I ride an ST1100 and have for almost 5 years. Longer than a 45 minute ride beckons a little more comfort and there are a lot of things you can do to help that. When it finally comes to the desire for a backrest it usually starts at 200.00 and you'll install the hardware yourself. If you want an aftermarket seat with a rider backrest, it will likely be over 500.00, unless you find one of those awesome deals I've heard of.
Thanks to a keen eye and a hardware store the 4 items you'll need will be less than 20.00 per bike, not including the foam or black vinyl I chose. In short, the two backrests I made totaled 64.00. Honestly, had I known this could be done, I would have had a backrest ages ago.
Before you get started. Look at negative spaces. This means, when you put a bolt through the top of your seat pan, under your seat foam, will the nut hit anything on the frame or a wire? If it's a tight fit, there may only be a couple different ways you can do this, but it will get done. The contour of your seat pan will most likely not be a straight line where the 3/16 flat bar comes up through the foam to how far under the passenger seat foam your foundation plate will go.
I'll just go ahead and say it, "Use the force". Look at what you have to place, where it's going to go and eyeball it. If something looks like it might not happen and you start the mod, it could get harder for you than if you were able to catch a dead end direction earlier.
You'll need a drill, a ruler, a vice will be helpful to hold the material so you can bend the 3/16 plate to suit the contour of your seat pan, a grinding disc, cutting disc and a welder. You'll also need a tap set if you want to thread the hole for the adjustment bolt. I believe there is a way to make it a stationary backrest, you'll just have to be creative with the backrest padding and add or subtract foam for your needs.
If you don't have some of these items listed above and a motorcycling buddy that doesn't have a rider backrest does, you can build backrests together.
For those of you who might take this on, I modded my backrest. I needed it to go higher.
Step 1: 2 5" Hinges, a 10" Bar 1/8 Inch Thick and a 10" X 10" Angled Bar 3/16 Inch
That's it. That's what they are, now lets see where they go and how to place them well enough to be good enough the first time.
Why these parts? I have metal at home, can't I just use that to make something like you did? Yes.
Not having the ability to make something hinge like. Using a hinge gave me an articulation point just above the seat. When I made adjustments to the bolt to bring the backrest closer, it would be able to move.
The second hinge had two functions. It gave me a way to attach the backrest through the existing holes in the hinge and had another articulation point behind the backrest, to help it contour my back as I change riding positions.
Step 2: This Is a Look Into the Future.
This is what your finished seat pan will look like underneath. These bolts and nuts will need room for your seat to go back on without a fight. Use your perception, and I know you have this if you're on Instructables website trying new things, look at where hardware "might" come through. Compare what room above your bike's frame with the seat removed offers you some space to get creative. You might find the bike's frame is right under where you'd like a bolt to come through but if it's short enough under the seat pan, it might still clear.
Step 3: Sit on It.
If you've seen "Happy Days" this phrase should be familiar to you. This begins the journey for the confidence necessary to pull the existing cover off, cut your seat foam, drill holes in your seat pan to secure what will be your foundation for your backrest.
By sitting on your seat, you'll know where not to come up through your seat. You also won't want to come through the seat right behind you. You have to count for the backrest and hardware thickness. Mine is about 2 inches. You don't want to go so far back that invades a potential passenger's space. Take your time. I did a lot of reverse engineering. It means if you have something you want to accomplish with known thicknesses and dimensions, you're able to deduce where it needs to be placed, to work best for you.
This is adjustable. I really wouldn't be that excited about it if it wasn't. Doesn't mean it wouldn't be awesome. It just means you don't have to worry about that if you build it like I did, because I have a way to adjust backrest. I didn't find this way to adjust it until after I started this project.
Make a mark representing the 1 1/4 inch wide 3/16 plate on the seat. This is your target from coming through your seat. By the time you're done, the receiver will look like the 2nd picture. The backrest will be removable because you're going to grind the pin out of one of the hinges and weld it to the 3/16 plate.
Step 4: Loosen the Staples on the Back 60 Percent of the Seat Cover.
Having made the mark on top of the cover, I transferred the line to the foam to always have a visual reference as to where I intended to come of through the foam. The most important thing at this point is not lose sight of what that reference is. It's not permanent. Think of this project, as you progress with your own seat, that line might need to move.
Step 5: At This Point Your Still Looking at How It Will Be Done, No Harm No Foul, It Can Go Right Back.
The first two pictures are what you'll be doing first. The third picture is what it will look like with a serrated knife to clear the foam.
