Advertise on Bikeforums.net



User Tag List

Page 2 of 4 FirstFirst 1234 LastLast
Results 26 to 50 of 78

Thread: Crash avoidance

  1. #26
    Senior Member hotbike's Avatar
    Join Date
    Dec 2006
    Location
    Long Island, New York
    My Bikes
    a lowrider BMX, a mountain bike, a faired recumbent, and a loaded touring bike
    Posts
    2,553
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by bike2math View Post
    Wet leaves are slippery.
    I would also say that wet leaves are a good thing to avoid. Even if they look dry, they can be wet underneath.

    Black ice is even worse, but not by much. Sometimes black ice can be hidden under fresh snow, so I fear to tread on any snow, unless I have my studded tires:

  2. #27
    Violin guitar mandolin
    Join Date
    Sep 2005
    Location
    Friendsville, TN, USA
    My Bikes
    Wilier Thor, Fuji Professional, LeMond Wayzata
    Posts
    1,171
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Cities. Avoid cities. And MUPs.

    On braking, depends. For heat dispersal, use both. Max stop w/max control, front only controlled by the right hand.

  3. #28
    `````````````` CaptainCool's Avatar
    Join Date
    Feb 2007
    Location
    san jose
    Posts
    765
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Trust your gut. If that car alongside you feels weird, they're about to turn across your path.
    Quote Originally Posted by Pete Fagerlin View Post
    The fastest panic stop is to use a great deal of front brake, shift your weight rearward (behind the saddle and down) while also applying the rear brake (which now has more traction potential because you are counteracting some of the forward weight shift inherent in braking by moving your weight rearwards).
    Moving your center of gravity back and-or down will increase your maximum stopping power, but not the method of achieving it. The front brake is all that matters, as long as the bike is likely to tip forward before the front wheel skids.

    If the road is slippery and the front wheel will skid, use both brakes. The best braking then is just shy of locking up the wheels.

    But get a feel for the rear brake in case you need to brake during a fast or sharp or steep turn. Just like in a car, heavy front brakes make you understeer. If you'd rather skid than go off the road, use the rear brake.

  4. #29
    Senior Member
    Join Date
    Oct 2005
    Posts
    5,426
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    [QUOTE=Pete Fagerlin;4986758]

    The rear brake is not worthless, if you're using the proper technique. Furthermore, locking the rear during an emergency stop is not likely to cause a crash.

    QUOTE]

    The fastest stop comes from using the front brake as hard as you can, but modulating the pressure on it to avoid the bike from doing an endo, or losing traction with the front. That is the limit of braking power on a bicycle.

    At max braking, the rear wheel is going to be near leaving the ground. So please explain to me how can a tire that is hovering on the ground provide any braking ability? It has essentially no wieght on it and no traction.
    Il faut de l'audace, encore de l'audace, toujours de l'audace

    1980 3Rensho-- 1975 Raleigh Sprite 3spd
    1990s Raleigh M20 MTB--2007 Windsor Hour (track)
    1988 Ducati 750 F1

  5. #30
    BeaverTerror Yan's Avatar
    Join Date
    Jan 2006
    Location
    Shanghai, China
    My Bikes
    2013 True North custom touring; 2009 Unicycle.com Club Uni; 1989 Miele Tivoli; 1979 Colnago Sport
    Posts
    1,549
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I was cycling on gravel the other day and used (only) my front brake out of habit. My front wheel lost traction and I crashed. Gloves saved my hands. Ripped my pants.

    Make sure you use the front brakes lightly on tractionless or wet surfaces.
    Yan

    2013 True North custom touring; 2010 Novara Randonee; 2009 Unicycle.com Club 24"; 1989 Miele Tivoli; 1979 Colnago Sport

  6. #31
    Senior Member
    Join Date
    Oct 2005
    Location
    Denver
    Posts
    1,621
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mr. Underbridge View Post
    From your link:

    "For a powerful stop, squeeze the brake levers harder and harder - the front always three times as hard as the rear. The rear wheel will eventually skid. But by this time, most of the weight will be off the rear wheel, so it will skid only lightly. You won't wear a big bald spot in the rear tire - though you will feel and hear the skid."

    Your description doesn't match theirs. According to them, the rear brake adds little to max braking power. They don't focus on the physics, but this is because it *can't* - a wheel with virtually no weight on it can't help you decelerate.

