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Two "4 second rules"

Effective riding, in the twisties or in traffic, is about constant analysis of your environment, and always evaluating everything that affects your riding environment. It is a never ending, really never relaxed process.

In the twisties I use a bunch of tactics for four-second+ planning:
1. I read the terrain, grades, slopes, road pitch/crown/camber, shoudlers (gravel or paved)
2. I read tree lines or power pole lines, for clues about turn radius, slope, pitch, runoff, sightlines
3. I evaluate potential sightline issues before I get to the turn, determine if I'll be able to see-through before I get to the entry, shadows, shaded areas
4. I read the road surface, cracks, tar strips, changes in pavement color, indications for gravel/sand/debris

Most all of this happens before the entry to the turn, and I certainly make adjustments well before my apex choice and "press-in" point of the turn.

In traffic I evaluate/assess anything that impacts my riding environment:
1. Traffic load and motion patterns, which lane is faster or more steady (may be the fast lane)
2. Watch for any traffic flow path changes due to markings, signs, time of day, traffic load, cross-traffic issues
3. Look for/evaluate anything that impacts my sightlines, trucks, signs roadside visual blocks ( for me AND for other road users), time of day/sun position in the sky, shadows, bright direct sunlight (for me and other road users)
4. Watch vehicle trends, cars that hug the lane line, even just vaguely. Quite often vague actions of cars lead to DIRECT actions within seconds or less, watch the tires as they almost never lie

Big thing is, and I could add so much more, is that effective riding is a highly intensive activity. When you think about the level of brain action, motor skills, evaluation/execution, sensory input/decisions that we do while riding it can easily overwhelm some people into a stupor about riding (like saying its too intense for me) or activate some people into a high level of concentration (like everything slows down and we can "see" it all) that removes all the crap of day to day. That is what riding does for me. I get so deeply involved in the riding, that everything else becomes secondary and unimportant. Probably the main reason I will NEVER consider using a Bluetooth device in my helmet to answer a phone. I feed on the high level of involvement in riding, to the point it relaxes the rest of me.
 
... regularly ride blind twisty roads at speeds where you don't have adequate stopping distance or swerving distance. You regard this as "normal speeds," not excessive speed.

I'm not trying to answer for racer7... however, the key to your question may be the definition of "normal speeds". I define it as "the speed of prevailing traffic". On many of the local curvy roads popular with motorcyclists I do not have 2-4 seconds of road in sight when going "normal speeds". If I were riding riding slow enough to always have that 2-4 seconds of road in sight I'd be at increased risk of someone else running "normal speeds" rear ending me. In my judgement the danger of being rear ended by a cell phone wielding driver not paying attention to the road is greater than the chance that I'll rear end someone else. So far this has proven to be true.
 
The various "second" guides help for sure, but also key to getting the most of the guides is to be constantly active with them. Like I said, my goal is to do a lot of evaluation before I get to situations of sightline issues, but also constantly re-evaluate/adjust the goal with every passing second.

I wonder if some riders percieve the concept as being in the moment of entering the turn or event. Then certainly, if you are at the entry of your turn, being at the event, and if you can see through to the exit or something else becomes an issue, you better be going slow enough or have enough space/time to adjust, slow, straighten, brake, whatever.

But a second by second evaluate/adjust technique seems to always be s tep or two ahead of where you'll be. I have ridden with others and they say they just see my bike flowing along the path and curves, no drastic adjustments, no drastic speed changes. That's my goal, a smooth, steady quick pace.
 
The various "second" guides help for sure, but also key to getting the most of the guides is to be constantly active with them. Like I said, my goal is to do a lot of evaluation before I get to situations of sightline issues, but also constantly re-evaluate/adjust the goal with every passing second.

I wonder if some riders percieve the concept as being in the moment of entering the turn or event. Then certainly, if you are at the entry of your turn, being at the event, and if you can see through to the exit or something else becomes an issue, you better be going slow enough or have enough space/time to adjust, slow, straighten, brake, whatever.

