Alt Bike Culture - Anatomy of a tall bike

By the way, God didn't make chocolate and vanilla, he only gave us the cocoa bean and vanilla bean, it was up to man to do the rest.

Yes, just as God gave us an infinite number of thrift-store Varsities... it's up to Man to do the rest!

Yeah, that 'three penny farthing' is a cool bike. I'm not sure if it would be 'unridable' with only two wheels, just incredibly difficult to learn. I'd like to make a reverse pedal bike sometime, just to see if it can be ridden..

peace,
sam

Gyro effect - with only two front wheels, they would cancel each other out and you'd be unable to balance.

Actually there have been bikes made as experiments that have two front wheels that spin opposite directions at the same speed, and while they are a bit more 'twitchy' than normal, they are perfectly ridable. A bicycle doesn't really balance by gyroscopic inertia, though that does play a small part. The greater part of bicycle balance is given to it by the trail of the front wheel, and the rake angle. When you turn the bars on a bike, the front of the bike lifts up a little bit. This means that the point of lowest center of gravity is found with the bars straight ahead, and so a moving bike will naturally attempt to realign the wheel forward to maintain course. When the bike leans, the wheel must turn, due to the trail again. That motion kicks the wheel out from under the center of gravity, and as it pulls back under, the bike stabilizes.

Anyway, the physical interactions end up getting pretty complex, but the end result is that gyroscopic forces don't affect balance as much as we used to think. A 'two-penny' farthing would be a tricky thing to ride, but certainly not unridable. :)

peace,
sam

How many 20" BMX Bikes would you need to stack in order for the bike to be considered "tall"?
Just two frames. That would be a tall 20. Two stacked mini frames (12" or 16" wheels) is a tall mini.

With nothing but experience to back it up I am going to have to disagree on the gyro and rake/trail stuff. Most of a bikes or motorcycles tendency to remain upright is beacause of the gyroscopic effect of the wheels. The tendency to go in a straight line(or not) is from rake and trail.
My coworker and I dicussed the opposing wheels canceling each other out, and concluded that, in the tall bike aplication it would not affect stability. We could be wrong. :)

As a science teacher, I must respectfully re-disagree. ;) Gyroscopic inertia exists, but it is a very minor part of bicycle and motorcycle stability. Here is an old, but interesting study about a guy trying to make unridable bicycles by examining each aspect of bicycle stability, negating it, and then seeing if the new bike is ridable, and if so, how its behavior changes. Gyroscopic inertia holds up a rolling hoop, but it can't hope to hold up a singletrack vehicle.

http://ist-socrates.berkeley.edu/~fajans/Teaching/MoreBikeFiles/JonesBikeBW.pdf

Bicycle and motorcycle stability are related more to steering geometry and the rider's ability to counteract leaning forces by moving the center of gravity back and forth. A unicycle rider maintains forward/backward balance by having a high center of gravity, and moving the base back and forth beneath it. Imagine balancing a broom on your hand, bristles up. A bicycle doesn't balance front to back this way, but it does balance side to side this way. As it leans to the right, the wheel turns to the right. But because turning the wheel to the right causes the center of gravity to rise, there is a reaction force that kicks the wheel straight again, and pulls the base of the vehicle back under the center of gravity.

You might also be interested in these dynamic simulations of bicycle motion. Note that they show a stable geometry (which looks very realistic) without accounting for gyroscopic inertia at all! This simulated bicycle stays stable through geometry alone.

http://www.win.tue.nl/dynamo/bike/bike.html

Up next is a very detailed analysis of the stability of fully faired two wheel HPVs. It is incredibly complex, but again comes to a conclusion that gyroscopic forces are not a big player in stability.

http://www.coe.uncc.edu/~rkeanini/humpowengrg/HPVE_Steering.htm

Intuitively, part of you knows that this is the case. Motorcyclists often replace heavy steel wheels with carbon fiber wheels that might weight as little as 1/3rd the original. Yet they will tell you that stability has not been noticably decreased! With 1/3rd the mass, you'd expect a drastic change in stability if gyroscopic inertia were the primary player in stability, since gyroscopic inertia changes proportionally with mass.

Anyway, I get a huge kick out of things like this, and its one of the reasons I love two wheeled vehicles, they are very facinating! We haven't even gotten to cool stuff like countersteering (which does have a bit more to do with gyroscopic inertia than general stability does).

peace,
sam

Just two frames. That would be a tall 20. Two stacked mini frames (12" or 16" wheels) is a tall mini.

Sounds like Starbucks to me. :D

Look at it this way, if you put whatever rake you want on a fork but a set of rollerblade wheels on the bike and get it rolling and let go, it will flop right over, do the same thing with a bicycle (ghost riding) and it will go til it slows down or hits something. I have come of the back of a motorcyle and had it go another hundred yards before hitting something and crashing.

