What say you?

[UDRider]

Was going home tonight on my Daytona 675. I had green left signal. So I braked before the turn, tipped the bike in and held throttle steady. About mid divide I pushed on inside bar a bit more and next thing I know I feel like the bike just dropped. When I say pushed on a bar I don't mean put weight on it, or pushed it down. I pushed it forward. No weight was on the bars.

The bike didn't spin out, and just kept sliding wheels first down the street. As I said neutral throttle. I wasn't whacking it like a whack a mole.

So eliminating most common causes of bubble gum and cold tires WTF happened?

The fall happened when I started tightening up my turn. From my recollection it was a minimal input. Maybe too abrupt and over loaded front tire?

Honest it felt like I just dropped the bike. Maybe I was going too slow and there wasn't enough centrifugal forces to keep it upright at the speed I was going?


Tires are Q2, and I am running 30 PSI at the front 34 at the back. They have 4 trackdays at T-hill, and were seating in my garage for a bout a year before I mounted them on my street rims.

Thx.

 

[dmaxAl]

That sucks dude. What was the intersection itself like, you didn't mention anything about the road surface or the left turn itself. oil..snot..??

 

[UDRider]

That sucks dude. What was the intersection itself like, you didn't mention anything about the road surface or the left turn itself. oil..snot..??

Hmm. When I went back and looked the intersection was usual asphalt surface. No debris, and I didn't see any obvious oil slicks. Shuffled my feet around where crash began didn't feel anything out of the ordinary.

It was a left hand turn from side street on to a four lane road (two each way), with concrete median. I initiated input right around or after concrete median.

 

[latindane]

Can you see any signs of loss of traction on your front tire?

 

[Ironbutt]

Here's my guess. You added bar pressure at low speed and wiped out; no peg pressure, sitting fat ass in seat, legs dangling(no tension on pegs)

OR a foot was off one of the pegs.

 

[Lunch Box]

Also, as much as it can sound like a BS excuse, take-offs can be somewhat hazardous on the street; particularly in cold/damp weather. Even if the tread is still pretty good, the tires have likely been heat cycled enough that they are a bit harder than they should be. That shouldn't have caused this type of fall, but it may have been a contributing factor. :dunno

 

[UDRider]

Can you see any signs of loss of traction on your front tire?

What would those be.

Here's my guess. You added bar pressure at low speed and wiped out; no peg pressure, sitting fat ass in seat, legs dangling(no tension on pegs)

OR a foot was off one of the pegs.

Now that I think about it I think was lazy and was just seating on the seat and not weighting outside peg.
I wasn't exactly dragging knee. The lean angle wasn't all that much. I am not clear how would of weighting pegs would have helped.

Also, as much as it can sound like a BS excuse, take-offs can be somewhat hazardous on the street; particularly in cold/damp weather. Even if the tread is still pretty good, the tires have likely been heat cycled enough that they are a bit harder than they should be. That shouldn't have caused this type of fall, but it may have been a contributing factor. :dunno

Might have been one of the factors. Will definitely put new tire on now. Back to trusty angel STs.

 

[tzrider]

Outside of the thread, you had mentioned the tires and surface were cold. The tires were take-offs, so as mentioned, the heat cycling and race compound makes for a tire that isn't going to work well until they have heat in them. This isn't a cause, but it sets limits on how much you can ask of the tires.

From your description elsewhere, it sounds like you lost the front, based on the bike having just dropped and slid straight without spinning. A lowside after losing the rear is typically accompanied by the bike yawing out and continuing to rotate when it hits the ground.

Do you recall whether you were fully off the brakes? Did you find your initial skid mark? Any bumps just prior to that point? Had you leaned the bike over that far on that side yet on that ride or was the lean angle substantial deeper in this turn than any prior one?

 

[UDRider]

Outside of the thread, you had mentioned the tires and surface were cold. The tires were take-offs, so as mentioned, the heat cycling and race compound makes for a tire that isn't going to work well until they have heat in them. This isn't a cause, but it sets limits on how much you can ask of the tires.

