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Why 'footdragging' is dangerous (other than the obvious).


NEOHMark

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Thank you Mitch..... thumbsup.gif

 

Given the level of intelligence generally displayed by the members of this board, I didn't believe further explanation was needed eek.gif

 

Appears I was wrong wink.gif

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Interesting discussion

We use a training film in Australia showing braking distances using front only, rear only and both. Both wins hands down. This is also demonstrated on our advanced rider courses.

 

So for me I only use both brakes together except for slow speed riding.

 

P.S. With the feet off the pegs the C of G is raised.

 

Ian wave.gif

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Thanks Ian W. cool.gifwave.gif

 

The best training, from my perspective, was being raised on British motorcycles, both road and track. The old SLS brakes DEMANDED that you use both brakes to slow down and for a sudden stop. With the advent of TLS brakes and Ferodo linings, braking improved greatly but you still needed to use both brakes! Even to this day, on my linked braking system, my body learning has me using both. Before Deb's crash, we had a CB750 with single disc front and drum rear and, trust me on this one folks, you NEEDED to use both to stop grin.gif

 

All this (fairly mindless) arguing about using just the front (especially on the track)is all well and good but in the real road world and especially with pillions, you should be in the habit of using both. You can't argue with testing and solid science thumbsup.gif

Well, you can, but you only end up looking fairly mindless eek.gifwink.gif

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Thanks Ian W. cool.gifwave.gif

 

The best training, from my perspective, was being raised on British motorcycles, both road and track. The old SLS brakes DEMANDED that you use both brakes to slow down and for a sudden stop. With the advent of TLS brakes and Ferodo linings, braking improved greatly but you still needed to use both brakes! Even to this day, on my linked braking system, my body learning has me using both. Before Deb's crash, we had a CB750 with single disc front and drum rear and, trust me on this one folks, you NEEDED to use both to stop grin.gif

 

All this (fairly mindless) arguing about using just the front (especially on the track)is all well and good but in the real road world and especially with pillions, you should be in the habit of using both. You can't argue with testing and solid science thumbsup.gif

Well, you can, but you only end up looking fairly mindless eek.gifwink.gif

 

 

Did you just call me mindless?(You who trailers your bike 300 miles to ride it it 30 and then put it back on a trailer and drive home)....I know where you live....matter of fact if your cookin I'll come over there and kick your a#$........... after dinner... lmao.giflmao.giflmao.gifgrin.gifgrin.gif

 

Whip

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Ok, just to keep this serious for one more post, and hypothetical, and remote, isn't it true that if you were braking in a corner with only the front brake and you hit oil and started to slide you would go down faster than if you did the same thing while using both front and rear? If using the rear with the front in this situation, when the slide started to happen you would obviously let off the front and the rear would continue to slow you to some extent, allowing a modicum of recoverability over not having the slowing affect of not using the rear. Assuming, of course the friction coeficient was such that recovery was possible in any case, and you acted fast enough, and you countersteered quickly enough, and the oil was of 50w or higher, etc.

 

Pete

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Kevin_Stevens
Ok, just to keep this serious for one more post, and hypothetical, and remote, isn't it true that if you were braking in a corner with only the front brake and you hit oil and started to slide you would go down faster than if you did the same thing while using both front and rear? If using the rear with the front in this situation, when the slide started to happen you would obviously let off the front and the rear would continue to slow you to some extent, allowing a modicum of recoverability over not having the slowing affect of not using the rear. Assuming, of course the friction coeficient was such that recovery was possible in any case, and you acted fast enough, and you countersteered quickly enough, and the oil was of 50w or higher, etc.

 

Pete

 

Just lay the damn bike down and get it over with! wave.gif

 

KeS

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isn't it true that if you were braking in a corner with only the front brake and you hit oil and started to slide you would go down faster than if you did the same thing while using both front and rear? If using the rear with the front in this situation, when the slide started to happen you would obviously let off the front and the rear would continue to slow you to some extent,

No.

 

That’s in my opinion though, and only my opinion.

 

If you hit oil and break loose on the front, you will do the same on the rear in fractions of a second as the back wheel passes over the oil. If the rear is under braking you will lose the gyroscopic effect from the rear, as well as from the front when this happens. Since it will (just like the front) momentarily lock under the braking force.

 

In the situation of both brakes on over the oil you will have a bike with tucking front end and no help keeping the shiny side up from the back wheel until the wheels get moving again which equals no gyroscopic help to stay up.

 

The likelihood of getting off both of the brakes in time and regaining traction is very slim in that sort of case anyway, since the oil will cling to the tires for a bit afterwards as well.

 

I suppose you could be traveling quite fast for the size of the oil patch so the event is ultra short, and not have a lock/gyroscopic help issue. If you regained traction In such a case due to the high speed momentary nature of it while using both brakes, front braking alone would also have regained traction.