Continued(Had to open the store :) ) As for the motorcycle wheels, while A carbon rim is lighter they are still pretty massy, as the part at the outer most of the hoop, the tire, still weighs the same. One of the reasons they reduce weight is to allow turn in, those big rims resist turning the front wheel. I have a lot of moto books and amgazines that talk about this.

Playing around in the shop, we put a wheel in a fork and spin the heck out of it, you can feel it resist movement as you try and move the fork around.

We decided to do the fork and wheel test again. I put a computer on the fork and calibrated it for the wheel, a 26x1,4 on a cheap single wall rim. Then we did a simple empirical test. We held the fork by the steerer, wheel down and spun it then tried to turn the fork. There was a resistance to turning as low as 2 mph, by 5 mph it is enough to require some effort to turn the fork and by 11 mph, very hard.

In addition I have ridden highwheelers that have zero rake and trail, the fork is pretty much perpindicular to the ground. You have to climb up into the saddle while rolling it down the street, using a peg on the frame. If it is moving the bike stays up by its self, it is pretty spooky the first couple of times because your weight is all to one side but the bike just tracks on until you swing into the saddle.

With your empirical test, I think you are feeling the precession that allows for countersteering more than you are feeling the forces of general stability. If you hold the fork free in your hands by the steerer, and attempt to turn it to turn it, as if you were turning the handlebars, you'll feel the wheel dive to the side, which helps initiate a lean for countersteering.

Try this, hold the fork so that the wheel is at a 45 degree lean. Get the wheel spinning, and then try to rotate it to vertical. It will resist you in the same way. If that gyroscopic force was the dominant stability force, you wouldn't be able to right yourself from a lean on a bike, since the same force holding you up at first would now be holding you to the side. Incidentally, it is very hard to recover from a lean on a hiwheeler, because they lack the geometry that a modern bike has.

The rollerblade wheel example doesn't work, because the size of the wheel contributes to the geometry, and the ability of the contact patch to change position as the wheel turns.

How do you explain the computer simulations of the gyroscope-less bikes displaying stability?

These discussions pop up regularly on motorcycling forums and biking forums, and are very difficult to resolve. There are many forces at work, and determining which is dominant is very hard (and hence the subject of phD research at times).

peace,
sam

Oh, come on, enough of this tech talk, let's see some more freak bikes!

Oh, come on, enough of this tech talk, let's see some more freak bikes!

Hear Hear!

I present to you, a friend of mine on SS Hotdog Bike!

http://www.bananabikebrigade.com/images/sshotdog.gif

"How do you explain the computer simulations of the gyroscope-less bikes displaying stability?"

It is wrong. :)

Sorry, I see them as more Jackson Pollock than Mozart or Rembrandt. And that's being generous.

More like Dali I think. :D

CHEERS.

Mark

More like Dali I think. :D

CHEERS.

Mark

Consider how Pollock died...

Consider how Pollock died...
Flopping around on the deck of a purse seiner in the bearring sea? ;)

Anybody make a tall trike or quad?

A tall trike would be neat.. It could be a truck, meant for hauling stuff, but instead of sitting in front or behind the load, you'd sit above it! Maybe have recumbent style seating position about 7 feet in the air, with a big load basket beneath it. I'd ride it!

peace,
sam

A tall trike would be neat.. It could be a truck, meant for hauling stuff, but instead of sitting in front or behind the load, you'd sit above it! Maybe have recumbent style seating position about 7 feet in the air, with a big load basket beneath it. I'd ride it!

peace,
sam


That is a damn cool idea! I wanna see it done. maybe instead of hauling stuff, you could haul people, kinda like a tall-trike taxi.

Hmm.. Tall taxi, eh? I'm liking it! It'd be like a double decker bus, only in bike form. :D

peace,
sam

You'd have to have a pretty low gear to get that mass moving... Maybe you could have some more sets of pedals down there for the people to help out.

I agree, the gearing would be an issue. You could also use a double reduction. A normal triple chainwheel up top (primary) running down to the large ring on another triple at the bottom (secondary) , that would drive a 5, 6 or 7 speeed rear hub. Then use the remaining two chainwheels on the sceondary to 'split' the primary ratios. This would effectively give you a transmission similar to the old twin 'twin stick' Mack truck 13 speed transmission with a two speed rear... only the ordering would be rearranged. This, 3 X 2 X 5, 6 or7 speed gearing should give adequate reduction to get the mass moving, yet offer enough top end to keep you from tiring too fast at an elevated cadence.

