BANDITO SWB RECUMBENT BIKE
The Bandito is a lightweight, responsive and speedy short wheelbase recumbent with over seat steering and a seat height designed for safe riding. The adjustable bottom bracket allows riders of most leg lengths to set up the bike to their inseam. Because the final design is based primarily on the parts you start with, many variations in design are possible to suit your budget, building style and riding requirements.
The Bandito's transmission is built for ease of adjustment and urban riding safety, so there is no crank arm or chain interference with either the front wheel or front forks. The height and angle of the seat have also been designed around typical city riding so that you can reach the ground while stopped, yet sit high up enough to look traffic "in the eyes". Of course, the recumbent riding position greatly reduces your frontal area and lets you maneuver corners easily while pedaling, so the Bandito is no slow poke in any regard. The recumbent riding position also lets you deliver as much force to the pedals as you can muster, unlike an upright bicycle, where force is limited to your body weight. The short wheelbase means that the steering is very responsive, very much like a standard bicycle, so you can ride in a close formation with friends, or navigate the same obstacles that you normally would encounter on any bicycle.
The Bandito can be easily built by anyone with a welder, a grinder, and a few scrap parts such as an old upright bicycle and 1 two-foot length of mild steel tubing. The completed recumbent is just as light as many production models, handles extremely well in traffic and at high speed, and will give you a lifetime of faithful service.
The cost of building the Bandito is up to the builder, and will be dependant on the quality of components such as brakes, wheels and transmission hardware used, but typically, the bike can be completed for under $100 if you already have a donor bicycle to use as parts for the frame. When completed and painted, the Bandito will look as good as or even better than some production "bents", and when you proudly proclaim that you build it in a few weekends, you may find the entire bicycle club lining up at your garage door with spare parts and a fistful of cash!
Most parts for the Bandito will come from your donor bike, which should have a damage-free frame with 26-inch wheels, and at least the rear wheel in tact, if you plan to use it. You will also need a 20-inch front wheel and a pair of front forks that will fit into the donor frame's head tube. If you look at the threaded area on your original front forks taken from the frame, your 20-inch forks should have at least as much threaded area as measured from the base of the fork stem. If the 20-inch fork threads are a bit longer, you can trim them with a hacksaw or grinder cut-off wheel, but if they are too short, you will not be able to install any of the of the top fork hardware properly.
The front forks should be sturdy, like the types found on freestyle BMX bikes, since a short wheelbase recumbent will have more load over the front wheel than a typical bicycle would. Suspension forks are perfectly fine, although I would avoid using the type found on typical department store bicycles, since the suspension is mainly there for looks and the manufacturing quality is so low that the forks will not hold up nearly as good as a simply fixed type. There are decent 20-inch suspension forks available, but they will cost you some extra money.
Because of the way the Bandito is assembled, there is no reason why you couldn't use a 24-inch rear wheel, or even choose 20-inch wheels all around to create a recumbent for a younger rider, as long as you follow along the building process in order. Whatever size rear wheel you decide to use, just make sure the frame is the same size or else you will have a difficult time installing the rear brakes. A 24-inch frame will not take a 26-inch wheel, and a 26-inch frame will not allow caliper brakes to reach a 24-inch rear wheel. Other than that, there is plenty of room for your own modifications and additions to the plan. Before cutting anything up, though, it is a good idea to either read the entire text, or at least venture a few steps ahead to see what direction things are going.
When you do find your donor bicycle, remove and check over all of the parts you plan to keep as shown in Figure 1. Clean all grease and dirt to inspect the bearings and bearing races, and replace any wear parts that are rusted or excessively worn from use. Bearings, chain, cables and brakes should be replaced if necessary.
It's time to start hacking! Cut the donor frame as shown in Figure 2 so that you remove the head tube and down tube from the frame with as little waste as possible. Try to get the cut as close to the head tube shell and bottom bracket shell as you can without cutting into them; this will minimize the amount of cleanup necessary and allow the top tube to remain as long as possible.
If you are using a cut-off disc in your grinder to make the cuts, then beware when cutting through any tube that forms a triangle with other frame tubing, as the frame will tend to collapse on your disc as you get through the last bit of metal, which could cause your grinder to stall, or run out of your hand. If you have no way to secure the frame while cutting, then leave a sliver of metal during each cut rather than going all the way through the tubing, and you can simply bend the tubing back and forth to release it after the cuts are made. If using a hacksaw, don't worry about it - just hack!
Looking at the completed picture of the Bandito, you might wonder why the frame needs to be cut up so much, or why you can't just throw the 20-inch forks into the un-butchered frame and be done with it. Well, if you did that, your completed cycle would handle like an angry bull since the head tube angle would be way too steep. Replacing the 26-inch front wheel and forks with a 20-inch unit would lower the front of the frame by several inches, causing the head tube angle to be quite steep, possibly as much as 90 degrees to the ground. This steep head tube angle would make the ride extremely twitchy and hard to control, a real nightmare at high speeds. When we are done modifying the frame, the head tube angle will be almost the same as it was on the original bicycle, but with the smaller front forks and wheel installed.