From your description elsewhere, it sounds like you lost the front, based on the bike having just dropped and slid straight without spinning. A lowside after losing the rear is typically accompanied by the bike yawing out and continuing to rotate when it hits the ground.

Do you recall whether you were fully off the brakes? Did you find your initial skid mark? Any bumps just prior to that point? Had you leaned the bike over that far on that side yet on that ride or was the lean angle substantial deeper in this turn than any prior one?

I was completely off the brakes. I don't trail brake on the street. All the braking before corner, then neutral/maintenance throttle (I keep hand at the same position on a throttle), with gentle roll on as I exit the corner.

Yes, it was right after the concrete median. If you imagine an arc I was past an apex of it. It would have taken me to outside lane where I would have stayed with minimal correction. I wanted to tighten up turn a tad and stay in left lane. I lost traction right as I initiated an input to lean a bike a bit more. Throttle was still neutral, no roll on.


As I walked around, briefly since I didn't want to get run over, I didn't see or feel any bumps.

Nope, most of it was straight, this was a first left hand corner. I went around 3-4 blocks from start.

 

[Ironbutt]

What would those be.


Now that I think about it I think was lazy and was just seating on the seat and not weighting outside peg.
I wasn't exactly dragging knee. The lean angle wasn't all that much. I am not clear how would of weighting pegs would have helped.



Might have been one of the factors. Will definitely put new tire on now. Back to trusty angel STs.

Coming from the perspective of riding motorcycles with class C traction on slick surfaces(flat tracks & blue groove); you have to keep the feet, at least one, firmly planted on the pegs, however it feels or looks on a sport bike; it's really all the same concept, just different traction.

Not only will this help you control the bike better, you'll be less fatigued and have less unnecessary bar input. Try riding around one handed. That will show you where the weakness is in your posture.

 

[tzrider]

Nope, most of it was straight, this was a first left hand corner. I went around 3-4 blocks from start.

It sounds as if you turned too much too soon on tires that weren't up to temp. It doesn't mean you can't ride those tires, but they take longer to warm up and lean angles must increase progressively until the tires will support "full lean," whatever that will mean in the real world.

Street oriented tires should be warmed up too, but they tolerate higher lean angles at colder temperatures, so riders get away with not being as cognizant of adding lean angle in increments.

 

[UDRider]

Coming from the perspective of riding motorcycles with class C traction on slick surfaces(flat tracks & blue groove); you have to keep the feet, at least one, firmly planted on the pegs, however it feels or looks on a sport bike; it's really all the same concept, just different traction.

Not only will this help you control the bike better, you'll be less fatigued and have less unnecessary bar input. Try riding around one handed. That will show you where the weakness is in your posture.

Will when slabbing with no traffic I usually ride just with right hand. Will try with left hand.

I did ROMT twice and played around on flat track on my dual sport. I thought weighting the outside peg was mostly to do with controlling rear traction.

It sounds as if you turned too much too soon on tires that weren't up to temp. It doesn't mean you can't ride those tires, but they take longer to warm up and lean angles must increase progressively until the tires will support "full lean," whatever that will mean in the real world.

Street oriented tires should be warmed up too, but they tolerate higher lean angles at colder temperatures, so riders get away with not being as cognizant of adding lean angle in increments.

The more I think about it, the more I think it was a too abrupt of an input, which corresponded to increased lean angle, for the front tire in it's condition/warmed up state.

It was just so sudden. I didn't think I was doing anything different then usual until the moment bike started to fall. Really screws with your confidence.

 

[dmaxAl]

It sounds like you decided, mid turn, to reselect your exit point? And it sounds like all else being equal, your original line would have gotten you safely through the turn?

:dunno I'd definitely defer to andy, but I've always thought a 'clean' arc through any corner allows the best contact point at any given point through the corner. Changing the primary exit point upsets this completely.

?

 

[UDRider]

It sounds like you decided, mid turn, to reselect your exit point? And it sounds like all else being equal, your original line would have gotten you safely through the turn?

:dunno I'd definitely defer to andy, but I've always thought a 'clean' arc through any corner allows the best contact point at any given point through the corner. Changing the primary exit point upsets this completely.

?

