My lowside on Rte 9

[RRrider]

Sad day. I low sided on the beginning of Rte 9 (http://goo.gl/maps/jGXU1). I believe the insurance company will total my new bike (EDIT: the bike was a Street Triple R and the insurance company did total it).

So here is my view of what happened, but welcome opinions and advice of this forum.

I had ridden from Palo Alto up page mill to skyline, over to 9 and down to saratoga, where I stopped to get gas. I was going to go home by way of 85 but decided that I was feeling good, so I'd go home the way I came. Bad decision it turned out. Just a couple of turns at the beginning of 9, not going that fast, but playing with body position and lean, I felt the front tire just go. I don't think I touched the brake or chopped the throttle. I believe I was doing a slow rollon. My suspicion is my tires were cold and I was leaning aggressively having just come off of a really great ride (hence feeling good). My tires cooled down geting gas, but I didn't. (that's my theory).

So at this turn, the front tire slipped, I lowsided, bike slid, and I followed, bike hit guard rail, and I hit bike.


EDIT: here is a picture (thx for instruction on how to do this):

I'm not really hurt. My knee is sore, and I'm icing it. and my thumb is cut up from where the friction wore a hole through my lee parks gloves. but otherwise I'm great. thanks for ATGATT...leather 'stich, daytona boots, etc.

But my new bike is f**k'd. Bummer. and my wife is pissed. worse bummer.

Interested in people's thoughts, explanations, and tips.

 

[Spec-ECU]

Yeah, let's rule out the tires. Do you remember any dirt or such on the road? What do you mean by "playing with lean (angle)?"

 

[RRrider]

Yeah, let's rule out the tires. Do you remember any dirt or such on the road? What do you mean by "playing with lean (angle)?"

I didn't see any dirt, but there is a big dirty area right beside the corner I crashed at. Possible there was dirt on the road, but if so, it was at best a thin veneer, not a ton of it. the tow truck driver did think that dirt on the road was the culprit.

playing with lean angle, means I was trying to sit forward in my seat (not way back like I tend to) and hang way off. but I wasn't going fast...I was trying to roll on smoothly and have no weight in my arms at the handlebars. It never occurred to me that I could low side in this turn (not an especially scary turn) at the speed I was going (not especially fast). It totally surprised me! bad surprise

 

[k9gsxr600]

What tire pressure psi do you have?

If it is over inflated, that's the reason.

 

[Spec-ECU]

What tire pressure psi do you have?

If it is over inflated, that's the reason.

He had been riding already well before the crash. If it was his tire pressure, I would think he would've crashed a lot earlier.

 

[Burning1]

Just a couple of turns at the beginning of 9, not going that fast, but playing with body position and lean, I felt the front tire just go. I don't think I touched the brake or chopped the throttle. I believe I was doing a slow rollon. My suspicion is my tires were cold and I was leaning aggressively having just come off of a really great ride (hence feeling good). My tires cooled down geting gas, but I didn't. (that's my theory).

The ride from the 76 station to the beginning of 9 is long enough to put some heat into your tires. I'd suggest looking for another reason.

 

[RRrider]

...My gf hates me too and I wish they'd understand accidents happened and getting mad is not the answer. Especially when I'm out of alot of money.

hear that!

The ride from the 76 station to the beginning of 9 is long enough to put some heat into your tires. I'd suggest looking for another reason.

Hmmm. OK. open to ideas. If it wasn't tires, if I didn't chop throttle/grab break, and if there wasn't dirt on the road, then I have no idea why I fell, and that is just spooky/scary.

Morning edit: as I had time to check out the road and didn't see a traction issue, tire pressure was mid 30's (which is ok for Diablo Rosso Corsa, and indeed, I had ridden a lot with what I consider more aggressive turns already in the day), and if tires were warm enough, then it must have been rider input. I wasn't feeling in any way uncomfortable: my emotion was surprise, not fear or concern. I suspect that I must have either eased off the gas or touched the brake blowing out the front contact patch, but I don't remember doing it. It was a slow fall...more of a gentle slide. It wasn't a body slam (until the guard rail )

 

[hitman5532]

Tires were fine.

There is a statement which caught my attention right away:

"playing with lean angle, means I was trying to sit forward in my seat (not way back like I tend to) and hang way off"

You made a dramatic change to the effective behavior of the bike by making this change. However, you still continued to use the same level of input on the front steering as before. This generally will lead to a steering input which was too quick for the new bike dynamics and hence added lateral acceleration to the 'friction circle'of the front tire, causing a loss of traction in the front tire.

Because you do not have video, this is a presumption based on what I have commonly seen over the years of people making a dramatic change in body postion to "hang way off".

 

[CaptCrash]

Tires were fine.

