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get2bill

Advice for First Tabletop

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Posted (edited)

I have 2 Grandsons that just turned 12 & 13.  Both are fairly new to riding, rode 50's a bit, then TTR 110's and just moved to RM 85's.   They have done no real jumping to speak of so I want something easy and safe but that they can grow into as well.  My land is totally flat and I have a really high water table so no digging down (also not an option for other reasons).  I have access to some good "clay bank run" dirt and I have a opportunity to get a bobcat dude for 1/2 price one time.   

Here's what I've come up with after researching.  I'm thinking a 5' high, 20' long table top. 

From what I've seen a 3:1 ratio for the take off ramp is good for amateur/beginners?   So the take off ramp for a 5" high table would be 15" long.  Does that sound right?  Thoughts/opinions?

For a safe landing, I understand that it should be 2x's the table top length so in this case a 40' landing ramp.  Does that sound right?  Thoughts/opinions?

Total overall jump being 75'long.  (15' ramp, 20' table 40' landing.) 

Not quite sure of proper width so looking for advice there as well.   Thanks!

Edited by get2bill

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40 foot landing is way overkill for a 20 footer 5 feet high. If the landing is 15-20 foot long it would be plenty.

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5 hours ago, dirtdigger617 said:

40 foot landing is way overkill for a 20 footer 5 feet high. If the landing is 15-20 foot long it would be plenty.

That depends on the speed of the jump.

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That depends on the speed of the jump.

You are right, but it’s for a 13 year old who hardly knows how to ride. No use to waste that much dirt on a landing that’s twice as long as the jump. It’s a 5 foot high table top, not the sky shot at Unadilla. When you’re having to buy dirt by the truck load it isn’t cheap.

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To the OP, the best thing you can do is just build the take-off however you want it. Then build however much dirt you are willing to purchase out as far as it will go flat with the take-off. Then when you get 15-20 feet out you can just blend the landing into the top of the table top so that you don’t have some huge lip on the landing if the rider cases it. Then the rider can jump 5 feet or 25 feet and they will be fine

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Posted (edited)

OP, are you wanting to replicate a motocross jump, or build a simple jump?  I built one out of old railroad ties on flat ground.  Buried the entrance end of the ramp into the ground for a smooth transition.  Sometimes you can find ties, or old construction beams for free.  HA! The down side is that the beams aren't as forgiving if you fall on them. .

Edited by Weezer the Geezer

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3 hours ago, dirtdigger617 said:

To the OP, the best thing you can do is just build the take-off however you want it. Then build however much dirt you are willing to purchase out as far as it will go flat with the take-off. Then when you get 15-20 feet out you can just blend the landing into the top of the table top so that you don’t have some huge lip on the landing if the rider cases it. Then the rider can jump 5 feet or 25 feet and they will be fine

I just want to be sure that the angle of the take off is safe but if right speed is applied as they get better over time you could make it to landing .  I had read expert was 2:1 and amateur should be 3:1, that's where I got the 15' take off for a 5' high table.   Any thoughts on safe width for top of table?  Thanks!

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3 hours ago, dirtdigger617 said:


You are right, but it’s for a 13 year old who hardly knows how to ride. No use to waste that much dirt on a landing that’s twice as long as the jump. It’s a 5 foot high table top, not the sky shot at Unadilla. When you’re having to buy dirt by the truck load it isn’t cheap.

I'm OK buying the dirt if I need it.  I really want this to be a safe jump for them now but one that they can grow with a well.  Do you have any thoughts on width of top of table?  I cannot find any info on that.  Thanks!  

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3 hours ago, Weezer the Geezer said:

OP, are you wanting to replicate a motocross jump, or build a simple jump?  I built one out of old railroad ties on flat ground.  Buried the entrance end of the ramp into the ground for a smooth transition.  Sometimes you can find ties, or old construction beams for free.  HA! The down side is that the beams aren't as forgiving if you fall on them. .

I'm looking for a slightly smaller version of a MX table top that has a safe take off and landing but one they will not outgrow in a year or two.  

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Posted (edited)

3:1 is a good starting place, but it doesn’t take into consideration curvature. If you don’t give a 3:1 lip any curvature the entire face will be at 20 degrees from flat. That’s not very steep, there is no curvature that helps you preload your suspension, and as such you would have to go pretty fast to clear it ( unsafe ).

 

Looking at a really poppy jump the last bike length of the jump my be 60 degrees from flat. A 45 degree last bike length will give you the most distance for a given speed ( can clear jumps at a slower speed ). 45 degrees may be a bit steep still so you can come in under 40 degrees.

 

You will want the least curvature on the first 1/3 of the length of the jump face, the most curvature on the 2nd 1/3 of the jump face and a medium amount of curvature the last 1/3 of the jump face.

 

Honestly 20ft is a bit big to be learning on. So what I would do is make it 20ft long, Make the table 10 ft wide, but make it so you can also hit it cross ways and have a 10ft table going across. You could make two different steepness 10ft tables along the length of it.
 

edit: I forgot the landing, I would go 1:4 on the landing and just make sure it’s got a smaller angle from flat then the final bike length of the lip.

Edited by temporarily_locked
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I just want to be sure that the angle of the take off is safe but if right speed is applied as they get better over time you could make it to landing .  I had read expert was 2:1 and amateur should be 3:1, that's where I got the 15' take off for a 5' high table.   Any thoughts on safe width for top of table?  Thanks!

