TOPIC:

Some of you have been following my progress on this in another thread, and the mods have granted me permission to post this sale thread for the custom front fork conversion triples that I’ve been designing. 

A little bit of background and what I’m trying to do. It’s been a dream of mine to fit a set of upside down forks to my Zephyr 550, and when I got a second bike earlier this year I figured that was a good time to seize the opportunity for the project. So since about August, I’ve been measuring, 3D modeling, asking lots of questions, and prototyping with 3D printed plastic. While I still have a ways to go, it’s coming along very well. 
 

Rather than “off-the-shelf” custom parts, or searching every model of bike for a set of triples that would accomplish this, I chose to design my own for one simple reason: I want to use as many of my bike’s original parts as possible. I want it to look natural, like it was born that way. 

The forks are from an ‘03 ZX6R, and the brake calipers from an ‘08 Triumph Street Triple R. There are some details such as axle spacers and disc rotor spacers that I’ve also taken into consideration, designed, and prototyped. 

The reason I’m posting about it here in the for sale section is just to gauge interest. I am wondering if there is anyone else out there in KZR land that would be interested in having a set of these parts for their own bike. This isn’t me trying to make money, it’s me trying to save money. See, if I just go it alone and get a single set CNC machined for myself it’s going to be expensive. Estimates I’ve been able to get so far put it around $1000 just for the triples (which doesn’t include the other parts). But, if I double the quantity then the cost per set drops down to only $600. That price is a lot friendlier! Imagine if three people wanted a set. 

Additionally, a lower cost per set means me and the potential other buyers could explore some concepts to make the parts nicer. Filleted corners instead of straight cut for example. This might raise the cost again, but if we have enough “bulk” buying power we can still keep things affordable. If I end up only making the one set, they’re going to be pretty basic, but if a couple of us all want them, we could get fancier. 

Anyway, I hope that’s a good introductory post about the project, but do please feel free to ask me any questions. At this point I am not asking for any money, this is just an inquiry about interest. I just want to know if there is anyone else here who might want a set. The more of us there are, the more affordable they will be. But for now the closest (albeit very rough) estimation I have is that if even one person wants a set, they will run about $600. All I’m looking for at this point is anyone who wants to say “count me in as interested.” 

I wanted to provide some more details about this, in hopes of expanding the conversation about it, and maybe drumming up some interest. As I've said above, I'm really not making any money on this, it's just something I want to do, and I'd like it to be affordable. Perhaps if everything is successful I might consider another batch down the line as well.

Fitment/Compatibility

While I am primarily focused on making sure it fits the Zephyr 550 model, I believe there are other bikes these custom triples will fit. It is my understanding that the other Zephyr models, 750 and 1100cc models, all use the same steering stem, and should therefore be compatible. Additionally the ZRX1100/1200 models are also supposed to use the same stem. Clearly those are all bigger bikes that you might not want to use forks from a 600cc model on. However the triples will fit basically any fork with a 50mm top, and 52mm lower diameter. Granted this isn't the most common size, but I believe there are other forks out there that match that spec, including those from the first gen Z1000 ( at least according to some ). 

It should also be possible to extrapolate additional compatible models using the AllBalls fork swap finder . For example I just ran a quick search for the 1980 KZ650F1, and found that they have bearings to fit the ZR550 Zephyr front end, which leads me to believe that with a Zeph stem, and the triples I'm designing, you could fit ZX6R forks to that bike. Granted I'm sure all of this is easier said than done. But I feel confident that my research is sound, and with a little patience and elbow grease these things are possible.

Stem

Since I already brought it up, it's worth discussing the stem. My design reuses the stock Zephyr 550 stem, which must be separated from the stock lower triple. Because it is welded in, you must grind off the welds, and then press out the stem. Early in the project I had a friend do this for me. I had removed, and subsequently ruined the lower bearing to do this. However now that I am more intimately familiar with these parts, I believe it is possible and actually preferable to not remove the lower bearing. After grinding or filing off the welds, you would press the stem out from the bottom up (likely upside down in reality). The part of the stem left below the bearing is about 23mm, and this length bottoms out in the lower triple of my design, when pressed in. 

