as far as "hanging ti out there" ... are unequaled except in sidehack racing.

My favorite is when they accelerate out of corners, still leaned way over, and lift the front wheel. I lack the courage to even lean that far, and they do it on one wheel ...


But yeah, the guy above is overbraking up front. Not much rolling friction if the tire isn't on the tarmac.
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Old 02-14-24, 09:20 AM
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[QUOTE=Maelochs;23156411]Dude .... wow .....

1) never claimed to be a scientist, I'm a technician. Got a degree? Understand Scientific Method, as proposed by Francis Bacon of whoever, and subsequently developed into observation, hypothesis, experiment, analysis, theory??

[QUOTE=LarrySellerz;23156038]2) you can get the back wheel to come off the ground in lots of ways, ever see a bunny hop? {/quote] When speaking in public, it is wise to recall both the immediate situation and the larger context when replying (what might be called the "I can scroll up, did you?" principle) ... to save oneself a bit of embarrassment.

No one who has suffered through my tens of thousands of posts thinks I don't know what a bunny hop is. Are you saying that bunny-hopping is in some way relevant to this discussion? If so explain how, please?

This is pure idioc... ridiculousne... a straight-up "reading should be Fundamental" moment. The lady fell because she locked he Front wheel after decelerating enough for the front wheel to grab hard under extreme braking. She flopped the front wheel. She panic-stopped badly and when she had slowed enough for the front wheel to lock she didn't modulate so she got dumped. She never mentions the back end sliding out. She mentions the back end Lifting.

She also doesn’t mention doing a bunny-hop.

As has been mentioned repeatedly, the rear wheel lifts Only when the front brake is used with extreme force.

Use your technician training … analyze the evidence and compare it to known principals of physics, particularly as it applies to bike riding.

Did i mention relevance, above?

If you hasdd learned during those years, you should have learned that eh back wheel rides in a panic stop Only when the front brake is applied with great force. Even when delivering food … so the whoel “I delivered food” comment adds nothitgn but to make it look like somehow you were lucky enough to ride by instinct without understanding what you were doing. Nothing to so with this post.

Originally Posted by LarrySellerz
5) I'm serious that learning how to use the front brake is the key to stopping on the fly. If you undo the back brake, you are forced to learn how to use the front. [/back] And peopel who actually know how to ride bikes know that using Both brakes properly is actually the key to minimum stopping distances. Sorry to be blunt ....

But I do agree her issue here was not using her brakes properly .... she hit the front too hard. However, given the situation (as car came out of a driveway too close for her to stop safely given her skill level) she did at least manage to stop the bike before she hit the car, and her injuries were minor. if she had practiced panic-stopping, maybe she would have sued Both brakes to their limits and stopped and not fallen.

However there are endless hypotheticals .... Like a world in which Stephen Colbert is as smart Stephen Hawking, or a world in which Stephen Colbert is funny .... or even a backward-physics world in which locking up the front brake makes the ear wheel hop ... but it not this world.

Care to point out the posts showing this please? And then explain why they matter in this discussion?

Yes …. Agreed ….. it is what happened here. Nothing to do with the rear brake at all, as you seem yoto understand … sometimes.

So now you seem to realize that the reason she crashed is that she over-applied the Front brake, not the rear? Progress.

You cannot learn to use the front brake by not using it. You can learn to use Both brakes by using them---which is why so many people recommend practicing panic stops where we learn to stop our bikes in the minimum distance without crashing.

And you later post this gem:

Let me brake it down for you (bad pun intended):

First, if you are fishtailing you are over-applying the rear brake. Learn how to to use the rear brake---Both brakes---before trying to educate others.

Second---you claim that the rear brake locks (causing the fishtail) only if the front brake is locked. This is nondsens. Since weight transfers forward when you stop, you can lock the rear brake even if all you have is a rear brake Ref: the classic coaster-brake brake slide done by pre-teen riders everywhere …. Chewing up the cback tire on a bike with only a coaster brake by jamming it on when approaching friend to do the “cool” brake slide/ controlled fishtail.

You might have delivered a lot of food but you didn’t learn much about riding.