But a second by second evaluate/adjust technique seems to always be s tep or two ahead of where you'll be. I have ridden with others and they say they just see my bike flowing along the path and curves, no drastic adjustments, no drastic speed changes. That's my goal, a smooth, steady quick pace.

Your responses (and also those of Racer 7) have been very constructive. I have NO problem believing you are both very experienced and safe (if we can use that term about riding) riders. But the fact remains you haven't answered my secondary question: "In a blind corner - let's make this a two lane road with little traffic - can you stop within your sight distance?" Let's add the fact that you are on a trip and don't know anything about hidden driveways or anything else you cannot see. Does Grodsky's "4-second rule" work for you or not, assuming dry conditions and no visible sand or gravel?

I'm completely serious in asking your opinion. If as expert riders you say you can stop in 3 seconds on a curve (and have done so,) my hat is off to you. Maybe under the same circumstance less expert folk (such as myself) DO need 4 or more seconds. I DO believe the "seconds count" idea is a good one for blind curves or topping hills as well as the "2-second rule" for following distance under ideal circumstances. My experience is that if you don't apply the 2-second "following distance" rule, you will probably follow too closely.

Look forward to your thoughtful replies.
 
But the fact remains you haven't answered my secondary question: "In a blind corner - let's make this a two lane road with little traffic - can you stop within your sight distance?" Let's add the fact that you are on a trip and don't know anything about hidden driveways or anything else you cannot see. Does Grodsky's "4-second rule" work for you or not, assuming dry conditions and no visible sand or gravel?

On a twisty road, following distances may have nothing to do with choosing a speed. You may not be following another vehicle. From "Motorcycle Roadcraft, the police rider's handbook to better motorcycling":

Never ride so fast that you cannot stop comfortably on your own side of the road within the distance you can see to be clear.
and
The ability to stop on your own side of the road in the distance you can see to be clear determines how fast you can go.

That is the principle. By the way, the above is an excellent book. You can get it from Amazon. It's from the UK.

Harry
 
On a twisty road, following distances may have nothing to do with choosing a speed. You may not be following another vehicle. From "Motorcycle Roadcraft, the police rider's handbook to better motorcycling":

Never ride so fast that you cannot stop comfortably on your own side of the road within the distance you can see to be clear.
and
The ability to stop on your own side of the road in the distance you can see to be clear determines how fast you can go.

That is the principle. By the way, the above is an excellent book. You can get it from Amazon. It's from the UK.

Harry

Thanks for your reply, Harry, and your reference to a book I've heard good things about but don't own. Must order it. I would point out (yes, I know I am becoming a PIA) that neither you nor your quotes makes reference to (4 seconds) visibility. I think quantifying the distance you can see in seconds (given good dry road conditions) would be a valuable tool for many riders. I'm hoping SOMEBODY will either confirm (or not) Grodsky's assertion by actually trying it out. THAT is how you find out if you actually can stop within your sight distance.

My comment on following distance had nothing to do with the above. Just another instance where counting seconds can provide a reality check which may keep you out of trouble.
 
Lets try it this way: 2-lane back road with moderate to tight turns, twisties if you will. Posted speed in general is 55 mph with many turns posted at 30 to 45 mph. Turn speeds as posted are determined to minimize lateral G-force for all vehicles legal to operate on the road, from cycles to large trucks. Turn speeds are posted to also account for visibility issues (or lack thereof). But most of us feel that for a cycle with a decent rider, the posted speeds for turns are easily taken at 10 to 15 mph higher speed just because the bike itself is more manueverable.

So given adequate sightlines before the turn, at the turn entry and through to the turn exit, turn speeds 10 to 15 mph over the recommended posted speed are actually quite easy and safely doable. IF there is nothing indicated before gettting to the turn, or before the turn entry, that indicate you should adjust your speed lower. For ALL turns, slow in/fast out is a reasonable overall guide. Fast in makes for a LOT of "vynil pucker" moments, with little or no recovery options.

