Introduction: Make a Portable Tallbike!

Picture of Make a Portable Tallbike!

Most tallbikes are not made to be transported. If you don't have a pickup truck, or maybe a roof rack, it's going to be tricky to take your tallbike anywhere. In my case, I was building a tallbike for a friend who lives about 100 miles away. I saw that there are only a few Tall Bike instructables, and they are very informative and inspirational, but I wanted to show another building method that turned out very well for me. If you have an intermediate level of bike-wrenching experience and can weld okay, this should be no problem.

This is my first instructable, so I hope it is clear, enjoyable, and inspirational! (give me your feedback on anything and I will revise) I re-use the same photo a lot because I don't have the bike in my possession right now to take others. Hopefully it is all clear anyway.

Goals for this tallbike:
-to be sufficiently tall, but can be easily dis-assembled, sort of like a folding bike. for fitting in a trunk or on a trunk mounted rack, or even in a rear passenger compartment if necessary.
-to ride as much like a "regular" bike as possible, specifically steering and pedalling.
-to be Relatively quick and easy to build with a minimum of welding, cutting, and custom fabrication.
-to be as strong and sturdy as any other tallbike building method
-to be disassemble-able with a minimum of tools and time

Ingredients:
-a couple of similar-sized bikes from the trash or wherever. If you're reading this, I assume you probably have a bike pile. I used department store BMX frames because they have nice straight forks (more on that later), thick steel that is easy to weld, and they are pretty to easy to find in the trash.
-a stem with a bolt on plate that holds the handlebars, not the kind of stem with a pinch-bolt.
-a steel seatpost for the bottom frame. This gets welded to the top frame.
-a front hub. find a wheel that is taco'ed beyond repair or has a bunch of broken spokes, or even a broken spoke flange. Make sure it is not too small or big in diameter to clamp into the stem!

Tools:
-standard bike tools like allen wrenches, adjustable crescents, chain breaker, pedal wrench, channel-lock pliers, etc
-hammer probably.
-a couple 4-foot long 2x4 pieces of lumber or other nice flat, straight pieces of lumber
-at least two 4" or 6" c-clamps, speedclamps, or something you can use to clamp to boards together.
-Welder. Whatever you have on hand that wont burn too hot. I used a $89 stick welder from Harbor Freight, some 1/16" rod, running at about 50Amps, plugged into regular AC outlet.
-Your other welding tools: helmet/goggles, gloves, chipping hammer
-Angle grinder, if you need/want to clean up welds.

Step 1: Headtubes

Picture of Headtubes

The key to having your tallbike handle like a normal bike is taking time make sure the head tubes (the tube of the bike frame that your front forks go through) of the two bikes are aligned as closely as possible. If they are not on a common center line, your bike will resist steering. You can get away with a little mis-alignment, but the steering will want to straighten itself and every time you turn the handlebars it forces your whole assembly to flex.

This building method eliminates welding in a longer head tube or chopping up forks and welding in a fork steerer extension. It also allows adjustments, dis-assembly, and helps during the rest of the build.

Step 2: Picking a Fork and Stem!

Picture of Picking a Fork and Stem!

The basic idea for the front end of your bike is:

the bottom frame has a stem with a bolt on handlebar clamp.
instead of a handlebar there, you use a spare front hub complete with axle.
the fork of the top bike bolts onto that axle.

The key of X:
Pick up the stem you want to use and measure the distance from the center of where the handlebar would be to the center of the expander bolt (the bolt that goes vertically through the stem to the little wedge shaped thing that goes into the forks). Call this length X.

On the forks, measure the distance from the center of the dropout (where the wheel axle goes) to the center of the steering axis. This is easiest on straight-bladed forks like I used. With curved forks this is trickier to measure. If this measurement is within a few millimeters of X, you're good to go. If not, find a clever way to bend your fork legs fore-/back-ward simultaneously to get that distance to X.

Alternately, you can put the hub in the stem, slide the axle into the fork ends and eyeball it to see if everything will be aligned.

Step 3: Disassembly and Frame Attachment.

Picture of Disassembly and Frame Attachment.

Strip the bikes down as much as possible. Leave the forks and headset in place on the bottom bike. The top bike you can leave the fork, headset, stem, and handlebar all on. You might as well remove the cranks and chains and wheels and stuff. Now would also be the time to overhaul the headset bearings if they are rusty (bike piles are not a friendly environment).

Now it is time to begin assembling and aligning the frames.

On the bottom bike, if you haven't installed the front hub into the stem clamp, do so. Make sure it is centered left to right and clamp it down as hard as you like. Tighten the stem expander bolt so it is secure to the fork.

With the bottom frame standing up, resting on the fork ends and the bottom bracket (the fat tube that the cranks went through), lift the frame that will go on top up above it. Bring the upper frame down with the works and slide them onto the axle of the stem hub. Tighten down the axle nuts. Now your bikes are connected on the front end! Hold them up one on top of the other. I figure this is at least as strong as a decent weld job up here. The axle is probably the weekest link. This clamping system is also a little more forgiving of misalignment than a weld.

Step 4: Vertical Alignment

Picture of Vertical Alignment

Take a couple 2x4 or 1x4 or some other nice flat straight lumber. Place one on either side of the frames, oriented vertically. The frames will be sandwiched between them. Put clamps on and tighten them down somewhat. The goal is to ensure that the top and bottom frames are both in the same vertical plane. If they aren't, your body weight will want to "fold" the bikes together instead of transmitting straight down through both of them.

I tightened the clamps enough to hold the upper frame in place, but so I could still pivot it around the front axle attachment point. Rotate the upper frame until it looks like the two headtubes are on one steering axis. Try turning the handlebars on the top bike. If they rotate freely, everything is aligned and that is where you will want the top frame to be. (NOTE: if you could make a universal joint out of two front hubs 90 degrees from each other, the headtubes wouldn't even have to be perfectly aligned this way. I think the offset for the fork and stem would have to be the same).

On the bottom frame, raise the seatpost until it hits the upper frame. On mine, it hit right behind the bottom bracket. If the upper bike has a kickstand plate, that would be a perfect thing to weld to. Tighten the seatpost at that height.

Step 5: Weld!

Picture of Weld!

The front of your bike is all attached and the rear seatpost is "marking" the point where you will weld. Now you can rotate the upper frame up and prep the area where the seatpost will be welded on, and prep the end of the seatpost. Strip off any paint or plating there. Cut/shape the seatpost or the upper frame so you only have a small gap to weld.

Rotate the top frame back down so the seatube is touching it. Tighten your sandwich board clamps really well once everything is in position.

Weld it up! I found it was a lot easier to do this weld if I turned the entire assembly over so the handlebars and seat were on the ground, just like some people do when fixing a flat bike tire.

The result is a real sturdy attachment from top bike to bottom bike, and only required welding in 1 place!

Another idea I'm going to try is to use another fork instead of the seatpost on the bottom bike. Then welding an axle to the top bike where the fork would hit it. Then they can bolt together there too.

Step 6: Final Assembly!

Picture of Final Assembly!

Finally, you'll want to install your wheels, then figure out how to route your chain. If you use BMX frames you may need to get (extra) creative because the small rear triangles only let a chain in from certain directions. You'll see what I mean.

Figure out a way to install brakes. Easiest to hook up only front brakes, otherwise it may be difficult to find long enough brake cables.

If you opt out of brakes, you can always just stick your left foot down onto the rear tire to stop. This works surprisingly well to stop, but it's not so great for your shoes.

Go riding! Figure out what you can and can't do on the bike!

Warnings and such:
DON'T RIDE IN FLIP FLOPS (see Brakes section above). Start Slowly! Do not be surprised if you end up doing a massive wheely and end up standing in the road with the bike flipped out in front of you. Adjust handlebars and seat as necessary to avoid this.

The bike pictured, though welded in only one place is really strong and steers just as easily as a normal bmx. It was sturdy enough I was able to bunny hop it a couple of times. It didn't collapse, and the bottom frame seatpost didn't telescope downward or anything. I weigh 210lbs. I was not at all worried.

Step 7: Dis-assembly for Transport!

Picture of Dis-assembly for Transport!

To fit this thing into a trunk or backseat, you simply (carefully) unbolt the top frame! This might be easiest and safest to do with the bike on its side on the ground.

STEP 1. Loosen either the clamp that holds the hub in the stem... OR Loosen the axle nuts so the fork can slide up out.

2: Loosen up the seatpost clamp. If the bike has a separate clamp (not welded to the frame), make sure it doesn't fall off or that you don't lose it! Some of the separate ones have a little set-screw that hold it onto the frame.

3. Undo the chain around the upper crank. Now the top bike should be totally separated.

For the pictured bike, I simply stuck the two frames next to each other so they took up a minimum of height. I wrapped a couple bungee cords around them. In this manner you can make your tallbike fit into the back seat of a 1995 Honda Accord.

Step 8: Re-assembly After Transport!

Picture of Re-assembly After Transport!

Do the disassembly steps in the reverse order. You made it this far, you can figure that out.

Have fun! Let me know what you think.

Peace,
S.S.

Comments

Amirzdf (author)2016-07-07

Excellent!!!!

grundisimo (author)2010-08-30

My friend has one 20 feet tall. I'm not lying.

0087adam (author)2010-08-01

that doesn't look dangerous at all.

Thank you for the constructive comment. It's no more dangerous than any other tallbike.

banterboy (author)2010-05-06

 Very clear and concise instructions. Could probably lose the back wheel forks on the top bike which would ensure it would take up less space when taken transporting.

True. However, part of the idea I was going with on this build was that both the top and bottom bikes could be disassembled and turned back into two normal bikes. All that would required on the top frame is to hack off the welded on seat tube.

cody316 (author)2009-09-21

id like to build one, can somebody please make an instructable on how to get on it though lol, its the first time i ever see something like this, i will put my bicycle trailer hitch and trailer instructable on this week.

efmca (author)2009-09-03

nice instructable! I put one together in a couple hours. My kids call it the "crazy bike" and the neighbors look at me funny. I love it! Thanx for the idea.

cjbikenut (author)2009-08-01

Nicely handled project and clear well photographed instructable. I tip my hat to you

cybergod (author)2009-06-15

WOW ! That looks fun. But to make it MORE portable, maybe consideration could be given to the following idea. I see the front forks of the top bike are attached using a bolt/nut fastener. That means it can be detached as needed. To make it more so, how about instead of welding the bottom seat pole to the top bike frame, could a "tee" bracket similar to that used in scaffolding to attach the two bikes. Don't know if it would work for sure, but a possible way to make it more portable? Thoughts??

I don't think that would make it any more portable as it already collapses into the size of two regular bikes which can easily be placed on a bike rack or in the trunk, the bike i have stands at just around 7'6" and it collapses to fit in the trunk of my camry so this being much smaller than that, should have no problem at all.

Ahhh, my apologies. I didn't think straight. I see now, you can remove the seat post and detach at the forks and it is then seperated. Well done. Must try this one day when I have some spare time.

Bartboy (author)2009-06-13

SWEEEET!!!!!

budgetbiker78666 (author)2009-06-12

Hey great instructable I did the same thing a while back it works great for a while but since the steering column is not straight the weld will break in a few months depending on the use of it, so if you add a brace from the bar you attached to bottom bracket and run it diagonally to the bottom tube, this one has held up for a few years and still riding. Oh and also if you run it straight from the bottom bracket to the rear wheel with a de-railer fixes all chain issues and also gets you some nice gear action. Good luck and GREAT INSTRUCTABLE. -Budget Biker-

Thanks for the feedback BB. Well, on this bike, the steering column is almost exactly straight. Before I hooked up a brake cable, I was able to do a barspin. That's the whole point of aligning the headtubes and matching the offset of the bottom bike stem and top bike's fork. I suppose the weld might break anyway, but I added a lot of metal there. At least, it's a stouter weld than some of the original welds on the frame! I am keeping my fingers crossed for my soon to be brother-in-law who will be riding it XD

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