Third---yeah, ebven you recommend using Both brakes for minimum stopping diastances.

Dude …. Sorry you are just wrong.
all I really took from this is that you struggle with emergency stops. You keep mentioning “pulling the front brake TOO HARD, which is impossible. When stopping as fast as possible, one harnesses the full stopping force of their front brake. At that point, any meaningful application of the back brake will make the bike fishtail. This can slow you down a little bit, yes, but can be disconcerting if you aren’t expecting it.

would you like me to DM you some exercises and drills for emergency stopping? Naturally, they would work better with the back brake disengaged, but you can keep it on if you like
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Old 02-14-24, 11:16 AM
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Originally Posted by Maelochs
He is overbraking the front and wasting available rear traction.

I love bike-racing (motorbike racing.) The things those guys do .... as far as "hanging ti out there" ... are unequaled except in sidehack racing.

My favorite is when they accelerate out of corners, still leaned way over, and lift the front wheel. I lack the courage to even lean that far, and they do it on one wheel ...

But yeah, the guy above is overbraking up front. Not much rolling friction if the tire isn't on the tarmac.
Razgatliagthu knows what he's doing. He's known for winning GP races by out-braking the others, and by his crazy lean-angles. I've worn out a few pair of knee pucks, but this Turkish kid needs eyebrow-pucks.
Also motorcycles are different from bicycles. We're riding around on little dime-sized contact patches at tires pumped up to 100psi. Riding on the track, you're on great big squishy, sticky tires pumped to 15-20psi, with about a dollarbill-sized contact patch in the back, and about 75-100 cents on the front tire, depending on how hard you're braking.
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Old 02-15-24, 01:16 AM
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Originally Posted by calamarichris
Razgatliagthu knows what he's doing. He's known for winning GP races by out-braking the others, and by his crazy lean-angles. I've worn out a few pair of knee pucks, but this Turkish kid needs eyebrow-pucks.
Also motorcycles are different from bicycles. We're riding around on little dime-sized contact patches at tires pumped up to 100psi. Riding on the track, you're on great big squishy, sticky tires pumped to 15-20psi, with about a dollarbill-sized contact patch in the back, and about 75-100 cents on the front tire, depending on how hard you're braking.
But your racebike weighs 18lb and is going 27mph; the motorcycle weighs a couple and more hundred pounds. It is going 156mph. More rubber on the track (if it were possible) for bike and motorbike wouldn't be too much to ask ...
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Old 02-15-24, 01:24 AM
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Originally Posted by calamarichris
Razgatliagthu knows what he's doing. He's known for winning GP races by out-braking the others, and by his crazy lean-angles. I've worn out a few pair of knee pucks, but this Turkish kid needs eyebrow-pucks.
Also motorcycles are different from bicycles. We're riding around on little dime-sized contact patches at tires pumped up to 100psi. Riding on the track, you're on great big squishy, sticky tires pumped to 15-20psi, with about a dollarbill-sized contact patch in the back, and about 75-100 cents on the front tire, depending on how hard you're braking.
Pretty obviously the guy has the finesse to control a several hundred pound, nearly three-hundred bhp motorcycle and not die.... winning is a bonus but just to ride the bike v... I would probably struggle to keep the thing on the road even at street speed. Not saying the guy isn't good .... you don't even get a chance to ride bikes like that (even for a consumer .... more than once) unless you are exceptionally skilled.

However, physics is physics no matter how skilled one might be.
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Old 02-15-24, 01:51 AM
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Originally Posted by Maelochs
However, physics is physics no matter how skilled one might be.
I dunno man. If you watch some of his highlights on Youtube, he seems to put physics on hold some moments.
The dude's Baryshnikov on wheels.

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Old 02-15-24, 02:29 AM
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Originally Posted by Leisesturm
But your racebike weighs 18lb and is going 27mph; the motorcycle weighs a couple and more hundred pounds. It is going 156mph. More rubber on the track (if it were possible) for bike and motorbike wouldn't be too much to ask ...
Sort of. So, on paper, something with, let's say, 10 units of area contact, and 30 units of weight, has the same friction force as cutting the area in half to 5, but then the unit pressure doubles, yielding the same friction force. However, tires do not behave linearly in friction. More area helps.

