Fatty’s Teeter Status Report
Stuff gets in my head. And once stuff gets in my head, it tends to displace pretty much everything else. Which is my way of saying that once I decided I really would make a mountain bike teeter, that’s been the focal point of my existence.
And I’m having a lot of fun building it.
Change In Plans
You know, nobody says they’re a big fan of designing by committee, so how come so many things get designed by committee? In the case of my teeter, the committee started designing because I asked them to. So, uh, my mistake. I’m pretty much going with my design, in spite of the dire predictions handed down by Very Experienced and Knowledgeable People.
That said, I have made some changes to the design. Specifically:
- I made the base wider: At 48" wide, the base is now nearly square.
- I made the pillar shorter: I really liked the idea of having three levels for the teeter, but realized as I was looking down at my feet while riding: the lateral distance between the outsides of my feet may well be more than 15.5". So when set at the lowest level for beginners, beginners wouldn’t ride it anyway, because the pillars in the center would be in the way. So I went with 36" pillars and two levels. This is still a plenty steep ramp, and when set at the lower level, the pillar will only be an inch or two above the level of the ramp — lower than the pedals ever get.
- I beveled the ends of the ramp: Actually, I always planned to do this, but the plan reflects that now.
If you’re interested in downloading and viewing this design in its 3D glory using Google’s free "Sketchup" 3D design program, you can see it from any angle, zoom in, and so forth. Click on the picture below to go to the page where you can download this diagram.
Getting to Work
I generally have a strange reaction to building stuff: I get stressed out, nervous, and very, very snippy. This hasn’t happened while building the teeter. I think it’s because I had already designed and built it on paper, so wasn’t as worried that when I started working on it, I’d discover there was a fundamental problem with my idea.
So planning before building has its benefits. Who’d have imagined?
Also, I’m not building this for anyone, and I don’t have a deadline. It’s just for me. So if it turns out to be a total disaster, I make kindling, and nobody’s the wiser. (Except all of you Fat Cyclist readers, who are going to have fun at my expense whether this thing turns out perfectly or horribly, horribly wrong, so what’s the difference?)
So yesterday I got Gary (everyone should have at least one friend with a truck) to give me a ride to Home Depot to pick up materials, and then my son and I got to work.
You know what happens if you use a table saw to cut out four different notches in the 4" x 4" posts you’re using as the base a saw-blade-width at a time? Two things:
- Your forearms get tired from pushing the board over the blade hundreds of times.
- You finally get over that terror of the table saw you’ve had your whole life.
Cutting a 45-degree angle with a table saw isn’t easy, either. My next tool purchase is definitely a miter saw.
You know what’s mysterious? It’s mysterious that a 3/4" pipe won’t fit through a whole drilled by a 1" bit. Which means I made a trip to the hardware store for a 1 1/4" bit, through which the pipe fits kind of loosely. So I drilled a hole with the 1 1/4" bit through an extra piece of wood, which I’m going to take to Home Depot and see if a 1" pipe fits through. I figure a snugger fit is better.
Here are all the pieces, laid out and ready to assemble.
And now here’s the completed base, 2/3 of a 5lb box of wood screws later:
And a view from a little higher above:
You can see that wherever it made sense, I used metal brackets to reinforce where the wood’s joined. Also, I’m very pleased with my idea of using an elbow and short section of pipe at each end of the pivot. The short section of pipe is used as a handle, making it easy to twist the elbow section on and off for when you want to move the ramp up or down.
This sucker’s heavy. I can move it myself, but not easily. And feels sturdy, too. Though I’m sure it’ll collapse into splinters as soon as I take it outside.
What’s Next?
Now my son and I need to build the ramp. That’s going to be a lot of work: Measure, cut, and drill ~30 slats, then glue and screw them onto the top of the 2"x6"x12′ boards. We might finish tonight, but will more likely finish tomorrow.
And then it’s teeter riding time. Anyone want to come try it out?
PS: One more question for the committee: I want the ramp to always come down on one side, so it’s resting firmly in place as you approach, then goes back down to its original position once you get off the ramp. I figure an easy way to do that is to have the pivot point of the ramp off-center. Right now, I’m figuring 4" off sounds about right, but that’s arbitrary. Any thoughts on how far from the middle of the ramp the hole ought to go?
