Marauder Lowracer - Part 1 of 7

Photo 0 - The original Maruader V1 built in 2001

Although it may only look like a pole with a wheel at each end, the Marauder is a great machine for both comfort and handling as well as being fast as lightning! The Marauder is the result of six months of redesigned frames and originally began life as a tricycle with two 20 inch front wheels and a rear 20 inch wheel. After for or five more major frame and steering alterations, it has become the sleek and fast lowracer presented here.

My main objective when creating the Marauder was to have a lowracer that had all of the positive characteristics that make a bike like this fast and fun, but none of the negative characteristics that would make it unpractical for street driving. Since I am not a big fan on going around in circles on a small racing track but do enjoy going as fast as I can with only my own power, I needed a bike that would be able to provide both speed and proper behavior on the street.

The problem with trying to use many of the commercially available lowracers on the street becomes apparent in the drive line. Since they are mainly designed for racing on smooth bicycle tracks and indoor velodromes, there is no real need to be able to make sharp turns or have a large field of view – as long as you can see the track and who you are about to pass, that is usually sufficient. Because of this, most of the commercially available lowracers have a short wheelbase design, and this places the front wheel in between your seat and the pedals. Because the front chain ring is placed ahead of the front wheel, the chain must pass along side the front wheel to get to the gear cluster on the rear wheel. Also, unless you have ultra long legs, there will be some crank arm overlap with the front wheel as you pedal. Now, having a chain running only an inch past the front wheel, and having a crank arm that could stop you from steering may seem a little dangerous, but since you only making the same small turns on a racing circuit, and not having to make ultra fast decisions as you may riding on a busy city street, these little quirks are not such a bad thing in a race considering the advantage they give to the bike.

The Marauder is designed to avoid the visibility and steering problems associated with short wheelbase lowracers by placing the front wheel ahead of the cranks, and placing the bottom bracket low enough so that you can see more than your feet in front of you. The disadvantage of a longer bike is that the turning radius will be larger, but it is still not so great that you can’t do a u-turn on a narrow city street. I would certainly choose a larger turning radius over having my crank arm jammed into the front wheel as I was trying to avoid hitting something or someone!

Most of the frame for the Marauder is made from 3/32 thick 1.5 inch diameter square or round tubing. Square tubing will be easier to work with especially when welding the angles, but I have seen this frame made with round tubing and it turned out just as good as my square tube version. Besides the square tubing for the main frame, you will also need two head tubes, a three-piece crank set bottom bracket, chain stays cut from a 26 inch frame, and two pairs of forks – one for a 20 inch wheel, and the other for a 26 inch wheel.

Have a look at Photo 1 to get familiar with the basic frame parts and dimensions. Don’t become overwhelmed if it may seem like there is a lot more information to contend with compared to the other projects in this book, these are mainly reference points to make it easier to refer to certain areas of the frame. Since the Marauder shares almost none of the familiar geometry of a regular double-diamond frame, I will call many of the frame parts by the letters assigned in Photo 1.


Photo 1 - Each part of the Marauder’s frame will be assigned a letter for reference.

Although you may want to change some of the measurements and angles to suit your own building style, many of them can be used exactly as shown to build your own Marauder with the exception of tube “G”, as this determines the proper length of the frame for a given rider.

For reference, here are the lengths, angles, and names for each letter of Photo 1…

A) Rear forks (made from a 26-inch set of front forks)

B) Chain stays (cut from a standard 26 or 27-inch frame)

C) Seat back tube (15 inches of 1.5-inch square or round tubing)

D) 130 degree angle between tube “C” and tube ”G”

E) 145 degree angle between the remote steer tube support and tube “G”

F) Steer tube (standard head tube cut from a bicycle frame)

G) Main tube (1.5 inch 3/32 thick square or round tubing)

H) 145 degree angle between tube “G” and tube “J”

I) 105 degree angle between tube “J” and head tube “K”

J) Front tube (9 inches of 1.5-inch square or round tubing)

K) Head tube (standard head tube cut from a bicycle frame)

L) Front forks (standard 20-inch bicycle forks)

M) Bottom bracket (standard 3-piece bottom bracket)

The first thing you need to do is determine the correct length for the main frame tube “G”. This length determines the proper position of the bottom bracket depending on the height or inseam of the rider. The following chart is a fairly accurate comparison between rider height and the length of the main tube, although, you may want to find this measurement out for yourself.

