Crash Analysis

[CryingWolf]

Hi all, I'm new to the forum.

I was hoping to get some expert advise on a previous mishap. I have just started riding again after coming off my bike last year. I had a Daytona 600 (and have now bought another, since my last accident dented my frame). I don't want to be making any mistakes again if it was myself to blame.

So, tyres on the bike weren't very well rated for wet conditions and it had been a light drizzle of rain that morning, 2 minutes into my journey so tyres were cold. I filtered through some traffic on a roundabout (bare in mind I'm in the UK so left side riding) turning right off the roundabout. Filtering left out of the roundabout and the road has another small bend left after the turn.

I am straightening up out of my lean and apply the throttle, next thing the bike slams hard on it's right side, crushing my leg and proceeding to slide down the road with the bike. In the wreckage I found a chunk of a suspension spring, which wasn't from my bike, so I've always blamed this for taking me off the bike, assuming I hit it.

I am struggling to understand why the bike slammed on its right side though, if I made an error would it not have low sided to the left? I would appreciate any help understanding what went on so that I don't end up in the same position.

Picture attachedbto show the state of the bike

[JohnCBoukis]

I am no expert, just a rider. Since no one has responded as of this writing, I will happily chime in.

If the rear slides out and continues sliding unabated, this will result in a relatively slow lowside, the same that you expected. If the rear begins to slide even for a moment, then regains traction, that can generate a rotational torque that flips the bike outward in a couple of milliseconds, resulting in a highside. That event is so fast and powerful that once it is initiated there is no recovery.

You pointed out several traction hazards from that day. If too much throttle exceeds the available traction: Once the rear starts spinning, keeping steady on the throttle may keep the tire spinning, allowing one some chance of recovery as the bike sheds forward speed, while countersteering the bike upright. Alternatively once the slide has begun, certain actions like shutting the throttle quickly or using the rear brake can stop the rear tire spin, resulting in the regaining of traction and the bike flipping outward.  

I think that giant spring could have hit the bike in a couple different ways causing a momentary loss then nearly instantaneous recovery of traction. It could have hit the rear tire or acted like a kickstand hanging due to a band spring launching the bike upward briefly. Is the spring painted? If you could find such paint on the bike, that forensic evidence might be helpful.

Here is a video of a highside. After the slide begins we can hear the rider chop the throttle, the tire chirp, the throttle rises then chops, the tire chirps a second time, then the highside.  The sound and view of the erratic throttle and the tire gaining traction while moving sideways are the hints of why the bike then violently flips. 

https://youtu.be/JwlZiArfnYg

[CryingWolf]

Thanks for your response.

My understanding of a highside is that the driver is ejected up amd forward from the seated position, as in the video.

Yet in my circumstance the bike slammed hard into my right leg and slid as per a low side, but the opposite side of the bike.  This is why I didn't think it was a high or low side

[JohnCBoukis]

I did not think much about the fact that you were perfectly attached still, but should have.

Here is a scenario: You are turning left but now countersteering up and come across the spring. It nails the outside of the front tire, perhaps lodging underneath, forcing the wheel to go hard left. That would countersteer you into the ground on the right. You would have perceived the sensation of a severe steering jerk methinks. Does this sound plausible? Is there any evidence of impact damage on that front tire or wheel?

[Hotfoot]

54 minutes ago, CryingWolf said:

Thanks for your response.

My understanding of a highside is that the driver is ejected up amd forward from the seated position, as in the video.

Yet in my circumstance the bike slammed hard into my right leg and slid as per a low side, but the opposite side of the bike.  This is why I didn't think it was a high or low side

Since the conditions were a bit wet, and tires were cold, it could be that the bike DID highside but just not as violently as in the video. I'm thinking that if the tire slid out to the rear, but then regained traction (perhaps over an oily patch on the pavement), it could flip it back over to the right but without that violent upward launch, because neither front nor rear tire would have as much grip as what we see in the video on dry pavement.

However, I think the scenario John describes above sounds very plausible - even if the wheel just was lifted up a bit by the spring as you went over it, that could take away the resistance on the bars and your countersteering pressure (to lift the bike up out of its lean) would suddenly be too much and cause to the bars to turn too much to the left, so that as the tire lands back on the pavement it would countersteer you into the ground on the right, as John says above.

I have had a similar experience on a dirt bike, hitting a round rock mostly hidden under some loose sand - I was leaned a bit to the left and coming up out of a turn, the front wheel was lifted up by the rock and when it came down it slammed me over on the right side.

Did you have any sensation of the rear wheel slipping, sliding out, or coming around on you, or any recollection of the bars twisting, or of losing "feel" from the front tire?

[CryingWolf]

It could just be that then I guess. Makes more sense now that I read it. 

I have had the back slide out before now under emergency braking, throttling hard in the wet and on loose sand when forced out of lane by a van. Everytime I felt it I've corrected it, never bothered me much.

This time though my memory goes from applying the throttle to being mid slide, i don't remember anything in between or how the bike responded.

I did ride past that same spot for the first time again this week and I'm not sure I i imagined it but it felt very slippery coming around that bend. Atm if feels like I have lost all confidence cornering and I am coming out of bends far too wide while tensing up and being a little twitchy in the bend itself.

I need to get past this to trust the bike again.

[Lnewqban]

14 hours ago, CryingWolf said:

I did ride past that same spot for the first time again this week and I'm not sure I i imagined it but it felt very slippery coming around that bend. Atm if feels like I have lost all confidence cornering and I am coming out of bends far too wide while tensing up and being a little twitchy in the bend itself.

I need to get past this to trust the bike again.

Welcome!

Perhaps the bike needs to regain the trust in the rider. 

Available traction can suddenly disappear under us, if the surface of the road is contaminated with Diesel, oil, sand, etc.

Always be careful when the road is wet and consider that street tires may never warm up properly in those conditions, because they are cooled down by the water and spray around them.

The road can be awfully slippery during a light drizzle of rain, because there is no enough water to wash away the dirt and contaminants mentioned above.

Also avoid the outer half of any runabout and curve, where Diesel leaking out of trucks and sand tend to accumulate.  

[Jaybird180]

Perhaps a definition of high side and low side crashes is in order.

To offer this simplistic definition: If the rider gets ejected and the bike has the trajectory to follow it fits the definition of a high side. If the rider is dismounted and the bike is leading the direction of travel it is a lowside. In this case, the rider was trapped under the bike and so it's owner hasn't yet established which definition more closely fits.

On 3/31/2018 at 3:17 PM, CryingWolf said:

Thanks for your response.

My understanding of a highside is that the driver is ejected up amd forward from the seated position, as in the video.

Yet in my circumstance the bike slammed hard into my right leg and slid as per a low side, but the opposite side of the bike.  This is why I didn't think it was a high or low side