jumping without throttle

[RM_Dude]

OK so I'm doing pretty well at jumping while on the throttle. I'm confident doing jumps of 50 feet or so 'on the pipe'. My problem is those jumps which have such a large run-up that you need to be completely off the throttle or even on the brakes. The only way I know to jump is accelerating completely off the face. I suppose this is just another thing that requires practice so I intend to work on it within the next few days on a tabletop. Any tips on this subject? The idea of no throttle scares the s**t out of me :scream: but I have to learn this in order to keep up.

How far should I lean back to hold the front up with no throttle, are we talking all the weight you can get on the rear and pull on up on the bars? I ride a 99 RM125 with the classic Suzuki clutch drag so I don't think holding the clutch will eliminate engine braking although it doesn't have much engine braking anyway.

 

[Hucker]

Depending on the jump, I just give the throttle a little *blip* right before the take off. I also ride a Suzuki (be it a older one) and the bike reacts fine in the air. Actaully it reacts better than being on the pipe. When I get hard on the pipe, my front end always likes to come up....

Here's a vid, notice I blip right before the take off. The jumps about 50ft give or take a foot or 2.

http://www.dreamwerx.net/gallery/2001-07-11_DirtBiking_At_Biedas/30foottable2.mpg

The vid is 13.3 meg, so just a warning.....

 

[Jeff Gilbert]

I ride a 01 KTM 125

When racing I have to hit the brakes hard on the face of practically every jump to prevent over jumping at my local track. I even find myself braking up the face of the jump but I always get back on the gas as I approach the end of the face right before I take off. I find it's not much different than being on the gas the whole way up the face except the suspension can react with more of a rebound, I guess from the preload of being on the brakes so hard. (did I make sence?) It's a wierd feeling to be going way too fast and brake so hard up the face and still have enough momentum to clear a jump. Depending if your'e either on the gas or "coasting" over a jump I would definantly be off the brakes before either tire leaves the ground.

 

[Pit_Monkey]

jumpin and a blip of the throttle

i learned how to jump by trial and error, i have a 3 ft jump in my yard and i land flat. i found that when i charge it my back end of my bike bucks up and kinda throws me off the bike and my front suspension takes all the force. but when i go into it fast then roll off and then blip the throttle i launch perfectly and land flat. is this just because of the angle of the take off and because im landing flat or is it body positioning. im racing next year and want to go to a local practice track to train and ive never jumped a real jump ya know like a 50ft double. im wondering if i am supposed to blip the throttle or just hit it wit it WTFO!!! :silly:

 

[Jeff Gilbert]

Re: jumpin and a blip of the throttle

Originally posted by Pit_Monkey
i learned how to jump by trial and error, i have a 3 ft jump in my yard and i land flat. i found that when i charge it my back end of my bike bucks up and kinda throws me off the bike and my front suspension takes all the force. but when i go into it fast then roll off and then blip the throttle i launch perfectly and land flat. is this just because of the angle of the take off and because im landing flat or is it body positioning. im racing next year and want to go to a local practice track to train and ive never jumped a real jump ya know like a 50ft double. im wondering if i am supposed to blip the throttle or just hit it wit it WTFO!!! :silly:

I'm not by any means an expert but I can give you my experiance. 1st of all how you hit the jump would depend several factors,the approach, face, landing and what's after the jump. If your anything like me when you do your 1st few races you will probably have an andrenline rush to help you go a little faster.

For a 50' double I would recommend watching & asking others at your track how they do that particular jump. It may also help if you follow someone over for the 1st time to get a feel for it.

I found in a race situation I tend to go a lot faster than I do in practice so I hit the jumps a lot faster. By the time I'm at the face & realize that I am likely to over jump I brake hard on the face but always back on the gas at the last second enough to launch me over. If it's a big jump you'll have time to relax for a nano second so take advantage of it by staying loose and just flow with the bike, you should have plenty of time to react for correcting a bad fly.
I'm always standing and in the attack position when I jump, I find I have more control by using body english in that position . For certain, if at all possible, be on the gas when you land, this will make your suspension work otherwise you'll bounce like a pogo stick.