5 foot 4 inches = 34 inches

5 foot 5 inches = 35 inches

5 foot 6 inches = 36 inches

5 foot 7 inches = 37 inches

5 foot 8 inches = 38 inches

5 foot 9 inches = 39 inches

5 foot 10 inches = 40 inches

5 foot 11 inches = 41 inches

5 foot 12 inches = 42 inches

5 foot 0 inches = 43 inches

5 foot 1 inches = 44 inches

5 foot 2 inches = 45 inches

5 foot 3 inches = 46 inches

5 foot 4 inches = 47 inches

When you have determined the correct length of the main tube “G”, cut it off square at both ends. Now you can cut the 15-inch length of tube for the seat back tube “C”. As shown in Photo 2, tube “C” rests on top of tube “G” to form an angle “D” of 130 degrees so it will need to have the end cut at the proper angle. Weld tube “C” so that the bottom rear corner meets the top rear corner of tube “G” as shown in Photo 2. The gusset is added for extra strength and is made from a piece of tube the same as the tube used for the frame. The gusset is necessary here because this is the joint that will support most of the rider’s weight.


Photo 2 - The main tube “G” and seat back tube “C” are joined and gusset is added.

Once you have tube “G” and “C” joined, cut the 9-inch length of tube needed for the front tube “J”. This tube will join the head tube to the frame and help lower the bottom bracket. It would be possible to eliminate this tube and just extend the length of the main tube “G” right to the head tube, but this would place the bottom bracket quite a bit higher, and you would have to look over your toes as you ride. As you can see in Photo 3, tubes “G” and “J” are joined so that an angle “H” of 140 degrees is formed. Grind the ends of the tubes to the proper angles for joining, and then weld them together.


Photo 3 - The main tube “G” and front tube “J” are joined.

The remaining end of front tube “J” is now grooved out to take the head tube “K” as shown in Photo 4. An angle of 105 degrees is formed at the joint labeled “I” in Photo 4. This angle determines the steering angle of the forks in the final design. If you want to experiment with this angle, then only add a small weld on each side of the joint for now, so you can grind it off later for alteration. An angle of 105 degrees from the front tube was chosen because it puts the front forks at about the same angle that they would be on a regular bicycle, and this has proven to be a good choice for handling and control on the Marauder. As you reduce the angle of the forks so they become closer to horizontal, you create steering with a much faster response, and this can give you a “twitchy” feeling when you ride – scary at higher speeds.


Photo 4 - The head tube “K” is joined to the front tube “J”.

Marauder Lowracer - Part 2 of 7

Photo 5 - Cut the fork legs from the stem as close to the joint as possible.

Now get ready for the hardest part of the entire building process – joining the fork legs to the frame. This can be a difficult task because the fork legs have to be positioned so that both are at the same angle, both have an equal distance from the frame center, and the lowest part of the frame should not have less than 5 inches of clearance to the ground when the rear wheel is in place.

This may seem like a daunting task to complete without a complicated frame jig, bit it is not – it is only a test of patience. Since I have successfully made three of these frames now, I have found an easy way to get the job done. First, place the cut for legs into the rear wheel you intend to use and tighten up the nuts so both fork legs are held securely in place at the same angle to each other. Now place the front wheel and forks into the head tube and lay the frame on the ground as shown in Photo 6. A long stick or string is placed between the wheels to represent a ground reference point to gauge how much clearance there will be between the lowest point on the frame and the ground (5-6 inches is a good amount).

