Advocacy & Safety - Crash avoidance

The only way you are going to be able to turn and brake hard is by using the front brake only! If you use the rear, it will lock up, if it locks up, you will go down, or you will not be able to steer.


:rolleyes: Locking up the rear wheel is controllable. My nine year old son does little else on his bike. Maybe you need a little more practice.

If you try to turn while hauling on the front brake you risk a front wheel skid. That will guarantee going down unless you're extremely skilled/lucky. But it's your skin. Go for it if you think you can get away with it. For me, it's a last resort only.

I even try to avoid turning under braking in my car. It's basic defensive driving technique. Brake before the turn, not through it.

I find experimenting with/learning braking to be very hard to duplicate real world events. As much as I've tried I can not get myself up to 20-25mph and brake hard (or too hard as needed to learn) and repeat. Either I know I will be braking in a moment and subconsciously pre-prepare or if I have someone else (say my wife) yell stop at 'random' times I still know she will be yelling for me to stop over some span I am riding, so I am ready.

Any tips for getting over this mental block of not being able to perform an emergency brake test without a true emergency? Maybe I need to get my wife to throw something in front of me. ;)

Al

Al, I would stop trying for an 'emergency' test, which would be nearly impossible to duplicate. Simply go out and see how quickly you can stop. Pick a crack on the road or something and head toward it at 20 mph then hit the brakes when you cross the line. Try for the shortest possible stop without crashing. That eliminates reaction time as a variable -- the emergency factor -- but that's fine. This drill will educate quickly on the necessary components of a controlled 'panic stop.' You'll see that it's at least as much about body control as brake control, that is, an exagerrated well-timed body movement will allow you to apply much more force to the front brake.

Robert

The major problem with a rear that is locked up and skidding is that you cannot turn. Go out and try it. Lock up the rear and turn the bars. What happens? I'll tell you what doesn't happen and that is that steering doesn't happen. The rear wheel will go out to the left or right, but the bike will go straight. So if you lock the rear, you are giving up the abilioty to manoeuve the bike.

You are correct that a rider in crisis should consider both turning and stopping to avoid contact. But you could put a ski where your rear wheel is and still be able to turn. It won't feel the same, granted, but it's certainly possible to turn a bicycle when the rear tire is locked up. I do it fairly often, just for fun. Trying to turn with a locked front tire, that's a different ballgame.

If skidding on a bicycle feels like the edge of control, something's missing. To people who feel this way I recommend: trail riding.

Robert

Learned the hard way:

A small patch of ice is all it takes
Fast turns at high speeds are controlled by laws of physics
Unclip first

Other lessons were learned without physical damage.

http://www.vicroads.vic.gov.au/NR/rdonlyres/CD4E65B9-3FDB-4E65-992C-809DB92DD776/0/Bike_Ed_Activity_2.pdf

Al, I would stop trying for an 'emergency' test, which would be nearly impossible to duplicate. Simply go out and see how quickly you can stop. Pick a crack on the road or something and head toward it at 20 mph then hit the brakes when you cross the line. Try for the shortest possible stop without crashing. That eliminates reaction time as a variable -- the emergency factor -- but that's fine. This drill will educate quickly on the necessary components of a controlled 'panic stop.' You'll see that it's at least as much about body control as brake control, that is, an exaggerated well-timed body movement will allow you to apply much more force to the front brake.

Sure I've done this, but it just seems so fake to me. I am not arguing or complaining, just noting how I feel when I do it.
I get the same practice in club rides in suburbia where we get just turned red lights. I know I can stop faster that most everyone else, which I have to be careful about. One of the reasons is I am always on fixed gear with just a front brake. Most others skid their rear wheels and don't seem to be using the front as much as they should.

Al

Sure I've done this, but it just seems so fake to me. I am not arguing or complaining, just noting how I feel when I do it.
I get the same practice in club rides in suburbia where we get just turned red lights. I know I can stop faster that most everyone else, which I have to be careful about. One of the reasons is I am always on fixed gear with just a front brake. Most others skid their rear wheels and don't seem to be using the front as much as they should.
Al

I've noticed this also on big group rides. In fact, if you look at the crashes in the major road races, like the TDF, it is surprising to see how many people go straight into a wall, or straight into a dog, with the rear wheel locked. You would think that pros would have learned a not to use the rear brake in case of an emergency, but old bad habits die hard.