But blind turns are something unique, for whatever reason that makes them "blind": heavy vegetation, old farm buildings on road edges, fences, rock walls, no shoulders, 180 degree turns, many factors classify blind turns because of limited sightlines. If you can't see through the turn at the very least, to your perceived turn apex (you DID determine your apex before you even GOT to the turn right?) then the turn is a "blind" turn and a safe approach is still slow-in/fast-out:
1. set up for a wide entry point near to the outside third of the lane: far right edge for a left-hander, near the center for a right hander (but be aware of other vehicles anytime you're close to the centerline),
2. slow BEFORE the turn, downshift to a gear that actually gives very good engine braking and one that gives you good strong drive our of the turn. In other words, a lower gear that brings the engine revs up. Reg Pridmore says most riders take turns in way too high a gear and "lug" the bike through the turn. Now off the brakes and stabilize the engine speed to be steady before the turn entry,
3. Go straight into the turn deep, as you approach the late apex you chose in setting up the turn,
4. By the time you have reached your chosen apex, you should be able to see to the turn exit, you are off the brakes, and have a stable bike in a gear ready to power out through the turn.
5. PRESS firm and assertive on the "inside" grip to quickly initiate the lean angle needed for the turn, and appliy steady to roll-on throttle to maintain steady loading of the contact patches of the tires.

All that works great IF there is nothing in the turn to cause you to quickly alter speed, position, attitude. What we also have to take into account is our "out option", meaning do we have runoff available? Shoulder width? Paved shoulders? Curbs? Gravel? Rock wall? The idea being, with your speed down, geared down, ready on the brakes just to the turn entry, you look through the turn and for whatever reason it can't happen. Then you must be able to quickly straight line slow (hard) or stop. That's where the slow of Slow-in/Fast-out really applies. Your out-option is another factor of turn setup before you get there.

Back to our tight blind turn, left turn, posted at 35mph, no sightline through the turn, wide shoulder (in this case): so slow to 35, downshifting to 2nd gear, steady your speed before the entry, set up for the right third of the lane, at the entry look into the turn, see that the exit is covered in gravel from a dump truck that had passed through the other way. Turn option is out, now its all straight line quick/hard braking, either to a complete stop or slowed enough to alter the line through the turn to do it mostly upright. Even at 35 mph, a quick hard straightline stop will take about 40 feet to do safely. But once you are in braking mode look straight ahead and focus on braking control and where you'll stop. Did you plan for that much runoff in your out-option? Do you have to the option to very briefly straighten up/brake hard/off brakes/press in to your new line and complete a new path? LOTS to think of.

Point is, slow-in/fast-out is a method for most turns, and more applicable to blind turns. If your "out-option" is further limited by lack of shoulder or run-off room, then the slow-in is slower yet, and in a lower gear. But it is all a VERY active mentally intensive process, most of it done BEFORE the turn. What catches most riders is the complacent riding attitude of accepting whatever comes once they're on top of it, which is FAR too late to apply much of anything other than a panic reaction, which is usually over-braking and dumping the bike: the "hadda lay er down" response. Safe twisties riding requires a LOT of mental activity, and physical ability. Again, what I think catches a LOT of riders is they arrive to the event unprepared, with no skills, no out-options, and panic insues. Crash.
 
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I would point out (yes, I know I am becoming a PIA) that neither you nor your quotes makes reference to (4 seconds) visibility.

For what it's worth, 2 seconds was the standard following distance called for by reputable safety organizations. Of course, that's an honest "one-one-thousand, two-one-thousand" two seconds. For many years I've evaluated my following distance by using poles or delineators, and I've also used that to check the following distance of the vehicle behind me. Lately, I believe safety people have recommended bumping that 2 seconds up to 3 seconds. I believe 2 seconds is adequate under most circumstances, while 3 seconds or more would be wise in heavy rain or snow. A following distance of 4 seconds on dry pavement is in my opinion more than adequate.

