Triumphrat

OUTLAWD · 04-22-2009, 12:02 PM

Just did my first track day/riding school at Pueblo Motorsports Park here in sunny CO. I am slowly getting my body position better, and getting way more comfortable, which are good things, I just had a question about how the bike was reacting, and how to remedy it.

On longer corners, say more than 90 degrees, at I'm not sure what speed (~45-50 mph?) the bike just kind of felt like it was slipping, or drifting to the outside, without me even driving out of the corner. If I tried to accelerate out it would push wide, which is what I wanted, but it still felt like it was slipping, or maybe just not gripping as much as I would like...it just was not cinfidence inspiring

Also, I see alot of folks grinding there peg feelers off, but the few times I have touch them down, it has unloaded the rear it seems, and really upset the bike. Which is not something I like to happen when I'm hanging off the seat in an apex.

The instructor following me said he was going to get in front so I could follow and hopefully carry more speed through the corners, but saw how close my center stand was to dragging (after he thought it was my toe...haha), and said he really didn't want me to push it any harder and risk dragging hard parts and dumping it. I know there are people pushing these things alot harder on the track, and the street, ahem, so I doubt I am at the bike's limit.

Oh, the setup: forks dropped ~3mm, heavier oil, overfilled a bit, rear set up relatively stiff. 120/180 Pilot Power 2CT's dropped to 31 psi F/R.

The only thought I had was that maybe the front was rising to fast from the initial braking compression, which is why it wanted to push wide...but are there any other reasons it would act like this? On the street I have never noticed this, so I am at a loss.

Thanks!

Shovelstrokeed · 04-22-2009, 12:13 PM

Hard to offer much in the way of correction/advise without seeing you ride. However, I will offer some tidbits that might prove useful on your next session.

1. Use a little slower entry speed and get on the gas a little sooner in the corner. Trail braking right to the apex is wonderful for passing somebody but leaves very little margin in lean angle. I like to actually get back on the gas, at least to neutral throttle, just as I am bending the bike into the corner. I then accelerate all the way through the turn getting on the gas harder after the apex, naturally.

2. Once you have your body positioned so that you are more or less balanced against the turning forces, try pushing the bike away from you and leaning your upper body inside a bit more. This will gain you lean angle so the hard parts don't scrape, and, if you are smooth about it, won't upset the bike a bit. It does require that your lower body be very firmly locked to the bike. You might try hanging your butt off less and being sure that your outside knee is locked to the tank. Use your core muscles to move your upper body from there.

OUTLAWD · 04-22-2009, 06:18 PM

i'm waiting for the photographer to post up some action shots, then I will have them to reference.

I definately gained alot in being smooth, linking turns, and following the line. what you said about braking early then getting back on the gas early is what I was trying to do, but when I would roll on it to drive out of the corner, it just was not confidence inspiring.

Thanks!

EvilSprint · 04-22-2009, 10:45 PM

And they actually LET you on the track with a center stand???

My how things have changed.

Shovelstrokeed · 04-22-2009, 11:02 PM

Quote:

Originally Posted by OUTLAWD

i'm waiting for the photographer to post up some action shots, then I will have them to reference.

I definately gained alot in being smooth, linking turns, and following the line. what you said about braking early then getting back on the gas early is what I was trying to do, but when I would roll on it to drive out of the corner, it just was not confidence inspiring.

Thanks!

Could just be a case of a little too much too soon. The reason for the roll on is to allow both the rear and front suspension to rise back to their mid-travel positions to both maximize suspension travel and help to stabilize the bike. If the bike isn't quite ready for it, too much throttle will lead to first, a vague feeling in the front end, and, at the extremes, head shake on corner exit.

To get a little technical about it, too much rebound damping might be the cause of this. With stock forks and rear shock, you are pretty much screwed and putting in heavier oil in the forks exacerbates the situation. Remember, as you lean the bike over, suspension loses effectiveness as a function of the cosine of the angle of lean. It therefore behooves you to keep the suspension at its maximum effective portion of its travel.

As you tip the bike in, roll on just enough throttle to maintain speed so the bike doesn't slow as the rear tire swings over onto a smaller radius. Maintain that and no more till you get to the apex. Then smoothly roll on throttle as you steer to bring the bike upright just past the apex, applying more throttle as the bike transitions to the vertical. This will feel slow at first and will be till you get to where you can judge entry speed and minimize the time it takes to get the bike from vertical (braking) over to maximum lean.

I ride with a guy who practically parks on corner entry, but he is on the gas and accelerating much sooner than I through the corner. Keeping in mind that we are riding on the street where stuffing him in a corner is not an option, the SOB will pull two bike lengths on me at the corner exit and be carrying more speed going down the following straight. Guess who gets to the next corner first?

OUTLAWD · 04-23-2009, 12:47 AM

Thanks again! Now I just have to wait til the next track day to try to put this stuff together in a safe environment.

The instructors/fellow riders were surprised to see that pig out there, but I got kudos for being able to make decent progress on my first day on a bike that no one expected to see on the track. Everyone told me that if I can learn to properly ride a bike that big/heavy, when I get on a smaller bike I'll be set. Now to find a smaller bike that I don't hate...haha

COBlue · 04-23-2009, 01:13 AM

Quote:

Originally Posted by Shovelstrokeed

Remember, as you lean the bike over, suspension loses effectiveness as a function of the cosine of the angle of lean.

Holy crap! There's some math!

3banger · 04-23-2009, 01:54 AM

Wouldn't be sin(lean angle)?

sin(90*) = 1 or 100% effectiveness with bike vertical
sin(0*) = 0 or 0% effectiveness with bike sliding into the kitty litter.

I suppose it depends on where you measure lean angle.

I did a track day in Dec 2001 at PMP. We showed up at 9am, met the guy at the gate, gave him $45 each, he handed us the lock and said lock-up on your way out. We had the whole track to ourselves all day!

OUTLAWD · 04-23-2009, 11:23 AM

I think its cosine of the angle, using the vertical bike as a reference point

cos(0)=1 in this case

yay math lesson!

BritBK · 04-24-2009, 12:16 PM

Just came back from a week in Germany and got to get up to
Nurburgring. 20 euros a lap on the 20km course and 30euros for
20 minutes on the new GP course. Had lots of fun beating the crap out of the rental car! Its amazing they did not even look at our car!
Lots of cool bikes and race cars in the paddock and They even rent
race cars ($$$$) A real good time!

George

I did a track day in Dec 2001 at PMP. We showed up at 9am, met the guy at the gate, gave him $45 each, he handed us the lock and said lock-up on your way out. We had the whole track to ourselves all day![/QUOTE]