Figure 3 shows my head tube cut from the remaining top tube leaving as little "stubbage" as I could with my grinder cut-off disc. A hacksaw will allow a closer cut, but will take much more effort.
The area on the head tube where the original top tube and down tube were once welded should be ground flush as shown in Figure 4, being careful not to dig into the shell. I normally start with a rough grinder disc then finish up with a sanding disc (flap disc) to avoid digging into the head tube shell. Removing the bearing cups is a good idea as well to avoid nicking them while grinding. Pound out the cups using a long bolt or rod from the opposite end of the tube.
Once you have the head tube cleaned up, reinstall the bearing cups by tapping them in with piece of tubing or long rod. Before going any further, ensure that the 20-inch forks and the bearing hardware fit together as shown in Figure 5. Keep in mind that there are three common sizes of bearing cups, races and bearings, so if there is a lot of friction once the hardware is installed, you may have mismatched parts. With the hardware hand tight and free of grease, you should be able to hold the head tube in one hand and give the forks a good spin with the other. If the forks do not spin easily, try different bearings; they may be too small for the cups.
The Bandito's bottom bracket will be placed on a boom tube over the front wheel, so the original bottom bracket will not be used. Unfortunately, you can't just cut out the original bottom bracket in order to relocate it elsewhere since it is an integral part of the frame, holding together the seat tube, chain stays and down tube. For this reason, we will leave the donor frame's bottom bracket intact and clean up the area where the down tube was cut as shown in Figure 6. Eventually, the bearing cups will be removed and the bottom bracket will be filled over with a bit of sheet steel in order to look like it was meant to be there, not just a leftover.
The head tube must be welded back on to the top tube where it once lived, but at an angle appropriate for the new 20-inch front forks and wheel. Too steep of an angle will cause small movements in the handlebars to translate into fast, jerky steering, and too relaxed of an angle will create a sluggish steering system that is hard to control at low speeds. When I refer to “head tube angle”, I am referring to the angle formed between the ground and an imaginary line drawn through the head tube until it reaches the ground as explained in Drawing 1.
Read ahead a few steps to see how all of this will be done before you make the necessary fish mouth cut at the end of the top tube as shown in Figure 7. The cut will be a product of your head tube angle, frame geometry, and fork size, so you should take a little bit of metal out at a time until the joint is ready for welding. I like to rough out the area with the grinder disc, and then carefully finish up with a round file to keep the gap to a minimum; this will produce a joint that is easier to weld.
As shown in Drawing 1, the angle between the ground and the imaginary line through the head tube will be 69 degrees. If you would like to experiment with this angle a bit, feel free, but keep in mind that a few degrees will have a large impact on the Bandito's handling characteristics. The chosen angle of 69 degrees seemed to be a good head tube angle for most riding conditions, and gave good results during high speed sprints and downhill runs as well as at slower speeds such as navigating crowded areas and starting off.
I find it easier to visualize the job by setting up the actual parts to be welded as shown in Figure 8. A stopper on the two wheels, and something to hold up the underside of the frame will make it easy to get the fish mouth cut in the top tube perfect for the 69 degree head tube angle. You should have all of the fork hardware installed, as well as the front wheel and inflated tire when you mock up the frame like this in order to get the head tube angle set correctly. To take the head tube angle measurement, use a straight piece of wood or rod aligned with the center of the head tube in order to form that imaginary line to the ground. Once the rod is in place, have a helper check the angle with an angle finder to make sure you are as close as possible to the correct angle.
If you plan to build bikes as a hobby, then you can make a good "head tube angle finder" by bolting two 3 foot lengths of 1 inch square tubes or hockey sticks together at the end using a bolt and wing nut. Just set the large angle finder with a protractor or adjustable square, and then place it on the ground as a guide.
Your fish mouth cut doesn't have to be water tight, but the fewer gaps you have to fill, the easier the weld. Figure 9 shows the head tube perfectly cradled in the top tube cut out ready for welding. There should be about half an inch of head tube past the top of the tubing at each end, and try to position the holes that are cut into the head tube shell so that the tubing covers them up once welded in place, just like they were originally. Also, if there is any leftover paint on the head tube shell, save yourself the agony of that horrific burning paint smell and sand it off before you weld!
The first tack weld will be made at the top of the joint between the head tube and top tube as shown in Figure 10. I like to make this weld with the bike mocked up like it is in Figure 8 so that I know the angle will be within a few degrees. The idea is to make the first tack weld at the top of the joint to hold the head tube in place so you can remove the forks. Before removing the forks, take the measurement between the head tube and top tube with an angle finder so you can use it as a reference as you make any necessary adjustments while the frame is on your workbench.
It is not important what the angle between the top tube and head tube is, just as long as it doesn't change over the next few steps, since you know the head tube was set correctly when you made the tack weld. Figure 10 shows my tack welded head tube with the front forks removed. Now, the frame can be easily handled and inspected on your workbench as you complete the head tube welding.