Comment by Zed | 10.5.2006 | 6:43 pm
Sorry, I’m still not an engineer, but I did want to say that it’s looking even cooler with real wood than it did in your diagram. Not to mention solid. Those steel bracings actually look pretty reassuring (as in, I don’t think it’s going to turn to kindling anytime soon).
So you are going to let us know where you plant this thing, right?
Comment by Fat Cyclist | 10.5.2006 | 7:21 pm
caloi – yep, i’ll definitely announce where this eventually winds up, if it doesn’t wind up staying at home. i don’t really want to keep it at home; it wouldn’t get nearly as much use as if it goes somewhere everyone can use it. meanwhile, though, you’re welcome to swing by anytime and try it out.
Comment by Kevin | 10.5.2006 | 7:32 pm
I’d put the pivot point where it makes the best/most exciting riding experience–then if the teeter doesn’t return correctly, use weights to ensure it does.
Comment by EricGu | 10.5.2006 | 7:42 pm
Use weight at one end to make it come back down. A lot easier than moving the pivot, and it’s tunable.
Not overjoyed with the lateral bracing on support – it’s too easy for the whole frame to deform to the right or left. If you turn it over and put in at least one brace from the spot where the upright attaches to the cross piece over to the other side at the top of the A, you would get some good strength.
I also don’t like the reliance on the strenght of screws – their tensile strength isn’t that high. I would bet that if you overload it, you’re going to rip the joints apart really quickly. I’d like to see some bolts and/or lag screws. If I had to do it at one spot, I’d do it where the upright and the angled braces come together. Get some real strength there, and it’s much harder for the other joints to deform.
Oh, and getting over your terror of that table saw can be a bad thing…
What are you using for the slats?
Comment by Fat Cyclist | 10.5.2006 | 8:01 pm
kevin – i figure 3" from the center, and then i’ll use weight in the form of extra bracing underneath to add extra weight as necessary.
10% – yeah, it occurred to me that "not being terrified" is related to "being undercautious" which is a close relative to "just lost 2 fingers." i’m using 2×4s for the slats.
Comment by BotchedExperiment | 10.5.2006 | 8:04 pm
Looks awesome. Now all you need is someone with a cell phone to call 911 when you first try it. That or someone stoopit enough to try riding it first. Now where would you find someone like that?
10% if used properly, there should be very little lateral force on the teeter. What Fatty’s built looks over-built compared to some of the teeters I’ve seen on the web.
Botched
P.S. Planning is for ninnies.
Comment by mtnbound | 10.5.2006 | 8:17 pm
Looks good. Just another comment from the peanut gallery. I would add a piece at both ends of the ramp itself, underneath joining the two side/bottom pieces where its beveled. Every time the ramp hits the ground (on either side), this extra piece will take the brunt and keep the beveled ends from splintering outward. This same area will take the most force when a rider puts his wheel on it, forcing it into the ground (this extra piece will spread the force out too).
Mtbike W (not an engineer)
Comment by Unknown | 10.5.2006 | 8:25 pm
How about some gas struts from the liftgate of a mini-van to assist in the return or totter in the see-saw affectionado community. And maybe wheels and a draw bar to tow it from circus to circus. Or how about a lock to keep it from teetering, so the unsuspected would launch out of control when hitting it at high speeds. Sounds like a project of unlimited possibilities. Cool.
Boz
Comment by Unknown | 10.5.2006 | 8:55 pm
mr. project guy,
shouldn’t there be some bailing twine somewhere on this contraption?
i mean, it’s better than duct tape. right?
also, what happens if people ride the course backwards? just curious.
looks dang cool on paper, er, screen.
sounds like your son is a lucky boy to have you as a dad by the way.
bikemike
Comment by Tim | 10.5.2006 | 9:12 pm
How about a bit of car tyre tube fixed to the underside of one side to make it return? Thats what most of the teeters in our local forest have. Cheap but effective.
Comment by Unknown | 10.5.2006 | 10:05 pm
So, you want to know where to drill the hole for a return to ground – why not add spice and drill 3 or 4 holes, so you could theoretically move the center of balance? Let Botched go first when you move it to the 4th hole though.
