Diagnose An Unknown Crash

[Jaybird180]

A few years ago, I went down and still to this day I don’t know how it happened. I am hoping to provide as much detail, so that in hindsight I can understand what happened and not do it again.

 

At the time I was about 230lbs (fully dressed) riding stock suspension on my F4i. I was wearing Dunlop D208 tires which had about 3 trackdays and an unknown thousand street miles of use on them. Visually, they were fine and never exhibited any slipping issues except once in the wet on the left side in a residential area (suspected to have happened due to wet autumn leaves). I was consistent with daily tire pressure checks but I’ve thrown away that pen-style gauge after discovering that it was cheap and faulty.

 

This day I’d caught up with a previously unknown rider on a newer 600rr where we tested our straight-line speed. After that was over, we met at the gas station and talked a bit and decided to venture over to a nearby twisty road that I’d been through several times.

 

The road was unfamiliar to him, and I kept looking back to ensure I wasn’t leaving him. A bit agitated by the break in rhythm, I kept trying to encourage him to stay closer so he could observe my lines, but he either didn’t understand or wouldn’t comply. Either way, I wasn’t going to leave him.

 

This was a bright and sunny midday with no adverse weather or visible fluid spills, road debris, etc to my knowledge.

 

The section in question has a mild elevation change with a mild ess. I glanced back to see where the rider was and decided that he was falling a bit behind again. I then went through the right and decided to slow a bit before the left by using a little front brake. I also downshifted so I could gain some rpm back. I’m off the brake as I tipped into the flat left (not a quick turn). I fully expected to get to my desired lean angle and glide into the left turn. Instead, I was on my left side and sliding on the ground towards a light pole off the road into the grass.

 

Stopping well short of the pole, I was unharmed. The frame sliders did their job, but my new leathers weren’t so new anymore. No harm except a little embarrassment and a broken left mirror and clutch lever.

 

The following rider said he saw the rear tire lockup, but I felt NOTHING except the impact of the pavement.

 

ANYONE have ANY suggestions or clues as to the cause of this crash? (even if it's wild and crazy)

[hubbard_28]

Could you have released the clutch in the turn? That would lock up the rear.

[Bpez]

Sounds like a problem with the nut that attaches the clip on's to the seat....

[Jaybird180]

Sounds like a problem with the nut that attaches the clip on's to the seat....

With the information provided, it doesn't lead me any closer to a diagnosis.

 

Could you have released the clutch in the turn? That would lock up the rear.

As I recall, the downshift was completed prior to my tipping in. But it could have been sloppy, leading to the (reported) lockup.

[hubbard_28]

Being in a different gear on a line you're used to can potentially change a few things about what you're doing. I've missed shifts so many times on one track after a straight, that I'm good either way. The benefits of consistent sloppiness.

[Cobie Fair]

OK, a few questions:

 

1. Do you recall which end went, was it the front or the rear, or did they both go?

2. How vigorous a pace, and how long had you been riding? In other words, if you were going slower than normal, and the tires weren't warm yet...? Tires have to be warmed on both sides.

 

There can only be so many things it can be, normally it can be figured out what it was. Let us know on the above.

 

C

[Jaybird180]

OK, a few questions:

 

1. Do you recall which end went, was it the front or the rear, or did they both go?

2. How vigorous a pace, and how long had you been riding? In other words, if you were going slower than normal, and the tires weren't warm yet...? Tires have to be warmed on both sides.

 

There can only be so many things it can be, normally it can be figured out what it was. Let us know on the above.

 

C

 

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

2- It was a moderate pace and it felt like I had good traction prior. We'd been riding about 10 minutes. After the crash I got back on and continued without further incident.

[hubbard_28]

Tires have to be warmed on both sides.

OK, that one is new to me. I thought the tire heat spread throughout the tire when the bike was warming up. I'd always been told that riders who lean their bikes back and forth are messing up the constant friction that riding straight produced.

[acebobby]

OK, a few questions:

 

1. Do you recall which end went, was it the front or the rear, or did they both go?

2. How vigorous a pace, and how long had you been riding? In other words, if you were going slower than normal, and the tires weren't warm yet...? Tires have to be warmed on both sides.