After removing the front forks, I checked the head tube angle again using the angle finder that was set while the bike was mocked up. If the angle needs a bit of adjustment just tap the head tube with a hammer or force it in place by hand; the tack weld will work like a hinge for now. Also, check the head tube angle from the front by referencing it against the seat tube as you look directly at the front of the frame. Both the head tube and seat tube should be perfectly aligned so that your two wheels are also aligned when the bike is put together.
If you are satisfied with the angle of the head tube as viewed from all angles, place another tack weld on the opposite side of the joint to secure the head tube for further welding. If you don't think the angle is set properly, and you can't move it enough to set it correctly, so break the tack weld and start over, if you must. A mistake here will cause errors in all the other welds that will be made on the frame.
With the top and bottom of the joint tack welded at the correct angle, you can now complete the welding of the top tube and head tube. Start with the top and bottom of the joint, then finish up around the entire joint as shown in Figure 12. The sides are done last to avoid pulling the head tube out of alignment from heat distortion.
With the head tube and top tube welding completed, it is a good idea to check things over one last time by installing the front wheel and forks. Check your head tube angle then view the alignment of both wheels directly from the front of the bike to make sure they are both aligned. If the head tube shows obvious signs of misalignment, it's not too late to practice your cutting techniques - a good welder always fixes his/her mistakes.
Professional frame builders use a jig to set up the parts for welding, but for custom bikes like the Bandito, the problem with that technique is: how do you know if your jig is straight? A wood jig is a joke, and a professionally made jig for a single frame would be extremely costly. Your eye is your best tool. I have been doing it this way for many years, and I can always produce a straight frame, maybe not always on the first try, but always before I paint!
From here, the frame practically builds itself. Well, you have to put in a little effort, but none of the angles will be a problem, since almost everything you do now is based on what you already have. As shown in Figure 14, the original down tube will now be cut and fish mouthed for re-installation where it once lived.
You won't have to take too much material off the ends to make a snug fit, so take you time and grind or file out a little bit at a time until the tube can be forced into place with minimal gap. Since I cut the tube very close to the bottom bracket and head tube, I was able to just follow the rough fish mouth cuts already in the tube to get it to fit. If there are cable holes or water bottle holes in the tube, try to place them in the same position when you reinstall the down tube.
Figure 15 shows the down tube re-installed in the frame with a short bead of weld on each side of the joint. It really doesn't matter which part of the joint you start with, but it is a good idea to weld only one quarter of the way around, and then switch sides, just in case the frame tries to pull to one side as the weld metal cools.
The same procedure is done at the head tube and down tube joint, welding one side at a time, and then switching sides to avoid distortion. It's always a good idea to remove head tube cups when welding, just in case you slip or strike the arc in the wrong place. To avoid a burn through, most of the heat should be concentrated on the head tube, since the frame tubing is much thinner. If you have poor ventilation in your work area, strip the paint back at least two inches from the joint, and there will be very minimal burning paint.
It's hard to tell that the frame in Figure 17 has been modified, except for the missing paint, but the geometry is radically different, and a 26-inch front wheel and forks would make a very odd bike, almost chopper-like due to the relaxed head tube angle. Continue welding until all of the gaps around the joints are filled in.
The welding should be solid and free of holes all the way around all of the joints as shown in Figure 18. Clean up any excess weld and fill any pinholes before you continue, since it is easy to work with the frame on your workbench at this stage. You can also re-install the head tube cups, which may seem to require a bit more force if the head tube shell has been warped a bit from all the welding. I like to start by tapping them in lightly with a hammer then finish by banging them in with a 2' x 4' piece of wood so the go in straight. If you only use a hammer, then you have to work around the edge of the cups or they will get stuck.
Normally, I leave the seat building until the end of the project, but in this case, we will need the seat installed in order to install the front boom, which will carry the adjustable bottom bracket. Since the Bandito can be built from practically any type or size of frame and wheels, the position and angle of the front boom tube will be based on where you are sitting on the frame, so a seat is necessary.
I like to make my seats using plywood as shown in Figure 19, foam, and some type of material covering. This method produces a strong, light and comfortable seat that suits just about any rider. I use 3/4 inch plywood cut out with a jigsaw. The seat size is totally up to you, but for reference, my seat base is 10 inches wide at the rear, and 7 inches at the front with a length of 10 inches, and the seat back is 10 inches at the bottom, 6 inches at the top with a total length of 14 inches. I also rounded off the top and front of each piece by tracing the edge of a dinner plate.
The angle of the seat is really up to you, and it will depend on where you bolt the bottom seat board, as you will soon see. An angle of about 120 degrees seems to be nice and relaxed, yet fine for city driving, so I just bent the three pieces of flat bar to approximate this angle The seat is strong, but the two halves can still be forced into a different angle if necessary, so there is plenty of room for tweaking later. Also shown in Figure 21 are the two foam pads used to make the seat - a 1-inch rigid foam for the back, and a softer 2-inch thick foam for the seat bottom.
When choosing a padding material, avoid that typical yellowish sponge stuff you find in seat cushions as it is way too soft to be of any use. It should be somewhat difficult to squash a 2-inch thick piece of good seat foam to half of its thickness with two fingers.