Sure I've done this, but it just seems so fake to me. I am not arguing or complaining, just noting how I feel when I do it.
I get the same practice in club rides in suburbia where we get just turned red lights. I know I can stop faster that most everyone else, which I have to be careful about. One of the reasons is I am always on fixed gear with just a front brake. Most others skid their rear wheels and don't seem to be using the front as much as they should.


Ah, the fixed gear. Fixed gears add a lot of interesting features to braking. The instantaneous and subtle speed control right on the foot -- not having to reach for it -- is a wonderful thing and a great advantage in heavy traffic. Fixed gears also provide important advantages in controlling deceleration on slippery or wet surfaces. But when it comes to an actual panic stop on a dry surface the fixed wheel will do you no favors. Even with a front brake -- even with two brakes -- there is no way you should be able to stop your fixed as short as someone on a regular road racing bike with a freewheel; if you can, they're not doing it right or their brakes are whacked or something else has gone horribly wrong. The minimum _controlled_ stop on a fixed is going to be noticeably longer than the minimum on a road bike, I'm guessing this is due not only to the momentum of the wheel but to the fixed rider's having to move with the drivetrain and thus not being completely free to really work the body movement that is the hallmark of a well-executed handbrake stop.

Your clubmates' rear tire skidding may be the hallmark of piss poor bike handling and faulty front brake use, and if you can stop shorter than them on your fixed wheel then it probably is. But remember that the rear tire skid is also a natural product of proper front brake use in a 'maximum stop' on a freewheel bike.

Robert

Ah, the fixed gear. Fixed gears add a lot of interesting features to braking. The instantaneous and subtle speed control right on the foot -- not having to reach for it -- is a wonderful thing and a great advantage in heavy traffic. Fixed gears also provide important advantages in controlling deceleration on slippery or wet surfaces. But when it comes to an actual panic stop on a dry surface the fixed wheel will do you no favors. Even with a front brake -- even with two brakes -- there is no way you should be able to stop your fixed as short as someone on a regular road racing bike with a freewheel; if you can, they're not doing it right or their brakes are whacked or something else has gone horribly wrong. The minimum _controlled_ stop on a fixed is going to be noticeably longer than the minimum on a road bike, I'm guessing this is due not only to the momentum of the wheel but to the fixed rider's having to move with the drivetrain and thus not being completely free to really work the body movement that is the hallmark of a well-executed handbrake stop.

Your clubmates' rear tire skidding may be the hallmark of piss poor bike handling and faulty front brake use, and if you can stop shorter than them on your fixed wheel then it probably is. But remember that the rear tire skid is also a natural product of proper front brake use in a 'maximum stop' on a freewheel bike.

Robert
What I was trying to convey is that my short stop distance is not because of the fixed gear itself, but because I only have a front brake, so I have learned to use it effectively. The other club riders have not be 'forced' into this and have not learned how to brake as effectively.

I thought it was clear that my short stopping had nothing to do with equipment, but with technique, technique that I was forced to learn.

Of course there are (maybe even a majority of) other club riders who have equal or better stopping skills than me, but the ones who stand out are the ones who skid past me when stopping or stop ahead of me skidding while I stop much faster.

If some of these folks with poor braking technique rode a fixed gear with front brake (or even their regular freewheel with rear brake removed) they would too quickly learn to maximize use of front brake. Then with rear brake added they could then learn to use it in combination with what they learned when forced to brake with only front.

Al

I've noticed this also on big group rides. In fact, if you look at the crashes in the major road races, like the TDF, it is surprising to see how many people go straight into a wall, or straight into a dog, with the rear wheel locked. You would think that pros would have learned a not to use the rear brake in case of an emergency, but old bad habits die hard.

Not using the rear brake would end in the same result, just quicker.