 

[KawieKX125]

When a jump has a huge "runway" and it is considerably small, I let off the throttle and use a combo of hard braking and absorbing the lift to land on the landing.
Be warned, we you brake without throttle on a jump, your front wheel will feel like a block of bricks, unless the jump has a large kicker. Just practice slowly until you can do it and then speed it up.

 

[MX823]

Ok so you have a run at the jump and are carrying too much speed. There are things you can do to scrub some of the distance. Suck the bike up with your legs just before take off.This will absorb some of the energy of the shock and also cause the bike to jump lower. While in the air pull in the clutch, give it a little gas and tap the rear brake. If you do this early in the air it will cut down on the trajectory of flight.
If you are used to hitting a jump with gas on up the face you can still approach the jump on the gas and drag your brakes just before the face of the jump then release brakes and motor up the take off.

Practice these techniques first seperatley on a safe, comfortable jump. When you get the hang of them try incorporating two or three together. This should help , but practice, practice, practice.

Important factors are body positioning, the controls [braking and gasing it at the same time] and to practice safely.

Even using a gap 10 or15 feet. You know you can over jump it easily but if you can do correctly it should be no different than one at 30 feet +.
Plus a crash only 5 feet from the ground is easier to take than one from 10 or 15 feet in the air.

 

[KawieKX125]

MX823, according to gary semics, you absorb the lift by sucking the bike into you when the suspension is rebounding, not as it is compressing.

 

[MX823]

Sorry maybe some confusion as to when I call the bike is taking off. Just before the rear wheel is starting to leave the ground. This way by the time you finish lifting your legs the bike will be finshed the rebound stroke.

 

[High Lord Gomer]

MX823: Thanks! There's a lot of good advice in there.

I have a question, though...how will hitting the gas and tapping the brake lower the entire bike? I'm faimilar with using those to change the attitude of the bike in the air, but my meager backgound in high school physics (mostly spend wondering how Mary Lou defied gravity) leads me to believe that once a collection of parts (motorcycle) leaves the ground, any reorientation of those parts shouldn't affect the flight path of the collection as a whole. Does that make any sense?

 

[MX823]

you are right it can not alter the distance completely. But when I know I am coming up a bit long on jump be it a double or table, if I hit the rear brake it pitches the angle of the bike nose down [and rather quickly] instead of a straight flight path ie one that looks like this ------ it looks like--\ [well not so dramatic] the front wheel will hit the ground sooner since it is now a foot to a foot and a half lower.
Again I know it will not stop momentum, but landing 6 inches shorter can make the difference from landing in the flat.


Does it make sense or did I confuse anyone [incl myself] anymore?:think

 

[Jeff Gilbert]

Originally posted by MX823
Does it make sense or did I confuse anyone [incl myself] anymore?:think

I gottcha.

 

[Camstyn]

I can see that working if you had wings.. Unfortunately, wings aren't feasible in a motocross race. This will not make you drop out of the sky, only make you land nose-down.

 

[MX823]

the point I was trying to make was ......what does eveyone do when they are going to overshoot a jump hit the rear brake ....and why......? [besides close your eyes]

 

[High Lord Gomer]

I stay confused...it's nice to be able to blame it on someone else occasionally! :confused:

Personally, if I'm going long I get on the gas so I can take it on the rear.

(Ok guys, I said ON!!)

 

[KTM520Man]

Well since physics has been brought into all of this and I teach high school physics (and use motocross examples all the time) I had to jump in(lol...sorry about the pun). I am probably the last person to give advice about over jumping since you have to be going fast to do it. As others have mentioned before once you have left the face of the jump there is little you can do to alter the trajectory. At least the trajectory of the center of gravity of the system. You and the bike form a system and have one CG. This will always follow a smooth arc in the air and unless a force completely outside the system acts on it the CG will land in one spot no matter what you do. I understand what tapping the rear brake does and that you are trying to get at least part of the motorcyle on the ground quicker. That said I use the gas it and let the rear shock take the hit. If you want to get your bike on the ground faster you can raise yourself up as high as possible on it. This will push your CG higher which will force the bikes CG lower to keep the CG of the whole system in the same place. In an extreme example if you jump off your bike it will land short and you will land long, but if you take the CG of the system it will land in the same place. Sorry to go on and on......just got done teaching this and could help myself.