 

There can only be so many things it can be, normally it can be figured out what it was. Let us know on the above.

 

C

 

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

 

 

Bikes dont lean further than you want them to, the rider has control of that! Maybe the back was stepping out, that may give a similar feeling to the bike leaning further than you wanted it to!

Were you riding a little bit faster than you would normaly that day, maybe pushing a little harder than normal because you didn't want the guy on the 600RR to think he was faster than you? I only ask this because it is a common cause of crashes every where, some guys at the track dont like being passed by girls, people on litre bikes dont like it when smaller bikes are faster than them! In the end they outride their own ability and crash.

Just a thought!

[Jaybird180]

I can see what you mean HUBBARD...but I wasn't being brave and I don't have any other way of describing how the crash happened. I just fell. I turned in and BLAM! I was on the ground. This is what is perplexing. I know that things don't "just happen", that there's always a pathology however, even in hindsight I don't see it. That's why I'm consulting the wisdom of the collective.

[Jaybird180]

Tires have to be warmed on both sides.

OK, that one is new to me. I thought the tire heat spread throughout the tire when the bike was warming up. I'd always been told that riders who lean their bikes back and forth are messing up the constant friction that riding straight produced.

http://www.sportrider.com/ride/rss/146_081...ires/index.html

[Cobie Fair]

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

2- It was a moderate pace and it felt like I had good traction prior. We'd been riding about 10 minutes. After the crash I got back on and continued without further incident.

 

OK--so thinking back, what is your perception of which end went first, front or the back, or both at the same time?

 

2nd question: did you have ANY throttle on, or ANY brake on?

 

 

CF

[Cobie Fair]

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

2- It was a moderate pace and it felt like I had good traction prior. We'd been riding about 10 minutes. After the crash I got back on and continued without further incident.

 

OK--so thinking back, what is your perception of which end went first, front or the back, or both at the same time?

 

2nd question: did you have ANY throttle on, or ANY brake on?

 

 

CF

[Jaybird180]

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

2- It was a moderate pace and it felt like I had good traction prior. We'd been riding about 10 minutes. After the crash I got back on and continued without further incident.

 

OK--so thinking back, what is your perception of which end went first, front or the back, or both at the same time?

 

2nd question: did you have ANY throttle on, or ANY brake on?

 

 

CF

Based on the way the bike slid, I'd say the front gave way. No brake on and throttle was on.

[hubbard_28]

I can see what you mean HUBBARD...but I wasn't being brave and I don't have any other way of describing how the crash happened. I just fell. I turned in and BLAM! I was on the ground. This is what is perplexing. I know that things don't "just happen", that there's always a pathology however, even in hindsight I don't see it. That's why I'm consulting the wisdom of the collective.

I never said anything about being brave. As a matter of fact, I was of the understanding that you were backed off so the other rider could keep up. Don't know what you're talking about. Sorry, but you have me at a loss.

Thanks for that tire warming article though. Good stuff.

[Jaybird180]

I can see what you mean HUBBARD...but I wasn't being brave and I don't have any other way of describing how the crash happened. I just fell. I turned in and BLAM! I was on the ground. This is what is perplexing. I know that things don't "just happen", that there's always a pathology however, even in hindsight I don't see it. That's why I'm consulting the wisdom of the collective.

I never said anything about being brave. As a matter of fact, I was of the understanding that you were backed off so the other rider could keep up. Don't know what you're talking about. Sorry, but you have me at a loss.

Thanks for that tire warming article though. Good stuff.

Yes, you're right! I was backing off. But I backed off from a moderate pace...nothing fancy. Probably doing a max speed of 40-45mph in the ess sections. I think I got up to about 60 on the short straight sections during the whole road. The guy didn't come off like a total newb, but he was really tip toeing and it was breaking my rhythm to keep looking back and wait a few corners for him to catch up.

 

I've since been through there many times. I think about it when I come up on that particular section. But I'd like to know what caused it, so I can fully put it behind me.