Lift up the foam from the seat pan, shouldn't be stuck permanently unless it had been glued by you or a previous owner. You're 10" angled piece will go up through the foam and get mounted under the passengers foam, on top of the seat pan. This is undetectable to your passenger if the plate follows the contour of the seat pan close enough. I found that eyeballing each of the necessary bends, I was able to make it look like the plate was made to go on the seat pan as my foundation for my backrest.
The fourth image shows what the plate looks like being cut off, counting for a small portion of half of the hinge having been welded to the front of it for your receiver.
Step 6: This May Not Even Be Necessary. I Though Some Lateral Support Would Be Nice.
the 1/8 plate going across was eventually cut in half. One of the halves was welded pretty close to where you see it pictures. I bent it down on each side of the plate and bent it again to contour the seat pan. This contributes to the passenger comfort without the metal pushing up too hard on the foam above. I drilled a hole on each side to accommodate a 1/4 bolt, complete with nut under the seat pan to secure it.
Step 7: By Now, If You Haven't Cut the Excess Off of the 10" 3/16 Plate, You'll Have a Lot Extra
As to not allow heat transfer in using your cutting wheel with the plate in the foam, mark where you want to make your cut allowing there to be enough height after you weld the small portion of the hinge on to be flush with the top of the 3/16 plate and protruding completely above the foam, just like mine.
Hint: if you bolted the plate to the seat pan before you made your mark to cut, it will likely be placed with great accuracy after your cut because you secured it before you marked it.
Step 8: Introducing That Small Portion of the Hinge to Weld to the Front of the 3/16 Plate.
Simple. Use the cut off portion of the 3/16 plate, mark the width, then cut away the excess of the hinge. As far as a lower line, where I have the plate placed in the picture is a good horizontal line.
You'll weld this piece to the front of the 3/16 plate, with the middle portion of the hinge protruding to the front. You'll see this in subsequent steps.
Step 9: This Is the Non High End, Non Conducting Variety Welding Table.
I only forgot to ground my work once, but noticed instantly.
Before I weld, I announce stupid check. For those of you who have made a simple mistake before that might be prevented with one extra breath worth of time know what I'm talking about.
Is the piece I'm about to join on a molecular level going to need to be ground out because I welded it to the wrong side of the plate that's coming out of my foam.
Step 10: The Plate Is Sitting on the Wood With the Same Orientation As It Will on the Seat Pan.
That means the orientation of your first weld will look like this. Since the adjustment bolt of your backrest will rest somewhere in the space between the 3/16 plate and the tube of the hinge that you ground the pin out of, I filled it in and ground it off as level as I could. I like to weld anyway so it was cool to add metal like that.
Step 11: This Is Where an Already Exciting Thing to Build Had an Engineering Surprise Along the Way.
I didn't know how to make it adjustable, until I got the idea to place the other half of the hinge backwards. It's at this point that I saw welding about a 1 inch remnant of the 10" 3/16 plate near the hinge. This is where I drilled the proper size hole and tapped it for an allen head bolt to be able to adjust it forward and back. I even considered a lock nut under the bolt so I could spin it down to the metal the bolt goes through to lock it in place.
Step 12: We're Close to Being Done, It Was a Lot of Work, But It's the Most Inexpensive Back Rest There Is.
There is a lot in the first picture. More than the way it looked as I got started because this picture was taken after a few more adaptations you might be able to combine and save you time. I had the prototyping obstacles, hopefully it's smoother for you.
Lets take a look at the plate the bolt is threaded through first. That's the first piece added as described in the last step. Notice because of the choice in the dimensions of that plate that it lands close to between the hinge and 3/16 plate. tighten that and the backrest comes forward, gotta love physics. What will save you time that I almost had to cut this plate off again, was add more space between the plate you add on and where the bolt touches as it comes through. Too close together and there isn't as much adjustment that can be made than if there's an 1/8 of an inch.
Why are those brace lookin things welded on to the adjustment plate going up to the hinge you say? When I put my weight against the backrest before these were welded in place, the hinge bent a little. Hmm, I thought. What can I do to make it not bend. So I cut 4 of these strips because I did the same technique to my wife's backrest, hers might bend exactly the same way so I headed that off before it became an issue.
Step 13: It So Happens This Instructable Was Created the First Ride With My Backrest.
I found I could use the backrest about an inch higher. Don't get carried away with drilling new holes lower in the backrest to make it higher. It will make it higher but the point at which the new point of contact the hinge is making in the backrest will push the lower part of the backrest to you and not make contact with the height of the backrest. It will be disproportionately putting pressure on your back. I intend on using a 5 inch piece of 3/16 metal in between the hinges that are bolted together. I will be able to raise the height and leave the hinge bolted to the backrest where it is. Questions