Rally tower concept

[random1781]

I've gone down a rabbit hole over the last couple of weeks looking at rally towers for. This started by looking at and being pretty unhappy with tablet mounts for navigation, all of which are heavy or overpriced...usually both! This led me to rally towers, but unfortunately none of the ones out there really have everything I want, and given that they're extremely expensive themselves, so not really worth it to me either. I figure that, if the cost is around $1000 US for one of these things, it should be comprehensive and do everything that I need (and want!) it to do, including replacing the OEM headlight. So I started sketching out my own and, after a couple weeks and helpful input from @Canadian-t7, have come up with something I'm fairly happy with. Pictures first:

 

 

 

My overall goals were to...

• Make space for everything - Currently with my handlebars and hand guards, I'm impacting my display a bit at full lock. On top of that,
• Weight reduction - Seems like a lot of towers add weight, and I don't think this is necessary.
• Strong - Needs to be as robust as the original assembly.
• Serviceability/flexibility - I'm putting together a BOM based off brackets produced by SendCutSend and hardware from McMaster. The design is just bolted together, so it's easy to make or repair. I chose Squadron Pro lights, but most aux lights could be used instead with the correct spacers/fasteners.

 

The design is pretty simple...

• A pair of small carbon fiber panels substitutes the metal bracket (BW3-2831V-10-00) that holds the headlight in place...

 

 

• From there, another set of carbon fiber brackets provides support for the lights and another bracket to support the display...

 

The outer brackets extend all the way up to the GPS bar for stability.

 

My concerns and things that still need to be worked out...

• I need to verify the alignment of everything, particularly the spacing with the GPS bar. I'll be getting some cheap prototype pieces cut to verify fitment first.
• There is no side-bracing. The OEM design uses the stay behind the headlight to brace the left and right fiberglass side panels. Since my crash bars wrap around and attach to this, I think I'll have enough support as is, but regardless, I'll measure out some support brackets when I get the test pieces cut to keep that option open.
• The lights are bolted directly in to the assembly. I am a bit concerned about their housing being damaged with a hit, but I think that's pretty unlikely, especially with the display bracket in the middle.
• Still need to add aux power/USB charger.
• I still need to figure out how to make a fairing for the front...

 

So far the total cost of everything minus the front fairing is under $1000 US. This includes the 2x Squadron Pros, a Skene dimming controller, and all brackets made out of 3mm carbon fiber.

 

There are some pretty cool designs floating around here:

 

https://www.tenere700.net/topic/3840-t7-90-offroad-build

https://www.tenere700.net/topic/4572-t7-rally-tower-build-carpe-iter

 

Looking for input/comments/suggestions if anyone has any!

 

I'm posting files here:

 

https://github.com/random1781/Tenere700/tree/main/tower

Edited May 18, 2023 by random1781

[Canadian-t7]

I'm going build a one piece windshield instead of using the factory one and adding a smaller one to fill the dead space. Pros are you can make changes to the height and shape of the windshield without cutting up the factory one and you can run a little bracket either off the tower to add more support to the body panels, or brackets that come off the back side of the winglet windshields on the sides to attach to the lower windshield area. I'm going to try doing the winglet brackets first. And I'm moulding/bending  a piece of polycarbonate using a heat gun. , not sure how it's gonna go.  Cons being it's harder to make then a filler piece.

[random1781]

8 hours ago, Canadian-t7 said:

I'm going build a one piece windshield instead of using the factory one and adding a smaller one to fill the dead space. Pros are you can make changes to the height and shape of the windshield without cutting up the factory one and you can run a little bracket either off the tower to add more support to the body panels, or brackets that come off the back side of the winglet windshields on the sides to attach to the lower windshield area. I'm going to try doing the winglet brackets first. And I'm moulding/bending  a piece of polycarbonate using a heat gun. , not sure how it's gonna go.  Cons being it's harder to make then a filler piece.

Just come down here to the desert, no heat gun necessary. You can lay your stock windshield down and let it droop over your stock one! I'm interested to hear how it goes.

 

Just got a quote for $10 to laser cut all the pieces here out of acrylic, so I'll be doing that tomorrow to check fitment of everything.

[Hollybrook]

Wow, that is a great price on the acrylic cutting! 

[AZJW]

Nice project,  following this one. Moved here as it'll get lost in the black hole " General Discussion ".