For steering under heavy braking, whether the rear tire is rolling, locked, or replaced with a ski is not going to matter that much. No matter what the rear tire is doing it is very difficult to turn a bike when the front brake is being pulled so hard that the front tire is on the verge of locking up.

Dare I say the front tire is the more important tire for steering a bike. I know a guy who can ride nose wheelies around corners and up curbs -- talk about breaking rear-tire traction. Ever seen speedway motorcycle racing? Ever watched a good downhill mountain biker? Ever seen the video MASH? Learn to love the skid. I'm not saying anybody should be able to do these things, just that bike control should not and does not depend on rear tire traction.

Robert

If you can lift your rear wheel using only your front brake, then you can achieve maximum decelleration using only your front wheel, and you will have more control than if you use your front brake.

Applying the brakes creates a torque that rotates the bike forward. This rotation causes weight to transfer from the rear wheel to the front wheel so that the torque on the bike is balanced. For a given amount of braking, the amount of rotation is the same regardless of which wheel the braking is applied to, because the perpendicular distance between where the braking force is applied -- the ground -- and the center of mass is the same. If the rear wheel is lifted, it is not contacting the ground and is not contributing to the stopping of the bike. If you are able to achieve enough rotation using just the front brake to do this, then you have achieved the maximum stopping power of your bike, since the amount of rotation is determined by the braking and not by where it is applied.

If you are able to achieve maximum braking using the front brake, it is a bad idea to use the rear brake at all. The reason for this is that it is very easy to skid a lightly loaded tire. When a tire is skidding, it offers no directional stability -- it skids equally easily in all directions. In contrast, a rolling tire, even lightly loaded, offers much less resistance in the forward direction than it does side to side, so it will keep the back of your bike following the front of your bike. Since bikes are articulated, when the rear wheel loses directional stability the bike tends to fold up along the steering tube and become unstable.

The most important condition in the above discussion is that it has to be possible to lift the rear using the front brake. This will not be possible under poor traction conditions, nor will it be possible with certain long-wheelbase designs such as tandems and some recumbents. Which brings me to an important advocacy point:

Most bike brakes suck.

Very few of the bikes I have ridden in my lifetime had front brakes capable of lifting the rear wheel. Bike brakes tend to go out of adjustment quickly, and most riders can't be bothered to do the maintenance required to keep them working. This is particularly troubling, given that even with well-functioning brakes a bike will typically have about 2/3 of the stopping ability of a car.

I ride mostly in traffic, and it took me a couple of braking-related accidents to go with disk brakes on all of my bikes. The disks are far superior to rim brakes, not so much when both are new, but particularly in holding their adjustment over time. With the disks I almost never touch the front brake.

If you can lift your rear wheel using only your front brake, then you can achieve maximum decelleration using only your front wheel, and you will have more control than if you use your front brake.

Applying the brakes creates a torque that rotates the bike forward. This rotation causes weight to transfer from the rear wheel to the front wheel so that the torque on the bike is balanced. For a given amount of braking, the amount of rotation is the same regardless of which wheel the braking is applied to, because the perpendicular distance between where the braking force is applied -- the ground -- and the center of mass is the same. If the rear wheel is lifted, it is not contacting the ground and is not contributing to the stopping of the bike. If you are able to achieve enough rotation using just the front brake to do this, then you have achieved the maximum stopping power of your bike, since the amount of rotation is determined by the braking and not by where it is applied.

If you are able to achieve maximum braking using the front brake, it is a bad idea to use the rear brake at all. The reason for this is that it is very easy to skid a lightly loaded tire. When a tire is skidding, it offers no directional stability -- it skids equally easily in all directions. In contrast, a rolling tire, even lightly loaded, offers much less resistance in the forward direction than it does side to side, so it will keep the back of your bike following the front of your bike. Since bikes are articulated, when the rear wheel loses directional stability the bike tends to fold up along the steering tube and become unstable.

The most important condition in the above discussion is that it has to be possible to lift the rear using the front brake. This will not be possible under poor traction conditions, nor will it be possible with certain long-wheelbase designs such as tandems and some recumbents. Which brings me to an important advocacy point:

Most bike brakes suck.