Now with the frame set for proper clearance, place the top of the fork legs into position at the top of the seat back tube “C” as shown in Photo 6. Don’t worry about the side-to-side alignment right now, this will be adjusted later – only be concerned with the height of the frame and position of the fork legs. Once the fork legs are placed in the proper position, add a sturdy tack weld to the top leg of the fork (the one facing you). With this sturdy tack weld holding one of the legs to the frame, you should be able to move the frame onto a workbench to clamp it into a vice without disturbing the angle of the fork leg.

With one fork leg holding the wheel in place, you should be able to look down the length of the frame in order to force the rear wheel into lengthwise alignment. While you do this, try not to disturb the horizontal angle of the tacked fork leg, or this will alter your frame-to-ground clearance. With a little effort and careful eying of the frame, you should be able to manipulate the wheel until it is in a perfectly aligned position. Once you have it, just add a small tack weld to the other fork leg, and this will hold the side-to-side alignment in place.

Now take your frame and wheels back to your ground reference point so you can ensure that your frame-to-ground clearance is still correct (between 5-6 inches). If your clearance has changed, you should still be able to force the fork legs back into the correct position without disturbing the side-to-side alignment of the rear wheel now that there is a tack weld on both legs.

Once you have the rear wheel aligned, and both fork legs tacked in place, add some real weld to the joints, checking alignment as you go. If you are worried about weld spatter or heat damaging the rear wheel of tire, you can remove it and place a scrap wheel or just a hub into the forks to hold them in place as you weld all around the joint. Once you are done, take a breather – the hardest part is now over!


Photo 6 - Use a ground reference point when jointing the fork kegs to the rear of the frame.

Now all that is left to complete the basic frame structure is to add the chain stays. As shown in Photo 7, and actual set of chain stays cut from a 26 or 27 inch frame are used to form a triangle between the rear fork legs and the rear seat tube. Without these extra pieces, the fork legs would instantly bend if you tried to sit on the frame (you didn’t try this, I hope). Because of the triangular structure formed by the chain stays, this becomes the strongest part of the frame.


Photo 7 - Chain stays are added to form the strong rear triangle.

Now you can sit on your frame, since the urge has probably been driving you crazy for the last few hours! Although quite a way away from the first test ride, you can see how low and reclined this unit is going to be. Find to old pieces of wood to place between your butt and the frame so you can sit right on the Marauder like you will in the final design. Notice that the frame has a small amount of flex, yet still remains very strong and stable – this is the reason you will not need suspension and can get away with minimal padding on the seat.

While sitting on the frame with a board between you and the tubing, have someone hold one of the crank arms you plan to use in place as if you were making a long pedal stroke. Have them mark the place where the crank axel should be on the frame while you do this. If all went well, there should be about two or three inches from this point to the joint between the main frame and the front tube. When you find this point (bottom bracket center), take into consideration the extra inch added from the seat padding, and make sure you do this with your shoes on.

When you find this center point, mark it on the frame, then place a bottom bracket half way up the frame so this line is under its center and trace the outline. When you have this outline on one side of the frame, use a square to transfer the lines to the other side of the frame, and repeat the process. The areas are then cut and ground out as shown in Photo 8 so the bottom bracket can be welded to the frame.

Marauder Lowracer - Part 3 of 7

Photo 8 - Part of the main frame is cut away in order to take the bottom bracket.

When welding the bottom bracket in place, take note of which end is right and left – there is a difference. The left hand threads should be on the chain ring side, and the right hand threads on the non chain ring side. Also, place the threaded cups into the bottom bracket before welding, to cut down on the amount of warping that may occur from welding heat. As shown in Photo 9, weld around both sides and underneath the joint to seal all areas.

The bottom bracket should also be aligned at a perfect 90 degrees to the main frame tube to ensure proper alignment of the chain ring. You may want to tack weld only one side of the bottom bracket a first, then place a crank arm in the other side so you can compare its alignment to the side of the frame making any necessary adjustments. If the chain ring is no aligned with the frame length, you may have chain derailment problems.