[random1781]

5 hours ago, Hollybrook said:

Wow, that is a great price on the acrylic cutting! 

Mexico...now I'm wondering what other changes I could make to the bike down here.

[random1781]

Finally got the prototype pieces for fitment! I was initially going to do only one of the duplicate pieces, but it was cheap enough that I figured both wouldn't hurt...

 

 

So far everything looks to be either spot on or close...

 

 

I haven't fit anything onto the bike yet - that'll be a task for tomorrow morning when it's not 106 degrees outside.

 

In the meantime, I've been spitballing slightly different designs.

 

One of my main concerns is bracing the stock fiberglass side panels. With the design as it is, the only cross-member between the two sides is the OEM GPS bar up top. One of the options I'm considering is putting a tube through the tower for bracing and for extra support...

 

 

Right above the turn signals behind the winglets are a couple bolts that could be used for this...

 

 

McMaster has a carbon fiber tube for $20 that would work. I'd secure it to the side panels with a pair of the bolts used for bar ends - whatever those are called. The bonus of this would be less material required for the panels...

 

 

I'm still working out exactly how to mount the stock screen and a tablet. It's not hard to just bolt them on, but I'd like to have a more elegant solution with some adjustability like tilt angle or rotation. Any smart people have ideas?

[Liquidape]

Very cool. Just curious where did you find the 3D model of the bike?  Or did you model it all in SolidWorks yourself?

[random1781]

41 minutes ago, Liquidape said:

Very cool. Just curious where did you find the 3D model of the bike?  Or did you model it all in SolidWorks yourself?

Absolutely not, I struggle making 2D sketches! I'm actually pretty new to this. I came across this model, which is allegedly from Yamaha, but it's not available to download. I was able to snag the version that you see in your browser though. It's a mesh, but it's actually broken down by component, and so far it's been remarkably accurate. I used it to get the hole spacing for the small bracket, and it matched perfectly.

 

The real test will be seeing how the big bracket I made matches up with the GPS bar since I used the model exclusively for those dimensions. If it does match up, that would be hugely validating. Being able to sketch all this stuff out based on a digital model has been ridiculously helpful. I can even group and pivot all the steering components to check for clearance issues. Let me know if you want to check it out.

[Hollybrook]

That's coming along nicely - glad to hear the model accuracy is good! 

[Endopotential]

If you end up making lots of these and need carbon fiber tubes and are not too exacting on diameter, a very cheap source would be CF archery arrows on Amazon.  You can get a dozen 30" tubes for around $40, enough to make towers for every forum member 

[random1781]

1 hour ago, Endopotential said:

If you end up making lots of these and need carbon fiber tubes and are not too exacting on diameter, a very cheap source would be CF archery arrows on Amazon.  You can get a dozen 30" tubes for around $40, enough to make towers for every forum member 

I won't be making a lot of these, but I do hope that at least some more are made! My intent is to design something modular that could be copied with low-effort, and lowish cost.

 

The components are basically...

• Lights - this is the most expensive part...hoping I can find some used ones eventually!
• Hardware - bolts, spacers, nuts, tubes, etc.
• Brackets - these are the custom-cut stuff.

I'm building a BOM and sourcing the hardware from McMaster, so that stuff is easily get-able.

 

I'm basing this design on Baja Designs Squadron Pro's, but I have 121mm between the panels and most aux lights fit within that, so pretty much any lights could be dropped in with just changes to the bolts/spacers. I do need to revisit the hole placement on the panels to compare fitment with different lights, but that's for later on.

 

The brackets are the custom parts and fairly expensive. However, the cost comes down quite a bit when ordering multiples: 5 sets gives a 22% discount from the site I'm ordering from, which is significant since they're the second most expensive piece to this. So yeah, this is something that would work out for a group!

[random1781]

Rough fitting is extremely promising!

 

 

Now off to a hardware store to try to find some spacers to align and tighten everything down.

[random1781]

It took a bit to scrounge up all the right hardware, but I finally got it bolted up. The good news is that the alignment was perfect. The holes for the GPS bar were spot on, and the alignment of a hole that leads straight out to the fiberglass panels also lines up nicely.

