Hitting gravel around a turn...

[puppychow]

I hit some gravel today (tried to avoid it, but the very narrow road didn't help) on the very narrow and downhill section of Bucks Lake Road coming around a right turn going at least 25-(30? unsure of speed but not more than 30 I think) mph, rear tire kicked out, throwing me into a drift onto the opposite lane. I put my right foot down and it dragged, but (I think) kept the bike from laying down.

Once I was in the opposite lane - the rear tire gained traction and the rear tire kicked back in, throwing the bike into a knee banging tank slapper, trying to buck me off , at this point I had the bike standing up straight, but all I could do was hang on to the handle bars for dear life as the bike tried to buck me off and I rode through that tank slapper which eventually subsided, however I am not sure if I did right or wrong by grabbing the handlebars and preventing them from shaking side to side and by staying off the front brake.

What would you do? What should I have done? I survived this incident by just "this" much (sheer luck?). However, if this happens again, I want to know what are the right things to do and what things are a definite no no?

 

[WBill]

Under that scenario, you're in real deep doo-doo, and the only choice is what you did. If another vehicle is coming the other way, kiss it good bye. Best to keep is real slow in the twisties, so you can maintain your line in your own lane. This ain't no race track.

I had the same situation last year on AZ SR 191, and I was trying to keep it very cool, as I had the same thing happen before on another trip on the same road. Yet, still, it happened (again). Maybe, just maybe, those speed limit signs are more than suggestions. Next time, when it says "20," I go 20. Whew! WBill

 

[Donal]

It's 'almost' impossible to do the right thing. You did really well up to the point where the 'tank slapper' got going.

The best way to control a tank slapper is to practically let go of the bars, the bike will correct itself within a couple of cycles of the bars. You often see this in Moto GP where the rider comes off, the bike is 'slapping' away but as soon as the rider lets go, the bike will straighten up and then carry on until it hits something. Bikes are inherently stable thanks to those big old gyroscopes. The impossible bit is to think fast enough and have the confidence to do it.

I guess the real answer is as WBill said and not get into one of those situations in the first place

Don

 

[Fred W]

Gravel is generally not spread completely, or evenly, across the road.

Your best bet is to try and find the tracks that have been swept clean by passing car tires, and execute evasive maneuvers (turn or brake) on those cleared spots.

You can't lean much to turn on gravel on top of asphalt. A dirt road is better than having loose stuff on top of hard asphalt. The biggest hazard is in having your front end wash out.

It's why you are supposed to ride "within your vision", ie only as fast as you can avoid what you can't see. If you come bombing around a blind corner, you never know if there is going to be gravel (or a moose for that matter) around that corner.

Of course this is much easier said than done (keeping the speeds down) .

 

[Old Michael]

...you never know if there is going to be gravel (or a moose for that matter) around that corner...

Moose, Fred?



I would ****.

 

[wheatonFJR]

Rocky AND Bullwinkle, Boris.

 

[Fred W]

Good point OM, the road hazard could be Moose ****.

Or cow, or horse... well you get the picture.

**** in the road is slippery as... ****.

 

[FJRless]

Gravel, sand, black ice. It's all the same and it feels pretty much the same too. It's happened to me more times in my riding career than I can count on all the hands and feet of those posting on this topic. Don't do anything; stay loose on the bars and wait for the tires to hook up. You don't want to grip the bars hard, brake, change your line, or chop the throttle during a slide. In every case I've encountered it's a small stretch of slippery stuff causing the rear (usually) tire to step out a few feet. If you see the offensive debris pre-slide then you do what you can to avoid it. Post-slide all you need is a puddy knife to scrape your boxers clean.

 

[rockmurf]

Ususally once you hit gravel in a turn you are looking up at the sky and don't have any decisions to make other than what side to slide on. If you seen the gravel you want to straighten up the bike but as stated above if you have traffic coming the other way you are in doo doo land. Glad you kept it up(the bike that is)

 

[ShinyPartsUp]

Two nights ago, I was reading Kevin Cameron's Top Dead Center, his compilation of articles . Interestingly, I was reading his article from the early 80's, when he was in Germany for a rally put on by Conti tires. In it (I can't cut and paste with Kindle for PC or I'd just quote him), he writes Continental hired street riders to test their tires rather than racers, because street riders have different skill sets. Specifically mentioned was wobble: it is a feedback loop between the front tire and the rider. Pros let go of the handlebar and try to get rid of as much unsprung weight as possible by getting their butts off the seat. The tire will straighten out if all else is equal. Most street riders put on a death grip, thereby worsening the tank slapper potential, so Conti wanted to know how (in their case) the tire reacted to street conditions for a street tire with a street rider (usual outriggers to avoid crashes).

