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Front End Wash Out


renais
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<_< picking up on an old thread I have a few thoughts which I'd like to share. My understanding of cornering (which may be flawed) is that once the bike is turned, most of the steering is done by the rear, hence the reason for bikes exiting turns with the front wheel in the air and generally not making much contact with the track. This being the case, front wheel wash out must happen before the bike is turned or it happens only after losing the rear!?

 

any further thoughts?

 

Renais

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<_< picking up on an old thread I have a few thoughts which I'd like to share. My understanding of cornering (which may be flawed) is that once the bike is turned, most of the steering is done by the rear, hence the reason for bikes exiting turns with the front wheel in the air and generally not making much contact with the track. This being the case, front wheel wash out must happen before the bike is turned or it happens only after losing the rear!?

 

any further thoughts?

 

Renais

 

The front end does most of the steering. You need to counter steer to turn the bike into the corner. The front end can wash out while turing, while leant over, exiting the corner. The front tyre will always be in contact with the track when turning. You cannot take a corner with front tyre in the air. If you use the rear wheel to steer then you would need the front to steer in the direction of the slide. If the front washes out while opposite locking then you will fall. I will leave the rest for the experts to explain. Im a newbie here and still trying to learn :)

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The bike will corner quite happily with the front in the air (my old gixxer was great for it). Because the front wheel is (hopefully!) still spinning, this helps to stabilise the bike. Turning the bars will still adjust the lean (and hence the path) of the bike although the effect will be far less than if the tyre was touching the ground.

 

Whenever both wheels are on the ground, the traction (grip) is shared between the two, depending on the contact patch and weight distribution. As you get on the gas to exit a corner, the rear is taking most of the load, which is why you very rarely see front end wash outs at the exit of a corner (I can't remember seeing any). In the case of losing the front end, nearly every case occurs whilst the rider is still on the brakes just as (or just before) the bike has completed it's turn (asking too much of the front tyre).

The critical point of any corner is from the moment you release the brakes to completing your turn to getting on the gas. Not surprisingly, this is also the time when you generally have the most to think about and work out. I think this is what Keith is getting at by saying that you need to have a plan for the corner, it removes some of this thought. Instead of thinking "What do I need to do now?", you should be thinking "What am I going to do next?"...

 

Once you're on the gas, the rear will almost always be the first to let go (unless you hit a patch of oil or ride over a Roo...), another good reason for getting on the gas as soon as possible.

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Just a quick one with reagrd to the perception of steering a bike. There are three things here refered to in thi thread as steering:

 

1) Steering with the rear

 

2) Counter Steering

 

3) Sliding/Spinning Up

 

 

Spinning the rear wheel or sliding the front can be used as steering if your good enough. No denial!

 

Counter steering is the only other way of doing it without sliding a tyre!

 

Steering with the rear seems to me a bit more of a vauge description of something else. Once the bike is leant over I feel there is no longer any steering involved until you need to make correction or exit the corner. The bike is leant over and on a set radius. The wheels are pointing where the bike is going and nothing has to be done. The bike would go round in circles until it ran out of fuel. No steering. It's riding a straight line but with a side-swipe of gravity thrown in for good measure.

 

Once you are on the gas (straight after initial turning in) the rear of the tyre should have somewhere around 60% of the tyre grip. After all, that's why it's a larger tyre! More weight is on the back wheel. If you open the throttle and get the front off the floor, then 98% of the weight is on the rear wheel with 2% being supported by win blast, maybe. The rear isn't steering, it is simply following it's pre-selected path. It is on the side wall and is affectively going in a straight line. The curvature of the tyre and gravity keeps the bike going round in circles! No steering here.

 

Once your on the gas, you can slide or countersteer out of the corner.

 

 

 

Therefore, with regard to front wash-out, I can only for see it happening when you are decelerating at any point of the track, or when you are cornering with the 60/40% weight bias to the rear wheel and you hit a reduced traction surface, say oil. (or rain if your pushing hard) If it is mid corner, it can be 50/50 as to whether the front or rear lets go, depending on what you are doing with the controls.