    Their description seems a bit prone to failure. Is it really worth engaging the rear brake at all, when the sole purpose seems to be adding a fun fishtail to your deceleration?

    I prefer Sheldon's method, to which he's added analysis of the actual physics involved:
    http://www.sheldonbrown.com/brakturn.html

    "Conventional wisdom says to use both brakes at the same time. This is probably good advice for beginners, who have not yet learned to use their brakes skillfully, but if you don't graduate past this stage, you will never be able to stop as short safely as a cyclist who has learned to use the front brake by itself.

    ...

    The fastest that you can stop any bike of normal wheelbase is to apply the front brake so hard that the rear wheel is just about to lift off the ground. In this situation, the rear brake cannot contribute to stopping power, since it has no traction."
    Skillful use of both brakes results in shorter controlled stops than using the front brake alone. This is because the rear brake can apply some stopping power in the half-second or so before weight comes off the rear wheel. The advantage of using both brakes together should be obvious to anyone experimenting with hard stops. Don't take my word for it, go out and try it both ways and see how it works out. The rear wheel skid is automatic and, as I see it, unavoidable in a really short and well-done stop near maximum controlled deceleration, but a rear tire skid is not something that should cause a loss of control. Enjoy it, I say.

    Robert

  7. #32
    Senior Member
    Join Date
    Oct 2005
    Location
    Denver
    Posts
    1,621
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by San Rensho View Post
    ...
    At max braking, the rear wheel is going to be near leaving the ground. So please explain to me how can a tire that is hovering on the ground provide any braking ability? It has essentially no wieght on it and no traction.
    Because when the braking process is started the rear tire is planted firmly on the ground.

  8. #33
    Banned. Helmet Head's Avatar
    Join Date
    Mar 2005
    Location
    San Diego
    Posts
    13,075
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Robert is absolutely correct.

  9. #34
    Senior Member
    Join Date
    Nov 2005
    Location
    Knoxville, TN
    Posts
    505
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    About the conditioned automatic response to an emergency, yes the front brake is generally more effective. However, I had a nasty crash a while ago in very light snow when I grabbed the front brake instinctively when I spotted a pothole at the last second. Of course I should have gone for the rear, but since I'm so used to using the front that's what I did. So perhaps the moral of the story is to be conscious of any special conditions at all times when riding.
    Same roads, same rights, same rules.
    Boycott Wal-Mart, union-buster.

  10. #35
    Yabba-Dabba-Doo! AlmostTrick's Avatar
    Join Date
    Feb 2006
    Location
    Bedrock, IL
    My Bikes
    1969 Schwinn Orange Krate, 5 speed stick shift
    Posts
    3,055
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It makes sense that maximum front wheel braking is achieved when the rear wheel is just about to lift off the ground. But if slightly less than maximum braking force is used on the front wheel, wouldn't the extra weight on the rear wheel allow it to brake slightly harder, thereby making up the difference of the less than maximum front? How many cyclists can reliably max out the front wheel without doing an endo anyway? I should probably practice more, because I know I can't.
    Have Bike, Will Travel

  11. #36
    Conservative Hippie
    Join Date
    Mar 2005
    Location
    Wakulla Co. FL
    Posts
    4,271
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Don't look at it if you don't want to plow into it.

  12. #37
    !on
    !on is offline
    Senior Member
    Join Date
    Mar 2008
    Posts
    74
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    similar thing here. learned all about over-endos when i was a kid. somehow i remembered, one lunch hour returning to work across heath land this car windscreen wiper gets in my wheel / forks. instinctively let the bike pass under me & manage to unclip even though i still tumbled, on my side. trashed the front wheel.

    watch out for evidence of burnt out cars on open heath land. they only take away the solid wreckage, not the bits & pieces.

  13. #38
    feros ferio John E's Avatar
    Join Date
    Jul 2000
    Location
    www.ci.encinitas.ca.us
    My Bikes
    1959 Capo; 1980 Peugeot PKN-10; 1981 Bianchi; 1988 Schwinn KOM-10;
    Posts
    14,775
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    My braking technique:
    1) routine stop on dry, secure pavement: front only;
    2) speed control on a long descent: rear only;
    3) slippery surface, including almost all offroad scenarios: both together;
    4) steep descent: both together;
    5) panic stop: both together.
    "Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
    Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
    Peugeot: 1970 UO-8, S/N 0010468
    Bianchi: 1981 Campione d'Italia, S/N 1.M9914
    Schwinn: 1988 Project KOM-10, S/N F804069