 

Sand is a better situation to speak about since a patch of it doesn’t linger on the tires as much. I’ve been in a situation this year where I recovered the front from a full front end tuck, due to sand area. My feeling is that I recovered due to the bike being under some throttle (since I maintained it through the loss/regain traction event), not already being completely on the full edge of the tire in the turn, and not stiffening up at the bars and so allowing the bike to do most of the recovery steering work itself under throttle on.

 

If I’d been on the back brake (heck, either brake) the front would have been too weighted to recover. I’m sure I’d have lost gyroscopic help from the rear wheel as well with both brakes on. There would have been no saving if I’d been trail braking in any form, however I did it.

 

The moral being, choose the surface well when trail braking or stopping in a turn.

 

Again, personally I’d sooner low side from the front going too far away, than high side from the rear going too far away and then regaining traction (as it tends to do away/regain more often than the front). If the front does manage to regain traction, the bikes steering modifies the suddenness of it (if you aren’t manhandling the bars at the time), making a high side less likely. It’s just harder to save the front. However if it gets too far under braking and you save the rear (except MAYBE with a very lucky handful of throttle, you are going for high flying lessons and landing thump on hard stuff without wheels or bike.

 

I’m not advocating anyone change their riding due to what I’ve written, just sharing my own present thinking on how I do my own in turn braking. It’s not to say I’ll never use both brakes, or just the rear mid turn, say for a specific reason/situation, on a downhill turn or something. Each individual situation carries it’s own cues as to how to approach handling it.

 

Edited for spelling fix.

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ShovelStrokeEd

Another view of the hypothetical situation proposed above.

 

You don't have to lock the front wheel for the front end to tuck in that situation. All you need is side load that exceeds available traction. Brake on or brake off doesn't really matter when it comes to hitting oil in a curve. The tire will happily slide sideways while still rolling. It will just do so sooner if there is braking involved.

 

As to rear wheel braking helping, well, the wheels are, in round numbers, 5 feet apart, in a 60 mph corner, 5 feet would equal 56 milliseconds, not a lot of time to react or to contribute much to slowing.

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Assuming, of course the friction coeficient was such that recovery was possible in any case, and you acted fast enough, and you countersteered quickly enough, and the oil was of 50w or higher, etc.

 

Pete

 

Would that be dino or synthetic, I am sure there is a difference. lmao.giflmao.giflmao.giflmao.giflmao.gif

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I let my feet dangle at speeds from 60 to 90 miles per hour to stretch out when I have traveled over 500 miles and still have a few hundred to go. I would stand on the pegs too but my little pillow that I sit on would blow away.( I have a ST... you know about the stock seat!!) I use the back brakes for panic f(*^ing deer stops.

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As a traffic homicide investigator, we use a general rule as to compuing braking %.... generally speaking, front brakes provide 70% and rear provides 30%. As for road riding on work or personal bike, I use front and rear together for most effective braking. I try to stay off the rear very hard as I hate the rear wheel slide (not possible with ABS...but what if it fails?), but I hate the high side worse. On cones or rodeo couses or low speed stuff, LEO's feather the rear for stability only, not breaking. As for putting the foot down at speed, well after 10 screws, bone grafts and plates, I don't recommend it, but if it gets you throught the night, knock yourself out. I shall now get off the soap box. thumbsup.gif

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P.S. With the feet off the pegs the C of G is raised.

 

Okay, I will bite on this one. What am I missing? The center of mass of the combined bike and rider will only be raised by taking feet off the pegs if you raise your feet higher than they were when on the pegs. Skimming your feet along the ground (as several of us have confessed to doing occasionally) would lower the combined center of mass.

 

Standing up on the pegs, with legs rigid would raise the center of mass.

 

Standing up on the pegs with legs flexing is a little less clear to me. I guess it would cause your body weight to act as if it were concentrated on the pegs and this would lower the effective center of mass significantly. Although then we are no longer analyzing a rigid body and the dynamics of the two bodies seems more complicated to me.

 

But sitting on the bike you are pretty rigidly attached to it and it seems to me that the only effect of having feet on or off the pegs will result from where you put them when they come off the pegs. Put them near the ground they will lower the center of mass; put them up on highway pegs or on the tank (I do this sometimes too), they will raise the center of mass.

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P.S. With the feet off the pegs the C of G is raised.

 

Okay, I will bite on this one. What am I missing? The center of mass of the combined bike and rider will only be raised by taking feet off the pegs if you raise your feet higher than they were when on the pegs. Skimming your feet along the ground (as several of us have confessed to doing occasionally) would lower the combined center of mass.

 

Standing up on the pegs, with legs rigid would raise the center of mass.

 

Standing up on the pegs with legs flexing is a little less clear to me. I guess it would cause your body weight to act as if it were concentrated on the pegs and this would lower the effective center of mass significantly. Although then we are no longer analyzing a rigid body and the dynamics of the two bodies seems more complicated to me.