Photo 9 - The bottom bracket is welded into the cut out in the main tube.

Now unless your arms are 6 feet long, you are going to need some way to bring the steering closer to your body. This is accomplished by creating an “indirect” steering system. Indirect steering mean that you are not directly controlling the front wheel from the head tube – instead, a rod with two ball joints at each end transfer steering movement from a remote head tube to the main head tube almost like the tie rods in a car keep the two front wheels in sync.

There are four parts that make up the remote steering head as shown in Photo 10 – a head tube, a fork stem (salvaged from the forks used at the rear of the frame), a short piece of tubing same as what is used for the rest of the frame, and a small control arm that will hold the ball joint.

The fork stem can be trimmed down to about half an inch under the bearing ring where the two fork legs used to be connected, since this area only needs to hold the control arm now. The fork stem shown in Photo 10 has already been trimmed. The control arm is just a two inch by one inch piece of 1/8 plate steel with a hole drilled at one end – this hole is used to bolt on the ball joint. I have used lengths between 2 and three inches for the control arm, and have found no difference in the feel of the steering as long as the distance from the center of each fork stem to the bolt hole on the control arm is the same in the front (main steering head) as it is in the back (remote steering head).


Photo 10 - The four parts that make up the remote steering head.

When the remote steering head is complete, it will look like the one in Photo 11. The angle formed at the main frame tube and the tube connecting the remote head tube “E” is 145 degrees. This angle is chosen so that both head tubes are at approximately the same angles in the final design – this makes the remote steering feel as though it were direct steering.

The small piece if tube that joins the remote steering tube to the main frame is place so that there is 11 inches between it and the seat back tube – this will allow you to install an 11 inch long seat base on the frame (plenty of room to shift around on while riding). The length of this tube is not critical, but it should be long enough so that the fork stem can be turned in a complete circle without the control arm hitting any part of the frame. In my design, I used six inches as the length.

A sharp builder looking at Photo 11 will notice that once this remote steering system is welded to the frame, there will be no way to completely remove the fork stem without breaking the weld, as it cannot be pulled from the bottom without hitting the frame. This has not been a problem, and if you ever had to change the bearings, it can be done by using individual balls (with the retaining ring removed) in the lower half of the unit. Keeping this in mind, make sure the entire remote steering system is put together before welding it to the frame, or you may find yourself grinding off some freshly made welds.


Photo 11 - The complete remote steering head welded to the main frame.

Since the control arm on the remote steering head must connect to the front forks through two ball joints and a rod, a similar control arm must be placed on the front forks. As shown in Photo 12, this control arm is made in the same fashion as the control arm for the remote steering fork stem. The only difference is that it is made shorter so that the distance from the center of the fork stems to the center of the control arm holes is the same for the front and back. Depending on your front fork’s crown width, this may vary, so choose the appropriate length.

Also, this control arm shall be welded to the left side of the fork (looking at it from the back) so that the rod connecting the two will be on the opposite side of the bike from the chain ring. This side of the bike is chosen for the connecting rod because there is more room due to the fact that the chain, chain ring and front derailleur are all on the other side of the frame.

Marauder Lowracer - Part 4 of 7

Photo 12 - The control arm is welded to the crown of the front forks.

To connect the two control arms together, two small ball joints and a steel rod are used like the ones shown in Photo 13. Small ball joints like this can be found at many mechanical supply or hardware stores, and are sometimes used to link such things as gas pedals or windshield wiper control arms. If you cannot find small ball joints, the type used on a snow machine steering linkage will also work, although a bit overkill on size.

The rod used in between the ball joints can be either a solid steel rod of at least 3/8 thickness, or a strong hollow tube similar to the size of tubing that make up chain stays on a bicycle frame.


Photo 13 - Control rod and two ball joints connect the two control arms together.

