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post #1 of 16 (permalink) Old 01-28-2006, 11:30 PM Thread Starter
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Question: throttle highside

Silly question, but it's been bugging me lately. Every bike reviews I read, the journos shiver about highside from so much power of literbikes. Even middleweights, caught in wrong situation, and little greedy on the throttle, yields a nasty high speed high side. But how is that even possible? My assumption was too much throttle could mean wheelspin, headshake, wheelie, slide/drift, and lowside. Highside comes from spinning or sliding the rear and then chopping the throttle shut right? So if it's too much throttle, and the throttle isn't chopped, worst comes to worst, it should be a lowside - lose traction and fall on side of the lean, why would it be a highside? Thanks.
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post #2 of 16 (permalink) Old 01-29-2006, 04:06 AM
 
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Highside comes from spinning or sliding the rear and then chopping the throttle shut right?
Yup and nope.

Generally what causes a person to chop the throttle is the speed and severity of the slide. With huge amounts of power on tap, you can get fairly sideways quick, at which point any human would let off the throttle.

Of course highsides will happen without letting off the throttle. Problem is that the further side ways the bike gets the more it wants to stand up especially if you are going fast. This results in more traction and a highside.

Watch gp or any other high performance mc race and see that many high sides occur just after the apex and they happen extremely fast.

It is generally accepteed that if the rear slides your probably in for a highside, if the front slides you going down easy.
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post #3 of 16 (permalink) Old 01-29-2006, 09:58 AM Thread Starter
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But in most MC races, especially televised ones, the rear slides every time coming out of the corner, the front float sometimes, and they get a tank slap once in a while, isn't that just part of going fast?

I still haven't understood what would transpire that highside without easing off the throttle. Generally, if the power of the slide can't be control, but the person keeps the throttle on, the bike should let the person off in the side of the lean, then the bike could possibly rotate sideways and catapult, but this would in some sense mean lowside due to side where the rider exited.
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post #4 of 16 (permalink) Old 01-29-2006, 10:18 AM
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Lean angle has a bit to do with it too....the further your over, the easier it is to spin up the rear, especially in the slow to med speed turns, the rider tries to get outta the turn quicker, prolly grabs too much too soon, and when the rear steps out to far the throttle usually, but not always gets shut off, which is a mistake..The best thing to do is either keep the gas on, or gently roll it on further. When you see racers spinin up the rear, they are usually more upright, also they have THE feel for keepping the gas where it should be, so they don't wind up on their head...Don't ask me how I know this..

If you happen to be leaned over, and spin the rear, just stay with it, your chances are better than to get off the gas.

I would take exception to Grashopper's example that if the rear slides, your prolly gonna highside. This really depends a few things, i.e. the speed, lean angle, the turn itself, and the rider.

Many times, I've seen a bike get sideways, and lowside, I also have experienced that too. Prolly the easiest turn to get into a bad situation is a downhill turn, where alot of the weight gets sifted to the front of the bike, hence the rear is unweigthed, and the rear spins up fairly easy..

Oh, one other thing...in the days of Grandprix raceing when they used 2 stroke 500's, you'll notice MANY more highsides, as opposed to nowdays, cuzz the power delivery on the 4 strokes is much nicer, i.e. a better power curve..

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post #5 of 16 (permalink) Old 01-29-2006, 10:49 AM Thread Starter
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Oh ok, that's what I didn't get before. As Grasshopper said, the further and faster the bike is sliding, it wants to stand up, and thus lead to highside due to prelimanary angle of the tire when the slide starts and then snapping off at different angle when slide ends. Which has a similar effect like rolling off the throttle, .i.e. stand up or run wide and traction changes.

However, if you remember one of Keith Code's advise, slides actually can help the bike to change the line tighter, with skill, the rider can coax the bike to get the inside line coming out of the corner. And I think this is where the theories collide.

My personal experience was different, although nowhere around that speed, but prior to the highside, the bike felt it was going to tip over and lowside into the lean of the slide, not stand up. And that's what tricked me, because in that situation, I actually wanted the bike to go upright.
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post #6 of 16 (permalink) Old 01-29-2006, 11:40 AM
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Quote:
Originally posted by Z_Fanatic

However, if you remember one of Keith Code's advise, slides actually can help the bike to change the line tighter, with skill, the rider can coax the bike to get the inside line coming out of the corner. And I think this is where the theories collide.

.

