Stupid Pratfall

[SFSV650]

Reviving a thread I've been thinking about:

By April it became apparent that my bike had developed an intermittent, temperature related failure in one of its ignition coils. This would cause the bike to choke or stall under load upon reaching operating temperature. The problem was more acute on cold days, and presented on three or four occasions (both before and after this crash) before crippling the bike and warranting significant investigation.

It seems to me that as I rolled on throttle gently - ten minutes from home on the coldest day of the year - to make my pass, the bike may have stalled and slowed the rear wheel, upsetting the (gently leaned) bike enough to send it down the road rather than along the intended path.

To date its pretty much the only good explanation I can think of.

 

[Kornholio]

Perhaps I missed it, but was there any painted lettering or numbers on the road that you passed over when arcing? Since it was in the morning and cool out, it's possible there was enough moisture on the road (or at least the painted surfaces of said lettering/numbering) that would've made it slick and your maneuver was enough to lose traction. :dunno

 

[bcv_west]

Sounds like you've taken the most important lessons from it. Kudos for the detailed analysis. Sometimes shit happens, bikes are unstable especially at low speed. An experienced rider friend of mine broke his ankle doing a low speed move around a left-turning car, similar 'bike just slipped out from under' sensation. He'd just left work in the evening. We couldn't find anything to explain it; best guess was cold tires + condensation + oil residue in the middle of the intersection.

 

[Alan_Hepburn]

Something that caught me several years ago: one of the Botts dots on the roadway. It had come loose from the road surface and flipped over. Almost invisible at night, but when my rear tire rolled up on it as I was coming to a stop at a stop sign the rear slid out from underneath me - and I gently put the bike down on its side. I had no clue what happened until I found that stupid dot near the rear tire. Hard plastic slides quite well on blacktop!

 

[clutchslip]

Crash analysis rule # 1 - it's never the tire's fault (unless they blew up right before the crash), so eliminate that from the factors.

I am NOT commenting about the O.P. mishap, but I don't think this is good advice. What if it is the tires? You never learn what are good or bad tires, or that some tires take more heat to work properly, if you just ignore the possibility. What about tire pressure? It can make a huge difference depending on tire/bike/conditions.

I have had two incidents that were cold tires. One was on the track and one was not. I have removed DOT tires for street riding because they never got warm enough. I have taken OEM BTs off with only 300 miles on them, because they were dangerous. I currently have DOTs that will not get up to proper temperature this time of year. I ride very carefully with them.

Tires are extremely important to motorcyclists. Ignoring them is not very wise, in my experience. End of black donut rant. I will get a real donut, now.

 

[Enchanter]

I am NOT commenting about the O.P. mishap, but I don't think this is good advice. What if it is the tires? You never learn what are good or bad tires, or that some tires take more heat to work properly, if you just ignore the possibility. What about tire pressure? It can make a huge difference depending on tire/bike/conditions.

I have had two incidents that were cold tires. One was on the track and one was not. I have removed DOT tires for street riding because they never got warm enough. I have taken OEM BTs off with only 300 miles on them, because they were dangerous. I currently have DOTs that will not get up to proper temperature this time of year. I ride very carefully with them.

Tires are extremely important to motorcyclists. Ignoring them is not very wise, in my experience. End of black donut rant. I will get a real donut, now.

The point is that in most cases, the rider knew what tires were on the motorcycle and had previously ridden on them. Then at some point became complacent and rode without consideration to the previous knowledge of the tires limitations.

So yes, don't blame the tires.

 

[clutchslip]

The point is that in most cases, the rider knew what tires were on the motorcycle and had previously ridden on them. Then at some point became complacent and rode without consideration to the previous knowledge of the tires limitations.

So yes, don't blame the tires.