[Cobie Fair]

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

2- It was a moderate pace and it felt like I had good traction prior. We'd been riding about 10 minutes. After the crash I got back on and continued without further incident.

 

OK--so thinking back, what is your perception of which end went first, front or the back, or both at the same time?

 

2nd question: did you have ANY throttle on, or ANY brake on?

 

 

CF

 

Hey JB,

 

Did you get a chance to answer these, did I miss it?

 

CF

[Jaybird180]

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

2- It was a moderate pace and it felt like I had good traction prior. We'd been riding about 10 minutes. After the crash I got back on and continued without further incident.

 

OK--so thinking back, what is your perception of which end went first, front or the back, or both at the same time?

 

2nd question: did you have ANY throttle on, or ANY brake on?

 

 

CF

 

Hey JB,

 

Did you get a chance to answer these, did I miss it?

 

CF

I think we were cross posting

http://forums.superbikeschool.com/index.ph...rt=0#entry10081

[Jaybird180]

1- The bike continued to lean past the point I wanted it to. I didn't realize what was happening until I was sliding on my shoulder. I was looking down the road at the time.

2- It was a moderate pace and it felt like I had good traction prior. We'd been riding about 10 minutes. After the crash I got back on and continued without further incident.

 

OK--so thinking back, what is your perception of which end went first, front or the back, or both at the same time?

 

2nd question: did you have ANY throttle on, or ANY brake on?

 

 

CF

 

Hey JB,

 

Did you get a chance to answer these, did I miss it?

 

CF

I'm reasonably sure the rear didn't break away (no rpm rise nor did the rear come around) What's left is front or both, but I'm not certain how to tell the difference.

 

I'd just completed the brake/down and had initiated the countersteer. The bike responded by leaning me into the ground.

[Cobie Fair]

OK, so to sum up, you just began the steering action, were not even all the way leaned over, correct? I"ll assume yes, and continue. 2 questions:

 

How long since you had been doing spirited cornering, and what was the temperature of the day? I've had a coach crash by pulling over for just a few moments (but the day was a little cool, with a cool breeze), go out to catch his next student at the same pace, and down he went. Tires can cool off that fast.

 

2nd question: did you have ANY front brake on?

 

Let us know on these please.

 

C

I'm reasonably sure the rear didn't break away (no rpm rise nor did the rear come around) What's left is front or both, but I'm not certain how to tell the difference.

 

I'd just completed the brake/down and had initiated the countersteer. The bike responded by leaning me into the ground.

[Jaybird180]

This was at the trail end of the summer...an autumn type day, so I'd say temps in the low 70s maybe. We'd been on the road about 10-15 mins at this time.

 

I did have a (worse) comfort braking habit back then. If I had brake on, then it was unconscious. However, I had been aware that brakes/steering (generally) don't mix well (you can thank MSF for that). When I went down, I'd been scratching my head as to why and I didn't consider front lockup as a candidate, but I'm willing to put a question mark beside it. It is possible I tried feeling my way through the turn with brake

 

I performed the brake/down while vertical just before beginning the ess section. Probably past an ideal TP. I was also positioned in the center of the lane. My focus was shifting between the 2nd and third parts of the ess and the entry. I was probably looking 10 feet infront of the bike when I performed brake/down and then quickly shifted my vision further, countersteered and fell until impact.

 

OK, so to sum up, you just began the steering action, were not even all the way leaned over, correct? I"ll assume yes, and continue. 2 questions:

 

How long since you had been doing spirited cornering, and what was the temperature of the day? I've had a coach crash by pulling over for just a few moments (but the day was a little cool, with a cool breeze), go out to catch his next student at the same pace, and down he went. Tires can cool off that fast.

 

2nd question: did you have ANY front brake on?

 

Let us know on these please.

 

C

I'm reasonably sure the rear didn't break away (no rpm rise nor did the rear come around) What's left is front or both, but I'm not certain how to tell the difference.

 

I'd just completed the brake/down and had initiated the countersteer. The bike responded by leaning me into the ground.