Yeah you’ve got the take off figured out. Just put a little curve in it and you should be good. For the width, on my little track I usually build the jumps 2 bucket widths wide with my skid steer so it works out to be about 14-15 foot wide. Should be plenty, but with a beginner the wider the better probably so just go with whatever is comfortable for you. And honestly man, just don’t overthink it too much. You’re doing the right thing trying to figure everything out but it really just takes a little common sense. Also, if you’re not used to working with dirt, it will really surprise you how much dirt you will use. Building table tops eats up dirt quick.

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20 hours ago, temporarily_locked said:

3:1 is a good starting place, but it doesn’t take into consideration curvature. If you don’t give a 3:1 lip any curvature the entire face will be at 20 degrees from flat. That’s not very steep, there is no curvature that helps you preload your suspension, and as such you would have to go pretty fast to clear it ( unsafe ).

 

Looking at a really poppy jump the last bike length of the jump my be 60 degrees from flat. A 45 degree last bike length will give you the most distance for a given speed ( can clear jumps at a slower speed ). 45 degrees may be a bit steep still so you can come in under 40 degrees.

 

You will want the least curvature on the first 1/3 of the length of the jump face, the most curvature on the 2nd 1/3 of the jump face and a medium amount of curvature the last 1/3 of the jump face.

 

Honestly 20ft is a bit big to be learning on. So what I would do is make it 20ft long, Make the table 10 ft wide, but make it so you can also hit it cross ways and have a 10ft table going across. You could make two different steepness 10ft tables along the length of it.
 

edit: I forgot the landing, I would go 1:4 on the landing and just make sure it’s got a smaller angle from flat then the final bike length of the lip.

Thanks very much!  My layout doesn't give me an option of riding cross ways (I have enough width in this section for 2 nice parallel lanes only with a safety  space in between) but that would have been nice. 

My thinking on the 20' top length was that initially they would land somewhere on the actual top and they would work up to landing on the actual down ramp over time as they grew into it (hence their growing into the jump all the while being pretty safe landing on a 5' high top).  So no expectation of them hitting the down ramp on day one but I wanted to maximize the machine time opportunity I have.  Regarding your "... 20' being a bit big..."  do you feel that would approach would be unsafe in some way or just overkill for their current skill? 

I should also say they ride pretty well, blast through tight trails in the woods pretty well on a hopped up 140.  They just have no experience with actual jumps (completely flat terrain except a couple small mound humps they jump 3-4' or so on).  Again, I really do appreciate it I want these guys to develop while being reasonably safe and maximize my machine time opportunity.   

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Posted (edited)
6 hours ago, get2bill said:

Thanks very much!  My layout doesn't give me an option of riding cross ways (I have enough width in this section for 2 nice parallel lanes only with a safety  space in between) but that would have been nice. 

My thinking on the 20' top length was that initially they would land somewhere on the actual top and they would work up to landing on the actual down ramp over time as they grew into it (hence their growing into the jump all the while being pretty safe landing on a 5' high top).  So no expectation of them hitting the down ramp on day one but I wanted to maximize the machine time opportunity I have.  Regarding your "... 20' being a bit big..."  do you feel that would approach would be unsafe in some way or just overkill for their current skill? 

I should also say they ride pretty well, blast through tight trails in the woods pretty well on a hopped up 140.  They just have no experience with actual jumps (completely flat terrain except a couple small mound humps they jump 3-4' or so on).  Again, I really do appreciate it I want these guys to develop while being reasonably safe and maximize my machine time opportunity.   

Yes, it’s a bit big meaning I’d be surprised if they clear it the first day. But that is what you are going for. It sounds very safe. And if they do start clearing it surprisingly fast, a few hours with some shovels and they can make it more poppy. 
the big difference between moto jumps and trail jumps is when downsiding a moto jump you land front wheel first (closer to front wheel first). As they are learning to jump it to flat have them play around with landing front wheel first. It helps bridge the gap from just yanking back like you do on trail jumps to cleanly downsiding a jump with a landing.

Edited by temporarily_locked

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Posted (edited)

Figure out at what speed youl be hitting the jumps.  Remember you need to gain all your speed prior to reaching jump unless its out of a corner. If they jump roll up and roll on they wont learn much. I'd go atleast 6 or 7 feet and taper the backside out at least 40 feet. This will help them attack and learn how to keep the bike low. Just make a smooth face not lipped out. Youl figure it out with them hitting it. 

Edited by 777654321

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On 1/7/2020 at 7:34 PM, temporarily_locked said:

Yes, it’s a bit big meaning I’d be surprised if they clear it the first day. But that is what you are going for. It sounds very safe. And if they do start clearing it surprisingly fast, a few hours with some shovels and they can make it more poppy. 
the big difference between moto jumps and trail jumps is when downsiding a moto jump you land front wheel first (closer to front wheel first). As they are learning to jump it to flat have them play around with landing front wheel first. It helps bridge the gap from just yanking back like you do on trail jumps to cleanly downsiding a jump with a landing.

thanks, great advice!

 

On 1/8/2020 at 7:22 PM, DEATH_INC. said:

Make sure the top rolls off into the landing, don't make it an abrupt change in angle, that way there's no chance of 'casing' if they come up a bit short.

will do!

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No track near by? Seems like a lot of effort for them to learn one jump. A big part of getting comfortable (and rounding skills) is variety. 2 cents from the peanut gallery. One thing I know is kids figure it out better than us old dudes. Good luck

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