Harry
 
I agree. For me, it took some years of riding and consistently checking my following distance to the 2-second count method till I finally got a "feel" for the distance. It is effective for most riding, but should be adjusted to 3 to 4 seconds when conditions warrant. But its a constant effort to maintain when other road users barge into your space cushion. But it makes a huge difference in risk reduction. Not to mention makes your ride much more comfortable.

Oh, and in the MSF cirriculum, the guides for distances are:
2-second; minimum following distance you should always try to maintain.
4-second; recommended whenever possible, certainly for any lower traction instances or for night riding. Also known as the "immediate path of travel" time zone, referring to anything that will have to dealt with very soon.
12-second; that is your search/scan zone, looking for anything that may eventually come into your immediate path of travel zone. At 70 mph, this means you are scanning out around you (mostly straight ahead) 1,232 feet. That's easier understood as a quarter mile.

As to the 4-second rule as you ask about for corners, consider that 35 mph = 51.3 feet per second, so in a turn you would be searching ahead 205 feet, almost 3/4 the length of a football field.
60 mph = 88 feet per second, so in a turn you would be searching 352 feet, 52 feet longer than a football field.

Point is, ALWAYS be looking far ahead, scan/search ahead as you go. Its constant and ever updating every second. That's survival.
 
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Lets try it this way: 2-lane back road with moderate to tight turns, twisties if you will. Posted speed in general is 55 mph with many turns posted at 30 to 45 mph. Turn speeds as posted are determined to minimize lateral G-force for all vehicles legal to operate on the road, from cycles to large trucks. Turn speeds are posted to also account for visibility issues (or lack thereof). But most of us feel that for a cycle with a decent rider, the posted speeds for turns are easily taken at 10 to 15 mph higher speed just because the bike itself is more manueverable.

So given adequate sightlines before the turn, at the turn entry and through to the turn exit, turn speeds 10 to 15 mph over the recommended posted speed are actually quite easy and safely doable. IF there is nothing indicated before gettting to the turn, or before the turn entry, that indicate you should adjust your speed lower. For ALL turns, slow in/fast out is a reasonable overall guide. Fast in makes for a LOT of "vynil pucker" moments, with little or no recovery options.

But blind turns are something unique, for whatever reason that makes them "blind": heavy vegetation, old farm buildings on road edges, fences, rock walls, no shoulders, 180 degree turns, many factors classify blind turns because of limited sightlines. If you can't see through the turn at the very least, to your perceived turn apex (you DID determine your apex before you even GOT to the turn right?) then the turn is a "blind" turn and a safe approach is still slow-in/fast-out:
1. set up for a wide entry point near to the outside third of the lane: far right edge for a left-hander, near the center for a right hander (but be aware of other vehicles anytime you're close to the centerline),
2. slow BEFORE the turn, downshift to a gear that actually gives very good engine braking and one that gives you good strong drive our of the turn. In other words, a lower gear that brings the engine revs up. Reg Pridmore says most riders take turns in way too high a gear and "lug" the bike through the turn. Now off the brakes and stabilize the engine speed to be steady before the turn entry,
3. Go straight into the turn deep, as you approach the late apex you chose in setting up the turn,
4. By the time you have reached your chosen apex, you should be able to see to the turn exit, you are off the brakes, and have a stable bike in a gear ready to power out through the turn.
5. PRESS firm and assertive on the "inside" grip to quickly initiate the lean angle needed for the turn, and appliy steady to roll-on throttle to maintain steady loading of the contact patches of the tires.

All that works great IF there is nothing in the turn to cause you to quickly alter speed, position, attitude. What we also have to take into account is our "out option", meaning do we have runoff available? Shoulder width? Paved shoulders? Curbs? Gravel? Rock wall? The idea being, with your speed down, geared down, ready on the brakes just to the turn entry, you look through the turn and for whatever reason it can't happen. Then you must be able to quickly straight line slow (hard) or stop. That's where the slow of Slow-in/Fast-out really applies. Your out-option is another factor of turn setup before you get there.