Figure 22 shows the completed seat ready for covering, which I will be doing later while the paint dries. The foam will be glued to the plywood using some spray on adhesive and then the corners are cut to conform to the plywood by tracing the edge with a grinder disk. The grinder disc makes a perfect curve around the seat, but be careful, as the foam might snag the disc and make the grinder fly out of your hands. If you are weary of this, use a long knife instead to cut the foam.
Seat covering is simply cut to fit, then stretched over the foam to be stapled on the back of the seat. A real seat is sewn together as a top cover with sides, but this "poor man's" upholstery system works equally as well and takes very little time. I am not big on cutting corners, but if you ride a lot, the seat material will wear out after a year anyhow, so why get too fancy? I chose a breathable spandex-type material that also resists moisture.
A few thumb tacks held the piece of plastic cut from the pail to the back of the seat as shown in Figure 26. Now the seat does not have the obvious home made look that it had with the ugly bare wood and staples showing. I will probably paint the plastic as well, so it was roughed up a little bit with some fine sandpaper.
The seat will be placed on the top tube so that the back of the seat reclines past the original seat post tube. To support the back of the seat, another tube will be welded to the end of the seat tube at an angle to allow a place to bolt the back of the seat. It is a good idea to read ahead a bit, just in case you have a different idea for a seat, or if you are taller than 6 feet, you may want to make adjustments that will put your body back a little farther on the frame.
You will not be needing the seat post clamp, so cut it off as shown in Figure 27 so that only a small bit of the tubing extends past the top of the frame. If your frame is rusty, you may have a tough time getting out the old seat post, so you might want to try gripping it with a pair of vice grips and then applying some heat to the frame with a torch. Heat the frame from the top of the seat tube to approximately the middle of the seat tube then stand on the down tube and try to crank out that old seat post. If you really can't remove it, just cut it with the tube, and it will become part of the frame forever.
The seat back supports is just a 7 inch length of old bicycle tubing, conduit, or even a steel seat post. As shown in Figure 28, it is cut at an angle so that the seat back will recline over the top of the seat tube when it is fastened to the top of this tube. The more that this tube is leaning back, the further back your seat will sit on the frame, so it may be a good idea to just tack weld this tube in a few places so you can decide the best fit for your body size and frame type.
My seat back support tube is at a 65 degree angle to the frame's top tube, and I am 5 foot, 8 inches tall. If you are 6 feet or taller, you may want this tube to recline a little more so your seat can sit further back on the frame. The angle of this tube does not affect the angle of your seat since it only support it at the top; it does, however, affect the position of the seat base on the frame as you will see in the next few steps.
With the seat support tube cut to length, it is a good idea to cap off the open end of the tubing so that it looks cleaner and keeps any moisture out. As shown in Figure 29, a washer is welded over the end of the tube and then completely filled in around the joint and the hole. To fill in the washer hole, several passes are made around the edge until completely covered in weld metal.
After welding the washer in place and grinding the area clean, you can't tell that the tube shown in Figure 30 once had an open end. Going the extra mile can make your final product look very professional, possibly even better than some mass produced machines, since they might have simply capped the hole with a plastic plug to save time and money.
The seat back support tube is welded directly to the cut end of the seat tube as shown in Figure 31. If you want to experiment with seat angle and position, then you may just want to tack weld it for now for easy adjustment. If you really like to invent, then a fully adjustable seat can be made by adding some type of hinge and locking device so you can set your seat up for racing, touring, or city riding. Have a look at a recumbent exercise bike for some good ideas.
The two components shown in Figure 32 will be used to fasten the seat to the frame. The small 1-inch bit of square tubing at the top will be welded to the 4 inch long piece of flat bar below it to form a seat base mounting plate. The angle of the cut on the 1-inch tube will determine the angle of the seat base in relation to the frame, so a little experimentation will be necessary in order to find your optimal position. Since I wanted my seat halves to be at a 120 degree angle, I just cut the tube to whatever angle was necessary to achieve this. When my seat is fastened to the bike, the seat base is on a slight upwards angle as compared to the ground; this way I don't tend to slide off of the seat.
On my frame, the seat base fastener is welded to the top tube so that the fastening plate sits near the front of my seat base. The exact position on the frame will be determined by your seat angle, size and the position of the seat back support tube. On my frame, it was about midway on the top tube as shown in Figure 33. This is another part you may only want to tack weld in place until you are happy with your overall seating arrangements.
To securely fasten the seat to the bike, another bit of flat bar is cut for a rear seat base fastener as well as one for the top of the seat back tube. Figure 34 shows the two parts cut from the same leftover 1-inch flat bar. The small tab with the single hole will be welded to the top of the seat back support tube.
Figure 35 shows all three seat fasteners installed. The seat base fastener closest the rear of the bike is welded directly to the frame since the seat will be angled a bit upright in relation to the ground. The frame's top tube is roughly parallel to the ground and the front seat base fastener is 1.25 inches higher than the rear, so this places my seat base in a reclined angle. If the seat were parallel to the ground, the rider might tend to slide forward when not pedaling. The single hole tab is also shown welded to the top of the seat back support tube.