I understand all that. I still think automatically eliminating the tires as a possibility is a mistake. You could go thousands of happy miles in sunny weather and then it rains, and you discover your tires really don't like the wet. For most people, it is probably difficult to access the limits of tires, or if you are inflating them properly, until one discovers the limits. You can get 5% more lean on one tire vs another, with all other things being equal. At that point you have learned the difference between tires, but nothing about your riding. If you keep chasing your riding mistakes, you will miss that one tire is better than the other.

 

[tzrider]

I understand all that. I still think automatically eliminating the tires as a possibility is a mistake. You could go thousands of happy miles in sunny weather and then it rains, and you discover your tires really don't like the wet.

In that case, are the tires the cause or is it that the rider had never progressively assessed those tires' behavior under those conditions?

To just write it off to the tires doesn't give the rider a plan for next time. He could change tires, but he may not know anything about them either. A foundation of safe riding is being able to predict traction. You're right that tires matter, as they set a limit on available traction. It's up to the rider however to learn how much grip is available and stay within the known envelope.

 

[clutchslip]

In that case, are the tires the cause or is it that the rider had never progressively assessed those tires' behavior under those conditions?

To just write it off to the tires doesn't give the rider a plan for next time. He could change tires, but he may not know anything about them either. A foundation of safe riding is being able to predict traction. You're right that tires matter, as they set a limit on available traction. It's up to the rider however to learn how much grip is available and stay within the known envelope.

I think you are doing the same thing Enchanter did, and saying that I am using it as an excuse. Which I am not. It is about learning about tires.

Look at your bolded statement. If the rider has never experienced loss of traction before, where the heck do you expect this wonderful knowledge to come from? It comes from experience. I really hope you are not suggesting that people keep riding on crappy tires, not look at tire pressures, and tire warming patterns, but just adjusting their riding to "deal with it". Getting better tires, paying attention to tire condition and characteristics is an awfully important part of safe motorcycling. This assumption that the tires don't matter is as dangerous as always blaming them. Eliminate tires as a factor, then you are clear to evaluate the riding. What is the big deal?

 

[tzrider]

I think you are doing the same thing Enchanter did, and saying that I am using it as an excuse. Which I am not. It is about learning about tires.

Good to know. I couldn't tell, so thanks for the clarification.

Look at your bolded statement. If the rider has never experienced loss of traction before, where the heck do you expect this wonderful knowledge to come from? It comes from experience. I really hope you are not suggesting that people keep riding on crappy tires, not look at tire pressures, and tire warming patterns, but just adjusting their riding to "deal with it".

The "wonderful knowledge" comes from treating an unknown tire/surface combination with suspicion and being very gradual and progressive about increasing traction demands on the tires. There are signs that the tires are about to lose traction before they suddenly cut loose. The rider who boldly leans the bike over much farther than they have during that ride won't detect the signs, he'll fall down. It's up to each rider to decide if they want to "just deal with" tires that offer less traction or get something better. Either approach can be done safely.

 

[SFSV650]

I'm no expert, and this doesn't relate to my experiences directly, but with a pretty common tire like the BT023 or the Pilot Road, it seems that if the tire suddenly let's go in a scenario (ambient temperature, speed, lean angle) where they have held before, it's probably not as a result of a characteristic of that tire. Does that make sense?

 

[etxxz]

this thread was going well until we started to focus on the tires. road conditions change. environment changes. drivers change. rider input can change. tires don't.

 

[clutchslip]

this thread was going well until we started to focus on the tires. road conditions change. environment changes. drivers change. rider input can change. tires don't.

Here we go again, and I can not sit quietly. You bought tires, and the pressure has stayed the same the entire life of the tire? Every tire behaves the same in 20F weather vs 100F weather? They never wear, get flat spots, or tears? All tires behave the same under all conditions? I have no idea how long you have ridden, but I am surprised you are able to post here.

 

[Enchanter]

Here we go again, and I can not sit quietly. You bought tires, and the pressure has stayed the same the entire life of the tire? Every tire behaves the same in 20F weather vs 100F weather? They never wear, get flat spots, or tears? All tires behave the same under all conditions? I have no idea how long you have ridden, but I am surprised you are able to post here.