Back to our tight blind turn, left turn, posted at 35mph, no sightline through the turn, wide shoulder (in this case): so slow to 35, downshifting to 2nd gear, steady your speed before the entry, set up for the right third of the lane, at the entry look into the turn, see that the exit is covered in gravel from a dump truck that had passed through the other way. Turn option is out, now its all straight line quick/hard braking, either to a complete stop or slowed enough to alter the line through the turn to do it mostly upright. Even at 35 mph, a quick hard straightline stop will take about 40 feet to do safely. But once you are in braking mode look straight ahead and focus on braking control and where you'll stop. Did you plan for that much runoff in your out-option? Do you have to the option to very briefly straighten up/brake hard/off brakes/press in to your new line and complete a new path? LOTS to think of.

Point is, slow-in/fast-out is a method for most turns, and more applicable to blind turns. If your "out-option" is further limited by lack of shoulder or run-off room, then the slow-in is slower yet, and in a lower gear. But it is all a VERY active mentally intensive process, most of it done BEFORE the turn. What catches most riders is the complacent riding attitude of accepting whatever comes once they're on top of it, which is FAR too late to apply much of anything other than a panic reaction, which is usually over-braking and dumping the bike: the "hadda lay er down" response. Safe twisties riding requires a LOT of mental activity, and physical ability. Again, what I think catches a LOT of riders is they arrive to the event unprepared, with no skills, no out-options, and panic insues. Crash.

ANDYVH, you always have something valuable to contribute about safety issues, and I always seem to have another question or opinion. Hopefully, we are making the readers, if not contributors, a little safer. This reply will refer to the six paragraphs above.

1. I know a number of riders who figure they can DOUBLE the "slow to" speed sign and take pride in doing so. No doubt they can if surface problems, over the line traffic, or an obstacle out of view don't rear up to bite them. I use those advisory speeds as a gear selection tool, rolling off the throttle and dropping a gear or two, and seldom braking before a curve. But I am down to my entry speed with the engine in a power band which can slow me further or accelerate. I would like to say I also have two fingers over the front brake for that emergency stop, but I don't. Something to work on.

2. Complete agreement.

3. The only way to pick an apex on a new road is to see the exit to the turn. On a left bend, you stay as far right to your lane as safe with a steady throttle until you see the point where you can accelerate and maybe kiss that center line and move to the right. On right bends you want to stay close to the center line as possible for visibility issues and be slow enough that you can swerve to the right for an oncoming vehicle over in your lane without going off the road.

4. Yes.

5. Yes.

6. Yes, but I AM STILL WAITING for someone to substantiate (or refute) Grodsky's "four second rule" on blind corners. I would submit that counting seconds (for whatever reasons) is a tool easily available to all of us, whether in our car or on our bike. I would also submit almost all of us are awful at judging distance when in a moving vehicle. Seconds (not car lengths, or feet or meters) should be what is taught and what experienced drivers/ riders talk about. That is the subject I'm still broaching.
 
I like the discussion, but I fear we are loosing people at this point. But I do want to comment:

1. Yes, I have on occassion, on a road I am very familiar with, under traction conditions I know(or assumed and was right, a "calculated" risk) doubled the posted speed for a corner. Not at the entry, but certainly by the exit I have attained 70 mph on a few 35mph posted turns. Once, on a Buell XB12 I managed to hit the rev limiter before exiting a corner in 2nd gear, which I'd guess was in excess of 60mph on a tight right handed turn. It was on a turn posted as 20 mph, probably because the turn had another road intersecting to it, but the sightlines were all clear. It is very possible.