However, assuming static friction, i.e., the tire not sliding, not accelerating or braking (very important), just rolling, the cornering ability, all other factors being equal, is about the same at 10 miles per hour as it is at 100 miles per hour. Other dynamics are at play here that can have more effect at high speeds, like the tire getting hotter (sometimes bad, sometimes good), but generally the above applies.

Where you do see enormous difference, is the brake rotors, calipers, and pads, required to stop from 100 to 0, versus 10 to 0. And it's not even just a 10:1 difference, but 100^2/10^2 = 100, so a 100:1 difference in braking energy capacity. And the same is true in acceleration, 50-100 takes a lot more power (energy per unit time) than 0-50. And that's not even counting aero drag, which increases as the square of the speed, and power needed to overcome increases as a cube of the speed.

But cornering ability under rolling conditions, is much more linear. BUT... under hard braking or acceleration, the cornering ability can fall quickly. This is known as the "friction circle". Assume a circular contact patch, easiest for talking points. Assume you can generate max 1G friction is all directions. You can corner at 1G. You can accelerate at 1G. You can brake at 1G. But if you try to brake at 1G and corner at 1G, the combined resultant force will equal 1.41G (square root of 2), and this is more than our 1G max tire can give, so the tire loses traction and you slide. In general, if you ask a tire to accerate or brake, you're going to lose some cornering ability. Qualifications: The friction circle on most tires is oval, can brake and accelerate more than cornering. Slight braking can help cornering (at least with older, taller section tires, I don't know about the latest tires). Braking and acceleration will change weight distribution and contact patch size on tire, which will change handling.
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Old 02-18-24, 10:59 AM
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Not adding much new, but there are a range of bike handling skills that are worth intentionally practicing- braking effectively and safely being number one! Also recommend learning to quickly swerve around potholes.
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Old 02-22-24, 01:26 PM
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When I first started doing rides on a 10-speed bike the front brake was adjusted so it would not clamp down 100% on the rim. It made it impossible to lock the front wheel and send be over the handlebars. This is still a good idea for all but mountain bikes where downhill braking on dirt makes greater use of the front tire.

I had a friend who was descending with me on a very steep grade and he took a blind corner wide and was heading straight at a car coming up the hill. The driver swerved to avoid him and so was going straight at me. I locked the brakes and brought my bike to a stop on the shoulder of the road. My front tubular tire that was cemented to the rim had come off completely. I was happy to have avoided being hit by the car and that I stayed on the side of the road as past the shoulder the ground fell off into a deep ravine. I was lucky to come away with only a damaged rim and tire.
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Old 02-22-24, 09:00 PM
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Originally Posted by Calsun
When I first started doing rides on a 10-speed bike the front brake was adjusted so it would not clamp down 100% on the rim. It made it impossible to lock the front wheel and send be over the handlebars. This is still a good idea for all but mountain bikes where downhill braking on dirt makes greater use of the front tire.

I had a friend who was descending with me on a very steep grade and he took a blind corner wide and was heading straight at a car coming up the hill. The driver swerved to avoid him and so was going straight at me. I locked the brakes and brought my bike to a stop on the shoulder of the road. My front tubular tire that was cemented to the rim had come off completely. I was happy to have avoided being hit by the car and that I stayed on the side of the road as past the shoulder the ground fell off into a deep ravine. I was lucky to come away with only a damaged rim and tire.
You can not lock the front wheel, and still go over the handlebars. In fact, maximum braking is experienced just before tire skidding, as static friction exceeds kinetic/dynamic (sliding) friction, for non-fluid things, and more so with rubber tires than some harder materials.

I need hard front braking for emergencies; I've been favoring my rear brake, as the front rim sidewalls are worn more; Was coming up to T-intersection at the bottom of a long fast downhill, hit the rear brake, not enough, squeezed the front and the rear started to lock up, then I *sat down* (I had been standing on the pedals because there is a hard bump at one of the concrete expansion strips there), gave full braking front and rear, bled off speed, made the turn.
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