 

[Jeff Gilbert]

Originally posted by KTM520Man
Well since physics has been brought into all of this and I teach high school physics (and use motocross examples all the time) I had to jump in(lol...sorry about the pun). I am probably the last person to give advice about over jumping since you have to be going fast to do it. As others have mentioned before once you have left the face of the jump there is little you can do to alter the trajectory. At least the trajectory of the center of gravity of the system. You and the bike form a system and have one CG. This will always follow a smooth arc in the air and unless a force completely outside the system acts on it the CG will land in one spot no matter what you do. I understand what tapping the rear brake does and that you are trying to get at least part of the motorcyle on the ground quicker. That said I use the gas it and let the rear shock take the hit. If you want to get your bike on the ground faster you can raise yourself up as high as possible on it. This will push your CG higher which will force the bikes CG lower to keep the CG of the whole system in the same place. In an extreme example if you jump off your bike it will land short and you will land long, but if you take the CG of the system it will land in the same place. Sorry to go on and on......just got done teaching this and could help myself.

Understand but is resistance considered and "outside force" even if the wind is constant? If you were to "whip" the bike sideways after leaving the face of a jump (like some of the more experienced riders than me) the CG would still be the same, correct? This would create more resistance in the air, limiting the "fly time" thus changing the trajectory and shortening the arc however it does change the opposing variable even though the wind is constant.

My example would be to jump off of a cliff holding vertically a sheet of plywood, the plywood and myself would cut throught the air like a knife. If I were to then jump off the same cliff with the same sheet of plywood only this time I was sitting on it, the CG would still be the same only I would reduce the speed of descent by incurring more resistance. I have not changed the CG and have the same propelling force for my examples. My emphasis here is to illustrate that you must consider resistance as variable because you have not changed the center of gravity, yet you will land sooner than you would without increasing resistance. This is of coarse taking into account that wind drag is not considered an outside force since the wind velocity has not changed and it will always be a part of the equation.

Not looking for the great debate here, I would just like to read your thoughts as an educator.:think

 

[High Lord Gomer]

Last weekend I came close to wadding up Ivan's 250F on several occasions because of an appreciable headwind. The first time I jumped the 60' double at the track (1st lap, I should've waited) I got up in the air, the wind hit me, and it felt like I stopped. I cased the landing badly, bounced up on the bars and luckily got it under control enough to go around the next turn instead of over it. The second lap I compensated by staying on the gas harder and ended up with the front end way high.

I think that aerodynamics can play a part, but I doubt I'll ever have the presence of mind nor the ability to get up in the air, realize I'm overjumping, then deliberately whip it sideways to create moe drag. If anything I probably pull myself through the air farther by the large inhalation that follows the realization of impending doom! :scream:

 

[Adrenaline]

How much room do you have to a corner?
If it's very short say 10feet I come into the jump and compress the suspension early enough that it will rebound before the face, This slow's me down most times. Other's I am on the brake's till I am up the face a good way's
Adrenaline

 

[KTM520Man]

Yes wind and air resistance are outside forces, however the air resistance you get moving forward is not going to be changed significantly by the orientation of the bike. To increase air resistance my usual method is to open my mouth wide and scream so I can increase my surface area and get the push back from the breath (equal and opposite and all). In a cross wind it would change as the surface area the wind had to push on would be different. The reason whipping the bike lowers the trajectory is because you are shifting the CG of the system as you go. When you whip the bike to lower trajectory you do it as you leave the face of the jump. When the bike is brought back to verticle the CG still follows the same path it would, but now the bike is completely below it. This lets the tires hit earlier even though the CG has followed the same path. It would be easier to show what happens with some pictures. Hell reading it without picturing what is going on in my mind confuses me, bu if you throw a hammer so it is spinning end over end it spins around the CG. The CG will try and land in the same place no matter what. If the handle of the hammer happens to be going down at the right time though that part of the hammer will hit sooner. As far as wind goes it is an outside force, but if it is constant you still follow a smooth arc, just one that has a sharper drop at the end of the arc. If a gust of wind hits that will really mess things up and make the path you and your bike follow change. Hopefully not too dramatically. On the face of the jump there are tons of factors that can change what happens when you jump, but once in the air all you can do is shift your orientation around the CG or hope that a friendly gust of wind helps save your bacon.:)