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Motorcycle Forum / General / Off-road / September 2008Anyone ever hit a ramp to flat(ish)? Also, suspension and other Q's
I am just finishing up construction of a 4' backyard ramp. It's not much, but something to tool around on and work on technique. So I was talking to my riding buddy last night about the landing, and he suggested that we may want to hit it a few times before building a landing so we know how it's going to throw us, and how steep of a landing we want. My original plan was to build a landing 4' high, same as the jump, and 10' long. Figured I may attach a 2' flat section at the front of the landing to cover coming up a tad short, but it would be an add-on since I've already got the PT 2x4 10's. My buddy was suggesting that since the ramp has a bit of curve/kick to it, we may be going higher than farther, so maybe we'd want the 2' flat on the same 10' run, making an 8' long landing ramp, which would be a bit steeper. Seems the best way to figure this out is to hit the ramp and see how it throws us. I'm concerned about landing flat from it (there's a slight hill we could use in the yard, but nothing noteworthy). My buddy figures we do drops substantially higher than that, have landed flat from substantially higher than that, and it'll be fine. I'm concerned that with the steepness of the ramp we'll be coming down a lot harder than we're used to, and don't want to blow out the suspension on either of our bikes. I've got an 02 KX125 with Pro Action suspension, my buddy rides a stock 02 CR 250. He's also got access to a fully worked YZ250. He's also a much better rider than I am. Am I over thinking this? Should we just hit the thing? Since that's probably what we're going to do anyway, any suggestions for how to set the suspension to minimize damage potential? My bike is 3-stage fully adjustable rear with revalved and adjustable forks. Finally, the only thing that's left for the takeoff is to attach the plywood. I was going to layer up a few sheets of 1/4", offsetting the direction/grain each layer. Now I'm wondering if the stuff is just too thin, and if I shouldn't put a layer of 3/8 on top of the first couple layers of 1/4". I don't think we'll be able to bend anything more than 3/8 to the curve of the ramp. The landing will be 3/4", since it won't be curved. Thanks, Dan I have zero advice to offer on anything involving more than 6" of air. However, I do have one request: please post videos of the experiment. :-O -Jeff- On Sep 5, 10:33 am, "HellSickle" <jldnospamee...@comcast.spammer.net> wrote: > I have zero advice to offer on anything involving more than 6" of air. > > However, I do have one request: please post videos of the experiment. :-O > > -Jeff- Trail riders... pffftttt;) Anyway, the only advice I would offer is to building the ramps. In boatbuilding, I have peers who use hot steaming blankets over plywood to assist in bending. However, to do it right, you would layer plywood, epoxy, fiberglass, epoxy, plywood.. The best way to form it would be to build a jig and use a simple vacume bag to hold the pieces in place while the epoxy cures.. It is a lot of work to laminate properly, but if you are up to it, email me, much easier to discuss by phone. I am not saying you need to do all this, but otherwise you need to get your structure under the plywood. If you hit the ply right without proper structure, your front end could poke right through it, you can imagine the rest....;) On Sep 5, 10:54 am, justwaitafrekinmin...@gmail.com wrote: > On Sep 5, 10:33 am, "HellSickle" <jldnospamee...@comcast.spammer.net> > wrote: [quoted text clipped - 18 lines] > without proper structure, your front end could poke right through it, > you can imagine the rest....;) I appreciate the advice, but that's more work that I want to put into a first time ramp. There's plenty of structure, and I'm going to have a few layers of plywood. Should be solid enough, and we'll test it incrementally. I must admit some fiberglass between layers of plywood does sound tempting (i'm a boater myself, raised on older boats that always required glasswork). If our initial tests prove sketchy maybe I'll throw some fiberglass in there. construction adhesive and a notched trowel? > construction adhesive and a notched trowel? I'm lost - what's this a suggestion for? > construction adhesive and a notched trowel? I'm lost - what's this a suggestion for? **** Sorry. Adhesive between the layers of bent plywood to bond them together, adding strength without too much fuss. I imagine you are screwing the plywood (not nailing) so the screws will also provide ample clamping action for the glue. >> construction adhesive and a notched trowel? > [quoted text clipped - 7 lines] > (not nailing) so the screws will also provide ample clamping action for > the glue. Oh, and the notched trowel just meters out a nice even application of adhesive so you get even strength across the surface, rather than point loads that would be carried by screws alone. > >> construction adhesive and a notched trowel? > [quoted text clipped - 11 lines] > adhesive so you get even strength across the surface, rather than point > loads that would be carried by screws alone. Gotcha. Good idea - I just may do that. You're correct that I'll be screwing the plywood, as I did everything else. Of course, that would make disassembly to replace the decking a major PITA - with the framework made of PT I expect that to live a lot longer than the plywood. Food for thought anyway. On Sep 5, 2:58 pm, "Dean H." <m...