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Old 11-26-2006, 11:58 PM   #1
Squidly McSmearstain
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Help me find my mistake!!

I have never dragged a knee. I've never done a track day or gotten any riding instruciton outside of the BRC.

I bought a SV650 about 4 years ago. After a year on that I upgraded to an FZ1. I rode that for a couple of years and then sold it to buy a Sprint ST. I sold the Triumph after six months (don't get me started) and bought a 2003 Tuono.

So, I have about 4 years of riding under my belt. I've never had an accident, but (like all of us) have had some close calls. I'm NOT an aggressive rider, but my inability to get low in the turns has me a bit frustrated.

This week end I decided to do some experimenting in an empty parking lot. I decided to work on shfting my weight, looking thorough the turn, and getting low. Since I was in a big, empty parking lot I thought I could get low for the sake of getting low. I could work up to it gradually at a slow speed.

So, I started working on figure 8 patterns. I was riding anywhere from 15 to 25 mph, and simply doing figure 8's as I worked on my mechanics. I was able to REALLY improve by using the techniques listed in "Total Control".

After about 30 minutes I was regularly dragging the scuff gaurd on my boot. However, I had not touched my knee down, nor had I dragged a peg.

I was going through my figure 8 patterns with heated up tires where I had not dragged any hard parts (just my scuff gaurds on my boots) when the bike slipped out from under me. I went down for the first time in my four years of riding (Incidentally I commuted every day for the last 8 months from San Ramon to SSF).

I was going approximately 20 mph on the same figure 8 pattern I had been riding on for 30 minutes. I don't think I went any lower than I had been. I certainly don't recall dragging a peg (I had dragged the pegs on my FZ1). The bike just slid out from under me. I would really like to know why. I went into this exercise with the intent of learning. I learned a LOT until I crashed. Now I need to learn from my crash. However, after playing the scene in my mind for 24 hours I still can't figure out what happened.

I'd appreciate it if someone could "CSI" my mistake.

Bike: 2003 Aprilia Tuono
Tires: Michelin Pilot Powers - plenty of tread and thoroughly heated up
Suspension: Stock Sachs front and rear. Set up for me by me which means it probably isn't optimal
Surface: Parking lot asphault. Clean with no leaves or gravel where I was riding. It looked like it had been sealed this year.
Weather: partly sunny and in the low 60's

Please let me know what other details you need.

BTW, if your bike doesn't have frame sliders you should get them. My Tuono suffered a grand total of $36 of damage. My left wrist got slightly brised. That's it.
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Old 11-27-2006, 12:03 AM   #2
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You can't see some slick spots on the floor sometimes. Going that slow, once you slide, it's over. You don't have any gyroscopic effect to help stabilize your bike.

Check your bike for leaking fluids.
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Old 11-27-2006, 12:04 AM   #3
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Parking lots usually have lots of fluids that leak from cars into the asphalt that may not be completely visible but are completely slippery. Sorry bout your crash.

You may also have given an abrupt input that the bike wasn't ready for???

Also, have your suspension set up by a pro.

Nice bike, btw.
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Old 11-27-2006, 12:11 AM   #4
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We'll move this to the crash forum...a perfect first case. That ok?
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Old 11-27-2006, 12:40 AM   #5
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you were right in the area between where I lean into the turn and where I counterlean to stabilize the bike.

Did the bike spin after it fell? It's not definitive, but if it did spin, it might give you an idea of which wheel lost traction.

Following ratters, perhaps you gave it a little more gas than you had been and that was enough to use the rest of the traction?

Does anyone know enough physics to explain whether or not the amount of lean angle you can hold is lower at lower speeds? It seems like the gyroscopic force would balance the gravatation force on the center of mass, meaning at higher speeds the net force at a given lean angle would be less.
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Old 11-27-2006, 12:42 AM   #6
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I agree with ratters. Parking lots tend to have a lot of grease/oil buildup on the ground. You probably hit a slick spot. I was doing the exact same thing as you not 2 days ago, and I was definitely worried that I'd hit a slick spot and have the bike come out from under me. You ok? How's the bike?
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Old 11-27-2006, 01:05 AM   #7
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Sounds like you were going too slow for the amount of lean. You probably fell inwards, and then the bike continued outwards, making you feel like it "slipped out" from underneath you.

