Nearly avoided a crash

[obelix]

About 2 weeks ago I was travelling over a high pass in the swiss alps. There were lots of motorcycles around that day, even a group in front of me. I drove about 100 yards behind them downhill through a right bend on a road not larger than 20 feet. I saw the last in the row braking so I slowed down too. To my surprise the bend turned sharper and sharper and I was too fast for it. Mind you, by fast I mean maybe 40-50 mph when 30 should have done it. Just when I hit the brakes harder a car came up, half on my side of the road.

I immediately knew I wasn't going do make it so I braked as hard as I could and at the same time tried to wrestle the bike into a sharper right. Then a strong wobble came up, so strong I almost got trown off. I couldn't just get the bike further to the right and prepared for a hit when this dumbass decided in the last second to pull over on his side and I somehow missed his front. However I hit him with the left hard bag, the FJR slid widely to the right and started to shake even harder. I let the brakes go for a second and the bike stabilized and I was able to stop. Luckily only the cover broke, the car missed my left leg by not more than 2 inches.

What puzzles me is this strong wobble. Where did it come from?

My tires are PR2s, moderately but evenly worn. Pressure was ok at 40PSi. ABS did not kick in AFAIK. Front and rear suspension were moderately hard. The bike was loaded with me (about 170lbs with gear) plus maybe 70 lbs of luggage, evenly distributed in side bags and on rear seat.

So any idea what happened? It's the first (and hopefully the last) time this happened.

 

[BwanaDik]

Do you remember if you were putting your weight transfer (hard braking=forward shift) into the bars with your arms or were you loading up the tank with your knees and putting weight on the pegs, i.e., little or no load on the bars?

 

[Vesparado]

Geesh glad you are of and your bike just got a little messed up. :blink:

Matt

 

[Bounce]

brake THEN swerve or swerve THEN brake. never both at the same time. you unsettled your chassis in the curve, braked when the traction was limited on the tires and (probably) target fixated.

never ride faster than your site line. if you can't stop in the distance given from something unexpected, then your over-riding your site line. a decreasing radius turn like you hit is a risk like a dump truck being parked in your lane as your come around the curve.

you got lucky this time. use it as a way to learn. practice more with the BtS and StB drills and slow down when you don't know what's up ahead.

 

[302]

I hit the front brake hard one time when a car pulled out in fornt of me and experienced a mild wobble. Later on the ride I tried a couple of more stops and the bike showed no signs of wobble, my thought is dirty rotors or break pads. Now on every ride I do one slow speed hard on the front brake stop and have not had the same wobble problem since. In normal riding I use both the front and rear the breaks very lightly.

 

[Knifemaker]

I had something simular happen years back, riding a loaded up Norton Comando 850.

I entered a turn way too hot and , although I now know you are supposed to brake before a turn, I began braking fairly hard while imputing more countersteer to try to tighten my arc ,as I was headed for the trees.

The bike seemed to start wiggling slowly, and only stopped as I finally gassed out of the turn. My theory at the time was I some how imparted an osolation in the frame because I was braking hard...and the bike was trying to stand up...and at the same time I was trying to heal her over more. The opposing forces here trying to win the battle caused a slow wobble or wiggle in the frame.

Never happened again to me but sounds simular to what you seem to be saying.

KM

 

[YAM TOM]

WOW bet your heart was doing a pitter patter. Glad you came out of it as well as you did. Live and learn keep the shinney side up my friend

 

[RAVENRIDER]

I'd be surprised if your ABS did not kick in because trail braking that hard without ABS is pretty much a guaranteed get off in its own right. There is a whole lot of physics going on while braking hard in a straight line - compressed springs, changed rake and trail, rear lifting, chassis flex, etc. - never mind a curve. That you felt a wobble braking hard in a turn on a heavy bike with luggage is no big surprise. I hope you tested your ABS on a straight since.

 

[CODan]

FWIW, back in the 70s I raced a GS750 Suzuki and learned to do most of my braking before beginning the lean, but also to taper off the braking gradually while beginning to lean.

This was in the days of flexible frames (though that bike handled very well for its era) and you could induce a wobble by braking hard with simultaneous significant lean. As it was explained to me, the frame would flex and unflex, causing the wobble. It was very noticeable.

I'm sure that modern bikes have much better frames, but the FJR is big and heavy. Lots of momentum going on.

I can't say if that is what caused your issue, but I believe its possible.

I would also wonder about the usual suspects like swingarm and steering head bearings being shot.

 

[obelix]

You are all correct when you tell me not to ride faster than your line of sight. But who did not do this at one time or the other even without noticing. OK, I learned the lesson.

Knifemaker, you got a point. Although this wobble started as a low frequency, low amplitude wobble and just got more pronounced, meaning more and faster side wobble though the speed diminished.