The front boom is made from a length of 1.5-inch mild steel square tubing with a 1/16-inch wall thickness. This tubing can be ordered from most steel suppliers and is very easy to cut and weld. Steel suppliers like to rate tubing wall thickness using a gage number, so 1/16-inch wall tubing will be called "16 gage tubing", and although there is a slight difference between the two, your best bet is to tell them you want a length of 1.5-inch square tubing with a wall thickness as close to .0625 inch (1/16) as you can get. Since you only need approximately 2 feet of the tubing, you might find a bit of leftover for free.
Round tubing of equal diameter and wall thickness can also be used, but as you will soon see, the square tubing actually becomes part of the sliding bottom bracket, and it would take some creative thinking on order to make this system work with round tubing. OK, let's start with a 2 foot length of the square tubing, which will leave plenty of room to adjust the bottom bracket for riders up to 6 feet tall. If you are taller than 6 feet, you should add 1/2 inch to the 2 foot length for every inch taller than 6 feet you are just to be safe. Sound like a math riddle?
One end of the tube will be cut at an angle as shown in Figure 37 so that when it is placed against the head tube, will allow the boom to extend parallel to the ground. Read ahead a bit and you will understand exactly how and why this is done.
As stated earlier, one end of the boom tube is cut at the same angle as the head tube so that the boom will extend outwards from the head tube parallel to the ground as shown in Figure 38. Since my frame's top tube is roughly parallel to the ground, the boom tube looks like an extension of the top tube. This angle does not need to be precise, just enough so that the head tube angle and cut angle are fairly close. The fish mouth cutouts to be made in the next step will reveal any slight errors.
I like to rough out the cuts with a grinder disc then finish up with a round file to produce a nice cutout as shown in Figure 40. The fewer gaps you have to fill when welding, the less chance of a misalignment due to heat distortion. Welded metal tends to shrink a lot when it cools, so a small gap greatly reduces this effect. Notice that both ends are cut out the same amount.
The other end of the front boom tube will be capped off with a bit of sheet metal, or piece cut from a bit of scrap square tubing. I cut some 1.5-inch square pieces from a scrap length of the same tubing, since I always cap open tubing ends. Just about any thin steel will do the trick, as long as it is approximately 1.5 inches square.
Once fully welded, the edges are ground with a rough grinder disc, and then finished off with a sanding disc to make the tubing look as though it never had an open end as shown in Figure 43. This is the front of your bike, and will be noticed, so a little extra effort here goes a long way in making the final product look more professional.
As stated earlier, the front boom tube will extend out from the center of the head tube so it is parallel to the ground. If you made the fish mouth cuts correctly, you should be able to place the end of the boom tube against the head tube and have a good joint when both ends are at the same height from the ground. A level placed on the top of the boom tube can be used to check this. If the tube seems to mate nicely with the head tube, then make a nice strong tack weld at the top center of the joint as shown in Figure 44. With the single tack weld at the top of the joint, you will be able to make any fine adjustments in alignment, which should be checked by looking from the front and top as well as the side of the frame.
Once you are satisfied with the level and alignment of the front boom tube, weld across the top of the joint as shown in Figure 45. Don't weld any more of the joint just yet, just in case something does not work out with your crank arm clearances. Chances are you will have no problem at all, but if you are shorter than 5 foot 4 inches, or you have made some modifications to the original plan, you may need to lift the boom slightly to avoid a crank arm or pedal hitting the front wheel. This will all be dealt with as the build progresses.
The bottom bracket and included seat tube will be mounted to the front boom tube with a clamp arrangement that allows the assembly to be placed just about anywhere on the boom to allow riders of varying heights to ride the bike. The two plates shown in Figure 46 will form the sides of the clamp that will hold the bottom bracket against the side walls of the main boom as they are forced together by two bolts.
The bottom bracket and front derailleur tube move together along the main boom, so you do not have to worry about the position of the derailleur over the chain ring. The chain is cut to the perfect length once the bottom bracket has been adjusted for the main rider, but will still allow for a few inches of adjustment in either direction without a chain alteration due to the spring loaded rear derailleur. Of course, the difference between a 6 foot 5 inch adult versus a 4 foot tall child will most likely require some chain adjustment, but this can be done in less than a minute with an inexpensive chain link tool.
Cut two 3/16-inch thick pieces of plate or sheet to make the shapes as shown in Drawing 2. The round area is cut to conform to whatever size bottom bracket you decided to go with, and the two bolt holes will be drilled for 1/4-inch bolts. The bolt holes are drilled at the edge of the plates so that there is 1/8 inch of material between the hole and edge of the plate. These two plates will form a "vice" that will clamp the bottom bracket to whatever position on the main boom you want.
Trace around the bottom bracket shell to draw a line on the plate as shown earlier in Figure 46. The marker line should meet the corners of the plate to ensure that you don't cut out too much off of the plate when grinding out the rounded area. If you take too much metal away from the plate, there will not be enough room between the bottom bracket and the clamping bolts for the main boom.
When grinding out the traced circular area for the bottom bracket as shown in Figure 47, place both plates in the vice so they can be done at the same time; this will ensure that both plates are exactly the same size. Try to make the gap as small as possible around the bottom bracket shell so that there is less distortion as the plates are welded. If the bottom bracket becomes overly distorted, it will be a serious challenge trying to screw the hardware back into the bottom brackets without stripping the threads.