The length of the control rod is determined by the spacing between the two control arms and ball joint ends while both control arms are set at 90 degrees to the frame (steering straight ahead). As shown in Photo 14, both control arms extend outwards from the frame when the front forks are in the neutral position. If your ball joints, did not come with threaded ends, or you just want to make sure they never move, then weld them directly to each end of the control rod as I did – taking care not to overhead the ball joints by welding only a little bit at a time.

You could use the threaded ends of the ball joints if you also cut threads into the control rod, but this is really not necessary, since adjustment of the steering alignment will be done by placing the gooseneck into the remote steering tube at the desired angle, not by adjusting the position of the ball joints on the control rod like you would to align a car’s steering.


Photo 14 - The control arms will be at 90 degrees as the bike steers straight ahead.

Now that the remote steering system is complete, you will know how large to make the base of the seat – the distance between the tube that holds the remote head tube to the frame and the rear seat tube. Before you can mount a plywood seat base, six plates of thin steel are cut and welded to the frame as shown in Photo 15. These plates are made from 1/8 thick plate and have small holes drilled to allow woodscrews to be used. Notice the center plates are bent in the middle in order to conform to the frame and also joint the two seat boards together.

Once the plates are welded to the frame, you can cut out seat boards from half-inch plywood to whatever shape and width you like. I found a width of 11 inches to be just right, but feel free to experiment. You will need to screw down the seat boards now, since the next step requires them to be in place.

Marauder Lowracer - Part 5 of 7

Photo 15 - Metal plates are welded to the frame in order to hold down the seat boards.

Once you have your seat boards in place, put the rear wheel, rear derailleur and crank set on the bike. You will now need to join about two and a half regular bicycle chains together in order to make one long enough to reach the entire length of the Marauder. As you connect the chain, notice how it rubs under the front of the seat board – not a problem, this is all going to be fixed by the addition of a chain guide pulley.

As shown in Photo 16, a large Teflon or plastic pulley is placed just under the back of the seat in order to make sure the drive chain gets routed under the seat without rubbing on any part of the seat board or frame. This pulley is held in place by a bolt that is welded to the site of the gusset between the main frame tube and seat back tube. The pulley in my design is six inches in diameter and has a built in ball bearing. This type of pulley is very common in gym equipment that uses a cable to lift a stack of weights and can be bought from a fitness supply store. I chose a large diameter pulley in order to keep the friction from bending the chain line down to a minimum and have tried smaller (2-3 inch) pulleys and noticed they seem to rob a little bit of your energy after a while – it’s surprising that many commercially available lowracers end up using cheap, small diameter soft rubber chain guides in their designs despite this.

With your chain connected, just hold the pulley in place until the chain just makes it under the seat – no need to go any further than that. When you get this point, mark it with a marker or pencil through the bearing hole in the pulley then weld the appropriate size bolt to that spot.


Photo 16 - The chain is routed under the seat by the large chain guide pulley.

Handlebars are made by extending the shaft of a gooseneck up to the appropriate height then welding a shortened set of curved handlebars to the top of this extension. Let’s start by making the extension for the gooseneck, this way you can sit in the seat and decide how tall you want to make your handlebars.

As shown in Photo 17, a gooseneck is cut so only the stem remains and a piece of ¾ inch tubing is welded off the side up to the required height to hold the handlebars. Since, you don’t know this height, cut the tube being used as the extension to at least 20 inches. Once the two parts are joined as they are in Photo 17, place the neck into the remote steer tube, sit on the seat, and pedal the cranks taking note of how high the handlebars would need to be in order to clear the highest point of your legs.


Photo 17 - An extension tube is welded to the side of a modified gooseneck.

Once you have determined how high the handlebars need to be, cut the extension tube at the appropriate height, taking into consideration seat padding if you haven’t added it yet. From here, a curved set of handlebars from a mountain bike are cut short (13 inches wide) and welded directly to the top of the newly added extension tube as shown in Photo 18.