  14. #39
    feros ferio John E's Avatar
    Join Date
    Jul 2000
    Location
    www.ci.encinitas.ca.us
    My Bikes
    1959 Capo; 1980 Peugeot PKN-10; 1981 Bianchi; 1988 Schwinn KOM-10;
    Posts
    14,775
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by farrellcollie View Post
    I am curious as to whether different wheels would make a difference in avoiding the type of accident I had on Sunday - I do not think I ran over the stick - I may have nicked it -or cars passing me may have tossed it up - I was watching road and generally try not to run over branches etc. It was a rather small stick. This is a tree lined street (one of our main bike path streets) and avoiding all tree debris is not possible. But my wheels (ona 2006 jamis quest) have spokes that are somewhat far apart - more so than on my hybrid - it is a jamis quest - would different wheels help with keeping stuff out of spokes? Or was this just a really freak accident that is unlikely to happen again? I ride this street all the time - it is my commute route and route to many of the other places I bike. I have only had the jamis quest fore three months.
    For myriad reasons, I avoid any wheel with fewer than 32 spokes.
    "Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
    Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
    Peugeot: 1970 UO-8, S/N 0010468
    Bianchi: 1981 Campione d'Italia, S/N 1.M9914
    Schwinn: 1988 Project KOM-10, S/N F804069

  15. #40
    Conservative Hippie
    Join Date
    Mar 2005
    Location
    Wakulla Co. FL
    Posts
    4,271
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Oh yeah, don't run over the banana peel, particularly not with the front tire. Those things really are slippery. Like running over a gob of axle grease.

  16. #41
    Senior Member
    Join Date
    Oct 2005
    Posts
    5,426
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by RobertHurst View Post
    Skillful use of both brakes results in shorter controlled stops than using the front brake alone. This is because the rear brake can apply some stopping power in the half-second or so before weight comes off the rear wheel. The advantage of using both brakes together should be obvious to anyone experimenting with hard stops. Don't take my word for it, go out and try it both ways and see how it works out. The rear wheel skid is automatic and, as I see it, unavoidable in a really short and well-done stop near maximum controlled deceleration, but a rear tire skid is not something that should cause a loss of control. Enjoy it, I say.

    Robert
    I don't agree that using the rear brake will make the stop any shorter because for the micro-second the rear wheel is on the ground in a threshold front braking situation, the rear wheel does significant braking. If you do it right, the instant you hit the front brake hard, the rear end immediately unweights and provides no braking.

    But much more important than a discussion of reducing braking legnths by a few inches is the very important fact that you admit to which is that if you use the rear brake in a hard-braking situation, the rear wheel will lock and the rear will slide. This is not something to "enjoy", it is very dangerous and to be avoided at all times. You are doing a huge disservice to the unwary on this site by even stating this.

    In the case of a very hard braking, crash avoidance manouvre, its not just coming to a stop in a straight line as soon as possible. Most crash avoidance also involves braking AND STEERING. You cannot steer the bike effectively if you have the rear brake locked up and the rear wheel skidding. You will go down if you try to steer with a locked rear and possibly into the path of what you are trying to avoid.

    Thats why it is best to train yourself to use the front brake only, or at least to set your rear brake so loose that it will not lock up your rear wheel in a panic, lever against the bar, stop.
    Il faut de l'audace, encore de l'audace, toujours de l'audace

    1980 3Rensho-- 1975 Raleigh Sprite 3spd
    1990s Raleigh M20 MTB--2007 Windsor Hour (track)
    1988 Ducati 750 F1

  17. #42
    Junior Member
    Join Date
    May 2007
    Posts
    17
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I once got into an accident due to a rear wheel skid so I agree that it's nothing to "sit back and enjoy".

    I was flying down a relatively steep hill when a car (a brand new Corvette) turned left across my path. Everything would have been fine except the driver decided to stop in the middle of the road. I suspect it was to prevent bottoming out his nice new car, but it's really anybody's guess. Anyway, I grabbed both breaks hard and swerved. I managed to get the front wheel out of the way of the back end of the car but the rear of the bike fishtailed to the right and slammed into the car. I was a little banged up, but otherwise okay.