In order to get the two plates aligned with each other and at the correct spacing, a bit if frame tubing can be clamped between the two plates as shown in Figure 48. This will allow you to set the bottom bracket into the correct position for tack welding, as well as ensure that both plates are aligned with each other so the bolt passes easily through both holes. I also placed a sheet of paper (folded in half) between each plate and the side wall of the tubing in order to allow a little clearance between the clamp plates so that the unit is not so difficult to slide when making adjustments. Without the small gap, it is easy to scratch the paint if you plan to move the bottom bracket around a few times.
As shown in Figure 49, I used an adjustable square set to the required 56 degrees in order to set up the bottom bracket and derailleur tube to place two small tack welds at the top of the joint. It may be a bit tricky to get the first tack weld in place while holding the bottom bracket in position, but once this is done, the rest is easy.
With the piece of frame tubing as a guide, you will automatically have the correct distance between the plates. Now, you will need to ensure that there is approximately equal distance between each plate and the edges of the bottom bracket. In other words, the bottom bracket will be in the center of the main boom as viewed from above.
Figure 50 shows the first tack welds done at the top edge of the plates in order to secure the parts together. Ensure that the derailleur tube angle is close to 56 degrees and that the bottom bracket is at 90 degrees to the square tubing. You can also move the clamps to hold the plates in a position that will allow you to weld around the entire joint, but do not begin welding without them as there may be distortion. Also, welding is only done on the outside of the joint, not between the plates. If the inside of the joint is welded, the weld bead will not allow the bottom bracket to sit directly on the frame tubing and could cause alignment problems. Because of the way the clamp system works, there would be no added benefit from welding the inside of the joint anyway.
The two plates will form a vice-like grip on the frame tubing when the 3/8 inch bolts are tightened. In order to drill the holes into the plate, draw a line that represents the bottom corner of the frame tubing as shown in Figure 51. Now you can punch and drill the holes using the line as a guide that will allow you to ensure that the holes stay below the line. If the holes are not below the line, you will not be able to pass the bolt through both plates because it will hit the frame tubing instead.
With the derailleur tubing cut to length, it is a good idea to cap off the open end of the tubing so that it looks better and keeps any moisture out. As shown in Figure 52, a washer is welded over the end of the tube and then completely filled in around the joint and the hole. To fill in the washer hole, several passes are made around the edge until completely covered in weld metal.
After welding the washer in place and grinding the area clean, you can't even tell that the tube shown in Figure 53 once had an open end. Going the extra mile can make your final product look very professional, possibly even better than some mass produced machines, since they might have simply capped the hole with a plastic plug to save time and money.
Place the bottom sliding bracket onto the front boom, then install the pedals and crank arms for a front wheel clearance test. Have a helper adjust the position of the bottom bracket while you sit on the seat and rotate the cranks. Don't tighten the bottom bracket clamps too much right now, just enough to hold the unit in place. Also, if you have only welded the top of the front boom, take it easy when you are pedaling, avoiding putting any real pressure on the pedals. You should be comfortable in the seat, and your knees will almost lock out on each rotation when the bottom bracket is set for your leg length. At this point, you should have no problem with crank or pedal interference as you turn the front wheel from side to side as shown in Figure 54.
If, for some reason, the crank arms rub on the front wheel when the bottom bracket is adjusted for your height, you will have to lift the front boom up a little bit to compensate. Chances are there will be plenty of clearance, but if you are a shorter rider, or have made frame changes, then some minor adjustments on the boom will be needed.
If everything seems to work without interference, then remove the front forks and complete all of the front boom and head tube welding by finishing the bottom of the joint, followed by the sides.
To place the handlebars high up enough so that the arms are in a relaxed position, an extended gooseneck will be needed. The gooseneck extension will be made by cutting the clamp section a standard bicycle gooseneck and welding it to a length of steel tubing cut from a standard steel mountain bike handlebar. This extension will then be welded to the bottom of the gooseneck so it can be inserted into of the head tube as normal. The two components are shown in Figure 55 before any cutting was done. Any steel tubing similar to the strength of mountain bike handlebars will also work, but the small bend in the handlebars could work to your advantage, as you will soon see.
The mountain bike handlebars are perfect for this extension because the gooseneck clamp will most likely slide right over top the end of the handlebar that normally held the handle grips. As shown in Figure 56, the clamp is cut from the original gooseneck so that an inch of tubing is left on the clamp. The mountain bike handlebars are then cut in half right at the center to include about an inch of the fatter part of the tubing. Again, feel free to experiment with the length of the extension and the angle of the tubing; it really is just a matter of what feels most comfortable to you. If you really want to get creative, you could make some type of clamp system for the base of the extension to allow the entire extension tube to move forward or backward.
The gooseneck clamp will be welded directly to the end of the handlebar tubing by placing the cut end of the gooseneck over the handlebar tubing as shown in Figure 57. Most common steel mountain bike handlebars and goosenecks are made with the same type of tubing, so they should fit snugly together. If the clamp tube does not slide over the extension tube, then you will have to make a butt joint weld, but this is not a problem. Take note of which direction the bend in the extension is facing compared to the handle bar clamp when you joint the parts.