3. No actually, there are many ways to determine an "expected" apex for a turn before getting to the turn entry. Read the terrain in the turn area, read the road slope/camber, read the turn FAR before you get there, perhaps 1/2 mile before in some cases, read the "treeline"; if you see a LOT of trees perpendicular to your direct ahead line of sight, its a tight turn. If you see trees at an angle to your direct ahead line of sight, its a broader turn (learned this in the unmarked turn/twisties of south central Missouri), read the shoudler painted line, read the centerline, read from traffic exiting the turn. READING a turn starts FAR before you ever get to the turn, taking in data that clues you to the turn setup. All that reading before the turn helps set up your apex choice before the entry.

I got caught on a cresting RH decreasing radius turn in Missouri. I did not read the "falling" tree line to clue me when riding uphill to the turn. I got in, it got tighter, and a truck in the other lane. I looked to the exit, maintained speed and pressed HARD on the right grip. Dragged my boot edge, centerstand and my passenger boot edge, and made the turn. My mistake was I did not read the terrain before getting to the turn, but I adjusted and made it. Not to brag at all, but just saying it is possible to adjust.

I'll have to claim ignorance on Grodsky's four second rule for blind corners until I find what was printed by Larry on that subject. Larry was a very competent cycle safety expert, but also a very competent rider who could describe techniques we can really use. Based on what the OP said, "Grodsky's informal tests seemed to indicate 4 seconds was the time needed for good experienced riders to stop in a curve when there were not any road surface problem.". I underlined "time" because as it relates to braking, especially in a curve. Back to 35 mph, or 51 feet per second, if in a curve and the rider had to suddenly stop, 1/2 sec is spent in simply reacting and starting the braking process. There goes 26 feet. A good straight line stop, clean dry pavement, from 35 mph is about 50 feet and about 2 seconds. So we've gone 76 to 80 feet through the turn. Larry is generous with his "four second" guide, taking 1/2 second off for reaction/application. leaves 3.5 seconds for braking, about 1.5 second longer than a straight line stop. So now we're into more like 100 feet to come to a stop from 35 mph.

You easily see the potential problem if the speed at entry is 70 mph. Because braking from speed is not linear to start speed. 70 mph braking is not twice the distance of 35 mph braking. More like four times the distance, especially in a curve. But very few riders consider braking performance in these terms, and fewer still practice any braking skills, until its pucker time.
 
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You easily see the potential problem if the speed at entry is 70 mph. Because braking from speed is not linear to start speed. 70 mph braking is not twice the distance of 35 mph braking. More like four times the distance, especially in a curve. But very few riders consider braking performance in these terms, and fewer still practice any braking skills, until its pucker time.

Indeed. The formula for kinetic energy, the energy of a moving body, is 1/2 m v[SUP]2[/SUP], or one half mass times the square of the velocity. If everyone kept that firmly in mind, there would be fewer wrecks on and off the road.

Harry
 
ANDYVH, I STILL think the "four second" rule for blind corners or hills has lot of viability and should be more widely known. I am most certainly not a "speed limits must always be obeyed" kind of person. But I am very interested in ideas which decrease the odds of my demise when riding. I have no problem with those of you who double or triple "suggested speeds" when you have the sight lines to know that is not only fun but safe. Blind corners are just the norm on all the back roads I've ridden. I thought a "4 second rule of thumb" might be a reality check for those of you who like to go fast around the twisties or crest hills at speed.

My hope is that this thread gives you something to think about. You wouldn't read it if you were not pretty "safety conscious." Try counting seconds around blind corners or topping hills at your usual speed. I'm most certainly not telling you how to ride. I am asking you to analyze your riding in those situations if you hadn't given it much thought. The decisions (and consequences of those decisions) are always your own.
 
It seems we are at odds on this 4-second issue. Yes the MSF says 4-seconds is your Immediate Path of Travel scan/search range, and the MSF does not define that as only straight line riding, so it certainly is applicable for cornering. I am not saying, and have not said, that Larry Grodsky's 4-second sightline guide for cornering is not viable or reasonable.