I agree, the gearing would be an issue. You could also use a double reduction. A normal triple chainwheel up top (primary) running down to the large ring on another triple at the bottom (secondary) , that would drive a 5, 6 or 7 speeed rear hub. Then use the remaining two chainwheels on the sceondary to 'split' the primary ratios. This would effectively give you a transmission similar to the old twin 'twin stick' Mack truck 13 speed transmission with a two speed rear... only the ordering would be rearranged. This, 3 X 2 X 5, 6 or7 speed gearing should give adequate reduction to get the mass moving, yet offer enough top end to keep you from tiring too fast at an elevated cadence.


Fantastic.

Fantastic.


Thanks, I try. :)

Pedal rickshaws do it, so it couldn't be that hard to move the people mass.

any video of that?sounds fun!
http://homepage.mac.com/rachelmeyrick/iMovieTheater8.html

ok, back to two wheel tall bikes, please, riksja and other are threewheelers, make new topic for them.

anatomy of bolted = without welding tallbike on http://tallbike.net on the left or much in the gallery.

many reasons why it's good solution.

greetz from lu

I have had a jonz for a tall bike for quite a while. Somehow the reuse of cheap bike frames to make something cool from them is the best kind of recycling. Lack of welding and brazing materials has been a problem. Someday...

There are many tall bikes in the St. Paul (okay and Minneapolis) area. One is a tall bike chopper and it appears he commutes to work on it. I just wish he'd follow a few traffic laws so he wouldn't get so much attention for running red lights, riding against traffic, on so on. Isn't the tall bike enough?

One tall bike I see is usually parked and locked to a balcony. Looks like a great mount spot. Then again, I've never ridden one.

Try typing Chunk666 into google.com.

here is a link to a cool tall bike trike tandem
http://mywilson.homestead.com/gallery141.html

here is a link to a cool tall bike trike tandem
http://mywilson.homestead.com/gallery141.html

how about the "worlds tallest tall-bike (http://www.scallywagsbikeclub.com/past/02_Maydayparade.html)" (it's in the background). Saw it in 2002 (and a few times after that)...if you scroll to the bottom of the page it's being ridden...

There are a few tallbikes in Oberlin, OH (made by the Oberlin Bike Co-op).

Our style is pretty primitive - two roughly matching frames welded BB to seat tube. To the get the fork extension straight we step on the rear triangle and spin the fork - if the extension isn't straight we heat it and whack it until it is.

A great way to get chain tension without a tensioner is to hook up the rear BB with a chainring, and you get a triangle of chain. you can also then attach feet or something to the bottom cranks and the thing looks like a running animal.

Anyway, as for style, it's whatever parts fit. we leave the top rear triangle on for a cargo berth/stereo mount. it does clutter the lines but makes them look heftier.

those riding talls are the kings of the rides. that perspective stuff - it's true. just like walking tall and sitting with good posture, riding a tall lets you sail in the clouds. it can also lead to funny scenes: i have a 20" that i ride quite a bit, and a friend of mine used a tall as his commuter, and whenever we would ride together I felt like the duckling following his mother. I'd like to see a chain of small bikes following a tall.

those riding talls are the kings of the rides. that perspective stuff - it's true. just like walking tall and sitting with good posture, riding a tall lets you sail in the clouds. it can also lead to funny scenes: i have a 20" that i ride quite a bit, and a friend of mine used a tall as his commuter, and whenever we would ride together I felt like the duckling following his mother. I'd like to see a chain of small bikes following a tall.

So true! A friend of mine is chopping his mini bike so we can go riding around on the 'tall and tiny task force'. Its going to be lots of fun.

If you ever come to St. Louis, shoot me a PM and we'll go riding.

peace,
sam

There are quite a few tall bikes in Seattle. Each year the Dead Baby Bike Club has a downhill race and after the race there is ALWAYS tall bike jousting. It is tons o' fun! I have never jousted, but I have done some tall bike riding. A friend of mine only rode a tall bike, it was his only bike. Then it got stolen. I have no idea how someone got away with a bright yellow tall bike...

check out the Dead Baby's bikes

http://www.deadbabybikes.org/bikes.htm

thats a beutifull tall bike!!!, mine is much less pleasing to the eye, but im working on #2 and i will put more thought and effort into this one.

And for all you haters-- stop it.

Tallbikes are indeed fun as hell to ride. Built a 15 footer and made to Guinness last year (look on page 134 of the 2005 edition) or check the beast out at...

http://www.atomiczombie.com/book-bonanza.htm

Decided that climbing a pole to get on the bike was just too dangerous, so I made a new 12 footer that you can climb and dismount while it is moving....

http://www.atomiczombie.com/gallery/brad-graham/skywalker.htm
There is a video on the site as well.

I recommend this rear ladder style of bike if you want to go tall - it's easy to ride in town (yes I do that).

Later,
Brad

Tall bike jousting in Portland at the Mutlnomah County Bike Fair, Saturday June 25. Hopefully some of the Dead Babys can make that event...