Very few of the bikes I have ridden in my lifetime had front brakes capable of lifting the rear wheel. Bike brakes tend to go out of adjustment quickly, and most riders can't be bothered to do the maintenance required to keep them working. This is particularly troubling, given that even with well-functioning brakes a bike will typically have about 2/3 of the stopping ability of a car.

I ride mostly in traffic, and it took me a couple of braking-related accidents to go with disk brakes on all of my bikes. The disks are far superior to rim brakes, not so much when both are new, but particularly in holding their adjustment over time. With the disks I almost never touch the front brake.

Me, I'm just interesting in reliably stopping my bike when and where needed in a timely manner, regardless of weather conditions; not maximum deceleration nor maximum stopping power. Coaster brakes have filled that requirement with minimal fuss for me for over 55 years of cycling on the street and roads with never, ever having a failure to avoid an obstacle due to lacking maximum stopping power.

I caveat the statement above with the disclosure that I have never commuted up or down a 4 mile 10% grade, nor participated in any cycling competition, nor off road events. If I were to take up such cycling activity, I might reconsider my choice.

With the disks I almost never touch the front brake.

oops, meant to say I almost never touch the rear brake!

I'm with ILTB on this one. The key isn't necessarily in the shortest stopping distance, the key is knowing the capabilities of the bike and rider. The key to avoiding an accident, IMO, is in making the correct decision to either brake or maneuver given the specific circumstance. Stopping is not always the best option.

I'm with ILTB on this one. The key isn't necessarily in the shortest stopping distance, the key is knowing the capabilities of the bike and rider. The key to avoiding an accident, IMO, is in making the correct decision to either brake or maneuver given the specific circumstance. Stopping is not always the best option.
So far in my limited time cycling I have never had to perform an emergency stop to avoid a collision. But it is a skill that may come in handy some day so I will continue to familiarize myself with how quickly I can stop.

Then again, I have bit of trouble in a practical sense differentiating between 'the shortest stopping distance' from 'the capabilities of [my] bike and [me]' when it comes to my stopping capability.

Al

Eh, I mean that I stop a fair amount in the normal course of things, and kinda have an idea for a maximum stopping distance. The "shortest possible stopping distance" I'm thinking of is essentially the front wheelie uncontrolled version. I don't practice those and don't rely on having that skill. If something came up on me that fast, I'd look to maneuver, or barring that, hit the obstruction as gracefully as possible.

Eh, I mean that I stop a fair amount in the normal course of things, and kinda have an idea for a maximum stopping distance. The "shortest possible stopping distance" I'm thinking of is essentially the front wheelie uncontrolled version. I don't practice those and don't rely on having that skill. If something came up on me that fast, I'd look to maneuver, or barring that, hit the obstruction as gracefully as possible.
Fair enough. I rarely stop quickly in every day riding as I come into stops gently as I like to bring following drivers in slowly too to help reduce getting rear ended.

The only hard stops I do are if a light turns red just as I get to it and there is no vehicle right behind me.

edit: Just for fun here is a video of the quickest stop I've ever made while commuting:
http://www.youtube.com/watch?v=WK3dku86eFY

Why? Because even though the light had just turned yellow when I was only 15ft before stop and I could have still legally proceeded thru intersection - I processed (a bit late) that the sun was behind my back and there were drivers waiting to turn left across my path. I could not be certain they saw me -especially considering the light conditions. I went way over the stop line (which I otherwise always stop before) and into the x-walk. I also checked there was not a vehicle behind me who likely would not have stopped and moved right in case they didn't.

Al

I recently took a motorcycle course and they taught us maximum brakeing and crash avoidance. Both brakes are used, but the front brake much moreso. The rear brake, once in a skid, can cause you to lowside if the rear rotates around the bike. Or, if you are really unlucky, you can high side when the back tire regains traction and get launched over the bike. They also taught us to make sure there was enough room behind you so that the car following doesn't run up your arse when you make your emergency stop. Counter steering around obstacles is fun! Just make sure you don't target fixate. Look where you want to go, not at what your trying to avoid.