 

I don't think you can really have a front wash-out once on the gas or when settled into the corner without the aid of oil, but the rear would let go as well! (Having more weight on it!)

 

Just my two cents worth!

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I've watched amateur racers at Brainerd lose the front while accelerating in turn 4 many times. What they say is there are bumps and a dip in the corner that makes the front light. If they turn in a little early and hit the gas hard before the apex the front goes. From their explanation, I am guessing that they are pushing the front with the gas. Basically going from a loaded front tire to too light a front tire. I don't have any experience with that, but I do wonder if they are able to overpower the front prior to apex with too much gas and a rear that stays planted.

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Good point. If you come from the brakes sraight to a fair bit of power on a very tight line and alot of lean angle it could lead to pushing the front.

 

What I meant by once on the gas the front can't wash, is where you have started getting the bike more upright, even if only slightly and then give it the gas, as the front wheel is often only taking say 20% of the bike load.

 

When you are turning tight, you need both tyres on the floor, push one sideways and the rear will follow. Same as a front wheel drive car when the wheels slip, the rear follows.

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I can think of two quick examples of my losing the front while on the gas.

 

1. Downhill left out of the "highlands" at Louden. (First practice. In the rain)

 

2. Right turn after backstraight at Indy entering the "parking lot" section.

 

The second incident occurred while passing on the outside where it is notoriously slippery and we are expressly asked not to pass there at the riders' meeting. Of course, in my younger days, being told, "You can't pass there", was like guaranteeing I would. Right up until the day it finally bit me. In fact, i believe that was the first and only time i ever touched a handlebar down in a race. Chasing Bruce Lind for first place at the WERA national 125gp. (1995?) Boy did that suck. I had a string of riders from John Ulrich to John Bickle walk past my pit to thank me for the entertainment, but, that was just the final event in a long string of passes and repasses driven by an emotional state of "I'm gonna win or crash trying." Funny how that became a self fulfilling prophecy. The really funny thing is that I had the fastest bike that day by a mile and all I had to do was ride around and pass on the straights. easy win. it was about 90f and 100% humidity. nobody else had anything close to a small enuf main jet but the guy i borrowed it from who was too scared to run it. No. I had to take the lead by the end of lap 2 or else. God what an idiot i was. or maybe just young. I remember JU riding up to my pit on his 4 wheeler, stopping and shaking his head, and just driving away without saying a word. that's saying alot considering the verbose wordsmith he is.

 

anyway, i'm thinkin if two wheels are on the ground, they share the traction. the loss of traction in both my cases was caused by slippery and/or lightened load conditon. on the gas. down hill. rain or slick.

 

in anycase, just dropped in to say "hi".

 

get back when i can. nothing personal. no time. no dsl. be home soon. cheers.

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reading through this thread has helped reinforce my belief that loading the front too much on turn in is bad and getting on the gas early helps with traction. Its obviously more difficult to cope with bad road/track conditions. Incidentally, my reference to steering with the rear comes straight from the Great Man himself, TOTW II Ch 13. Very interesting concept and worth reading if you can get hold of a copy. thanx to everyone for their input BTW

 

Renais ;)

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  • 3 months later...

I think I see a misunderstanding here...

 

There would seem to need to be some clarification between steering (turning) and cornering. Perhaps it would be best to think of turning as "changing direction". As in counter steering or "steering with the rear". I have a car racer friend who likes to think of a corner having three parts. Entry or direction change. Mid-corner. And exit. For lack of better terms at this moment. Counter steering at the entry is a direction change. Steering with a rear wheel slide is a steering or direction change. Once the bike has achieved equilibrium in a turn...sorry, once the bike is leaned over and stable you get on the gas to shift weight bias toward the rear (this might be called mid-corner or cornering). Well, depending on different variables and factors, and how you want to label things, from just beyond this point it is possible to continue adding throttle to lift the front wheel, while still leaned over. Um, at least that's what Woody says. haha. I generally wait until I'm kinda close to straight up and down. But I'm a wussy. :lol:

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