 

The bad news is that the outer panels come out too much, so the forks impact them when turning. I should have checked this beforehand on the model, but I didn't.  Here's what's happening:

 

Bars straight, all is well

 

Bars turned, and apparently in real life things don't work out like this does

 

Fortunately the fix is easy: just push the mounting point forward a bit...

 

 

 

The down side is that it adds some cost to the panels. Now I'm just working out the tablet mounting.

[random1781]

I've replaced the display bracket on my bike and made some modifications to it. The display has plastic bits sticking out the back that I didn't account for, but I updated the current design to reflect those.

 

The intent was to make a bracket that could be mounted on a few places. Obviously I wanted it for my tower, but it also mounts fine in lieu of the big, stock bracket. I also added holes that correspond to the handlebar bolts and an AMPS pattern, so you could potentially mount it to your handlebars. Since I have different bars, my handguards were impacting the display on full lock. I wanted something that would push the display down and back a bit, and this accomplishes that.

 

 

Considerations:

• The cable comes out of the display about 25mm, so depending on where you mount it or what material it's made out of, you might need spacers. Handlebar definitely requires spacers. Bolted to the stock mounting point, it's tight but it fits as it is with the material this one is made out of, which is a bit flexible. A couple washers or small spacer would give the cable more space.
• The material should be about 3mm to accommodate the grommets.
• The ambient air temperature sensor is located on the stock bracket. I simply zip tied it to the display cable.

 

Design is here:

 

https://github.com/random1781/Tenere700/tree/main/tower/bracket-meter

 

This part made out of 3mm stainless steel or aluminum is about $30 US and carbon fiber is about $100 on SendCutSend. I'd go with aluminum personally.

[random1781]

Finalized the first working prototype design today:

 

 

 

 

 

The bracket for the display now has some bends and adjustability for angle:

 

 

For this prototype, the big panels are going to be aluminum to test fitment again and get some riding in before committing to carbon fiber, which is significantly more expensive. The smaller panels for the bracket that replaces the OEM headlight mount will be carbon fiber since I'm confident those are correct.

 

I wound up going with a single Baja Designs XL80. It's heavier, but it's cheaper and brighter than other combinations. The design still allows for the addition of another smaller light underneath this one if I decide to add something in the future.

 

Hopefully this will all be made and ready to test out in the next 1-2 weeks.

[random1781]

I just sent everything off to be fabricated.

 

I added a both a tablet mount and a bracket that allows you to adjust the angle of whatever navigation device you have. It should look like this:

 

 

The only bracket I ordered in carbon fiber is the bottom one, since I'm confident in the layout. The big, main brackets are being made out of 7075 aluminum for now to test them out. It cost $54 for those 7075 brackets, and that's an acceptable cost to prototype them before committing to carbon fiber. The total cost for all brackets (including the tablet mount) was $257. The XL80 is going to be around $400, and then the rest is hardware, so around $700 total. Big brackets in carbon fiber would add about $175, so the total cost for this build in carbon fiber would be around $875.

[Canadian-t7]

@random1781 I have concerns with the single bolt at the bottom. I realize the upper bar goes through it, but the whole front section is flimsy and non structural. I feel like it will sag forward and put un necessary load on to the front bodywork. Other than that, I'm really digging what your doing, looks good. 

[random1781]

2 hours ago, Canadian-t7 said:

@random1781 I have concerns with the single bolt at the bottom. I realize the upper bar goes through it, but the whole front section is flimsy and non structural. I feel like it will sag forward and put un necessary load on to the front bodywork. Other than that, I'm really digging what your doing, looks good. 

Yeah, I have those same concerns, especially since there's no positive clamping force on the GPS bar.

 

So I left these holes in place...

 

 

I haven't been able to get exact confirmation, but they should line up with the side panels. I'll steal your picture here...

 

 

I thought we were going to be back in the US only briefly, but I think we'll be here for a bit longer, so it'll give me some time to do validate things and tinker.

 

What I'd like to do is clamp each panel of the tower to its respective side panel...

 

 

The notion is that, while the bottom bolt will still be supporting most of the weight, the side panel bolts will provide rigidity and the "hooks" on top for the GPS bar will provide a third point of contact for stability and bear some of the excess rotational and vertical forces. This is also the furthest-back attachment point on the side panels, which I hope will reduce the load on them by keeping everything as rearward as possible.