    I would definitely advocate zero or very light use of the rear break in an emergency.
    Drive Less Think More

  18. #43
    Devilmaycare Cycling Fool Allister's Avatar
    Join Date
    Aug 2001
    Location
    Wynnum, Australia
    My Bikes
    1998 Cannondale F700
    Posts
    3,819
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    On braking, I generally try to avoid getting into situations where I'm braking so hard that the rear wheel lifts. I use both brakes all the time. In normal braking you still get plenty of brake power to the rear wheel (and if it does start to lift, shifting weight rearwards is always advised). I think it's a worthwhile habit to get into to use both brakes whether they're needed or not, so that when you do get in a panic stop you instinctively reach for both. Apart from anything else, it means your brake pads don't wear out as quickly, and when they do, front and rear go together. Less of a maintenance burden.

    Of course, I now ride a recumbent, and the danger of endoing is much reduced. I've had it in emergency braking situations a couple of times, and while I did get the rear wheel skidding, I neither lost control nor endoed. I was surprised and impressed, really.
    If we learn from our mistakes, I must be a goddamn genius.

  19. #44
    Devilmaycare Cycling Fool Allister's Avatar
    Join Date
    Aug 2001
    Location
    Wynnum, Australia
    My Bikes
    1998 Cannondale F700
    Posts
    3,819
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by San Rensho View Post
    Most crash avoidance also involves braking AND STEERING. You cannot steer the bike effectively if you have the rear brake locked up and the rear wheel skidding. You will go down if you try to steer with a locked rear and possibly into the path of what you are trying to avoid.

    Thats why it is best to train yourself to use the front brake only, or at least to set your rear brake so loose that it will not lock up your rear wheel in a panic, lever against the bar, stop.

    I disagree. Braking hard and steering at the same time is a recipe for disaster no matter which brake you're pulling. If you're going to try and turn to avoid a crash, let go of the brakes. If you're braking hard enough to skid, keep it straight and hope you stop in time. I'd rather take the chance of not stopping in time and maybe hitting, or trying to turn and brake and going down for sure.
    If we learn from our mistakes, I must be a goddamn genius.

  20. #45
    Senior Member
    Join Date
    Oct 2005
    Location
    Denver
    Posts
    1,621
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by San Rensho View Post
    I don't agree that using the rear brake will make the stop any shorter because for the micro-second the rear wheel is on the ground in a threshold front braking situation, the rear wheel does significant braking. If you do it right, the instant you hit the front brake hard, the rear end immediately unweights and provides no braking.

    But much more important than a discussion of reducing braking legnths by a few inches is the very important fact that you admit to which is that if you use the rear brake in a hard-braking situation, the rear wheel will lock and the rear will slide. This is not something to "enjoy", it is very dangerous and to be avoided at all times. You are doing a huge disservice to the unwary on this site by even stating this.

    In the case of a very hard braking, crash avoidance manouvre, its not just coming to a stop in a straight line as soon as possible. Most crash avoidance also involves braking AND STEERING. You cannot steer the bike effectively if you have the rear brake locked up and the rear wheel skidding. You will go down if you try to steer with a locked rear and possibly into the path of what you are trying to avoid.

    Thats why it is best to train yourself to use the front brake only, or at least to set your rear brake so loose that it will not lock up your rear wheel in a panic, lever against the bar, stop.
    To clarify: in the shortest stops, rear braking is basically irrelevant. But the shortest possible stops are generally not _controlled_ stops. These are stops where the rear tire is not touching the ground, by definition. Not very many people are smooth enough bike handlers to control a stop like that. In the real world, our 'panic stops' tend to be much more subdued, with the rear tire remaining on the ground, and thus able to contribute something to braking, especially when combined with a well-timed body movement.

    If the rear can't contribute to braking that means it's not on the ground. You're talking about stops where the rear tire is in the air, and worried about a loss of control from a skid? Anyone who can control a nose-wheelie panic stop could easily control a rear tire skid.

    The shortest controlled stops involve use of both brakes. Anyone who doesn't believe this should go out and experiment with front-only versus both-brake stops. It's not even close. You won't need a tape measure to tell the difference.

    A rear tire skid should not on its own lead to a loss of control. Something else going on there, I don't know what. In fact you should be able to initiate a rear tire skid and control it, to the left or right, deliberately under quite forceful front-brake deceleration with no thought of crashing because of it. Not that a skidding rear tire is all that helpful for your braking, but, like I said, it's an inevitable by-product of proper 'panic stop' technique and nothing to strike fear in the hearts of men.