The reason for the curve is so that your wrists will be in a natural relaxed position while you ride – a totally straight set of handlebars would feel uncomfortable after a while. As for the narrow width of the handlebars, this is done to keep your arms as close to the sides of your body as possible to increase your aerodynamic position. If your handlebars were as wide as the ones found on a regular bike, you would collect wind at your sides, and this would slow you down slightly – something not desired on this type of racing machine.

Because of the narrow width of the handlebars, shifters where mounted on the extension tube to save room.


Photo 18 - A short curved set of handlebars are welded to the extension tube.

Since the Marauder can easily reach speeds well beyond what you may be used to on an upright bike, good brakes are not an option – they are a requirement. You could get away with a decent set of caliper brakes mounted to the rear forks, but I have tried this and can tell you that you will wear those little rubber pads out every few days if you ride hard and the stopping power produced by these brakes is less than adequate.

An alternative to caliper brakes is the disc brake. This brake is gaining in popularity and can be purchased as a kit (brake, cable and lever) for a reasonable price. To mount a disc brake, you will need two things – a rear wheel with a hub that supports the mounting of the actual disc, and a plate to mount the braking system to the rear forks. This plate is made from a piece of 3/32 inch plate steel formed to whatever shape is required to hold the brake to the forks. As shown in Photo 19, this plate is mounted just above the dropouts on the rear forks.

In my design, I utilized a fully hydraulic disc brake system. This system is not only smooth and silent, but has enough power to lock up the wheel at any speed – even on clean dry pavement. I originally used a caliper brake in the original design but after melting down the rubber pads on a hill at over 85 km/hr, I would never go without the disc brake again!


Photo 19 - A plate is made to hold the disk brake to the rear forks.

Well, what are you waiting for? Get the rest of the components on the bike, and get out for a test ride! Learning to ride the Marauder is a simple matter of loosing the “shakes”. For some reason, everyone who learns to ride the bike tends to wobble around a little for the first hour or two before they become smooth. Once you get used to the feel of being so low to the ground, you will really enjoy the comfortable and exciting ride that this bike can deliver, and you may put your upright bicycle away for good.

Marauder Lowracer - Part 6 of 7

Photo 20 - The Marauder is so low to the ground you just put your hand down to stop.

Well, I hope you enjoy the Marauder as much as I do! The first time I rode it around the block, I was addicted – not only to the amazing handling, blasting into a high speed corner, but the absolute comfortable feel of the bike even after hours of hard riding. I doubt I will ever again ride an upright bike after having such a great recumbent – ever heard the phrase “get bent”?

Here are a few more previously unpublished photos I found in my archives folder.


Photo 21 - Closeup photo of the rear wheel and transmission.

The rear derailleur and chain drive operates in the same manner as a regular bicycle.


Photo 22 - Closeup photo of the remote steering linkage.

Remote steering means that the pilots head tube is linked via control rod to the main front head tube.


Photo 23 - Rear disc brake added for better stopping power.

I used a rear disc brake and a standard front caliper brake, and that was plenty of braking power, even for steep hills.

Marauder Lowracer - Part 7 of 7

Photo 24 - The original Marauder as built in the year 2001.

Here is a shot of Marauder V1 a few days after I built it. Later I added a back rest, a trailer hitch and even an electric front hub motor.


Photo 25 - Here is Marauder V2 – now with suspension.

Marauder V2 (Click Here) is a much more advanced version of the classic LowRacer, this time with rear suspension, and adjustable bottom bracket to accommodate riders of any height, and room for rear cargo.


Photo 26 - Marauder V2 also adjusts for riders of all heights.

The Marauder V2 DIY Plan (Click Here) is 116 pages in length and includes a lot of detail on all apsects of building this and any other similar long wheelbase recumbent lowracer.

Here is a video of the original Marauder form 2001. Sorry for the low quality, we didn’t have smart phones or even decent video cameras way back in the day!



For comparison, here is a video of me messing around on the new Marauder V2.



Stay low, ride fast, and get bent!