Anybody interested in a CR/F front end conversion for XR650R's

[jesusgatos]

I swapped a CRF front end onto my XR650R using stock tripleclamps and I wasn't happy with how the whole thing went together, so I decided to design a set of custom tripleclamps to do it right. I contacted SCOTTS to get some dimensions from their steering stabilizers and the forward-mount stabilizer post, and ended up talking with them about the possibility of adding these tripleclamps to SCOTTS product line. Their biggest concern is that the XR650R's are being phased out and there might not be much demand for a product like this.

So, what do you guys think?









Here's a link to a thread I started on ThumperTalk about all this and there's a lot of discussion about geometry and trade-offs, etc.

[ganshert]

What is to be gained by swapping the forks?

[jesusgatos]

Originally Posted by ganshert

What is to be gained by swapping the forks?

Depends on who you ask. Some people would say nothing. The CR/F forks have 1.2" more travel, they don't flex as much (good or bad depending on who you ask) and the complete CR/F front end is about 3lbs lighter than the stock XR parts. Follow the link I posted to the thread on TT and I included a lot of links to other relevant discussions about this swap. Search a little and you'll find a lot of information (and a lot of BS) about this swap.

[kenaroo]

Yep.. there is going to be a small demand for these units.

but... You have got a great design.

PM me if you go ahead and make a few.

I'll take one

Ken

[gaspipe]

USD vs conventionals really boil down to what terrain you're riding, and how particular you are. A preference thing, if you will. Those that want 'em know what they want and will buy them. Nice looking design, btw.

FWIW, Gary Emig has been making these conversion clamps for a while, they seem to sell well, and they're still in production. The 650L, 600R & 400R can do the same swap with a steering stem change.

So if you dig a Scott's damper, another cool option for a neat swap.

[jesusgatos]

Thanks, I'm aware of the Emig tripleclamps but he only makes a sub-mount setup for his own steering stabilizer and I would rather run a SCOTTS. His tripleclamps are also only available with 24mm offset. That's the same as the stock XR650R and the CR/F tripleclamps, but the stock XR forks have about 4.5mm's more offset at the axle than the CR/F forks. I'm running a CRF450 front end on my bike right now with stock tripleclamps and it's kinda twitchy. It's great for woods and tight riding, but I've got a 250 for that so I'd prefer to add a little more offset at the tripleclamps to mimic the stock geometry.

[Hair]

Not to be negative.

But

Your clamps seem to have a lot of material removed. I like that, but are you using a model or running calculations that gives you the confidence that these things are as strong and as ridged as they need to be?

[jesusgatos]

Originally Posted by Hair

Not to be negative.

But

Your clamps seem to have a lot of material removed. I like that, but are you using a model or running calculations that gives you the confidence that these things are as strong and as ridged as they need to be?

No offense taken. I'm not an engineer but I design and build a LOT of stuff.

I started off by taking measurements of other tripleclamps (stock XR, stock CRF and various aftermarket tripleclamps) and comparing them to see what type of material thicknesses they're using in different areas; most of them were within a few mm's of each other and they ALL have material removed from the underside of the upper and lower tripleclamps.

Where the material is removed (and what's left afterwards) is really just as important as how much material is removed. See how the ribs criss-cross the bottom of the tripleclamps? That's not a random pattern. It's a 'best guess', but I decided where to put those reinforcing ribs based on the type of forces that a set of tripleclamps is likely to see. It's not too hard to picture how a set of tripleclamps might get twisted, pushed and pulled on.

Personally, I'd feel comfortable running these tripleclamps without any further testing, but if a company like SCOTTS ends up selling them, you can be certain that they'd sign-off on the design before anything would go into production. I talked with an mechanical engineer friend of mine about this project about running some type of stress analysis. I'm sure we'd learn something that would allow me to improve on this design, but the truth is that it's probably not worth the time for the limited number of these that will be produced.

[cyclewizard]

I would like to do the USD swap.
I'll take one too.

[Hair]

When I said model I meant did you model them after an existing product. Seems that you have. Then if that product is good one can assume that your product will also be good. But that logic even has flaws.

I am sure that you build a good product. I just thought that it was worth asking about.

Originally Posted by jesusgatos

No offense taken. I'm not an engineer but I design and build a LOT of stuff.

I started off by taking measurements of other tripleclamps (stock XR, stock CRF and various aftermarket tripleclamps) and comparing them to see what type of material thicknesses they're using in different areas; most of them were within a few mm's of each other and they ALL have material removed from the underside of the upper and lower tripleclamps.

Where the material is removed (and what's left afterwards) is really just as important as how much material is removed. See how the ribs criss-cross the bottom of the tripleclamps? That's not a random pattern. It's a 'best guess', but I decided where to put those reinforcing ribs based on the type of forces that a set of tripleclamps is likely to see. It's not too hard to picture how a set of tripleclamps might get twisted, pushed and pulled on.

Personally, I'd feel comfortable running these tripleclamps without any further testing, but if a company like SCOTTS ends up selling them, you can be certain that they'd sign-off on the design before anything would go into production. I talked with an mechanical engineer friend of mine about this project about running some type of stress analysis. I'm sure we'd learn something that would allow me to improve on this design, but the truth is that it's probably not worth the time for the limited number of these that will be produced.

[jesusgatos]

Here are a few more screen captures. One shows the webbing and reliefs that are cut into the bottom of the upper tripleclamps on the solid-mounted version (I'm working on a rubber-mounted version too). The other images show the SCOTTS forward-mount stabilizer ring and how that works with the upper tripleclamp. That's the other thing I didn't care for about the Emig tripleclamps (the oil-fill hole stabilizer mount).

[jesusgatos]

I've got another question. What type of headlights and/or numberplates should we make these tripleclamps accommodate? Would anyone want to run a CRF250/450X headlight? Stock XR headlight? A CRF250/450R numberplate? I will probably run a 8" Baja Designs racelight (or maybe one of Kenaroo's fairings) myself, but I have all of the dimensions for each of those other headlight/numberplate mounts. I just don't want to clutter-up the tripleclamps with mounts for stuff that nobody will use.

[jesusgatos]

SCOTTS and BRP have decided not to produce these tripleclamps due to a perceived lack of demand, which I completely understand with the 650 not being offered for sale in '08. I'm going to continue looking for another tripleclamp mfg that might be interested in the design. If I don't find a company that wants them, I'll just have a set made for myself. If I end up doing that, I'll be able to make a few extra sets if anyone is interested.

[XRR-kat]

jesusgatos,
Now that I am committed to CRF 450 forks for the BRP, what's the status of your research?

Any alternatives?

[husky123]

......