I just got Larry's book "Stayin Safe". On page 118 he describes the basis for his 4-second guide. In the follow paragraphs and page he describes much what I said earlier about braking capability (not saying I know what Larry knew, just that my MSF training principles do relate to what known safety pros publish). On page 119 he details the braking capabilites required for the speeds some of us like to carry into turns, well sighted turns and blind turns. What is most telling, is what he calls "response envelope" and how long that can get as speed increases. The response envelope is also the total distance required to stop. It relates to our natural response time. In clear straight line stopping its about 1/2 second. But Larry details that as speed increases, the response "zone" (that time/distance we cover in transition from throttle to braking) rises in almost direct proportion. So if you double your speed, you also double your response zone.

Taken into a curve, at twice posted speed, your visual lead of 2-seconds (MSF minimum), could become six to eight times/distance in response envelope. At 60 mph in a turn posted at 30 mph (likely not a blind turn), that equals 528' to almost 704'. At 45 mph in a blind turn posted at 20 mph (45mph = 66 feet per second) that equals to 528'. Clearly NOT safe if you are expecting everything to be all right through the turn based on what you CANT see. Larry says it like this, "However arbitrary these figures, it's apparent that riding fast on the street takes more nerve than skill."

A VERY telling statement when you consider how many riders have FAR FAR LESS skill than nerve.
 
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I have a commercial license good for anything up to 80k doubles and triples. For anything large enough to fall under HOS rules I like a 10 second rule as much as possible. For bikes and 4 wheelers I like a 5 second rule. 4 seconds is marginal in some situations although certainly better than the old 2 second rule that used to be popular. Those are obviously geared more toward following distances. You often can't get that much in peripheral safety margin.
 
I think that it is important for the rider to keep several things in mind even when leaving a very long following distance. That driver that is entering your road from an intersection, ramp or driveway up ahead, if alert & conscientiously trying to drive safely, will see you approaching, do a mental time speed distance calculation to determine whether to pull out ahead or behind you. The very different frontal area of a motorcycle vs that of a car complicates this calculation as to the available distance for a safe merge. The speed of the motorcycle will more than likely be mentally calculated based on the speed limit and or the observed speeds of passing traffic. If the oncoming vehicle (you) is closing at a significantly higher rate of speed, the driver's calculation of a safe entry will likely be incorrect & cause a conflict with you.

Seems strange reading that motorcyclists are concerned with aggressive drivers. The pot calling the kettle black?
 
The British police riding manual, Police rider's handbook to better motorcycling, recommends that you be able to stop in the distance you can see ahead of you. That distance constantly changes due to curves, traffic and hills. A blind curve is just that, blind. How can one adjust to 4 seconds ahead if it is blind? Can you stop in the distance ahead that you can see?

Further, in reference to blind curves no one can see what is hidden there. There is a blind curve I ride almost every ride. What is around that curve? One time it was a vehicle coming in the opposite direction in its lane. No problem. Another time it was a small amount of gravel exactly where I needed to ride based on my chosen line and lean into the curve. At another time, a few small branches from a tree. I do not know what I'll find. It could be a slow truck, a road crew, an animal crossing the road.

How can I know what to expect on new roads with new blind curves? The 4 second rule is impossible to determine until after the fact. "Can I stop in the distance I see before me?" is the way to go. On page 47 of the above police rider's handbook it says, "Adjust your speed according to how well you can see, the complexity of the situation and the distance it will take you to stop. You must always be able to stop within the distance you can see to be clear" and on page 81, "Never ride so fast that you cannot stop comfortably on your own side of the road within the distance you can see to be clear."

Good thread. I'm pleased that so many think about this issue and ride accordingly.
 
... I AM STILL WAITING for someone to substantiate (or refute) Grodsky's "four second rule" on blind corners. I would submit that counting seconds (for whatever reasons) is a tool easily available to all of us, whether in our car or on our bike. I would also submit almost all of us are awful at judging distance when in a moving vehicle. Seconds (not car lengths, or feet or meters) should be what is taught and what experienced drivers/ riders talk about. That is the subject I'm still broaching.