As for gravel, my first experience was when I low-sided. Since then, with experience and luck I have had the rear tire step out several times without too much drama. I practice every day being "loose as a goose" on the bars (an old racer/mechanic/friend drummed that into me after my crash on gravel some years back). I figure if I practice a firm but no death grip in my usual riding, it will hopefully serve me well in the pucker moments. If my wrists start to ache or I get the beginnings of arm pump, I know I'm gripping too hard and probably running too fast for my skills and the road. I repeat the mantra of "stay loose as a goose" and my riding gets better almost instantly.

YMMV

You did great to keep the bike up and I'm glad you are safe.

 

[Fred W]

Pros let go of the handlebar and try to get rid of as much unsprung weight as possible by getting their butts off the seat.

Not to be picky, but... Unsure if Cameron said the above or if that was your paraphrase, but technically this it is an incorrect term.

"Unsprung weight" is only the weight of the wheels, tires, brakes, etc. that bear weight on the road without the benefit of suspension. So whether your weight is in the seat or on the pegs it is never "unsprung weight".

I think what was probably meant was to get the weight supported as low on the frame as possible to lower the center of gravity?

 

[ionbeam]

Specifically mentioned was wobble: it is a feedback loop between the front tire and the rider. Pros let go of the handlebar and try to get rid of as much unsprung weight as possible by getting their butts off the seat.

+1 Shiny

Had a V-Max that would periodically try to kill me by instantly going into a tank-slapper. I never did figure out what triggered it; seemed to be independent of road, tires, and most speeds (as well as steering bearings, wheels, triple tree, swing arm bearings, frame, forks, etc). The one thing that would quell the slapper would be to stand up on the pegs and decouple a lever point at the seat. The trick is to be able to do this when suddenly and out of the blue you get the **** scared out of you and the outcome of the event is decided in a couple of seconds. Standing on the pegs isn't about unsprung weight as much as it is about removing a lever point between the frame and the bars. Grabbing the bars with a death grip while the frame/forks are trying to oscillate is tantamount to using counter steering against yourself. It creates a self-reinforcing oscillation.

Wife just finished the NH MSF training (freshly minted motorcycle license in hand). She was told by the instructor that if you are leaned over with the rear wheel locked that you are usually better off to keep the brake locked and take your chances. For some reason the instructor did not go on and tell the class about high-siding if you release the brake and the rear tire regains traction.

 

[madmike2]

It's why you are supposed to ride "within your vision", ie only as fast as you can avoid what you can't see. If you come bombing around a blind corner, you never know if there is going to be gravel (or a moose for that matter) around that corner.

Also known as "riding within your sight line".

Wide approach until you can see through the corner/easy in (no "Ricky-racer apex that leaves few options)...accelerate out picking your exit line because you can "see" the exit.

Of course this is much easier said than done (keeping the speeds down) .

Ahhhh, Grasshpopper, that is the conundrum!

 

[FJRBluesman]

Sam - What you did is the best, it worked and that's what counts. The bad part is you drifted into the oncoming lane, that could have been disastrous. But again, you couldn't really have prevented that. Those panic situations can really be hard to navigate.

Fred and MM2 offer some great advise about riding within your vision. I for one do not like blind turns on roads, rocks, gravel, etc, can bite you hard. I go a lot slower when I can't see thru the turn, just for this instance.

Now if you were really good and had that mad man dirt biker in you, when the rear end kicked out, and your foot went down you would have been hard on the throttle, controlling that 600lb beast around the turn, once the rear end hooked up you'd then be riding the wheelie out of it and looking like a star.

You did good Sam, you didn't go down.

Ride safe buddy.

 

[puppychow]

Thank you for the advise fella's! I was indeed lucky. I saw the gravel too late and didn't have much space to navigate in that narrow lane. I agree, I might have been carrying too much speed for that turn and it is a lesson well learnt without disastrous consequences to accompany it.

I did however make the mistake of grabbing on to the handle bars - having never been in a tank slapper before, I instinctively grabbed the handlebars as the bike was trying to buck me off, trying to hold on and to prevent being knocked off the bike! Somehow, the outcome came out all right and I rode through it, but I will keep this in mind.

PS - My right leg is starting to hurt from being dragged across the pavement holding the beast up...off to pop some pain killers...

 

[Tree Doc]

Way to cheat death, Sam....keep it up!