At low speeds the game isn't lean angle, it's balance. Here's some nice low speed riding/balancing http://video.google.com/videoplay?do...eid=zeitgeist.
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Old 11-27-2006, 01:43 AM   #8
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Originally posted by cardinal03
Sounds like you were going too slow for the amount of lean. You probably fell inwards, and then the bike continued outwards, making you feel like it "slipped out" from underneath you.

At low speeds the game isn't lean angle, it's balance. Here's some nice low speed riding/balancing http://video.google.com/videoplay?do...eid=zeitgeist.
That video is insane! After much practice I should be able to do some of that with the Suzuki... I don't think he was talking about that kind of low speed turning, though. I was practicing near full leans at 15-20mph in a parking lot a couple of days ago just like him and didn't have any trouble. I have to say that getting the bike down at 65mph is tougher than doing it at 20mph, though.
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Old 11-27-2006, 01:46 AM   #9
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Quote:
Originally posted by rritterson
Does anyone know enough physics to explain whether or not the amount of lean angle you can hold is lower at lower speeds? It seems like the gyroscopic force would balance the gravatation force on the center of mass, meaning at higher speeds the net force at a given lean angle would be less.
Your bike has a finite turn radius, meaning you cannot turn on a dime even if you want to.

This means that there IS a minimum speed in which you are going too slow to balance the bike and maintain it in equilibrium. I don't think 20mph is below this minimum speed, however.

I think you hit a spot of shit or something.

One great way to see what happened is to examine your tires and look for slide marks which are not in the direction of wheel rotation. Try that and post in the morning.

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Old 11-27-2006, 02:20 AM   #10
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Originally posted by cardinal03
Sounds like you were going too slow for the amount of lean. You probably fell inwards, and then the bike continued outwards, making you feel like it "slipped out" from underneath you.

At low speeds the game isn't lean angle, it's balance.
While you might have had something on the tarmac, cardinal03 is probably accurate here.

The lower the speed, the more you steer.
The higher the speed, the more you lean.

I have made this mistake goofing around. So, don't feel bad about it.
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Old 11-27-2006, 05:29 AM   #11
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stop trying to drag a knee, and wait till you are at the track. you crashed trying to do something there was no need to do. Knees go on the asphalt when they need to, not when you want to put them there.
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Old 11-27-2006, 05:44 AM   #12
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Lean is not really done for the sake of lean. Its done to accomplish a task. That being turning. If you were taking the same curve at 20 mph, and then again at say 70 mph, your lean would be way way lower on the faster pass. I would say that going 25 miles per hour all the way down was probably the reason you fell. Not enough gyro to keep you stable. Also you mentioned you were doing figure 8s. If you switched directions too aggressively you may have upset the chasis. Good luck!
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Old 11-27-2006, 06:29 AM   #13
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There were probably a few different factors.

Tire temperature - Speed flexes the carcass of the tire, which puts heat into it. 15-25 mph doesn't do much for heating a tire up.

Tire pressure - you didn't mention it. If you were at the manufacturers recommended pressures, they were too high. Higher pressure = less carcass flex = less heat = less traction.

Peg weighting - Weight on the inside peg can contribute to a slide. Ideally, you should weight the inside peg to lever a bike into a turn, then crack open the throttle while pushing the bike up using the outside peg, putting it onto the meat of the tire.

Improper throttle management - Cracking the throttle open once you're on your target line in a turn stabilizes the load between the front and rear tires by transferring weight to the rear, flexing the carcass and increasing the size of the contact patch.