 

But sitting on the bike you are pretty rigidly attached to it and it seems to me that the only effect of having feet on or off the pegs will result from where you put them when they come off the pegs. Put them near the ground they will lower the center of mass; put them up on highway pegs or on the tank (I do this sometimes too), they will raise the center of mass.

 

The one thing missing in helping to understand where the CG is on the bike is where the weight is, not just where the appendage is. eek.gif

 

When you are seated the center of gravity moves toward where the weight is. In the seated position, this is going to be the derrier, butt, hiney, keester, or tookus.

 

When standing, the center of gravity moves toward where the weight is again. In the standing position, this is going to be the feet.

 

The difference between the butt and the feet in the two scenarios shows the movement of CG. Just dangling the feet does not significantly change the CG.

 

The lowered CG is one of the reasons why you have greater control in an off road setting, i.e. GS or dirtbike or RT for Weiner. grin.giflmao.gif

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I have an 1100S which has only half the brake dive (10% vs 20%) as most other Beemers. Neener neener! smirk.gif It has ABS.

 

I front brake only most of the time except for very low speed technical stuff.

 

Panic stopping, I use both.

 

REAL panic stopping, I use both...go full ABS mode and let the computer brake.

 

Should I use the rear more, for regular riding?

 

-Eff

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ShovelStrokeEd

Eff,

I would tend to say no. I too ride an 1100S, mine being a 'prep' model, has no ABS but does have some of the nicest and most easily controllable brakes I have ever had the pleasure to use. Easy to bring the front tire to squalling and leaving black marks on the ground with no loss of stability. Look earlier in this thread and find where Russell and I discuss using the rear brake in the initial part of the stop and then modulating it so that braking force goes from an initial probably 30% rear 70% front to a full on 10%, or less, rear, 90% front. I have actually gotten my S to do a stoppie on occasion, albeit a little one, so it does go to 100% front at times. Won't do it with my fat butt on the seat but if I stand on the pegs a bit, up the rear wheel will come.

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P.S. With the feet off the pegs the C of G is raised.

 

Okay, I will bite on this one. What am I missing? The center of mass of the combined bike and rider will only be raised by taking feet off the pegs if you raise your feet higher than they were when on the pegs. Skimming your feet along the ground (as several of us have confessed to doing occasionally) would lower the combined center of mass.

 

Standing up on the pegs, with legs rigid would raise the center of mass.

 

Standing up on the pegs with legs flexing is a little less clear to me. I guess it would cause your body weight to act as if it were concentrated on the pegs and this would lower the effective center of mass significantly. Although then we are no longer analyzing a rigid body and the dynamics of the two bodies seems more complicated to me.

 

But sitting on the bike you are pretty rigidly attached to it and it seems to me that the only effect of having feet on or off the pegs will result from where you put them when they come off the pegs. Put them near the ground they will lower the center of mass; put them up on highway pegs or on the tank (I do this sometimes too), they will raise the center of mass.

 

The one thing missing in helping to understand where the CG is on the bike is where the weight is, not just where the appendage is. eek.gif

 

When you are seated the center of gravity moves toward where the weight is. In the seated position, this is going to be the derrier, butt, hiney, keester, or tookus.

 

When standing, the center of gravity moves toward where the weight is again. In the standing position, this is going to be the feet.

 

The difference between the butt and the feet in the two scenarios shows the movement of CG. Just dangling the feet does not significantly change the CG.

 

The lowered CG is one of the reasons why you have greater control in an off road setting, i.e. GS or dirtbike or RT for Weiner. grin.giflmao.gif

I'll stand by my earlier statement. The center of mass is a calculation that only depends on where the mass is, it does not depend on how it is connected; so standing up on the pegs raises the center of mass. If your knees were locked that would be all it would do. However, with knees flexed, the rider's knees isolate the rider's mass from the bike and it behaves as if the center of mass were lowered.

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We all have our own ways of doing things -- and as everybody knows "my way" is always the best way.

 

I probably have less riding time than most of the contributers on this thread, however, merely riding a motorcycle for umpteen miles doesn't necessarily make you a skilled rider. Practicing braking, turning, accelerating, accident avoidance, etc. makes you a more skilled rider.

 

I do not make any claim of being a "skilled" rider myself, but consider the following:

 

You play like you practice.

 

Thus, if you do not use your rear brake during regular normal braking, you are kidding yourself if you think you're suddenly going to start using it in an emergency stop situation.

 

This also applies to using your feet for balance. If you are used to putting your feet down at slow speeds for balance, odds are you will revert to this tactic when you have an "Oh, Crap" moment at higher speed. -- Trust me, getting your foot jammed under your motorcycle at high speed is no fun (or so says my previously broken big toe).

 

Lastly, assuming you ride like Eddie Lawson and your rear brake contributes only 5% of your braking power, wouldn't like to shorten your stopping distance by just that much? When the rear end of that semi carrying "Flammable Liquids" is coming towards you blush.gif and your life flashes before your eyes frown.gif I think you'll agree.

 

On that happy note, enjoy riding and keep the rubber side down. smile.gif

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