@groove.calm> wrote: > >> construction adhesive and a notched trowel? > [quoted text clipped - 12 lines] > adhesive so you get even strength across the surface, rather than point > loads that would be carried by screws alone. >Gotcha. Good idea - I just may do that. You're correct that I'll be >screwing the plywood, as I did everything else. Of course, that would >make disassembly to replace the decking a major PITA - with the >framework made of PT I expect that to live a lot longer than the >plywood. Food for thought anyway. Just screw only the perimeter of the first sheet of plywood, (1/4" should conform to the shape very well....then apply glue and screw the heck outta the top sheet (through both sheets and well into the frame and purlins...obviously). That way come time to remove, you can take out all the center screws, hit the perimeter with a sawzall and it should come off in one piece. All of this is assuming that you don't glue the first sheet to the frame and purlins :-). Oh, and some water preservative would help the longevity of the plywood, but has a tendency to get a little slick when damp....if you go that route, mix some sand into the sealer to help with grip. KW Sorry if this is a double - good old IE just crashed on me. Anyway, the ramp doesn't look as steep now that it's got a couple sheets of plywood on it - hitting it to flat a couple times shouldn't be an issue. http://picasaweb.google.com/DanKMTB/Ramp# or http://tinyurl.com/5nr27u Just ran out of hardware (@ 11PM) so I'm done for the night - more screws in the AM, another couple sheets of plywood, a little transition to get up to the start of it (I'm thinking 1 thick piece of plywood with a couple supports under it) and it should be testing time. I'll put some sandy paint down for traction as well, but I'm not sure when - if the weather holds I'll be wanting to ride off it a couple times more than I want to paint it. It can dry while I build a landing. Caution - obsessive perfectionist carpenter killjoy stuff follows: > Sorry if this is a double - good old IE just crashed on me. Anyway, > the ramp doesn't look as steep now that it's got a couple sheets of [quoted text clipped - 10 lines] > couple times more than I want to paint it. It can dry while I build a > landing. I would try to make that triangular bracing into a cross-bracing situation. I would have set the horozontal members on top of the posts not between. Consider getting some "jack" studs under each horizontal member instead.. I would use more fasteners. And I'd inspect the ramp after every couple hits. I would consider a load of dirt instead of lumber for the landing. Have fun. Be careful. Cool project. > Caution - obsessive perfectionist carpenter killjoy stuff follows: > [quoted text clipped - 22 lines] > I would use more fasteners. And I'd inspect the ramp after every couple > hits. Thanks for the suggestions. I'll take them all into consideration, and implement at least some of them. I'll keep the group posted. > I would consider a load of dirt instead of lumber for the landing. I'd like to, but due to location can't. > Have fun. Be careful. Cool project. Will do. Thanks. > issue. http://picasaweb.google.com/DanKMTB/Ramp#orhttp://tinyurl.com/5nr27u That looks almost exactly like the ramp I built, as far as shape and curve - it'll work good, but you WILL be surprised at how far that gentle curve throws you up. OTOH, given how hard my kids (at ~12 y/o) could hit it, you'll be a girlie wuss if you don't hit it tapped in 4th. Of course, you're gonna die on that, right after you punch through the ramp face. You need WAY more support. The 2x4s on the sides don't do much, the plywood on the sides do the work, so you're all set there. Install the plywood on the sides, then flip the ramp over and install additional 2x4s on the back of the ramp face between your existing supports. I'd go at least 2 extra supports per existing space. That'll only take 4 more 2x4s - it'll be the best $10 you ever spent. You don't need any more the 2x4s that go down the sides - just put the 2x4 in place across the ramp, them nail/screw them through the side plywood. Screw across the ramp face, and that'll do it. JayC > > issue. http://picasaweb.google.com/DanKMTB/Ramp#orhttp://tinyurl.com/5nr27u > [quoted text clipped - 3 lines] > could hit it, you'll be a girlie wuss if you don't hit it tapped in > 4th. We'll get there, I'm sure. I'm thinking a landing will be helpful at those speeds though. > Of course, you're gonna die on that, right after you punch through the > ramp face. You need WAY more support. The 2x4s on the sides don't do [quoted text clipped - 8 lines] > > JayC Thanks for the suggestions. Do you really think I'll punch through 4 1/4" sheets though? We're talking about a whole lot of plywood there. Appreciate the advice, and will take it into consideration. This whole thing is a learning curve, I never really expected to get it all right on the first try. I would like to live for a second try though. In article <da377327-74c5-4872-b97c-9475293883ae@25g2000hsx.googlegroups.com>, > Thanks for the suggestions. Do you really think I'll punch through 4 > 1/4" sheets though? If they aren't sufficiently laminated to act as a single 1" thick sheet of plywood, then yes, you'll punch through. It also depends on what's directly behind the impact--if it's support framing, sufficiently braced you'll be fine. The plywood is acting as a beam whose length is the distance from your tire to the nearest support times 2, sort of. The closer the support framing, the more load the plywood can withstand. The best situation would be to put enough support in the center so that your riding line is directly over the supports, which puts the plywood "beam" length to zero, and gives it approximately the same beam strength as superman. I think it was JayC who mentioned that the support frame should be your ramp, and the plywood is just the surface that holds the supports together. Good luck.  SignatureCharles '99 YZ250 > > construction adhesive and a notched trowel? > [quoted text clipped - 6 lines] > strength without too much fuss. I imagine you are screwing the plywood (not > nailing) so the screws will also provide ample clamping action for the glue. Construction adhesive w/ a trowel, no. Been there, done that - disaster in the making. If you want to stick the two sides together, use one of the floor adhesives that they use for linoleum. JayC On Sep 5, 10:33 am, "HellSickle" <jldnospamee...@comcast.spammer.net> wrote: > I have zero advice to offer on anything involving more than 6" of air. > > However, I do have one request: please post videos of the experiment. :-O > > -Jeff- heh... I'll see what I can do. I don't have access to anything with decent video quality, but it might be enough for a laugh. >I have zero advice to offer on anything involving more than 6" of air. When did you get 6" of air? I was watching CHiPs the other night... an episode called Super Cycle that had Bud Ekins in it. The theory was they had to catch a "daredevil" played by Rex Blackwell (jumps... not the acting). They had a ramp set up at a track where they took a KZP off a 2.5' jump and somehow managed to look good doing it, but who knows how many takes/bikes they went through. Right before the jump, they actually wheelied the KZP... not far, but a longer wheelie than the bottom half of the people (like me) reading this ever pull off. Actually, in that episode there was a nice off road chase that involved a dirtbike and a KZP. I ride mine in the dirt all the time but don't have the stones to do the stuff they do (I assume it was Bud Ekins or JN Roberts... Roberts supposedly specialized in off-road stunts with big bikes and was tied into the Rosner and Webb productions teams). You've got mail (last night or the night before) Mike -- Mike W. 96 XR400 70 CT70 71 KG 100 (Hodaka-powered) 99 KZ1000P (training) 99 KZ1000P (rider) 00 Beta Rev-3 > On Fri, 5 Sep 2008 08:33:27 -0600, "HellSickle" > [quoted text clipped - 28 lines] > 99 KZ1000P (rider) > 00 Beta Rev-3 They still run Chips reruns? What channel? When? That was one of my favorite shows growing up. >They still run Chips reruns? What channel? When? That was one of my >favorite shows growing up. TVLand was playing them at 430am for a while, but I watch them on DVD's now. Season 1 and 2 are out so far. Mike -- Mike W. 96 XR400 70 CT70 71 KG 100 (Hodaka-powered) 99 KZ1000P (training) 99 KZ1000P (rider) 00 Beta Rev-3 > On Fri, 5 Sep 2008 11:03:30 -0700 (PDT), "DanK...