 

In my mind, the main benefit of two bolts (pairs of bolts technically) on the bottom is to prevent the tower from pivoting front to rear. I think one M8 plus the carbon fiber is enough to bear all the weight. I'm hoping that moving the second pair of bolts up to a much further radius from the pivot point will help stabilize the rotation with less effort and also provide some side-to-side strength so the panels don't cave inwards if I drop the bike on them.

 

The main problem with this option is that it's ugly. There's about a 3" gap between my panels and the bike's panels. So do I bridge this with a long bolts and spacers? Maybe just a threaded rod and nuts? Some small diameter carbon fiber tube is fairly cheap, so I could get that and then use some expansion anchors (like for handguards) to clamp them in.

 

Barring all of this panning out, I just got my hands on some Hepco Becker crash bars that have a bracket that attaches to the headlight bracket. If I do wind up needing reinforcement for the whole tower itself on the bottom, I could use the bottom holes on my panels meant for a second light to brace against the crash bars or their bracket, which would be akin to having two bolts on the bottom.

 

That's the thought behind it, anyway. I'm building in the contingencies because I honestly have no clue what I'm doing here.

[Canadian-t7]

@random1781 your thinking about the supports backwards. Like with the stock setup the body panels are "hanging" off the headlight. That whole front end is only attached to the bike with 1 bolt on either side(circled in my picture) the body panels are attached with a couple bolts but won't be able to support any load. Your tower will want to rotate forward causing  over loading on the body panels/supports. When you get moving through rough stuff I think it will come apart in the worst way.  The tower needs to be the support so that the body work can "hang" from it. If you make the bracket that attaches to the frame an l-shape it will allow you to run 2 bolts so the tower can fully support its weight(my second pic), plus the weight of the side panels/windshield assembly. 

[random1781]

17 minutes ago, Canadian-t7 said:

your thinking about the supports backwards. Like with the stock setup the body panels are "hanging" off the headlight.

Oof, yep, I'm backwards. I can see how the I-structure keeps load off the side panels, and that's a simple change that I'll work on, but devil's advocate for a minute.

 

The forces put on the panels from here mostly push/pull in line with the panels, right?

 

[Canadian-t7]

@random1781 yes, but there in lies the problem. All the weight in your tower is infront of the bolt, so it will want to tip forward. The body support panel has the 1 holding bolt at the rear of the panel, so it also will want to tip forward. They are on 2 different axis', but falling in the same direction. The tower will rotate forward and down, forcing the bodywork forward and down but on a different axis, causing the stress. The body panels will break where they attach to the bike. See my lame picture attached with arrows showing load direction.  Adding the L-shaped mounting bracket to hold the tower will allow all of the weight to be supported and for the body panels to hang instead of using them to carry a load.  Not sure on the math, but space the bolts far enough apart vertically so that the load is spread out. You should be able to apply a good amount of weight downward on the front of the tower without having a failure. 

[random1781]

17 hours ago, Canadian-t7 said:

@random1781 yes, but there in lies the problem. All the weight in your tower is infront of the bolt, so it will want to tip forward. The body support panel has the 1 holding bolt at the rear of the panel, so it also will want to tip forward. They are on 2 different axis', but falling in the same direction. The tower will rotate forward and down, forcing the bodywork forward and down but on a different axis, causing the stress. The body panels will break where they attach to the bike. See my lame picture attached with arrows showing load direction.  Adding the L-shaped mounting bracket to hold the tower will allow all of the weight to be supported and for the body panels to hang instead of using them to carry a load.  Not sure on the math, but space the bolts far enough apart vertically so that the load is spread out. You should be able to apply a good amount of weight downward on the front of the tower without having a failure.

Okay yeah, that makes sense.:

 

 

But putting another bolt vertically to get that "I" removes the force from the side panels.

 

This first prototype is committed, but I'll build that into the next version.

[random1781]

Here's the first functional prototype...

 

 

 

It mostly came out as expected. The light is actually a bit wider than I expected, so the hardware is off a bit, 3mm on each side. If the extra width clears, I'll probably keep this and add some rubber washers on the dash and nav mounts for some dampening.

 

A few of the parts have deformations in them from the bending, but they're functional.

 

Overall very happy with this first stab, at least before fitment. I'll be doing that tomorrow.

[random1781]

Coming together...fit is pretty much spot on. Need to do wiring today and then finally go for a test ride...the bike's been apart for three days now.