The base of the extension tube will now be welded to the cut end of the gooseneck as shown in Figure 69. A small fish mouth is cut in the gooseneck to make a better joint, and then welded all the way around. Again, you will have to make sure that the clamp is aligned so that your handlebars are at 90 degrees to the gooseneck tube, just as they were before you cut the clamp. I find it convenient to have a straight set of handlebars inserted in the clamp to get things lined up when I weld these parts together.
As shown in Figure 60, the handlebar clamp is positioned in such a way that if you drew a line extending from the center of the gooseneck tube, it would hit the center of the clamp; this is why the extender tube is welded in place at a slight angle. This is another place where you want to make sure your welding will hold up, especially if you are in the habit of gripping the handlebars tightly while racing or climbing hills.
To install the steering system, place the fork stem into the head tube and tighten the bolt when your front wheel is aligned properly. For handlebars, I found that the old "granny bike" style bars shown in Figure 61 work perfectly for overseat steering recumbent cycles as they allow good knee clearance, offer plenty of room for all shifter and brake hardware and place the wrists at a good angle. Of course, there are thousands of sizes and shapes of handlebars, so experimentation is the key.
Make sure that all of your seat padding is installed when you are testing handlebars - that extra inch can make a huge difference. You should be able to turn the handlebars in both directions to at least 45 degrees and still pedal without any knee interference.
Although your Bandito is almost ready for launch, there are a few loose ends that need to be tied up first, such as chain management. If you tried to install a chain directly from the front chain ring to the rear wheel as it was on the original bicycle, it will rub on the front wheel when you turn. This may be fine for a closed circuit lowracer, but not for a street safe recumbent, so we need to get that chain out of the way of the front tire. The two pulleys shown in Figure 62 are garden variety v-belt idler pulleys found at any hardware or yard machinery shop. They have a diameter of 2.5 inches, and are designed to guide 1/2 inch v-belts and have an included roller bearing for low friction operation.
Since we are only guiding the return chain, which has no tension applied to it, practically any idler wheel will do the job, but I recommend that you choose one that is larger than 2 inches in diameter, and ensure that the pulley has a proper bearing, not just a brass bushing. Metal or plastic idlers will be fine, and if you want to get creative, a skate blade wheel with a groove cut around the edge will also work for this purpose.
You will need two of the same idlers for reasons soon to be explained, as well as bolts and nuts to hold them in place. The two discs traced out on the 1/16 inch sheet metal will be welded over the unused bottom bracket holes to finish up the frame as well as provide a place to mount the second idler pulley.
Cut the bottom bracket covers from some leftover sheet metal as shown in Figure 63. The cuts do not have to be perfect, so you can make them with a grinder cutoff disc as I did, or take your time with a metal cutting blade in your jigsaw. The two covers will be welded over the bottom bracket shell, so draw circles of whatever size you need. There are two sizes of bottom brackets - a larger one for one piece cranks, and a smaller one for three piece. The bottom bracket I covered up is the larger 1 piece type, and the sliding bottom bracket I made for the Bandito is the smaller size.
The bottom bracket covers are welded all the way around on both sides of the bottom bracket as shown in Figure 64. Take both bearing cups out before you add the covers or the welding will be messy due to the hardened steel used to make the cups. The welds will be cleaned up. Don't try to be a perfectionist here, just get the entire joint welded all the way around on both sides.
Now that "leftover" bottom bracket looks like a well-thought part of the frame construction and provides a place to mount the lower chain idler pulley as shown in Figure 65. Although the front idler pulley will keep the chain out of the front wheel, you still can't get away with only one since the chain will ender the rear triangle over the top of the chain stay tubes. This may not seem like a problem at first, but you would soon find out that your chain would rub on the frame when shifted to the two smallest chain rings on the rear cluster. For this reason, the lower idler pulley puts the chain on the underside of the chain stay tube, just as it was on the original bicycle.
The idler pulley mounting bolt is welded to the center of the right side bottom bracket cover. You can cut the head off the bolts like I did, or leave them as is - both methods will work just fine.
The front chain idler pulley will be placed a few inches from the head tube on the down tube as shown in Figure 66. My mounting bolt is 4 inches from the head tube, but it is probably a good idea to throw a length of chain in place and check to see that that chain is clear of the wheel before you weld the bolt in place. The chain should clear the wheel and top of the front forks by at least half an inch or so.
The Bandito's bottom bracket is much further away from the rear wheel than that of an upright bicycle, so you will require a chain almost twice as long as normal. Shown in Figure 67 is a wad of chain consisting of two new lengths of standard derailleur bicycle chain and an inexpensive tool that makes joining chains so much easier than old hammer and punch system. Two chains may be a little too long, but it's a good start, so go ahead and join them into one long single chain. Look out for those brain teasing loops!
When you are setting up the correct chain length, you will need the rear derailleur installed. Place the chain on the largest front chain ring, and the center rear cluster ring and cut the chain so that the rear derailleur is pointing towards the ground. Figure 68 shows my newly fitted chain, and there is no front wheel interference thanks to the idler pulley.