Upset the chassis while the bike was on the edge of traction - If you weren't loose while practicing those manuevers, you may have been feeding some bad inputs into the chassis. You may have been a little "stiff" in your attempt to drag a knee, possibly holding onto the bars a bit too tightly, upsetting the handling when you were on the edge of traction.

Also, it's tricky to be smooth with the throttle and keep the chassis composed at low speeds. The slightest change in throttle could upset the chassis at those speeds, overloading either of your contact patches.

Pavement quality - The stuff that parking lots are made of generally isn't of the highest quality.

In the 6 or so years that I've been involved with rider education (primarily AFM Race School Instruction and Trackday instruction), I've been able to read a fair amount of material, talk with several experts, and see a few patterns in newer riders. You've seen a few different opinions now - what do you think the causes could be?
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Old 11-27-2006, 08:16 AM   #14
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Tire temperature - Speed flexes the carcass of the tire, which puts heat into it. 15-25 mph doesn't do much for heating a tire up.
+5000

My experience with Michelin motorcycle tires has been that they're very cold-blooded and don't give much warning before they slide. It's the reason I don't use them anymore. 25mph won't do anything to get them, or any other tire, up to temp...

In addition, as others have already suggested parking lots are a terrible place to practice due to the amount of fluids dropped by cars. Oil, anti-freeze, brake fluid, you name it and some car has probably dropped it on the pavement. And, of course, they never get cleaned up!
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Old 11-27-2006, 08:38 AM   #15
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Thanks for some of the insight.

I do want to make a couple of comments.....

While I agree that putting a knee down is for the track, I think it is a little unrealistic to assume that I could show up at the track and appropriately get my knee to drag. If it were that easy, everyone would do it.

I was doing variations on exercises described in "Total Control", they seemed completely reasonable. Yes, I was interested in seeing if I could get me knee down, but my primary purpose was to work on my turning mechanics. I saw a VAST improvement. If you don't work on this in a parking lot, under controlled conditions, starting at low speeds, where and how do you do this?

I checked my cold tire pressure right before riding. Both tires were 1 pound below the spec. I decided that 1 pound wouldn't create too much of an issue. Was this wrong?

I DID give a couple of "ham fisted" inputs to the bike during my practice. I was going slower with less lean than when I crashed. I didn't go down at this time, and learned from my mistakes. When I DID go down I was very smooth with the throttle. I didn't goose the throttle, I didn't chop the throttle.

I wasn't consciously weighting my inside peg, but I could have been. Given some of the earlier threads on this site, I really don't want to get into a debate about weighting or not weighting the inside peg.

I had been doing the figure 8's in the same spot for half an hour. I walked the area before riding on it to make sure that there wasn't any fluid on the tarmac. The lot looked like it had been sealed this summer. It was very smooth and very black.

When I did go down, the bike slid away from me in a straight line.

I had been riding for a little while before I started my turning practice. It is entirely possible my tires weren't warm enough. I think I lost the front tire based on marks on the front tire.

I'm going to be working under the assumption that (like all crashes) it was a combination of issues:

Tires not as warm as they could have been.
Hit a slightly slick spot
Lean angle overly aggressive for the speed.

While NONE of the above issues would have caused my crash ALONE, the combination of these factors probably casued my get off. Maybe a hit some paint, and it ate up my final bit of traction.

Right before I fell, I was starting to get a feel for things. Eventhough I hit the groud, it was worth it to learn in a controlled manner.

As far as the bike goes, I BROKE the left frame slilder. It did its job, but when I pulled on it after getting the bike up it came off in my hands. The rear stand spool protected my swingarm. I went down on the left side (the exhaust is on the right side). I broke the orange cover from the front turn signal, but the light inside the signal still works.

There is SLIGHT scuffing on the bar end weight, the back of the mirror, and the shift arm. After two days, there has been no fluid leakage.

I went to Calilfornia Speed Sports in Livermore and got a new left side frame slider for $32. The GAVE me a new orange turn signal cover. Those guys are great.

Thanks for the feedback. Keep the info coming.
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