MULTNOMAH COUNTY BIKE FAIR
Col. Summers Park, SE 20th & Belmont
2:00pm - 7:00pm
A *FREE* one-day festival of bicycle music, mayhem and madness. Competitions, tall bike jousting, beer garden, marry your bike booth, food, performances, awards and more. Sign up the day of to compete at the Competitions Stage. Performances by: Sprockettes - Gov't Issue Orchestra - Pheramones - Trash Mountain Boys - Johnny Punchclock - and more. Bring your own bike for jousting & competing, no loaners available. VOLUNTEERS NEEDED - contact EliciaCardenashotmail.com; free arm bands and accolades for all volunteers.
http://shift2bikes.org/pedalpalooza/index.shtml#June25:MCBF

Thinking about using a shaft drive on my next (30 foot) tall bike. At 30 feet, chain is hard to manage and weighs a lot. The problem is finding 2 right angle gear drives with at least 1/2 inch shafts on both sides of the box to connect cranks to. Found one in an old snowblower, but it again, was a little too heavy.

Mcmaster sells crown gears and bearings, but after adding up the cost of two units, it starts to impact on my bear supply - not good.

Any ideas?

Thinking about using a shaft drive on my next (30 foot) tall bike. At 30 feet, chain is hard to manage and weighs a lot. The problem is finding 2 right angle gear drives with at least 1/2 inch shafts on both sides of the box to connect cranks to. Found one in an old snowblower, but it again, was a little too heavy.

Mcmaster sells crown gears and bearings, but after adding up the cost of two units, it starts to impact on my bear supply - not good.

Any ideas?

A shaft that long will have so much flex, there will be a huge delay in pedal input. How about a concentric gear drive (I think that's what they're called) like on trains?

By the way, how many bears do you have?

I think this guy is from Asheville, NC. Pics are from Snowshoe on Memorial Day.

http://img.photobucket.com/albums/v246/pinit/tallbike2.jpg

http://img.photobucket.com/albums/v246/pinit/tallbike1.jpg

He was also doing a big ramp to ramp gap...it was great.

Shaft drive would be cool, but 30' of 1/2" rod is like a giant spoke, it'll twist like crazy. But then, chain would have delay too, as you built up tension in the pedal stroke. I suppose it would work out, and it would probably be easier to maintain (and cheaper, since you wouldn't need to buy 10 chains to hook together.).

Good luck with it!

peace,
sam

Yes, the 30 foot shaft drive has been scrapped, as it would weight much more than chain and probably have odd characteristics. I am currently experimenting with a motor/generator drive - using wheelchair DC gear motors. So far this seems to work very well - takes off smooth, has very little power loss, and includes brakes! The only thing that runs from one motor to the other is a single wire (the frame is ground).

To brake, you just resist or back pedal - it is almost like fixed gear, but much smoother. I would not want to use this system on a daily bike, but I think it is going to work out fine for my second world record tallbike. Sure opens up new frame design possibilities as well.

Brad

Amsterdam supposedly has a pretty good collection of tall bikes. I think a lot of them flip the bottom bike upside down when making the tall bikes.. I've seen some weird ones out of there, very different from our St. Louis style bikes. ;)

Mine has a water bottle mount on the bottom down tube, which is totally useless. ;) However, I'm putting brazeons onto the top-top tube for a bottle cage. Hose clamps would work in a pinch!

Falling isn't too bad. I actually have only fallen off of this one once, and with the stepthrough top frame you can swing a leg over and sort of bail out without too much trouble. The worst accident I've been in was on a tall tandem w/ two wheel drive. The front person pedaled the front wheel and steered, and the back person pedaled the back wheel. Total coordination was necessary for any riding at all, and you sat so close to the other person that there was no room for manuverability. We were swinging around to challenge another tall bike to a jousting match when a guy on a mountain bike who wasn't paying attention rammed us, which collapsed the front fork, taco'd both wheels, and sent us careening uncontrollably toward the ground. The bike is undergoing some redesign now. ;)

Also, remember that tall bikes are actually of practical use! (or rather, they were, a long time ago). Lamp lighters in the late 1800s used tall bikes (that look surprisingly like our tall bikes, just huge framed safety bikes) to light the gas lamps in cities. They'd get on to the bike from a ladder, then ride along. As they hit each lamp they'd lean up against the lamp to light it, then pedal to the next. Eventually they'd end up back at the start and would dismount from the ladder again. :)

peace,
sam

very interesting bike. they also have hash bars in Amsterdam, another way to get high. seriously though i don't have the skills for that. i like to meet someone to build me the ultimate chopper. 10 ft long, extra fat tire in rear say 8-10 ". my schwinn chopper only practical use is to turn heads. Nice Job, Jim.