[Cobie Fair]

This was at the trail end of the summer...an autumn type day, so I'd say temps in the low 70s maybe. We'd been on the road about 10-15 mins at this time.

 

I did have a (worse) comfort braking habit back then. If I had brake on, then it was unconscious. However, I had been aware that brakes/steering (generally) don't mix well (you can thank MSF for that). When I went down, I'd been scratching my head as to why and I didn't consider front lockup as a candidate, but I'm willing to put a question mark beside it. It is possible I tried feeling my way through the turn with brake

 

I performed the brake/down while vertical just before beginning the ess section. Probably past an ideal TP. I was also positioned in the center of the lane. My focus was shifting between the 2nd and third parts of the ess and the entry. I was probably looking 10 feet infront of the bike when I performed brake/down and then quickly shifted my vision further, countersteered and fell until impact.

 

OK, that is not a warm day, tires could easily not been up to temp, especially if you were going at a slower pace for the rider behind. Remember, tires at full operating temp are hot--didn't Will say it was 180+? AND there was a little front brake on (maybe just a little).

 

If you had said the bike went down AFTER you had reached full lean angle, we might have another issue, but you said right as you started to turn in.

 

When the bike slid, did you recall the front going away from you, or the back coming around a little? Do you recall what the bike did right after it ejected you?

 

C

[Jaybird180]

This was at the trail end of the summer...an autumn type day, so I'd say temps in the low 70s maybe. We'd been on the road about 10-15 mins at this time.

 

I did have a (worse) comfort braking habit back then. If I had brake on, then it was unconscious. However, I had been aware that brakes/steering (generally) don't mix well (you can thank MSF for that). When I went down, I'd been scratching my head as to why and I didn't consider front lockup as a candidate, but I'm willing to put a question mark beside it. It is possible I tried feeling my way through the turn with brake

 

I performed the brake/down while vertical just before beginning the ess section. Probably past an ideal TP. I was also positioned in the center of the lane. My focus was shifting between the 2nd and third parts of the ess and the entry. I was probably looking 10 feet infront of the bike when I performed brake/down and then quickly shifted my vision further, countersteered and fell until impact.

 

OK, that is not a warm day, tires could easily not been up to temp, especially if you were going at a slower pace for the rider behind. Remember, tires at full operating temp are hot--didn't Will say it was 180+? AND there was a little front brake on (maybe just a little).

 

If you had said the bike went down AFTER you had reached full lean angle, we might have another issue, but you said right as you started to turn in.

 

When the bike slid, did you recall the front going away from you, or the back coming around a little? Do you recall what the bike did right after it ejected you?

 

C

Bike kept going straight while on it's side. Fell on the left side (I was turning left...or wanted to at least) But, I didn't have eyes on it until it was in the grass. The rear came around about 30 degrees...counterclockwise direction. I'm sure the frame sliders (vortex) had an effect on the slide (was full of mud/grass as was the bodywork).

 

So, you're thinking cold tires and brakes on?

Wowsers!!! I don't think I've ever felt my tires at 180F, but I also haven't tried.

 

I'll try and feel the rubber next time I get in the gas with my car.

[Cobie Fair]

Bike kept going straight while on it's side. Fell on the left side (I was turning left...or wanted to at least) But, I didn't have eyes on it until it was in the grass. The rear came around about 30 degrees...counterclockwise direction. I'm sure the frame sliders (vortex) had an effect on the slide (was full of mud/grass as was the bodywork).

 

So, you're thinking cold tires and brakes on?

Wowsers!!! I don't think I've ever felt my tires at 180F, but I also haven't tried.

 

I'll try and feel the rubber next time I get in the gas with my car.

 

I don't know how often car tires get to that temp (don't spend much time on a track in a car ), but bike tires at temp--you can't put your hands on them, it burns.

 

Just a little front brake, tires a little cool, maybe a little humidity in the air, nice autumn day back east. I fell in a parking lot back east in '82--it was a little damp and I didn't notice it!

 

CF

[Jaybird180]

I can go for that.

Weather + cold tires + rider error (for the conditions).