4 – Wheel Bicycle for Playa

[robotland]

Hi, we have a girl in our camp with a mountain board that she rides quite a bit while being pulled behind our art car.

I have the $60 harbor freight helmet and it works great.

We have a couple in the sculpture department at KIA*, and they work just fine. The beginning welders find 'em MUCH easier to use.

I've been hoarding parts for a while, hoping to give it another try at building a vehicle that will break down for transport in my Element...I've studied AntiM and Larry's Rhoades Car and a few other cool rigs, and built a TERRIBLE three-wheeler a couple years back that travelled about 100 feet and then got parked for the rest of the week. Much of it was wood, so I got to burn those parts for revenge.
I'm hoping to hit some good yard sales this year, since those superfat-tire chopper bikes have been around for a while and I'd really like to use a couple of them for the vehicle if it's to be ANYTHING like last year. Ridiculous! I actually made a little map of the major dunes for navigation!

[robotland]

*KIA = "Kalamazoo Institute of Arts". It's actually bigger than it sounds.

[BAS]

I'm glad to hear that, because I bought a $60 Harbor Freight helmet! Haven't got a chance to try welding yet.

[lowecifer]

http://vids.myspace.com/index.cfm?fusea ... d=40641691

check out this video of a pedal car i made last year

[Finnegan]

That car sounds like a race car all right! I can probably understand most aspects of steering geometry if I sit down and study it again, but it’s been 30 years since I learned it, so it would take me all day now. And there are many forms of racing, and countless thousands of individual race cars.
But full power and hard braking means suspension travel at the extremes, and the steering linkage can be arranged so you get toe-in at the extremes when directional stability is needed most. Then, in the middle of the suspension travel, the toe will be slightly out, which helps with turn-in.
Old Mr. Ackerman is very much part of a race car’s turn-in. Remember that the tires must be toed out in the turn. And for straightway stability, they must be toed in. The transition from toe-in to toe-out must necessarily cause a jolt in the system -- from everything being in tension to everything being in compression (or vice versa). That sudden transition is trivial in a grocery-getter, but is undesirable in a race car where the tires are already at the limit of traction, and any kind of upset in the forces will slow the car down.
The camber angle is also part of the suspension travel equation. The common system of short upper suspension links and long lower ones... is specifically intended to change camber to maximum negative (contact patches as far apart as possible) for stability under extreme conditions. And the camber of a tire affects which way it wants to go, so camber set for going fast around corners can also make a car squirrelly on the straights.
Keeping a squirrelly car going smoothly straight... is one of the key skills of a racing driver.

Hmm. Must remember to buy this Elliot person a pbr, and grill him about how my car works..

[Elliot]

Thank you! Please bring the ice cold PBR to Camp Apokiliptika. We expect to be on A, just south of 3, as before. (In Terminal Village.)

[montkw]

I scratch built a 4 wheel 'bike' for the playa a couple years ago and have been working on improvements ever since. I used 2 independent adult tricycle axles. Each drives it's own side and allows each person to set their own gearing. It has disc brakes, sliding adjustable seats and a big cooler on the back for ice runs to Artica. Steering was quite a challenge. I rake the front wheels forward and a little to the outside to improve the cornering. It's not ideal but it works great on the playa.

However, this was by no means a cheap project. If you want to keep the costs down, use scrap bikes or build a PVC bike. I've seen several of them on the playa and they looked fine for a single person.

Indy,

www.time-traveler.org/quadracycle

[Elliot]

What a fabulous quadracycle! Art -- truly art!

One thought:

We added 7 degrees of forward rake to the front wheels try to cut down the tires scuffing in tight turns. Giving it a quick test, it looks like it helped, but perhaps not enough. At this point it will have to do.

What you need is correct Ackerman angle on the steering arms that are on the spindles. Imagine -- or run a string or whatever -- thru the spindle and thru the tie-rod mounting hole. Extend this line all the way to the rear axle. It should hit the center of the rear axle.
Google Ackerman and you will find drawings and explanations.
The point is that the outside wheel must turn less than the inside one, because it travels a wider radius.

Keep up the great work!

[Da Mule]

Way cool, montkw.

Welcome to eplaya!

[Finnegan]

Thank you! Please bring the ice cold PBR to Camp Apokiliptika. We expect to be on A, just south of 3, as before. (In Terminal Village.)

Sure thing! Or, you could walk the 50 feet to the Booby Bar, where I will be tending bar.

Cheers,
Finn

[Elliot]

Hah, hah! I did wonder! Same name, but different avatar. It's my first year actually joining Apok, but I have been a "secret ally" for three years.
We ought to paint the Ackerman illustration on my bus!

[MarkM3]

Hi all,
This year I'm contemplating retring the mutant vehicle and making a 4-wheel bike instead. For those of you with 4-wheel pedal powered vehicles, how well did they do on the terrible playa conditions (i.e. sand dunes) last year? Are you able to get through with a little extra muscle, or do you need to dismount to get un-stuck?

Thanks for the pointers!

FYI, I plan to use standard mountain bike tires, so feedback on using regular size tires would be helpful.

[AntiM]

Even with 36 gears and two of us peddling, we had to get out a couple times. Never had to do that before.

[Oldguy]

Pushing thru the dunes last year, off my adult size pedal car, I lost a bolt holding my left pedal onto the hub. I'm bringing two spare pedal bolts this year, 8.8 mm with fine thread plus lock washers,

[mdmf007]

What a fabulous quadracycle! Art -- truly art!

One thought:

Google Ackerman and you will find drawings and explanations.
The point is that the outside wheel must turn less than the inside one, because it travels a wider radius.

Keep up the great work!

hmm.

[Toolmaker]

Heres some stuff handy for making bikes and choppers in case anyone has a need.

http://home.comcast.net/~pinnah/dirtbag ... oject.html
http://kogswell.com/siteTUBEcalc.php
http://www.chopperhandbook.com

You also might find some stuff on instructables

[BAS]

I'm getting anxious for my next four day weekend. On the last one (Mother's Day weekend), I did get nearly all of the stuff dragged up to my dad's workshop and got a start on using the angle grinder on one of the salvage bikes. (Note, next time wear at least a dust mask! Amongst other things, I discovered that I had cut through a thick layer of plastic, and felt really sick the next day.)

I need to buy a better face shield, and to locate MY goggles! The ones my dad has are in pretty rough shape, making them hard to see through. My dad was impressed with the ear protectors I bought, since they are better than his.

The bike I was cutting up is the bargain store full suspension mountain bike I picked up. As it turns out, the thing was even more rusty than I had thought, but the important parts (the rear suspension and rear fork) should still be usable. I'd kind of hoped to use the front chain rings, but they proved to be incredibly cheaply made, and hooked together with some sort of pop rivets. They, and the cranks, wound up in the garbage.

I'd kind of hoped to get the recumbent trike part of the velomobile completed in time for Lakes of Fire, but I seriously doubt I will. I still have more bikes to cut apart, and need to find the money to obtain some parts, and need to figure out what parts I need to obtain! (The hubs I bought didn't come with axles, so I need to find 20mm axles, for one thing...)

I need to bring a camera with me next time, so I can document whatever progress I make. (Then, of course, I need to figure out how to get the pictures online! I don't have a Photobucket account or anything like that.)