When I first started riding fixed gear, I had an emergency brakeing situation due to a couple of ninjaguys on bikes in the middle of the road. I grabbed too much front brake and nose wheelied between the two of them. It was awesome and I nearly crapped my pants.

Knowing how to make emergency stops and avoid crashes is all well and good, but personally, I prefer to look as far ahead as I can and know whats going on around me. Most of my rides on my fixed gear bikes, I hardly ever use the brakes due to resisting. Its just like the compression brakeing I do in my stick shift car and on my motorcycle. I just use the brakes to flash the brake lights so the cagers behind me know I'm slowing down.

So far in my limited time cycling I have never had to perform an emergency stop to avoid a collision. But it is a skill that may come in handy some day so I will continue to familiarize myself with how quickly I can stop.

Then again, I have bit of trouble in a practical sense differentiating between 'the shortest stopping distance' from 'the capabilities of [my] bike and [me]' when it comes to my stopping capability.

Al

Brakes requiring well practiced skillful application to obtain maximum stopping power/theoretical shortest stopping distance may not play out according to theory in the real world if and when an emergency avoidance stop also includes surprise, panic and adrenaline affecting the response of the cyclist.

Brakes requiring well practiced skillful application to obtain maximum stopping power/theoretical shortest stopping distance may not play out according to theory in the real world if and when an emergency avoidance stop also includes surprise, panic and adrenaline affecting the response of the cyclist.

Of course. Is anyone suggesting otherwise?

I still believe however that the more one practices 'maximum stop power' in a controlled environment that one will be less affected by the emergency drama when doing so in a true emergency.

Al

Of course. Is anyone suggesting otherwise?

I still believe however that the more one practices 'maximum stop power' in a controlled environment that one will be less affected by the emergency drama when doing so in a true emergency.


Maybe. IMO some of the posters place way too much faith in the theoretical capabilities of gee whiz equipment to maximize their efficiency/safety.

If ownership of that stuff combined with the knowledge of theoretical capabilities maximizes (or even improves) anyone's cycling pleasure and sense of well being, wonderful!

Most bike brakes suck.


This is an excellent point, and getting back to the OP's question about crash avoidance is something every roadie (commuter or otherwise) should be aware of, esp if you are biking around traffic in a big city. The manufacturers are partly to blame for cheaping out (Cannondale is especially bad for this - eg, Dura Ace FD/RD + 105 or worse level brakeset) but most of the blame comes back to us and our competing desires for cheap bikes with Ultegra/Dura Ace drivetrains and low prices...

My big recommendation to the OP and anyone who commutes regularly in heavy traffic is to 1) learn and practice how to brake in an emergency on both dry and wet surfaces, and 2) resist the temptation to blow your wad on drivetrain alone, and make sure that the brakeset on your bike is the best equipment you can afford (with good pads). I rebuilt my older Cannondale all Ultegra (including brakeset which was RSX level when new) and the difference in braking is incredible, especially if you are riding on half decent tires. (GP4000 in my case)

My $0.02 on the front vs. rear brake debate is all front on dry surfaces (I regularly bring the rear wheel about 2-3 in off the ground practicing this) and a balance of front + rear on wet surfaces as front wheel skids are no fun at all.

all Ultegra (including brakeset

Is there any evidence that a properly set up Ultegra brakeset will stop a bike better than similarlyl set up Tiagra one?

I've held both in hand side by side and could not see why one would be better than the other for stopping power.

Al

My $0.02 on the front vs. rear brake debate is all front on dry surfaces (I regularly bring the rear wheel about 2-3 in off the ground practicing this) and a balance of front + rear on wet surfaces as front wheel skids are no fun at all.

Hope you never have to find out the value of those $0.02 in a real deal crash avoidance situation. Your $0.02 will be far more valuable if you can repeat the same results in a critical moment. Good Luck.

