Sissy Bars weren't really anything 'new' for Choppers back in the old days as they simply evolved from the 'push-bars' found on most drag bikes of the time, adapted to a new purpose, that being to keep your passenger from flying off the back of the bike.
They are easy to build and enable the fabricator to express their 'artistic' talents as might be appropriate. A quick study of the old chopper rags from the 60's and 70' will show that such 'expressions' sometimes reached epic proportions.
From a utilitarian standpoint bars don't need to be much taller than 15 to 18" above the fender to provide good back support for the 'passenger' or your 'gear' bag but that's just my personal observation.
You can buy ready-made' bars from a variety of parts suppliers but as with most things 'mass-produced' they can sometimes look like crap once bolted to a bike and just scream 'store-bought'.
In order to avoid being laughed at by your friends it's a good idea to build your own bar that's dimensioned to fit your particular ride.
The diameter of the bar stock you decide to use is largely dependent on the overall 'mass' of your bike. Half-inch stock is the minimum. I prefer 9/16" material for everything but I've seen guys use 5/8" bar on big bikes but to me it looks way out of proportion. A general rule of thumb is to use thinner diameter bar for tall sissy's and thicker diameter bar stock on shorter sissy's. I know that's exactly opposite of what logic says should apply but 'appearance' is everything. Tapered bar stock would be better than sliced bread but I don't think it's readily available.
1018 cold rolled bar stock is cheap so buy 1/2, 9/16, and 5/8" if you want to experiment.
It's really not a good idea to 'heat bend' steel but that largely applies to structural parts so heat bending of 'decorative' steel is perfectly okay although I do know of shops that cold bend bars using a 'bar stock bender' that's like a mini tubing bender. I grew up heat bending so that's what I do since I'm to old to go out and find a nice cold bender.
I was taught to build bars when I was around 14 years old by a guy who had to be at least 70. I had worked, for free, at a couple of shops to learn the ropes before I finally broke into the 'big-time' and got a real paying job at a big shop. My boss hired me to do seat upolstery but 'promoted me to doing sissy bars after a few months. That basically meant I went to the other side of the shop to the 'dirty' area as I called it.
Virtually every thing we built there was entirely 'custom' so we didn't have a bar welding 'fixture plate' as such but instead just welded short 3/4' 'dowels' to a slab of steel and used those as 'bend points'
The pic below that I grabbed from the web shows a variation on this scheme. Although the photo is pretty dark I think you'll get an idea of what I'm trying to describe as a quick and dirty bending fixture.
A step up from this type of setup, better suited for 'production custom work' is a real fixture plate as seen below that we use on an almost daily basis.
This setup consists of a 3/4" thick plate drilled with variety of 3/4" diameter holes at 1.25" centers. The dowels or 'bending pegs' are 3/4" bar stock that extend about 1" above the plate surface. These are removable and when heating and bending they can be temporarily removed so the bar never has to be lifted from the surface.
You'll need a heat source and if you don't have access to a oxy-acetylene torch you can get by with one of the cheap 'Map-gas' rigs.
No matter which type of jig you use one key point is to make sure that the 'pegs' or 'dowels' are polished 'bright' otherwise the mill scale on the dowel will try to transfer to the bar you're trying to bend and leave a nasty pitted blemish on the bar that can't be polished out. In fact it's a really good idea to polish the bar you want to bend prior to heating and bending to remove any mill scale.
The practice in process envolves laying out the 'pattern' for the prospective sissy bar, full size, on some wrapping paper so you'll know where the 'bend points' need to be located. You could also just lay the design out in chalk right on the fixture plate if you wanted to. Measure the total length of the proposed bar stock. Add in an extra six inches on each end so you have something to hold on to as your bending.
Always begin the bends from the top down. I secure the bar to be bent using a long pipe clamp to prevent it from moving during the bending process. I usually bend only one half of the bar at a time but some folks like to do each side in sequence from one bend point to another. Six one way and a half dozen the other. As your bending always keep the bar 'flat down' on the fixture plate to avoid lateral distortion or warping. If you lift the bar you'll get it twisted out of a flat 'plane'.
Building sissy bars can be addictive. It's a lot of fun and a really satisfying experience when you can create something that is truly hand-made for a customer.