You have a bunch more seat time than I on the FeeJ and once in the midst of the ****, I'm not sure I would have done anything different. My additional thought is along the lines of a couple others in that the avoidance is paramount but that's the obvious. I can honestly say that after doing the StreetMasters course a year ago March with Walt and Nancy, I know for fact that I have avoided this conundrum many times over on my old ride as well as on the FJR by living and sticking to the late apex method of riding. Having the bike set up in the proper configuration (lane position, braking, downshifting, speed, throttle posit) BEFORE turn entry, really allows you to safely deal with the unexpected **** that one might encounter in an instance like yours. I'll be the first to admit though that I'm overly cautious, especially on unfamiliar twisties and tend to be a bit slower because of it. I'm going back to SM on the FeeJ in September.

Thanks for posting up your experience. It really helps keep my mind on solutions to problems that I haven't yet experienced.

 

[SacramentoMike]

Nobody could deny the best solution to a problem is to avoid it, but sometimes, there you are. Right in the middle of "the problem."

I've busted more than one turn over the years, gone wide, crossed the center line, even crossed right over and ended up on the apron on the wrong side of the road at least once. So far, no oncoming traffic to guarantee I'd never do it (or anything else) again, though. But it's a hell of a bad moment. It's hard to plan for something like that, but I do know what I've done wrong on every one of those occasions: something. Sometimes I've let off the throttle very abruptly. Sometimes I've braked. Sometimes both. The bike straightens out, and there you are, blowing another turn.

In theory, I've finally come to understand the best approach is to do NONE of the above, and "ride through" the problem, trusting the bike and your tires, even if the rear tire slides out what feels like six feet, but really is probably not much more than a very few inches. Hard to do when you're panicking like a M-F'er and see your life flashing before your eyes. Too bad we can't practice riding through a bunch of turns on gravel at increasing speeds till we slide the back end, and then get so we can handle it without soiling ourselves, over and over. Well, we could I suppose, but . . . naaahhh. Too many crashes in the learning curve, for one thing.

Glad you made it through this one, Sam.

 

[madmike2]

Way to cheat death, Sam....keep it up! <snippage>

I can honestly say that after doing the StreetMasters course a year ago March with Walt and Nancy, I know for fact that I have avoided this conundrum many times over on my old ride as well as on the FJR by living and sticking to the late apex method of riding.

<snippage>

Thanks for posting up your experience. It really helps keep my mind on solutions to problems that I haven't yet experienced.

Streetmasters, the best farkle you can buy for your FJR....and it's transferable from bike to bike. :yahoo:

 

[Wee Willy]

Good job staying aboard Sam. There were really two discrete (connected, but discrete) things in your description. The slide then the oscillations. Sounds like the slide ended up being a net positive event. You were still on two wheels, none the worse for wear and not going backwards or some other weird direction. Great job...as we all know, the first task in any situation like this is to ride the bike; keep the pointy end into the wind and the shiny side up. You might do better next time (avoid, encounter and manage...whatever) but that kind of expertise usually comes with practice. Like with some dirt track time.

The slapper is another issue entirely. This is a very complex dynamic and many things influence the outcome. I'll name just a small number of them here: front suspension characteristics; sprung vs. unsprung mass; damping characteristics of the steering system (your arms, shoulders and upper torso included); CG location and change as big things move around (like you); tire contact patch characteristics; road surface condition and surface friction; tire condition and pressure; entry state and speed (what was your bike doing when it started to oscillate)...this list could go on for another 15 to 20 items. Note that right in the middle of all this mechanical stuff is a complicated control system (you) that is driving complex but relatively slow meat actuators to change things in the system in an attempt to affect the outcome.

Your best bet in this situation is the same as in the first...to first and foremost keep riding the bike. Do those things your experience tells you will keep you upright and aboard (assuming you're not running out of room to maneuver). This tends to happen automatically for experienced riders with only simple decisions being made to the recovery response. While you're doing that, begin to pull energy out the system: slow down, damp the oscillations, keep the magnitude of the oscillations manageable. I did this once in a front blowout on my gold wing at 75 mph by putting first one foot down quickly then the other almost like slow motion running while bleeding the speed off. Ruined both sides of a perfectly new pair of sneakers doing it.

Oscillations feed on the net energy. They can be divergent (net energy input is positive and is in phase with the oscillation and leads to departure) or convergent (energy input [if any] is out of phase and net energy is a loss; the oscillations will converge to a steady state condition like you experienced). In this situation it was probably a safe call to stay off the front brake. The back brake is a good idea though as it will pull energy (speed2) out of this system.

Sounds like you did OK. So go change that underwear and get back in the saddle.

Cheers,

W2