Did the tire pressure change from the beginning of the ride to the crash scene? Did the ambient temperature swing from 20-100F during the ride? Did they wear out, flat spot, or tear in-between the last turn the rider completed until this one?

The tires didn't magically shit the bed in this turn. That is the point. If it was the tires, why did they behave just fine in the miles before this turn, and then give up the ghost in this particular turn?

Hint: They didn't. It wasn't the tires.

 

[kiwi_outdoors]

how about?

How about "tires don't change as much or as quickly as other factors, relatively speaking?"

Would that be OK?

 

[clutchslip]

Did the tire pressure change from the beginning of the ride to the crash scene? Did the ambient temperature swing from 20-100F during the ride? Did they wear out, flat spot, or tear in-between the last turn the rider completed until this one?

The tires didn't magically shit the bed in this turn. That is the point. If it was the tires, why did they behave just fine in the miles before this turn, and then give up the ghost in this particular turn?

Hint: They didn't. It wasn't the tires.

Once again, you apply what I say to this specific incident instead of reading what the OTHER people post. They post absolutes: "ignore the tires" and "tires don't change". You agree with that crap? I am surprised. And EVEN in this case, his tire(s) could have been poorly suited with inflation or over factors, but they were not tested to their limits until THAT moment. As I stated before: you can go thousands of miles in nice conditions, and love your tires, then the conditions change, and your tires may not be so good. P.S. I stated in the first post that I wasn't talking about this o.p. - Read it!

 

[Enchanter]

Once again, you apply what I say to this specific incident instead of reading what the OTHER people post. They post absolutes: "ignore the tires" and "tires don't change". You agree with that crap? I am surprised. And EVEN in this case, his tire(s) could have been poorly suited with inflation or over factors, but they were not tested to their limits until THAT moment. As I stated before: you can go thousands of miles in nice conditions, and love your tires, then the conditions change, and your tires may not be so good. P.S. I stated in the first post that I wasn't talking about this o.p. - Read it!

Given what you just typed, your comments are off topic for this incident and Crash Analysis. It's an interesting discussion, but it doesn't belong here. Consider starting a different thread outside of CA.

 

[clutchslip]

Thanks Tim. I understand that I was out of the specific discourse on this particular incident, only because I thought others had done the same. I will temper my temper in analyzing these distinct mishaps.

 

[MagicMike]

I realize this isn't on topic as crash analysis, more related to collision avoidance. Sometimes--depending on the location of nearby businesses, etc.--these right-turning cars are desperate to immediately move over to the leftmost lane in order to make a left/u-turn at the next light.

That kind of car behavior makes swerving around the entering car more risky than braking, at times.

Good Point, but beware of getting rear ended, the most common of 2 vehicle accidents. I personally prefer to swerve over brake, but during those precious split-seconds of impending impact, its difficult to make an informed decision:dunno

 

[LectricBill]

OP, did you ever get a clear understanding of what happened and therefore how to avoid it?

The details just make no sense to me. How could even WOT at 30 mph in 3rd gear on a 650 break traction (unless there's slippery fluid)?

How could a bike doing 30 mph slide 250 feet?
How could a body doing 30 mph slide 100 feet?

My only reference point is I was knocked off my bike at about 30 mph from a car veering into me (illegal turn from wrong lane) and I slid about 13 feet and my bike slid 25 feet (but hit a light pole with enough force to total it, so it could have slid further).

I suspect this sentence may hold the crucial clue:

"I believe the turn was executed quite smoothly; I was anticipating a very slight lean, maybe 5 to 10 degrees. Instead, very little input on the bars resulted in a huge amount of lean."

To me, that speaks of slippery fluid.

I don't see how 3rd gear at 30 mph could have lightened the front wheel enough to get it off the ground.

Very puzzling...