If the urge to test ride your creating is killing you, then fear not, all that is needed is at least one brake to be installed. Figure 69 shows my rear disc brake hardware and two small tabs cut from some 1/8-inch steel. I wanted to have both a front and rear brake, but since most of the braking will be done on the rear wheel, I decided to go for a quality disc brake. Disc brake hardware is inexpensive and common, and it is highly recommended, especially if you like to go fast or down hills. Caliper brakes also do a decent job when set up correctly, but at the base of a hill doing highway speeds; I feel good knowing that my brakes will be reliable.
Brakes are easy to install on the Bandito, since the original rear brakes and front fork brakes will work the same way they did on the original bicycles.
There are many different sizes and styles of disc brake systems, but I have found that this simple "tab method" has always worked well for installing them. As shown in Figure 70, I bolt the tabs to the brake hardware, and then engage the lever to let the calipers grip the disc to center the hardware. With the lever tied tight, place the mounting tabs in the correct position then carefully tack weld them in place. This method ensures a perfectly aligned disc brake. Keep in mind that the rear wheel still needs to come out of the dropouts, so try to mount the disc brake at the top of the axle. A little tape on the brake hardware will also protect it from weld spatter when making the tack welds.
Once the mounting tabs are securely tack welded at the correct place on the frame, remove the brake hardware and finish the welding on both sides of the mounting tabs. Figure 71 shows the welding completed and brake hardware reinstalled for a test fit. If your disc rubs on the hardware and you cannot fix this with small adjustments on the rear wheel axle, place a small washer or two in place on the brake mounting bolts. This is how it is done on many disc brake equipped bikes.
You can now safely test ride your bike to see if there are any last minute modifications that need to be done before the painful process of waiting for primer and paint to dry.
It's bad luck to head off to the paint shop before you test your machine, so throw at least one brake on, set your derailleurs for mid-range gearing, and hop on for a ride. If all goes well, you will be smoking in to the first corner at high speed with the wind in your hair. If you have never ridden a short wheel base recumbent before, and then you may be flopping around like a freshly caught fish right off the start, but fear not, it doesn't take long. What I found difficult to get used to was the fact that your feet stay in a fixed position when you are turning, and since you can't see the front wheel, this seems a bit odd at first.
A good spray primer and paint can look as good as a professional paint job if you take your time and apply it in several coats. I hang my frames from an outdoor clothesline for painting, and this always turns out a paint job that looks great as long as there are no mosquitoes stuck to the paint! Figure 73 shows my painted frame curing for a few days so that the paint will not scratch easily when the bike is put back together. The can said to let paint cure for a week, but let's get real - I need to ride!
The painted Bandito in Figure 74 looks like it came directly form a bike shop! All bearings are freshly greased, the tires are brand new, and most of the components are mid-range quality. I added a few lights, a bottle holder and a carrying rack to finish up the bike. Fenders will also be added, but locating a matching 26-inch and 20-inch pair may be a chore.
The patient process of adding all of the cables is a bit time consuming, but like all jobs, patience always wins. Cabling a bike is an art that requires a bit of planning and strategically placing tie wraps in order to look neat and clean. Avoid any sharp bends, and ensure that there no cables are rubbing on any of the moving parts, such as the tire or cranks.
Derailleurs will likely need adjustment on the minimum and maximum screws so that the chain travels to the largest and smallest chain rings without falling off. There are many choices for shift levers, but I seem to get along well with the old school road bike styles that mount to the gooseneck. These simple shifters need no adjustment and rarely break down. Indexed shifters are really nice, but do cost a fair amount and can be difficult to set up correctly.
The Bandito is an easy recumbent to get used to, once you learn to start properly. Start off with your launch foot on the crank placed at the 12:00 position and shove off. If you have never ridden a recumbent before, you may over steer a bit at slow speeds, but after an hour or two, riding the Bandito will feel natural, and you will be perfectly stable at any speed. It feels nice to be able to keep the cranks working while turning tight corners and you will find that the Bandito responds with great acceleration as you pour on the juice.
Some say hill climbing is a chore on a recumbent, but I disagree, and perform far better on a recumbent bike than I do on a "wedgie bike". On an upright, your body weight is all you can deliver to the cranks, which limits your effective power since most people can press two times their body weight. On a recumbent, you are only limited to your own strength and the will power to conquer the terrain.
If you have had a bicycle between your legs for many years, then there a re a few things you have to get used to on a recumbent; you do not have to stop pedaling on every corner since the pedals won't scrape the ground. You can really carve the Bandito hard into the corners since so much weight is on the front wheel. I have blasted into corners at speeds that made me nervous, but I doubt that I was anywhere near the bike's limits, which had already surpassed what I could have accomplished on an upright bike. A good set of minimal tread high pressures tires is a must on a bike like this.
Well, I hope you become great friends with your new recumbent bike, I sure have. Besides those sore quads from all the sprinting I like to do, there is no pain at all on such a comfortable bike, and long distance hauls are truly enjoyable.
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