Good morning Doug and all... Interesting discussion here.

Doug, I think Grodsky's four second rule is probably a good rule of thumb for total time to stop. Keep in mind that, as we teach in the MSF program, there are three items involved in a stop: Perception, Reaction, and Actual stopping distance. Most of the instructors I work with pretty much agree that the two second following rule is not viable simply because most riders do not actively practice emergency quick-stops and swerve maneuvers. Essentially from perception to initial reaction, application of brakes, (assuming the brakes are not being covered) tends to be something over 1 second if you have very good reflexes., Given the age demographic of most riders, the reaction times are probably degraded even more. Then you have the actual stopping distance to deal with.

As far as how I ride, the slow in fast out rule is appropriate. If I enter a blind curve, I always slow to a point that I can stop in the sight distance. This rule served me very well a couple of years ago when entering a tight 140 degree outside curve (2-lane country road) leaning a good 30 degrees probably doing 15 mph at that point, and came face to face with a large combine in the middle of the road with the knives up at chest level pointing at me. Did a quick-stop in the curve and had no problems of any kind. Combine operator made the comment that he probably needed to get out of the road. Indeed !.

Distance judgment is problematic too. I tend to think a lot of drivers (and riders) have very poor depth perception due to vision problems. Many do not seem to have a clue that vehicles cannot stop in one car length from 75 mph on a freeway when following within 1 car length.

Several comments above note the problem of trying to maintain a safe distance to the vehicle in front, and other drivers pulling into the gap. That happens, but generally if you are moving approximately the speed of the surrounding traffic it is a minimal issue. I personally like to ride just slightly faster than the prevailing traffic which does two things: First, it keeps most of the action I need to worry about in front of me, and secondly, It will make a lot of drivers notice you just a bit more. It also will not attract unwanted LEO attention.

As far as intersections, I always assume any vehicle in the intersection does not see me or cannot estimate my approach speed. Slowing way down and covering brakes saves a lot of pucker factor.

Ride safe out there: You are invisible and everyone is out to kill you. Act accordingly in the combat zone.
 
Just to add another rule of thumb (or speed). Every 10 mph is about 15 ft per second so 20 mph=30 fps, 60 mph=90 fps, 80 mph=120 fps etc.

A football field or an average city block is 300 ft long so at 60 mph you need just over 3 sec to stop inside a football field so should be scanning that distance. Make your own visual realities to compare and no need to count when you can relate to something you know.
 
Very good thread. I think about how to stay alive on the road a lot. IMHO, the 4 second rule, 12 seconds, or any general rule needs flexibility depending on the situation.
I watched Jay Leno on Youtube riding an Indian and going pretty fast on the right side of the road and lane passing many driveways and it made me very uncomfortable just watching him. Harder to see him, he would have no time to react, and he can not see in the drive ways and/or intersections at all.
I am a Very conservative rider on the highway and I am always looking for the threats so I can position the bike to reduce the risk. If on a two land highways with traffic coming the other direction I will put myself a little closer to the cars ahead of me so a car coming the other direction can not start an overtake with me in the way.
With traffic from the other direction you can put yourself on the right side of the lane so you can have an escape path but this limits your visibility to see into driveways and intersections from the right so at times using the car ahead as a blocker helps. Of course a little closer does not mean close. This is using the 4 second rule I believe.
With no traffic form the other direction I always ride so I can see into intersections and driveways by being closer to the left. Of course watching for any left turning vehicles ahead where you may need to modify the plan. I will try to use a car ahead of me as a blocker for a left turning vehicle too or slow down if necessary. This would be the 12 second rule per the MSF.
I guess it is a matter of constant threat awareness and putting your bike in a position to reduce the risk using many generalized rules to assist out decision making. It has worked for me so far in several countries and riding environments.
 
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