There is a statement which caught my attention right away:

"playing with lean angle, means I was trying to sit forward in my seat (not way back like I tend to) and hang way off"

You made a dramatic change to the effective behavior of the bike by making this change. However, you still continued to use the same level of input on the front steering as before. This generally will lead to a steering input which was too quick for the new bike dynamics and hence added lateral acceleration to the 'friction circle'of the front tire, causing a loss of traction in the front tire.

Because you do not have video, this is a presumption based on what I have commonly seen over the years of people making a dramatic change in body postion to "hang way off".

I like this a lot. You're on the bike, treating it differently than you have in the past--shall we say "experimenting"? In which case this experiment failed. Epicly. Though the picture is spot on money.

Lesson to be learned? Making multiple large changes at once isn't the best idea.

 

[PorradaVFR]

Can someone post the map location of that canal? I'm stumped as to where that happened - assuming the avatar in the OP's profile is not the rider I'm thinking rider error is quite likely and not road conditions.

 

[hitman5532]

It is the first left hander after passing hakone gardens

 

[sckego]

It's posted in the first line of the original post. Right here, I think:
http://goo.gl/maps/IP0qN

 

[PorradaVFR]

It's posted in the first line of the original post. Right here, I think:
http://goo.gl/maps/IP0qN

My bad, I was just looking at the picture trying to figure it out. Duh.

OP - you went under that guardrail?? Holy CRAP did you get lucky not to come out far worse. It seems to me you quite likely grabbed some front brake, tucked it then lowsided into the armco then down.

Be thankful, that could have been REALLY bad.

 

[Lunch Box]

Ouch, glad you're ok. As others have said, it was likely due to poor weight distribution due to "hanging way off" the bike. Either that or chewing gum in the road.

 

[RRrider]

Can someone post the map location of that canal? I'm stumped as to where that happened - assuming the avatar in the OP's profile is not the rider I'm thinking rider error is quite likely and not road conditions.

Actually the avatar *is* a picture of me at one of the Keith Code CSS days...a couple years ago.

It's posted in the first line of the original post. Right here, I think:
http://goo.gl/maps/IP0qN

yup!

My bad, I was just looking at the picture trying to figure it out. Duh.

OP - you went under that guardrail?? Holy CRAP did you get lucky not to come out far worse. It seems to me you quite likely grabbed some front brake, tucked it then lowsided into the armco then down.

Be thankful, that could have been REALLY bad.

Fortunately NO, I didn't go under the guard rail...the lowside was a slomo fall, so the bike slowly slipped to the ground and then slid faster than me along the street...so it hit the guard rail, and got caught by the handle bars (good thing I wasn't on my litre bike!), and then I slid along and banged into it, coming to a stop. Then I simply stood up, and looked at my bike, and said oh shit!

yes life would have been a lot worse if that guard rail wasn't there. On the other hand, life would have been better if there had simply been flat land out there instead...I think the bike would have slid along on the frame sliders, and I could have just picked it up and rode away. Then again, this could have happened earlier on my ride where I was doing much more aggressive turns higher up in the hills (9, 35, pagemill) where the slide would have been worse....

There is a statement which caught my attention right away:

"playing with lean angle, means I was trying to sit forward in my seat (not way back like I tend to) and hang way off"

You made a dramatic change to the effective behavior of the bike by making this change. However, you still continued to use the same level of input on the front steering as before. This generally will lead to a steering input which was too quick for the new bike dynamics and hence added lateral acceleration to the 'friction circle'of the front tire, causing a loss of traction in the front tire.

Because you do not have video, this is a presumption based on what I have commonly seen over the years of people making a dramatic change in body postion to "hang way off".

I don't actually consider the change I made to be all that dramatic. I have been hanging off for a while. So I put this more in the minor adjustment category...and I've been playing with this adjustment for the last 4 or 5 rides. And decided to try this tweak after discussing and analyzing some gotbluemilk pictures of me from this months track day at Sears point on the 13th (I've been hitting a trackday a month this summer).

And although on several turns earlier during the day, yesterday, I did make mid turn corrections (meaning I consciously trail braked or eased off the throttle to maintenance throttle - all of which could have upset the suspension if I wasn't smooth), on this particular turn, everything felt comfortable, so I didn't consciously try to make an adjustment...I thought I was just smoothly rolling on. I was *really* surprised when I realised that the bike was losing grip and I was going into a slide. There wasn't any spike of adrenaline during the turn (until of course I realised I had fallen :cool )

When I said I was hanging way off, I guess what I meant, was I wasn't going fast enough to necessarily require hanging off...but as I am drilling / playing around with this technique adjustment, i was hanging off anyway. so I was hanging way off compared to what was necessary to navigate the turn at my speed. Make sense?