I'm of the fist full of brakes (front and rear) school of thought. I've locked up the back to angle/slide the bike around the obstacle and let go of the brake and pedal to avoid ( you can high side a bicycle)..lol. I've also slid around corners with a foot skimming the ground and back fully locked up..messenger fun. In some harder braking situations I've used my legs and ankles to push the back wheel down onto the ground harder (while leaning back), the back wheel alternating between skidding and not. Sort of like anti-lock system but with more weight being applied to the wheel as opposed to off/on of the brakes. Practicing a front wheel death stop is no fun, but a very handy thing to have done at least a couple times. The couple times I could not avoid...locked the back , got the bike sideways on purpose and took the car with the side/hip, dispersing the impact over a greater area, a la Judo. They drove away and I rode away both times. Brakes are good, change your pads.

This is an excellent point, and getting back to the OP's question about crash avoidance is something every roadie (commuter or otherwise) should be aware of, esp if you are biking around traffic in a big city. The manufacturers are partly to blame for cheaping out (Cannondale is especially bad for this - eg, Dura Ace FD/RD + 105 or worse level brakeset) but most of the blame comes back to us and our competing desires for cheap bikes with Ultegra/Dura Ace drivetrains and low prices...

My big recommendation to the OP and anyone who commutes regularly in heavy traffic is to 1) learn and practice how to brake in an emergency on both dry and wet surfaces, and 2) resist the temptation to blow your wad on drivetrain alone, and make sure that the brakeset on your bike is the best equipment you can afford (with good pads). I rebuilt my older Cannondale all Ultegra (including brakeset which was RSX level when new) and the difference in braking is incredible, especially if you are riding on half decent tires. (GP4000 in my case)

My $0.02 on the front vs. rear brake debate is all front on dry surfaces (I regularly bring the rear wheel about 2-3 in off the ground practicing this) and a balance of front + rear on wet surfaces as front wheel skids are no fun at all.


I disagree. I have yet to ride any modern bike (medium quality+) with a properly adjusted front brake that I couldn't get to threshold braking (either about to lose traction, or the rear wheel just starting to come off the ground).

Heck, even my Raliegh 3 spd, with steel rims, which is notorious for bad braking, I can get close to threshold braking in the dry. Now the wet, thats a different story.

Is there any evidence that a properly set up Ultegra brakeset will stop a bike better than similarlyl set up Tiagra one?

I've held both in hand side by side and could not see why one would be better than the other for stopping power.

Al

I'm not aware of anything scholarly on the topic of bicycle brake effectiveness, so we can probably only trade anecdotal stories.

However, my RSX (now Tiagra) to Ultegra experience was eye opening. The differences in brake pad softness (hard, long lasting brake pads seem to be a design priority for the entry/mainstream brakesets) and responsiveness were huge. I could extract gobs of braking force with a very small amount of effort, which translated into better modulation and control. Again, just anecdotal but for me this translated into far better braking overall, including stopping power in an emergency. This is why I am so disappointed in the manufacturers for consistently cheaping out on this, as most of the people who buy 'Ultegra' level bikes with Sora/105 (or worse) brakes probably don't know how or can't be bothered to pay for and install a brakeset of an equivalent or better gruppo... maybe they need to make the logos bigger, who knows...

I'm sure Sora/Tiagra has gotten significantly better over the last 6-7 yrs, but I have a tough time believing the only benefit derived from the incremental cost of moving up from Sora to Ultegra is weight savings. The ProTour has no problem making 6.8 kilos nowadays, so why not just use Sora brakes as well as a comfy saddle? Seems unlikely...

However, my RSX (now Tiagra) to Ultegra experience was eye opening. The differences in brake pad softness (hard, long lasting brake pads seem to be a design priority for the entry/mainstream brakesets) and responsiveness were huge.

I put Tiagra as my front brake on my fixed gear. I never used the stock pads and put kool-stop pads in when first installing them. I adjusted them to my liking (generally quite a bit of lever travel before engagement with rim which I find makes for easier to control a range of braking force) I can apply the range of near zero to full on over bars braking power with no jumps or grabbing.

In dry conditions I could not imagine how they could be better. As far as responsiveness I'd guess the very short brake cable with lack of any sharp bends (for front brake) is more of a factor than the brake itself.

Al