I have waffled back and forth about whether to make the press-fit part a true perfect tight fit, where a hydraulic press would likely be necessary, or making it 0.1mm oversize in the triple, which allows for a "slide-in with no wiggle room" fit. While looking for a good method to secure the stem to the lower triple, I found that a bicycle stem "star nut" could be installed in the stem, and using a bicycle top cap, the stem is bolted to the lower triple. Any decent bicycle shop should be able to install one of these nuts, though it should be noted that it requires the less common 1" size and not the very common 1-1/8" size. Currently this is how my design works, but I am open to making the adjustment for a regular press-fit if that's what potential buyers prefer.

Headlight and Gauges Brackets

This is going to be a long section, so buckle up. Because I am trying to retain so many stock components I have designed in all of the mounting points so that virtually everything can be used. I have two concepts I am experimenting with for this. The lower triple stays the same for both concepts, but the upper triple varies. In the first concept the upper triple is one solid piece. In the second concept, it consists of two pieces, the actual clamp which could be considered "universal" and a second piece which is bolted or glued to the first piece and holds the mounts for the gauges, ignition column, and headlight bracket.




These photos represent concept 1 (green). As you can see, it is similar in many respects to the stock upper triple, it's basically "plug and play." Obviously that is the major advantage of this concept, however the downside is increased manufacturing costs. I do not have exact figures on that yet, but again this thread is about gauging interest. If enough people want to go in on this together, maybe we can afford to go "plug and play" all the way.




These photos represent concept 2 (purple). The main actual triple clamp is a lighter shade of purple than the attachment piece. It is intended to be made with a CNC machined primary clamp, and 3D printed, or fiberglass/carbon fiber molded attachment. They could be joined together by either running a longer bolt through the handlebar clamps and affixing a nylock nut to the underside, or using a high strength adhesive. The first advantage of this concept is that with a "universal" top clamp, you wouldn't be locked in to only using the stock gauges and brackets. Custom 3D-printed attachments could be designed for mounting virtually anything, or the clamp could be used with nothing else attached at all, for a very clean look. Clamp a Quad Lock to your handlebars, use your phone as a speedo, and really go full minimalist. The other advantage to this design is that the cost to make the main clamp should be lessened. The attachment piece would be an additional cost, but 3D printing can be pretty cheap these days. And finally, the downside to this concept is that attaching the two pieces together by any means is not quite as nice and convenient as the "plug and play" ability of the first concept. I personally would prefer the first concept for my bikes, but I'm just trying to find ways of making this affordable for everyone.

One thing you'll notice about both concepts is a 10mm drop at the clamp. I wanted to make sure that the fork top caps do not touch the handlebars. As a bonus, this helps correct the steering geometry for a closer to stock feel, however extending the forks an additional 20mm is recommended for a full steering correction. You can see how to do that elsewhere on this forum. 

Lastly, I want to mention that the lower triple has a single mounting point for the Zephyr headlight bracket, but does not have a place to mount the stock brake hose splitter. Because the whole conversion requires the use of alternative brake calipers, you'll be running all new brake lines anyway, which means you won't need it. The headlight also needs a bracket fabricated for the angle adjustment. This is one detail I am still working out, but my guess is that if you are mechanically inclined enough to take on a conversion like this anyway, you will probably be able to figure that one out. I'll be sure to post about what I end up doing.