Yes it is exactly what happened. That is not the usual mode of operation for me either.

 

[latindane]

What would those be.

Depends on how hot the tire is. Since it was cold, I would guess it would look similar to the mark of somebody taking very gritty sandpaper and rubbing the tire from the middle towards the outside.

It just sounds very weird that the bike would just "drop" without any loss of traction.

 

[UDRider]

Depends on how hot the tire is. Since it was cold, I would guess it would look similar to the mark of somebody taking very gritty sandpaper and rubbing the tire from the middle towards the outside.

It just sounds very weird that the bike would just "drop" without any loss of traction.

Well there certainly was a loss of traction. It just felt like the bike just "dropped". I'll take a look at front tire to see if I spot anything when I get back home.

Interesting observation. The three low sides I had were all on left side.
1) I was making left turn with gravel.
2) lost front during braking on down hill with tar snakes
3) curret one on left hand turn.

 

[tzrider]

Yes it is exactly what happened. That is not the usual mode of operation for me either.

While it's ideal to get through a corner with a single steering input, sometimes you have to change lines for any number of reasons. Your throttle action was correct under the circumstance; either flat or slightly negative throttle, tighten line and resume rolling on once the lean angle is set and the bike is pointed.

A cold, heat-cycled race tire on a cold street simply may not support the lean angle you reached. If we can assume that's the case, what could you do differently if you needed to tighten your line a little bit without adding lean angle?

 

[UDRider]

While it's ideal to get through a corner with a single steering input, sometimes you have to change lines for any number of reasons. Your throttle action was correct under the circumstance; either flat or slightly negative throttle, tighten line and resume rolling on once the lean angle is set and the bike is pointed.

A cold, heat-cycled race tire on a cold street simply may not support the lean angle you reached. If we can assume that's the case, what could you do differently if you needed to tighten your line a little bit without adding lean angle?

Hmm. Interesting question. So question is how I would tighten the corner when I already tipped in the bike and it has some lean already.

Well assuming we are dealing with sport bikes and not flat track type of situation. To keep the same lean angle and decrease radius of a turn speed needs to be reduced. Two ways of doing it is 1) roll off he throttle 2) apply brakes (front or rear or both). Rolling off the throttle would transfer some weight on to front tire. Which might lead to over loading front tire and causing a fall just like increasing a lean angle. The same for applying front brake. So I would think using rear brake carefully would be the answer. I think it's safer then front because it's easier to control rear slide then the front. Although it's harder to modulate it as carefully as the front. So if someone not used to it they might apply too much pressure lock he rear and still go down. This is more prevalent in an emergency situation when adrenaline is pumping. Since this was not a case applying rear brake, lightly, would be a good solution.

One could also play with BP, but doing it mid corner is dangerous as it might upset bike suspension and lead to same result of sliding on ones ass.

To avoid this situation picking a better line to begin with would have been better.

 

[tzrider]

Well assuming we are dealing with sport bikes and not flat track type of situation. To keep the same lean angle and decrease radius of a turn speed needs to be reduced. Two ways of doing it is 1) roll off he throttle 2) apply brakes (front or rear or both). Rolling off the throttle would transfer some weight on to front tire. Which might lead to over loading front tire and causing a fall just like increasing a lean angle. The same for applying front brake. So I would think using rear brake carefully would be the answer. I think it's safer then front because it's easier to control rear slide then the front. Although it's harder to modulate it as carefully as the front. So if someone not used to it they might apply too much pressure lock he rear and still go down.

Right, the short answer is to slow down a little. At the same lean angle, the line will tighten.

Note that any slowing will transfer weight forward. Thus, the idea that using the rear brake is preferable to rolling off isn't valid. In the scenario you were in, rolling off might have slowed you enough. Rolling the gas off, as opposed to chopping it off, will avoid sudden load changes and allow you to better feel what the tires are doing.

Your thoughts about the difference in subtlety between the front and rear brakes are right on. If I need to shed more speed than rolling off will achieve, I pick the bike up a little and use a bit of front brake. As the bike slows I can add lean angle back to keep the line tight.

 

[UDRider]

Kool, will keep it in mind. :thumbup