@gmail.com" > [quoted text clipped - 16 lines] > 99 KZ1000P (rider) > 00 Beta Rev-3 Cool. I'll have to check that out. > I was watching CHiPs the other night... an episode called Super Cycle that > had Bud Ekins in it. The theory was they had to catch a "daredevil" played [quoted text clipped - 8 lines] > JN Roberts... Roberts supposedly specialized in off-road stunts with big > bikes and was tied into the Rosner and Webb productions teams). I remember that episode vaguely. Didn't they set Jon up with a hot rod bike to chase the Super Cycle? I have a fairly clear memory of a broadslide under a semi-trailer that I'm pretty sure was from that same episode. You know, Ponch and Jon would've caught Bo and Luke easily. Just saying. Craig >> I was watching CHiPs the other night... an episode called Super Cycle that >> had Bud Ekins in it. Just watched 'Black Moon Rising", wherein BE did stunts -- probably in a car since I didn't see any motorcycles except the one in Linda Hamilton's apartment. > You know, Ponch and Jon would've caught Bo and Luke easily. Just > saying. "Nice bike. Mind if I kick it over?" SignatureCheers, Bev /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ When cryptography is outlawed, only outlaws will qwertzuio asdfghjk pyxcvbnml -- M. O'Dorney >> I was watching CHiPs the other night... an episode called Super Cycle that >> had Bud Ekins in it. The theory was they had to catch a "daredevil" played [quoted text clipped - 13 lines] >broadslide under a semi-trailer that I'm pretty sure was from that >same episode. Sorta, yes... Ponch was the rider of the supercycle which supposedly had a supercharged engine and off-road suspension. Off-road suspension... my own personal dream there. I could be wrong but I don't think the slide under the truck was that episode, though I've seen that too. Mostly, I'm watching the real CHP guys in the long-distance shots though I have to say Wilcox was paying attention when they showed him how to ride. Mike >You know, Ponch and Jon would've caught Bo and Luke easily. Just >saying. > >Craig -- Mike W. 96 XR400 70 CT70 71 KG 100 (Hodaka-powered) 99 KZ1000P (training) 99 KZ1000P (rider) 00 Beta Rev-3 On Sep 5, 10:33 am, "HellSickle" <jldnospamee...@comcast.spammer.net> wrote: > I have zero advice to offer on anything involving more than 6" of air. > > However, I do have one request: please post videos of the experiment. :-O > > -Jeff- Yes, please video the trial run. When I first read this I had visions of Napoleon hitting that sweet jump. DaveB On Sep 5, 10:58 am, "DanK...@gmail.com" <DanK...@gmail.com> wrote: > I am just finishing up construction of a 4' backyard ramp. > Should we just hit the thing? I've jumped higher than 4ft to land on flat, with suspension much worse than yours. Start slow, you should be fine. If you have fully adjustable suspension you might want then stiffer for jumping than for trail riding. Make sure your ramp is strong enough for you+bike+impact from bike coming with speed, you do not want it to collapse when you are on it. btdt... -- tiago > On Sep 5, 10:58 am, "DanK...@gmail.com" <DanK...@gmail.com> wrote: > [quoted text clipped - 9 lines] > > -- tiago Thanks. We'll def. start slow, and I will set the suspension to stiffer than normal - although it's already set fairly stiff. This bike has only been "trail riding" a couple times - it's life has consisted of MX & pit riding (which, with me, means mainly jumping and watching other people jump, off whatever we can make into a jump). On Sep 5, 9:58 am, "DanK...@gmail.com" <DanK...@gmail.com> wrote: > I am just finishing up construction of a 4' backyard ramp. It's not > much, but something to tool around on and work on technique. So I was [quoted text clipped - 40 lines] > > Dan The best piece of advice I can give you is that anything with 'older' suspension will get mainly height off of a kicker ramp, where newer bikes absorb the 'kick' and get fair distance off the same ramp (well, that's why they had to make kicker ramps in the 1st place). A woods bike with soft suspension may bottom on a kicker, with unpredictable results. Dave > On Sep 5, 9:58 am, "DanK...@gmail.com" <DanK...@gmail.com> wrote: > [quoted text clipped - 54 lines] > > - Show quoted text - My buddies bike is def. set up for woods riding, where mine's set up for pit riding. Guess we just figured out who's going first. Damn... I was really hoping to watch his form and throttle to get a better idea how to do this, since he's better. Maybe I can get him to bring down the YZ... Just hit it. I built something similar a while back for my kids. It was a curved- face kicker-type ramp that (I think) was about 3' high and 6' front to back. I used 3/4" plywood for the sides and back, and a single sheet of 1/2" for the face. They beat it to death for years before it finally bit the dust and became fire-pit fodder. It was originally a skateboard/bicycle ramp, but quickly progressed to motorcycle use. I even jumped my XR400 over it a bunch of times - it threw me up pretty high, so it made for a rough landing on the flat. My son would set it up on the lawn, and launch down a ~6ft. embankment that ended at my driveway. If he hit it fast enough, he'd get the 25' of horizontal distance to clear the entire embankment and land flat on the driveway. I still can't figure out why his XR80 didn't break in half. You need to provide ample reinforcement under the plywood to resist punching through. This is more important than thickness - think of the plywood