I have a 25' table top for my son to practice on in our yard...it's about 3-4' high...what should the take-off and landing ramp measurments be? He can only seem to get about halfway to the top of the table after jumping off the takeoff I have now rather than clearing it and landing on the landing ramp? Do I need to make it steeper, longer, shorter etc???
Tabletop dimensions
- Thread starter p411m
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High Lord Gomer
Poked with Sticks
- Sep 26, 1999
- 11,788
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The danger of making it steeper is that it may kick him too much. If a jump is both short enough and steep enough, it is possible that the front tire may already be in the air by the time the rear tire hits the takeoff incline. That setup would throw the rear up/front down violently.
Especially if he's learning, I would not go any steeper than 30 degrees. That would be a takeoff incline 8 feet long and 4 feet high.
Any chance he just needs better form or more speed to clear it? Is he accelerating all the way up the jump and into the air, or is he backing off and coasting any of it?
Especially if he's learning, I would not go any steeper than 30 degrees. That would be a takeoff incline 8 feet long and 4 feet high.
Any chance he just needs better form or more speed to clear it? Is he accelerating all the way up the jump and into the air, or is he backing off and coasting any of it?
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- #3
He is finally getting used to using steady speed up the face of the jump rather than trying to blip the throttle at the end of it which I think is good correct? I probably need to teach him to push down on the pegs and bars on the way up and pull up when he is ready to take off to get a further launch correct?
High Lord Gomer
Poked with Sticks
- Sep 26, 1999
- 11,788
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Not really. The BMX style jump is not usually needed and while learning, it is better that he work on body position and throttle control more than trying to horse the bike around.
BTW, he should have steady acceleration, not just steady speed while hitting a jump. As the front of the bike rises when he hits the face of the jump, the natural reaction is to lean forward more so that your body is still vertical. Most beginners, when they front rises and they lean forward, they also roll the throttle forward and lose drive going up the jump.
Also, what bike? Any pictures/video of him hitting it?
BTW, he should have steady acceleration, not just steady speed while hitting a jump. As the front of the bike rises when he hits the face of the jump, the natural reaction is to lean forward more so that your body is still vertical. Most beginners, when they front rises and they lean forward, they also roll the throttle forward and lose drive going up the jump.
Also, what bike? Any pictures/video of him hitting it?
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- #5
He has a kx65...I have a intake spacer and fender washer between the exhaust and head right now to tame down the powerband...don't have a pic of him up the tabletop yet but here is a old one of a jump before I made it a tabletop...does it help? where should his body position be?
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High Lord Gomer
Poked with Sticks
- Sep 26, 1999
- 11,788
- 35
The harder you are on the gas, the farther forward you need to be to balance that out. When coasting, or just crusing, over a jump, you need to be farther back to counteract the kick that the rear end will take once the front tire leaves the ground. The fact that he is fairly far back implies he's just cruising over it and not accelerating all the way up the jump.
It might be possible for him to clear that jump hard on the gas (not just at a high RPM, but rather with a high amount of acceleration) in 2nd gear, while cruising over it while merely maintaining speed might require going twice as fast in 4th gear.
There are times and places for both approaches. If the jump is right out of a corner, you need to be able to accelerate hard all the way up the jump to make it. If the jump is in the middle of a long straight where you have more speed than you need/want to easily clear it, you want to be able to maintain your speed while staying as low as possible and not overjumping it (if that would hurt).
It might be possible for him to clear that jump hard on the gas (not just at a high RPM, but rather with a high amount of acceleration) in 2nd gear, while cruising over it while merely maintaining speed might require going twice as fast in 4th gear.
There are times and places for both approaches. If the jump is right out of a corner, you need to be able to accelerate hard all the way up the jump to make it. If the jump is in the middle of a long straight where you have more speed than you need/want to easily clear it, you want to be able to maintain your speed while staying as low as possible and not overjumping it (if that would hurt).