We had one client who actually stayed in the shop and watched his bar being made and he was amazed at the entire process. He ended up having three different designs bent and paid for each one until he found exactly the one he felt best suited for his bike.
Even though the bending starts at the top and moves down the design process itself starts at the bottom and moves up.
I've attached a crude diagram of the general configuration of a typical sissy bar, viewed from the back end of a bike, as seen below'
I've labeled the 'bends' starting from the top from 1 to 5. Depending upon the fender you use you may be able to skip bends 2 and 3 and just make an angled straight run from the top bend down to bend 4.
Bends 4 and 5 are needed so that the bar clears the chain cover on the sprocket side and the disc rotor on the opposite side.
If you're bending a bar that has a 'square' top you'd have bend 1-right and bend 1-left.
When bending, as mentioned before you start from the top and move down. When making the top bend or bends you heat up and bend both sides of the bar down at the same time. From that point on you can alternate heating, bending and working on one side at a time. Never lift the bar from the surface of your bending table to avoid distortion or 'twisting' or getting the bar 'warped'.
When your're finished with the bending trial fit the bar to the bike. Determine where you need to weld on the lugs or tabs and then cut the excess length off the bottom of the rods. Install the tabs. Polish everything up as shiny as possible. Fill in any 'voids' in the welds with brazing, sand it smooth and you're ready to head to the chrome shop. Be sure you take your wallet.
You can get some good ideas on various ways to mount the bar to the axel plates and the bar to the fender by searching the web and visiting any one of the numerous chopper discussion boards. Lugs and tabs can be found at 'Throttle Addiction' and also at 'Bung King' if you don't want to build your own. Forth Worth Chopper Supply Company also sells the lugs shown below, some of the best I've seen in years..
The nice thing about these is that the mounting hole is threaded so it makes for a nice mount without having to use a nut protruding past the axle plate.
Speaking of axle plates. Before you start the design process you need to decide whether you want the tabs or lugs to mount on the outside of the axle plates or on the inside since it makes a difference on how wide you make the space between the ends of the bar.
The lugs above are designed to be mounted with the tabs on the inside of the plates.
Stock Harley frames have 9.25-inches of space measured on the inside of the plates as do most aftermarket frames but you need to actually measure up the frame you're working on to be safe.
The Sissy Bar is one of the most important 'features' of most choppers and along with your handlebars and tank form the overall visual impression of the bike that makes it unique. For this reason you don't want to build something that looks dorky and you certainly don't want something that looks 'store-bought bolt-on'.
One key element in good visual design is the aspect of 'entasis', first appreciated by ancient Greek architects. Basically what the human eye 'sees' is not necessarily what you want it to be so sometimes you have to 'fool' the brain into believing what it perceives is what you intend it to perceive and not what exists in reality
Where entasis comes into play with respect to Sissy Bars is in that section of the bar between the lower axle plate mounting tab and where the lower most bend occurs in the leg. To acheive a nice visually appealing look the lower section of bar between these two point needs to 'lean in' slightly, around an eighth of an inch on each side in towards the fender. In other words the distance measured between the lower centerline of the bar at the axle plates needs to be about an eighth of an inch on each side narrower at the point measured between the legs of the bar where it meets the fender mounting points otherwise the bar will appear to the naked eye as if it buldges out on each side where it meets the fender.
Another thing to consider during the design stage is 'strength'. Is the bar to be 'decorative' of intended for serious duty?
If you intend to really be strapping on a load of crap for long runs you might want to consider 'bar supports' as pioneered by the SoCal builders like Dick Allen shown below.
These types of supports help to not only strengthen weight carry capacity but also help to reduce bar vibration.
A good example picture of such supports is shown below.
Thats an auxillary fuel tank hung off the bar in this snapshot but you can see the curved support braces welded to the main sissy bar.
Another variation on this scheme and also sometimes used in conjunction with the curved bar supports is the 'industrial' method seen below. I pirated this picture from Irish Rich on one of his build write-ups. I hope my transgression is forgiven.
This was the side view.
This is the rear view. Very cool brace design and execution for a serious rider.
Bar design and fabrication all comes down to what your particular bar is designed to do but there is nothing to say that you can't have more than one bar for any particular bike. It's not uncommon to have several bars in the garage that can be switched out for different occassions.
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