    Robert

  21. #46
    Very Senior Member MikeR's Avatar
    Join Date
    Aug 2001
    Location
    Central Pa
    My Bikes
    2000 Bianchi San Remo and a mint 1984 Trek 720
    Posts
    1,762
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by bike2math View Post
    Wet leaves are slippery.
    So is wet metal - even slightly damp metal.
    It's better to cycle through life than to drive by it.

  22. #47
    Al noisebeam's Avatar
    Join Date
    Jun 2004
    Location
    AZ
    My Bikes
    Cannondale SuperSix, Lemond Poprad. Retired: Jamis Sputnik, Centurion LeMans Fixed, Diamond Back ascent ex
    Posts
    13,900
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by RobertHurst View Post
    Anyone who doesn't believe this should go out and experiment with front-only versus both-brake stops.
    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

  23. #48
    Nerd girljen's Avatar
    Join Date
    Mar 2008
    Location
    Wheat Ridge, CO
    My Bikes
    K2 T-9 Crosswind
    Posts
    450
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by dipy911 View Post

    It sidewalk riding, don't try to go off the sidewalk onto grass and try to get back on the sidewalk when the grass is two inches lower than the sidewalk, especially with road tires.
    I got some gawdawful road rash doing just that when I was a kid!

  24. #49
    Senior Member
    Join Date
    Oct 2005
    Posts
    5,426
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Allister View Post
    I disagree. Braking hard and steering at the same time is a recipe for disaster no matter which brake you're pulling. If you're going to try and turn to avoid a crash, let go of the brakes. If you're braking hard enough to skid, keep it straight and hope you stop in time. I'd rather take the chance of not stopping in time and maybe hitting, or trying to turn and brake and going down for sure.
    In a true emergency you have to be able to brake very hard and turn at the same time. One example is the right hook. A car suddenly turns right in front of you. You have to brake hard and turn to the right at the same time in order to avoid getting hit. Brake in a straight line and you will go straight into the side of the car. Turn without braking and you will not be able to turn sharp enough to avoid the car. You have to be able to turn and brake.

    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.

    In a panic, you will always revert to behavior that you are trained in, so if you consistently use the rear brake, you are "training" yourself to use the rear brake and in a panic, you will use it to possible disatrous results.

    So don't use your rear brake at all, is the best policy. The front is more than enough to stop in all non-panic situations, and using the front only in a panic is the best guarantee of getting out of the situation without crashing.
    Il faut de l'audace, encore de l'audace, toujours de l'audace

    1980 3Rensho-- 1975 Raleigh Sprite 3spd
    1990s Raleigh M20 MTB--2007 Windsor Hour (track)
    1988 Ducati 750 F1

  25. #50
    Senior Member
    Join Date
    Oct 2005
    Posts
    5,426
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by RobertHurst View Post
    To clarify: in the shortest stops, rear braking is basically irrelevant. But the shortest possible stops are generally not _controlled_ stops. These are stops where the rear tire is not touching the ground, by definition. Not very many people are smooth enough bike handlers to control a stop like that. In the real world, our 'panic stops' tend to be much more subdued, with the rear tire remaining on the ground, and thus able to contribute something to braking, especially when combined with a well-timed body movement.

    If the rear can't contribute to braking that means it's not on the ground. You're talking about stops where the rear tire is in the air, and worried about a loss of control from a skid? Anyone who can control a nose-wheelie panic stop could easily control a rear tire skid.

    The shortest controlled stops involve use of both brakes. Anyone who doesn't believe this should go out and experiment with front-only versus both-brake stops. It's not even close. You won't need a tape measure to tell the difference.

    A rear tire skid should not on its own lead to a loss of control. Something else going on there, I don't know what. In fact you should be able to initiate a rear tire skid and control it, to the left or right, deliberately under quite forceful front-brake deceleration with no thought of crashing because of it. Not that a skidding rear tire is all that helpful for your braking, but, like I said, it's an inevitable by-product of proper 'panic stop' technique and nothing to strike fear in the hearts of men.
    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.

    Are you saying that you don't need to have the ability to turn the bike in a panic crash avoidance situation?
    Il faut de l'audace, encore de l'audace, toujours de l'audace

    1980 3Rensho-- 1975 Raleigh Sprite 3spd
    1990s Raleigh M20 MTB--2007 Windsor Hour (track)
    1988 Ducati 750 F1

Page 2 of 4 FirstFirst 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •