Hello My names is Michael.
Welcome to my Instructional on making a truck bike (butcher bike) from a vintage steel mountain bike the hack way. I'd say one in one hundred cycling enthusiasts is serious about owning a cargo bike, and one in 20 of those people are serious about making it themselves, and one in five of those people are going to have the bare bones metal fabrication experience it will take to follow these directions, so this post is for all ten of you people in all the world who are as excited about truck bikes as I was six years ago! Making a truck bike from an old mountain bike was my first project when I decided to have my own shop where I would make bicycles seven years ago.The main reason to do this project this way is that the tail end of the bicycle frame is the most complicated part and you save yourself a whole heck of a lot of hassle by just taking something that already exists and adding a cargo bike front end to it, and really there's something to be said for just taking something off the shelf. Nobody can do it all on their own, and people who think they can are generally just kidding themselves.
WHAT DO YOU NEED TO KNOW?
Seven years ago, when I undertook my first salvage truck bike, I already had a lot of heavy duty welding, precision machining, and bicycle maintenance experience but since this project requires neither of the first two and plenty of the third I was about where you hopefully are now. If you know the difference between a head tube and a steer tube that's a good start. You want to be able to do your own mechanical work for this project so that some poor mechanic in a bike shop won't have to tell you you screwed up. Also you want to have all the parts you're planning to use on the final build on hand when you start. That's always a good idea. In this lesson I planted a bunch of photos of my finished truck bikes, some of which have salvaged parts and some of which do not. My main reason for this was to show a couple different ways of doing things. I recommend you go with a square mid tube like I show in the Microsoft paint instructions, the most important Bike I included was the Surly steam roller truck bike made by Dirty Dave in San Francisco. His philosophy when it comes to utility bikes is something like this, "the easy way is hard enough", so be like Dave and get your bike done in a reasonable amount of time.
WHAT is a SALVAGE TRUCK BIKE?
The basic theory behind a truck bike is that they use a standard adult commuter sized frame and rear wheel that's typically a 700C or 26" and a 20" BMX wheel in the front. The utility is in that the small wheel allows you attach a front rack right to the frame and gets your load beneath the swing of the handlebar, and lower to the ground which improves handling and means the 120 pound box of sensitive laboratory instruments (or whatever) you're carrying won't have as far to fall once you get to wherever you were going. Attaching the rack to the frame rather than the front fork and handle bar also improves handling as your cargo doesn't have to swing back and forth when you turn.
WHY make it?
This value added custom bike project is cool because it's something you can make after work at the fab shop or in community college welding class, bikes and especially utility bikes are incredibly useful, it is an alternative transportation for yourself and others, it will be made at least partially from reclaimed materials, you will learn a lot about bikes, anger management, and welding in the process, a well done truck bike hack is hard enough to pull off that other geeks will think you're cool, and because truck bikes are hard to attain any other way. Even if you could find one for sale it would be more expensive than a small old car. Probably the coolest part about home made cargo bikes is that what you're building will be closer to the Corvette end of what's available than the 65 pound Maytag washing machine end of the spectrum. But keep in mind no matter how much your truck bike weighs you will have plenty of fun peddling your "friend" and their baggage to the airport at five am on a Saturday morning.
Step 1: Dutch Truck BIke From Old Mtn Bike
Things you'll need.
1 mountain bike frame
1x 1-1/8" head tube (2 feet long), source it from Henry James, or Nova. Buy the thickest piece they have unless you're a whiz with the welding/brazing process you're using. Remember the longer the material is hot and or the thinner the tubing is the more distortion you're gonna get, so for beginners who are slow welders, (I don't do anything quickly) that means you want the BMX or mountain bike, heavy duty head tube stock.
1 20" inch front wheel, preferably disk brake, but drum or rim brake would work. I recommend the Avid bb7- they're about the price of a low end hydraulic, but they are virtually maintenance free
Triple down tube cable stop, or three single stops, If you're cutty, you can just pull them from the main tubes of the "old mountain bike".
A park stand.
A piece of particle board or butcher paper to draw your frame on. If you use wood, you can bolt the bike to it later to help tack, just like when people make small airplanes or race car chassis.
A Bevel Gauge.
A half round file.
Welding hood or goggles.
Rubber chem gloves or a wire wheel.
A fire extinguisher.
Chromoly airplane tubes are choice. You can get them through wicksaircraft.com. Remember, you want wall thickness of .049" for main tubes and .058" for steer extension. You can go thicker but it won't make your bike any stronger, a little flex in the tubing takes the stress of the welds. I suppose you could use mild steel in .065" for main tubes. As far as main tubes go, I wouldn't go any smaller than 1-1/4 round, or any larger than 1-5/8. In-fact I recommend 1-1/4 OD for the top tube and 1-1/2 OD for the down tube. I believe you can use 1-1/2 .083 for head tube. I think using a square 1.5 inch mid tube is a good way to go, a great way to go!, just to make it easy to mount the rack. The easiest way I've attached a rack was by using two pieces of 1-3/4" angle to a square mid tube and letting the ends extend past the HT and form the rack portion.
Hole saws, one 1-1/8 and an a 1-1/2 will probably get you through the project if your brazing, if your tig welding buy holes saws after your tubes have shown up, tubing notched, and or printer for generating
Welding rod if your welding, brazing rod if your brazing, MIG set up if your Mig welding. For tig welding I use weld mold 880-t or 80s2 tig rod, I don't use chromolly tig rod anymore since I don't have my bikes normalized after welding. And you want your welds to be somewhat elastic. I like 035 and 049 diameter wire. I don't recommend Mig because its so difficult to obtain a high quality finished appearance with that method, but if your know what your doing it will hold. The nice thing about brazing if your ocd is that its easy to go back and fuss with your work afterwards with Tig less so, but with MIG each weld is a one shot deal. You can get your welding rod from wicks.
Brass Flux and brazing rod, and sorry to be a pain but not all brazing rod is equal, get the stuff through Henry James, but don't let them sell you lugs, if you use lugs you will need to make fixtures, or at least I did! Do not use harware store flux unless you want to chip it off with a hammer afterwards, the henery james flux will soke off overnight.
3'x4' piece of butcher paper, for 1/1 scale drawing
Regarding Fork, you may be able to find a recumbent fork that will do, but otherwise get a bmx fork.
Disk brake tab, I recommend a bb7 cable disk brake but since its hard to source twenty inch wheels with a disk tab you could also go with a drum brake front wheel. I usually use 32 spokes, 3x lace for front wheel, double wall rim for these, (plus they're easier to build) try to get this stuff for free, except for spokes, have a shop calculate length unless your a real masochist.
I use a little disk brake plate I made myself, it was one of the first tools I made, you can find ISO disk brake specks here, I have a photo of the disk brake plate and the rest further on.
Hand to have but nor required, angle finder, used copy of the Performance Welding by Ritchard Finch, Sink or Swim fabrication by Tom Lipton and for how to draw something that works Paterick Manual for frame builders by tim paterick.
Step 2: Making the drawing 1-1
The first thing your going to draw is the bike as it is before you cut into it., tubing projects are typically dimensioned center to center. I use a tape measure and measure the frame as it is, the bb drop on an old 26er mountain bike should be something around 5cm leaving you a seat tube angle between 71 and 73 degrees. Study trail, its interesting, wheel flop is also worth considering on cargo bikes but if your using a bmx fork you don't have a lot of options.Remember don't let the perfect be the enemy of the good. This is the anarchist truck bike for heavens sake!
On your drawing set your ht up at 72 angle that way you can be off a degree either way and still have fair handling.
On your dawning make second axle line at the height of the front axle.
From the end of your top tube, extend 1-1/8 ht, all the way to the axle line.
Draw your fork in, don't forget about fork offset which is rake.
Label the fork crown on the drawing
Label the race ring seat.
Add 15mm for a headset on top of that.
Now everything on top of all that is Head Tube.
About 50 mm up from there is the center of where your Down Tube is going to land,
Draw in your down tube.
Now draw in your mid tube, I recommend you use 1-1/2 square tube. To make it easy to bolt on angle iron.
Draw three 3/8 inch holes like 2-1/4 inches apart towards the front end of you mid tube.
For kicks draw in the front rack. I usually extend mine about 20".
Step 3: Somehow... aquire an old steel mtn bike
You probably wont have to make your own hack saw, depending on where your reading this from.
Look Around, Find an old TIG welded mountain bike laying around. It's best to find one that's not of a lugged as this will just complicate operations down the road and if your anything like me your probably already confused. Conveniently enough old mountain bikes, though they are some of the most practical as far commuting and touring are concerned, most cyclist aren't so discerning and bikes likes these are typically under valued, so you shouldn't have to pay too much to acquire one. Try to find one that fits with a working drive chain so once your done brazing or welding you don't have to run around looking for parts, don't worry too much about the front end of the frame, for extra credit find a Mountain bike that's been in an accident and has a totaled front end, as taking something useless and making something super useful out of it is maximum value added! Also don't worry about the fork, or the 26" Front wheel, that stuffs not going to fit on your truck bike anyway.
Step 4: Hack Frame Builder Philosophy 101
I.D. = Inside Diameter
O.D. = Outside Diameter
B.B = bottom bracket
T.T. = top tube
HT = head tube
You can make bicycles that are in better than industry standard, as far as planetary alignment is concerned, without a commercial frame fixture.(remember in an economy based on hyper specialization and price point competitiveness precision equipment is still directly interchangeable hours of skilled labor plus a little by guess golly ingenuity, and you have to make one hell of a lot of bicycle frames at at an opportunity cost of say $2000 each (that you could be making with the same skill set) to pay off a $5000 dollar bicycle frame fixture and I know there's at least one guy out there still building with a frame fixture sitting behind his table against the wall collecting dust. Your better off buying a tig and mill and a laith, and six months of shop rent with that money anyway)
Tolerance on your truck bike? The head tube shouldn't be out of plane with the seat tube or the rear wheel, but nothing is ever perfect, hold it up to the light and if it looks out, install a set off bb cups and put it in the vice and twist it until its perfect". At the limits of our ability to detect a problem, imperfection fades away and out minds move on to the next nagging issue, thus tolerance.
I have seen the insides of several professional frame builders and have heard tell of production frame facilities in which frames are produced in quantity, and in all of these shops, in a dark corner, far outside the fall of the limelight, there exist an heavy flat table where the unmentionable process of cold setting is preformed, watch a you-tube video if you don't believe me. I suspect all frames but carbon and bamboo are cold set at the end of the line, Cold setting is a process in which you carefully bend an intolerable malleable object until its tolerable. Thus as a general rule, bicycle frame producers preform cold setting or crooked frames.
To cold set a bicycle the bottom bracket is bolted to a table and various padded and or tight fitting torture instruments are wedged or inserted. You can make your own with 2x4s padded with pipe insulation and pipe and you don't need a feeler gauge and Blanchard ground table to make your truck bike perfect, you wont be able to ride with no hands with 4 cases of beer budgied to the platform anyways. Get a Jack Taylor approved string and learn how to sight down two tubes to see if they're parallel, on most bikes handling issues are a result of improperly machined head tubes, poorly adjusted headsets, wheels out of dished, or not dished to match the frame, or twisted forks, carbon forks, forks with mismatched blades, and or forked up forks.
A Tack is a partial weld, the best welders Ive watched work make lots of these tiny easily cut welds before checking for dimensions and test fitting and making sure everything correct before they make even more permanent. Only beginners get excited and weld before they have to, in fact the best fabricators/welders I've met hates welding and put it off every chance they get. Resisting the urge to make permanent increases overall optionality.
Mistakes, one of my big mistakes is getting all hung up on my mistakes, if this is your first bike frame project it will likely be a comedy. At least from someone else perspective.Your better off getting two frames and going as fast as you can and screwing everything up and verifying its worthlessness throwing it out and making the second one inside of two weeks than procrastinating for two years worrying you'll screw something up and verifying its worthlessness and starting over. Trust me, just screw it up already, keep it a secret if that's how you are, but screw it up.
To get away without a fixture your probably going to need to make a sub-assemblies, this helps line things up later, makes the welding work easier to access so later you don't have to wrestle the entire bike around to access all around the head tube/down-tube joint.
Forget about heat sinks, they can be nice, if your selling them and people are buying them, but you want to get your brazing done and quickly and none of this is thin enough to matter except per say the seat tube top tube junction, I recommend you keep the original top tube so long as the bike frame you start with is your size.
Step 5: Get a 20" freestyle bmx fork 1-1/8 ht (not chrome!)
ALT look for a recumbent fork with a disk brake tab. These forks are around and for as little as 40$ you will still have to extend the steer tube
Step 6: Stripping paint from frame and fork,
Paint stripper is nasty stuff, these days I wear a carbon respirator, safety glasses and a homemade mock laminate film glove, that is I wear two different types of rubber gloves at once, a neoprene base outer glove and a latex inner glove. That cooling sensation is a cocktail of evaporating solvents and the dissolving of the glove material itself! Talk about an endothermic process! Don't believe me? Read the link. Anyhow its probably less harmful to you than grinding the paint off with a wire wheel as you can actually control where the paint winds up, instead of airborne all all over your shop. My secondary advise is to round up everything your going to pull paint paint from in the next two months and pull the paint off everything at once so you don't have to do this over and over. Best of luck.
Step 7: After paint removal and drawing, cut around the bb and ht
As dumb as it sounds draw a line and plan your cut and then go post photos and come back and explain the cuts to your self and why your cutting where you are and ovce it makes sence take a hacksaw a or a di grinder with a cut off wheel, and cut right on the welds all the way around the tubes. Don't cut into the bottom bracket but what you miss you will have to grind off so real close! It's easier to cut than to shave. See image above
Step 8: Mitering your main tubes and makeing the sub assembly
If your tubes aren't mitering on center, make a shim with piece of hacksaw blade.
Be sure you feed real slowly, On my mill I miter at the lowest possible speed, my hole saws dont get hot and everything last and last, sorry to say, if your feeding the notcher by hand your in for a real treat. Just make sure your wearing safety goggles.
Starrett brand "six pitch" hole saws are creme de le creme and are used industry wide, are even used for mitering titanium tubes however hardware store hole-saws like Milwaukee work fine, finer teeth the better, and yes you can miter titanium with them all the same, and are the same price as the others finding an online store that has them stocked is a bit of a pain though.
The trouble is when a tooth catches and deforms the tube and then pinches the saw and all the sudden your really, that's the romance part I mentioned right there. So be sure to hold your tube tightly, be sure to pad the tube with copper if it is thin, you can also hammer a dowel in to support the tube on the inside. I used to miter chain stays and aero tubes with my "joint Jigger", so have confidence, and be an "artist".
Step 9: Mitering/coping the tubes
A tubing notcher can be obtained from harbor freight for 49$ there are guys online who have modified them to increase their precision and longevity I happened to come in to an American made one when I first started thanks to my bike guru so I cant say.
Hole saws for this project will add up to 20$, but last for several projects, just be careful to not over tighten the tubes in the clamp, i used to use leather or copper shims for .028 chain stays and scary thin main tubes, there's not only an art to working with bargain basement equipment there's a romance to it as well. Learn to revel in idealistic non sense, it's all we have!
You can also miter the tubes with a hacksaw and file them clean, there are tube profile generators online, that allow you to print the profiles, afterwords you wrap the paper and trace the profile onto the tube. I've never done this, I prefer the eyeball and sharpie method. There is no right way to make a cargo bike out of an old mtn bike, choose your own adventure.
Paragon tubing blocks are a game changer. If your going to make more than one bike go ahead and buy two of the for each round tube size your using, or make some out of wood if your reading this from some sort of sci-fi post apocalyptic waste land.
A. You don't have a Notcher, and really this does work and perhaps better than the notcher, I wouldn't know my printer has been out of ink since 2007.
You can find your fish mouth generator online here.
Your transferring print outs, or notching by eye, either way You can draw a straight line down the tube by placing the tube in the inside of a piece piece straightish angle iron and a brand new sharpie.
Once you have taped your print outs to the tube you can view the suggested cope from the side and make the two main cuts and clean up the rest with a file
B. if You have a notcher. Insert the tube into the You can check your angle by holding your bevel gauge up to the drawing and locking the swing arm in the correct spot and then holding it on Miter not perfect? Well your brazing or welding will compensate if your half the hack I am, and it's.049 tubing after all (if your doing it the way I recommend) and probably not titanium, so check your miter with a square or an angle finder and and if its within a 16th mark the long end with a sharpie and tack the long side of your miter first.
Remember a Hack is a person who's willing to role up their shirt sleeves and do whatever it takes to get it done and if people weren't willing to do things the wrong way (and don't tell anyone) we'd still be locked in some dystopic iceage rubbing sticks together trying to build a camp fire.
C. If you also have milling machine, put your tube in a block, mount your tube at the desired angle in the vice, find the center, engage the auto feed and get out your selfie stick!
Step 10: Brazing or welding main tubes
How to hold tubes securely while tacking, before you take the time, to let them cool and check them against your one to one drawing!
I really hope you have either a set of tube blocks or a vice
Step 11: Ballance the front triangle, or block it up on partical board, or call anvil and buy a fixture
Once ive checked my head tube/down tube sub assembly against my drawing and see that its good (or cold set) untill it was good enough, and mitered or filed a notch for seat tube in down tube/bottom bracket junction. its time to make some marks on your drawing and frame
I say, have a friend help you attach the new tubes, or build a fixture, or if your really hard up build up some clay mounds and stack everything in place. remember it just has to be in the right place long enough to place some tacks and double check.
I just made a couple of drawing and had a crash so, here Reference chopper builders handbook, Real applicable fabrication tips.
Step 12: The drawing alighnment, sighting, string or straight edge, tape measure
So the first photo is a bike directly over a one to one drawing, remember if your within 2 mm of your drawing your with a 1/3 of a degree over the length of a normal bicycle tube and looking good! The second is Sheldon Brown preforming the string test, you can be sure he's using jack Taylor approved twine, (be sure to use twine), you want to surround yourself with objects that promote an aesthetic of old world quality and know how. As a salvage cargo bike builder hack type, your clients are depending on you to provide that pre fiat currency back in the good old days when things were real, gold standard type feel.
Watch this video
Jack Taylor cycles didn't use a frame fixture. There used to be a video where they show two of the bothers working together, and talking about pull and why they don't use a fixture, and bending two fork blades at once,and sighting down the frame into a window looking to make sure the head tube is on the same plane as the seat tube, and don't get me wrong I think fixtures are great, i use a fixture for tacking chain stays, and another fixture for the main tubes when materials require back purging, but they don't necessarily keep the frame straight during welding, and frames are usually removed from fixture anyways after tacking so that welding can be preformed more uniformly and thus reduce pulling, and afterwards most frames go to the alignment tables or just go out the door crooked. But I can see the logic behind a crooked race bike, for one people often don't know their frames are out of alignment because they've never ridden straight bikes with the coplanar wheels. Vertical dropouts make a straight bike hard to achieve and once again when your racing your going to miserable no matter how straight your bike is and your gripped to the bar regardless and besides fine tuned alignment takes a back seat to weight savings, or whatever.All Im saying is you can suffer through a bike a two without the right stuff. Go get it!
Step 13: Gravitational Fixturing. Checking miters with your eye, tape measures.
I put a little white paint on that smaller tube to make the junction more visible. Once you tack in the front and the back you can tack one side and then the other, you should still be able to see the miter and if the two tubes are still tight together good job, check it against the drawing and, weld or braze it up. Don't melt your tacks when You need to start in a new place. A tig tack is 1-5 mm across, brass tacks maybe 5-12 mm across. Also remember if your miter was a little out, you need to tack the long side of the miter first.
A mechanic at a local bike shop was once explaining to me why Santana tandem frames are the most extensive steel frames in the cycling industrial complex. He said something about how any error mitering was magnified over distance and the tolerances on a tandem were half that of those on a singe, or some such nonsense. I figure he was thinking that adding a tube to an assembly was like sailing a ship across the ocean 400 years ago, and a degree or two off and you'd miss your destination by hundreds of miles and not find land nor gold, and be be keelhauled by your thirsty and starved mutinous crew. Well its only half that bad, tape measures are just as inaccurate at 50cm as they are at 150. and if your head tube is out by even a single degree it will show up on your tape measure like overheating fuel rod in a submarine movie. So get a good metric tape, and use the same one for the entire project, constantly compare you physical model to the one to one drawing you made. Before You tack the hocky stick to the rest of the bike check the measurement between the center of the st/tt junction and the HT/DT junction.
Step 14: The fork, Extending the steer tube.
If the steer tubes to short it's nothing to worry about, Your going to need to find two more tubes to take care of this, one tube that sleeves tightly into the top of the bmx forks exististing Steer tube, then your going to sleeve anouther peice of 1-1/8 od tube over whats left sticking out of the second peice. drill some holes in the steer tube and the exstention before you start on all this. If the fits are tight on these you shouldn't need to do any fancy alignhnent work, If your going to need to hammer it all together besure you coat the entire set up with brass flux before you put it together. if they're not just grab a peice of angle and clamp it all down in the corner, Now grab a torch and some rod and fill it all with brass or carfully tig the gap and fill the holes you drilled with plug weld.
Step 15: Disk brake for extra credit
Step 16: Top veiw-making angle iron rack
Step 17: Exstra credit kickstand
This is by no means specific and cant be since I don't know what kind of frame you modifying what fork, or what rack you made or chose, but here's most of what I know about truck bike kick stands.
Step 18: Reaming facing ht
Cutters only go forward, never turn them backward, (except for bb taps), keep the entire cuter covered in cutting oil while cutting. If your lucky a local frame builder or community bike shop will help you get this done.
Step 19: Franchise
Now that you've built your first salvage cargo bike go ahead and Franchise!