Yup, but that's a "Controlled" slide, which would be different than what's being discussed. That's not to say, that in that sistuation, things can, and do go wrong.

As a rule, slides are broken up into a few different catagories...Slid upon entering a turn, sliding around the apex, and sliding at the exit, oh then there's the point where you slide because your on that Fine line of traction i.e. lean angle, which unlike the apex, and exit are controlled by the gas, although I suppose you could get ham fisted anywhere in a turn and go down, these are just general guidelines.

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post #7 of 16 (permalink) Old 01-29-2006, 01:15 PM
 
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Controlled power sliding is so different to where the rear wheel as started to slide & spin to where the rear wheel is trying to catch up with the front, you drop the throttle, not realizing it was to drastic a drop, the bike stands up & both of you are into a high side.

In dirty power sliding is so common & a MUST in flat tracking otherwise you will not make the bend, still get on the high side of the track & not the bead we like to slide on and then you are in trouble, though some can ride the high side to get around you.

MXing is also often sliding the rear wheel, to extreme of where the bike almost wants to scoot to the extreme left or extreme right & that is when you ease off the throttle a bit to regain control & still stay on the bend of the track ONLY sometimes you have a competitor that sees this drop in speed, to regain control, & will take advantage of that pause in pace of the competitor in front of them. I use to do this often in pushing a rider to make said errors or in some cases I would realize he was going to take the high part of the burm, so I would go for the lower side & pass him. Same if a road racer or flat tracker takes a bit more outside the turn & if a competitor had planned on it he would take the lower or inside of the bend.

Also some of the riders can square off the bend & Duhammel was great in doing this so that means power sliding into the turn & do a bit of a trot across the bend to power slide again. Or he would take the outside & power slide into the turn to straighten out & squirt down the bit of the straight.

Any of the above is NOT for twisties or normal road riding. All is in the matter of competition with all riders going in the same direction so no matter what if there is an error one can only go down & not have to worry about oncomming traffic. Plus most competitors behind you can avoid hitting you or your downed bike, but then not always if they are to close.

Well do I remember when we got MXing restarted in the 70s we had chaps from all over B.C., coming to compete, I was still riding Greeves 250 & noted an ex-aggressive rider was not riding & his son was racing that CZ-250. Sure enough he rode just like his Dad & I was having trouble staying in front of him, still I thought "okay I will slide out fo this bend to keep the rear end sliding as I "hot footted" (like flat tracking) it to the next bend & let him try to pass me on the outside if he is a sucker". Sure enough he did & failed to notice my r/wheel was close to the ribbon of the track, he breaks the ribbon in attempt to get by me in this almost uncontrolled rear wheel slide & bam he hits the tree while I eased off the thorttle a the next bend to regain traction.

Later we were waiting for an ambulance for poor Stan had busted his leg on that tree & Pete, his dad, had warned him to not play around with that Smith on the ONLY Greeves for he would play it dirty. I felt bad about Stan busting his leg & was into the hospital to visit him before he was transferred to the west & he simply laughed it off as a good lesson he learned the hard way. Like later on we often ran into each other with him riding Suzy & I would be on a Bultaco. We both knew each other played it rough & took chances, but that is m/c comp for you.

Last edited by Smitty; 01-29-2006 at 01:22 PM.
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post #8 of 16 (permalink) Old 01-29-2006, 01:30 PM
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the highside happens when you chop the trottle in a lowside and get traction again, it can also happen if you stay with the throttle and get traction again, the suspension compresses while you are in the slide and shoots you off the bike like a catapult when the bike stands up.
A little too much rebound dampening in the rear can help save you from a highside.

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Last edited by Fatman; 01-29-2006 at 01:37 PM.
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post #9 of 16 (permalink) Old 01-29-2006, 03:28 PM Thread Starter
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Quote:
Originally posted by Fatman
it can also happen if you stay with the throttle and get traction again,
Right, and I think this is what happend to me. Anyhow, so how do professional riders prevent getting the second traction or maintain the slide and go for positive traction? Since even being on the throttle, this could happen. I understand it's not always possible to have it your way, but I would say the odds are on rider's side if he knows what he's doing, as Hammer mentioned, 4 strokes power curves are much nicer.
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post #10 of 16 (permalink) Old 01-29-2006, 03:34 PM
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Quote:
Originally posted by Z_Fanatic
...how do professional riders prevent getting the second traction or maintain the slide and go for positive traction?...
Experience certainly works in their favour.

Remember, though, there's many a pro who's been highsided in his life.




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