Wheel/Rotors/Speedometer Drive

For me, I'm trying to use my stock wheel, rotors, and retain the speedo drive, so there are a number of things to consider there. I have axle spacers, disc spacers, GSXR rotor bolts, and I still don't honestly have any idea how I'm gonna actually keep the speedo drive from trying to rotate on it's own. But those are all my problems to deal with and I won't bore you with the details, just say that if you want to discuss it we can. Why? Because you are probably smarter than me, and you will probably just use a ZX6R front wheel and axle and rotors and the stock brake calipers and everything will just fit. Swap in the rear wheel from the ZX6R as well, mount that wider rubber, and have yourself a little track day fun or something. 

TL;DR

Just some info, man. 

Fantastic work so far, the possibility of 750 and 1100 owners should make this popular. Well done. over 40 years now since i swapped front and back ends on my 400/4 for CB400N super dream parts. My days of this sort of thing are over but there must be plenty of folk with genuine interest and can make valid contributions.

regards

rob B (UK)

Bumpity bump bump.

Just wanted to see if I could get some more eyes on this, if there might be any questions or comments about it. I'm hoping to have them made and installed on at least one of my bikes by April, as that's when the 1 Moto Show in Portland is, and I submitted my bikes to be shown. I've been in contact with Cognito Moto about having them do the actual production, though no word yet about if that's going to work out. I mean it will, and I'll be using them for sure, unless they unexpectedly come back with a quote that's double what I've been getting from places so far. 

So yeah, anybody maybe thinking about it?

Project update. 
I’ve been busy with work and college lately, so I haven’t had much time to work on it. But I was exploring a few ideas I thought might be worth discussing. 

Spacing and Rotors
First of all I was considering a suggestion from Wookie about narrowing the spacing between the fork legs to make it so that I do not need to use spacers under the disc brake rotors. I went through a few versions of this, and found that 196mm is what it would be. For comparison, the stock ZX6R forks are 210mm, and my stock Zephyr forks are 205mm. 

I asked around about if such a narrow spacing would work, and didn’t get any replies. The idea has some other complications to it as well, so I’m thinking I might have to go another route. 

As such, I want to try and revise it to match the stock Zephyr 205mm spacing. I figure that’s a safe bet. This will of course necessitate a spacer under the disc rotors, unless I can find an off-the-shelf rotor that bolts right up and has a greater offset. The stock offset is 13.5mm, I would need 18mm. I have found it virtually impossible to even search for such a thing, as no rotor manufacturer lists enough information on their websites. 

Forks
I’m also exploring different fork options to see if some other fork besides these ‘03-‘04 ZX6R forks will be easier to work with. Non-radial brake mount forks might make it so that I only have to design an adapter to move the brake caliper in closer to the wheel (basically just a wider adapter than what’s already there), rather than shim the rotors. 

Wheels
I am of course also looking into options for other wheels that might make things simpler. It might be nice to find something that would let me swap both front and rear wheels and take advantage of wider, modern rubber. The challenge is that I really like the five-spoke design of my stock wheels. There’s maybe the Zephyr 750 three-spoke wheels, which would at least still be in the Zephyr family, but there’s not much else that wouldn’t look out of place. If money were no issue I could get some Galespeed or Marchesini wheels or something, but they are very expensive. 

—-

Thats all for now. I haven’t given up, but I will admit that all the complications are a bit disheartening. I knew this would be difficult and potentially expensive, but now its also taking so much longer than I thought it might. 

On the plus side, I recently acquired a 3D printer of my own to make prototypes with. It was free to me, other than buying some PLA filament for it. So at least after I get the hang of using it, I can make my own prototypes for a lot less. 

You appear to be going down a "rabbit hole" with this. Mixing and matching parts will always come with challenges (otherwise everybody would be doing it) from what I can see going with the 205 spacing and 4.5mm rotor spacers is "the compromise" if everything else works. If you start introducing more variables with different forks, wheels etc then the whole process starts over again as this will inevitably bring different chanllenges. I think you will struggle to find rotors with an 18mm offset (my ZX9R Rotors only have 11mm)
I would settle for the 4.5mm rotor spacers, draw a line in the sand and move forward