Clubman Bar Design
We are in the middle of designing a new series of titanium cafe racer hardware. Here I will detail some of the design process for our basic clubman handlebars. First, this will be based on the ever popular chrome bars similar to the type you would see on Carpy’s bikes. Having ridden around with these bars, I must say that they killed my wrists and had some clearance issues with round headlights on a couple of my bikes. Usually handlebars use terms like rise, pullback, center and width. After measuring a number of clubman bars, i realized that the rise and pullback mentioned in the catalog don’t necessarily match up with the bars. Since I’m not too concerned with the actual numbers but am trying to provide more comfort, I’ll build this model where i’m adjusting the angles and lengths rather than the typical terms. It is just easier for me to think about the modifications in that way. I can make the model give a report which will say what the rise, pullback, etc. is if it’s really necessary.
Center Line Sketch
From this starting point I will input a center line sketch measured off of the bars that I used on my old Yamaha. You could do the line sketch in 3D sketch mode with solidworks, but i think it’s easier for this design to make modifications to two separate sketches that intersect on a plane. So, i start on my front plane and draw a horizontal line from the center representing the section of the bars that will be clamped to the triple tree and a vertical line which offsets the handle bars forward a few inches. Then i did a simple fillet based on the mandrels that I have available. Simple enough, but you only have bull horns right now.
Weldment Creation
The next step is to take your vertical line and make a plane on which to draw the center line of the section which will hold the controls. I built this so that i can simply put in an angle off of center to adjust the angle off of perpendicular from center at which the grips will sit. Within that sketch I have another angle which is the how far off of horizontal the grips will be. With those two angles i can make all the changes I need.
Angle Modifications
Once the sketch is complete I’ll want to make a weldment feature. Solidworks does this in a very nice way. You simply select your stock tube profile and the sketch and it automatically builds swept shape. In Pro/E, at least the versions that I used pre-Wildfire 5.0, you had to draw a cross section on a perpendicular plane and sweep the shape. Not much difference, just a little bit more streamlined one vs. the other.
Now I’m ready to make my drawings with a cut list and notes for the weld joint and knurled areas. I’ll have a few sets welded to test, so I simply make new configurations where i change the two angles that I described before. Beginning to end this takes about 15-20 minutes.
My next project will be to do a frequency analysis so that I can try to predict the vibration issues if any using titanium tubes.
Note: Our comparison of CAD systems has ground to a halt. Turns out Dassault Systemes has great customer service and the other two are lacking in ability or desire to get trials out to buyers. I have the Siemens NX disks loaded in my computer, but it’s taken three weeks to get the reseller to get the license to work. Perhaps that is the best thing that can be said about Solidworks. Their licensing works. One thing about the licensing of NX and Pro/E that always bugged me was that these companies are so worried about their software being pirated that they make it a pain for their paying clients to use. Meanwhile, Solidworks with their simple automated activate/deactivate has been cleaning their competitors clocks. It’s kind of too bad, because NX 7.5 looks awesome but I may just never know.
For more information on parts design in Solidworks, check out these books:
SolidWorks 2011 Assemblies Bible
Engineering Analysis with SolidWorks Simulation 2011