I'm not saying I didn't make a rider input error...as right now, that is my conclusion...I must have. I just don't know what it was, as I didn't think I was giving any new input when the bike slid...I thought I was smoothly and happily in motion.

Appreciate you guys helping try to figure this out.... Always better to have a theory and something you can work on vs. just worrying that in any given turn, you will suddenly find yourself sliding... :eek

 

[hitman5532]

so I was hanging way off compared to what was necessary to navigate the turn at my speed.

Exactly.

Let me pose it to you this way, using hypothetical numbers for the sake of demonstration:

Situation A (the methodology you were riding prior to "hanging way off" or "experimenting"):
Entering a turn at 50mph, you apply 150 newtons of force through the chassis input via weight bias from setting body to the inside. In addition, you apply 40 newtons of force through the bars for steering input to begin the turn. The turn is accomplished smoothly using a constant throttle input of 15%. The combination of the lateral and forward forces places the the front tire near the limit of adhesion.

Situation B (the methodology when you were "hanging way off"):
Entering a turn at 50mph, you apply 250 newtons of force through the chassis input via weight bias from setting body to the inside. In addition, you apply 40 newtons of force through the bars for steering input to begin the turn. The turn is attempted by smoothly using a constant throttle input of 15%. The combination of the lateral and forward forces places the the front tire above the limit of adhesion.

Presumptions:
1) The coeffecient of friction of the tire remained constant
2) The forward/rearward accelerative forces remained the same between both situations
3) The inputs remained smooth and didn't create spike in the friction circle charing of actions
4) The traction level in situation A was nearing the limit for the given enviroment

Reality:
1) The presumptions were not held 100% true, considering the enviroment and situation; however they were close enough to consider the variance negligible
2) It is a multivariate problem which we are attempting to answer with a single variable, thereby needing to look at the largest contributing single varible.
3) Given the fact that you were making a variable change of body input by an effective increase in force, its affect on the traction equation must be evaluated.


Conclusion: With the increased level of chassis input, there needed to be a reduction in the steering input in order to maintain the same level of adhesion. Because you were attempting to change one thing (body input) you likely kept everything else the same, including steering input.


Food for thought....

 

[RRrider]

Hmmm...ok, so your argument is in essence, by hanging off more, I had introduced more steering input "without realising" and then applied what I thought to be a reasonable amount not taking into account the extra "hanging off" input.

yes?

So it wasn't a smoothness issue, a chopping the throttle, grabbing the brake, it was just "my normal" input which turned out to be stronger than normal because I was trying something new. right?

And even though I had been playing around with this on many other rides, I may have actually been closer to the traction barrier on this particular turn as compared to the other turns i had done, which is why I "discovered" this "extra input" on this turn....

Hmmmm...interesting. Let me let this sink in a bit...
thanks!

 

[hitman5532]

Hmmm...ok, so your argument is in essence, by hanging off more, I had introduced more steering input "without realising" and then applied what I thought to be a reasonable amount not taking into account the extra "hanging off" input.

yes?

So it wasn't a smoothness issue, a chopping the throttle, grabbing the brake, it was just "my normal" input which turned out to be stronger than normal because I was trying something new. right?

And even though I had been playing around with this on many other rides, I may have actually been closer to the traction barrier on this particular turn as compared to the other turns i had done, which is why I "discovered" this "extra input" on this turn....

Hmmmm...interesting. Let me let this sink in a bit...
thanks!

Yes, possible. That is why certain presumptions had to come into play. Without riding with you or having video, we rely on common occurrences and your perception of actions/inputs/"smoothness".

Have you ever seen a two gravity friction circle graph before?

 

[Spec-ECU]

Rich, if what you were experimenting with when this happened was moving your upper body more off the bike with your lower body, then yes, that would be a steering input. Albeit a minor effect compared with steering at the bars, during a lean for a corner, this minute adjustment helps you turn the bike more without actually leaning the bike more. So if you had done this and still steered at the bars like you usually would prior to this technique, I can see how you would have inadvertently leaned the bike past its adhesion.

If this was the case, I apologize friend. I should have properly forewarned you.

 

[RRrider]

Rich, if what you were experimenting with when this happened was moving your upper body more off the bike with your lower body, then yes, that would be a steering input. Albeit a minor effect compared with steering at the bars, during a lean for a corner, this minute adjustment helps you turn the bike more without actually leaning the bike more. So if you had done this and still steered at the bars like you usually would prior to this technique, I can see how you would have inadvertently leaned the bike past its adhesion.

If this was the case, I apologize friend. I should have properly forewarned you.

yup, i was moving my upper body more "forward" and over to where the inside mirror is, so this seems to be the answer. I'll need to let this sink in as I consider what this means in terms of how I change what I do....

thanks!