as something to smooth out the support spars, not something to bear the load. You should construct your ramp so that you could ride up it easily with NO plywood (so it looks like the inside of a barrel) - of course, the plywood also keeps the thing from racking and falling down, so you wouldn't REALLY do that. Place your support spars no more than 6" apart, the put the plywood on - a 1/2" sheet is plenty. Plywood already has alternating grain, so you don't really need to worry about grain direction, but placing the sheet longwise (going up the ramp) is best. You can layer multiple sheets to get a smoother curve, and I'd recommend that. Two 3/8" sheets will be plenty. JayC > Just hit it. > [quoted text clipped - 3 lines] > of 1/2" for the face. They beat it to death for years before it > finally bit the dust and became fire-pit fodder. This is 4' high, and about 8' long. It's a scaled down version of the Aussie FMX ramp. Gets kinda steep toward the top. That's what concerns me - if it were more of a flat distance-type thing I wouldn't think twice, but this one is going to send me upward, and what goes up must come down. I didn't think I'd be able to bend 1/2" enough to make the curve, so I bought a few sheets of 1/4" and plan on layering up. My framework is all 2x4. I've build BMX ramps using the plywood sides, but didn't think it would be strong enough for the abuse of 400ish lbs at speed over and over again. > It was originally a skateboard/bicycle ramp, but quickly progressed to > motorcycle use. I even jumped my XR400 over it a bunch of times - it [quoted text clipped - 4 lines] > the driveway. I still can't figure out why his XR80 didn't break in > half. Heh... sounds like fun. 25' to flat is awful harsh - what did he have for suspension on that XR? I'm guessing low overall weight helped (him+bike). > You need to provide ample reinforcement under the plywood to resist > punching through. This is more important than thickness - think of [quoted text clipped - 11 lines] > > JayC Thanks for the reccomendation. Since I've already got the 1/4 I think I'll just use 2 or 3 layers of that. There are a bunch of spars going across, but not quite as close as 6". here's a *very* rough idea of what I've built so far, since i'm short on time and going from memory. All lines represent 2x4s. http://picasaweb.google.com/DanKMTB/Ramp#5242596454690476930 or http://tinyurl.com/659qwg I think it's safe to say "overkill" was the theme here. If I had strong enough decking and a second ramp I could drive a truck up this thing. It may end up seeing quad and sled use as well. (yeah, i've got a few friends with quads - can't seem to convert them). I wish I'd brought it up here before I built it. I really didn't think the plywood sides with 2x4 spars would be strong enough for extended dirt bike use, which is why I overbuilt this thing like I did. I'm familiar with the technique for BMX use. Oh well... at least I know it's not going anywhere. Dan > My original plan was to build a landing 4' high, same as the jump, and > 10' long. Figured I may attach a 2' flat section at the front of the > landing to cover coming up a tad short, but it would be an add-on > since I've already got the PT 2x4 10's. My buddy was suggesting that > since the ramp has a bit of curve/kick to it, we may be going higher You're on the wrong track here. The 2x4s go across the ramp face, not down it. This will show some of the basics of ramp design: http://www.rickdahlen.com/hpplans/Halfpipe.pdf JayC > > My original plan was to build a landing 4' high, same as the jump, and > > 10' long. Figured I may attach a 2' flat section at the front of the [quoted text clipped - 10 lines] > > JayC I have them going across it, as well as down it. The 10' length I was referring to is for the sides of the rectangle that sits on the ground, upon which everything else is built. The landing will have 2x4s across the landing face a'plenty, no doubt. After this conversation maybe I'll make the landing more like a BMX ramp, using the principles shown in your link. Something to think about, anyway. > I am just finishing up construction of a 4' backyard ramp. It's not > much, but something to tool around on and work on technique. So I was [quoted text clipped - 40 lines] > > Dan Years ago, while they were building a track for a weekend race they had the plans online to show folks what the track would look like and it had spec's, feet between whoops, height of whoops, etc, thought they had posted the wrong document, might want to google 'mx track buldiing' and bet you could find something............. Reminds me of being 12 and bulding jumps for the honda trail 90, which BTW did not like to jump, the first guy 'Fred', who was crazy went like 20' probably more like 2-5' and landed on the front wheel, bottom line, no one else even tried to jump!] |
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