I don't know if the ABS did kick in but in reflexion it must have done so. The road was mildly wet. What puzzled me was that I was not able to pull/push the bike to lean further.

Weight transfer was surely an issue as it always is under hard braking. I don't think the rotors were dirty, I just came down the mountain and had to brake before every corner. And overheating was no issue either I think.

But as this did not happen to many of you out there I suspect I must recheck the bike. I will do the bearings later just to make sure they are OK next year.

Thanks to all for the input.

 

[Bounce]

FWIW, back in the 70s I raced a GS750 Suzuki and learned to do most of my braking before beginning the lean, but also to taper off the braking gradually while beginning to lean.
This was in the days of flexible frames (though that bike handled very well for its era) and you could induce a wobble by braking hard with simultaneous significant lean. As it was explained to me, the frame would flex and unflex, causing the wobble. It was very noticeable.

I'm sure that modern bikes have much better frames, but the FJR is big and heavy. Lots of momentum going on.

I can't say if that is what caused your issue, but I believe its possible.

I would also wonder about the usual suspects like swingarm and steering head bearings being shot.

good points. back then it was stiff tires and floppy frames. now it's stiff frames and floppy (radial) tires.

 

[BwanaDik]

What puzzled me was that I was not able to pull/push the bike to lean further.Weight transfer was surely an issue as it always is under hard braking.

This is exactly what I was getting at. During a Stayin Safe course last year, I discover I was putting too much weight on the bars on the "spirited" down hill runs in North Carolina. I too, could not figure out why I couldn't get the bike to lean over further, while under hard braking (not yet scraping the pegs). Shoulders were a bit sore at the end of the day also. Next day we figured out that I was bracing against the bars so I adjusted and put all my weight transfer into the tank and pegs, lightly gripping the bars. Like a different bike! Try these

Clicky

 

[dcarver]

It's the cheesy aluminum frames used by Yamaha. Harley's have steel frames and show no signs of what you experienced. I suggest placing your Yama motor into a Harley frame. That should do it. :rofl:

Oh, glad to hear you're ok!

 

[Iris]

............This is exactly what I was getting at. During a Stayin Safe course last year, I discover I was putting too much weight on the bars on the "spirited" down hill runs in North Carolina. I too, could not figure out why I couldn't get the bike to lean over further, while under hard braking (not yet scraping the pegs). Shoulders were a bit sore at the end of the day also. Next day we figured out that I was bracing against the bars so I adjusted and put all my weight transfer into the tank and pegs, lightly gripping the bars. Like a different bike! Try these
Clicky

"Clicky" doesn't seem work for me.

EDIT: pardon me, it did finally work.

 

[obelix]

You might be right that I was putting too much weight on the bars. I can't remember if I put the weight on the bars or on the pegs as I was a little distracted by the car trying to hit me.

Aluminium frames are less stiff than steel frames? Well, then I learned a new thing. I thought it was just the opposite with modern space frames. Oh, I'm not quite ok, I needed new underwear after this. Keep in mind that the drop off on the side was not less than 1000 feet - just one step.

The grip pads are a nice idea. Hmm, maybe Velcro is even better? :lol: :lol:

 

[madmike2]

Aluminium frames are less stiff than steel frames? Well, then I learned a new thing. I thought it was just the opposite with modern space frames.

NEVER trust a Harley rider/owner when discussing technology (unless it concerns radial aircraft engines). :bleh:

The grip pads are a nice idea. Hmm, maybe Velcro is even better? :lol: :lol:

Duct tape?

 

[pcd]

I have experienced a similar wobble when turning and braking on a different cycle. It was a CX 500 Honda with the engine block as a stressed member of the frame (not unlike the FJR). It's a really scary feeling and I made a point not to push that bike to that braking/lean limit again. It was definitely a repeatable experience. Probably when the frame begins to torque, it doesn't return to neutral, hence the wobble. There's been a couple times maybe I've sensed a bit of frame torque on the FJR, but nothing dangerous.

The fact that the wobble resumed after impact with the car supports my hypothesis as the impact would also tend to torque the frame.

Glad you are ok!!!

 

[pcd]

and the bike stayed rubber side down.

 

[obelix]

Yes, the bike stayed up although I must admit it was only by sheer luck. Remember the race drivers just before being trown from the bike (upsider)? It was just similar but not yet so pronounced. Believe me, if something so heavy as the FJR starts to rapidly move under you it's not funny.

And I have also a GL650 which is basically the same as a CX500/650 plus an added fairing. On that cycle I had a similar wobble when heavily loaded as pcd told. In that case the way you loaded the bike made a hell of a difference. In extreme cases (loaded with gear for 2 weeks) it was undriveable from the start. I must take really care when I load the dog on that bike as his weight alone may already start the wobbling.

The FJR wobble felt similar but on the Honda it is caused by the comparatively weak frame.