Comment by Katie | 10.5.2006 | 11:42 pm
Is anyone taking bets on it falling to pieces first go?
I’ve got $5 on this…
Comment by Zed | 10.5.2006 | 11:49 pm
Cool. Thanks for the invite.
Comment by Jsun | 10.6.2006 | 1:08 am
dear commentors- did you not read what Fatty said? He doesn’t want any more advice, jeesh. If he doesn’t care if it falls apart while his 10 year child is riding it, why should we? Katie- I am still betting the uprights crack after a few teeters. I hope he posts up a video of the carnage.
Comment by Fat Cyclist | 10.6.2006 | 1:58 am
botched – it’s ready to ride when you are.
mtbike w - i’m thinking i’ll staplegun sections from old MTB tires at the contact points.
boz – i’m not much of a "lol" guy, but your idea of making it lockable did in fact make me lol. thanks, man.
bikemike – the bailing wire and duct tape will come shortly, when stuff starts falling apart.
t1mm0 – i think i’ll go with old bike tires because i have an endless supply of those. otherwise, your suggestion is spot-on.
no-name – i want this to be thrilling, but am not necessarily aiming for terrifying.
katie – i’d take that bet, but i just got back from doing the inaugural ride on it — half a dozen or so times — and had no trouble whatsoever. so while that bet is no longer takeable, i do take great pleasure in knowing you’d have lost.
noname – if you define "few" as "6 or less," you already lose. i did have my wife take video, though. i’ll try to figure out how to post it on youtube. (me=youtube neophyte)
Comment by BIg Mike In Oz | 10.6.2006 | 11:51 am
bikemike – bailing wire went out when duct tape came in, but duct tape has been superceded by zippy ties for several years. You need to do a refresher course at the MacGyver school of dodgy repairs.
fatty – aren’t you glad you didn’t have to saw notches for all the slats on top?
P.S. (just like a little trainee botched experiment). I know an orthodontist who would like to put up some signage near where this thing gets installed.
Comment by Unknown | 10.6.2006 | 3:08 pm
Your dad would be proud. Now all that’s left is killing an elk, and catching some fish.
Rocky
Comment by Unknown | 10.6.2006 | 3:09 pm
What I said earlier….
Comment by Unknown | 10.6.2006 | 3:27 pm
I am all worked up over this project and the cute letters you get from your rabid followers. So, I went outside and thought about where I could put something like this in the lower 40. I had just about given up on trying this project at all, when I decided to turn an old (big) wheelbarrow upside down and practice doing some trials-type hops over it.
I used to be good at that kind of stuff, and would probably be better at it on my road bike, (funny, that). I now need the name of that orthodontist, and a new pair of handlebars. Thanks a lot.
Comment by Unknown | 10.6.2006 | 3:53 pm
i heard a cool song on prairie home companion last week about bailing twine. i was just fishing to see if anyone listened to this radio show. it’s on npr so, it might not be everyone’s cup of tea.
i would have actually put the whole thing together with super glue but, that’s just me.
bikemike
Comment by barry1021 | 10.6.2006 | 4:31 pm
Notice how cleverly FC shows the LAST building project, the PVC bike rack, off to the side in his pictures? You’re turning into Norm from This Old House, FC. Next thing we know, blueprints of all projects will be available for $10 and an SSAE.
Remember when FC talked about the third parking space in the garage and how much room he had? Three to one odds says someone’s car spends the winter in the driveway….
B21
Comment by mark | 10.6.2006 | 6:01 pm
DP Cowboy–I very nearly needed an orthodontist earlier this year and promptly purchased a full-face helmet. I highly recommend them. Heavier and hotter than an XC helmet, but well worth it when riding very technical terrain.
FC–that is about the best-built stunt I have seen. Nice work. I’m jonesing to give it a try. Just be careful where you put it, as we had a really nice freeride trail here in Boise that got ripped out when the Forest Service went non-linear over the man-made obstacles. It definitely should be on a trail somewhere, but get permission before installing it. Otherwise it will be someone else’s kindling.
-mark