Saturday, May 26, 2012 at 11:39AM
I have been working hard on a scratch built chopper design over the last 3 weeks. The entire bike including the engine block, frame, tank, etc was drawn by myself and I am really happy with the outcome and I hope you find this blog post interesting.
I have always enjoyed watching American Chopper but have found the recent series with PJD really inspiring. I don't ride a bike myself but I am really drawn to the long leaned out style of the chopper, its really form over function as I can't imagine riding one of these on the roads where I live!
PJD's AntiVenom bike was a strong reference, I love its proportions with the motor, seat and exhaust tightly compacted in the rear third of the bike. The Harley Davidson Night Rod Special is another favourite of mine, the way the tank fits around the frame and the position of the exhaust can be seen in my FusionWeld bike. The simple matt black paint scheme with the red highlights are another feature of the Night Rod that I really liked. Finally the aggressive surfaces on the tank of the Ducati Monster Diesel was styled onto my bike as well as the cushion design off the seat.
The motivation for this design has been to enter it into instructables.com's “Make it Real” challenge which ends on June 4th, check out my submission here. I have wanted to work on my own bike design for a few years now and managed to find some time between a few other projects I am working on.
- A huge 20" front & 16" rear wheel
- A one piece tank and seat housing
- A super stretched out 35 degree rake
- Dual exhaust with integrated LED lights
- A stripped back, long and low slung stance
Apart from drawing out all the details at the end of the build, I spent most of the time working in Solidworks on the frame. Originally I wanted to integrate a cool swing arm design that kept with the traditional chopper look but I couldn't get it to work so I kept with the standard hard tail. I have been obsessed with proportion and angles, trying to achieve a certain look I had in my head. My technique was to tweak the frame, wheelbase, etc print it out and then sketch the rest of the bike by hand. This quickly gave me a good idea how the look would turn out and I could compare different configurations until I was happy.
I am really pleased with the stretched out look of the tank and the way it flows from the backbone of the frame, it is also a continuous surface that forms the housing for the seat. I wanted this continuous form as I don't really like the separated look of most chopper tank and seat designs.
I'm pretty sure I am not the first to come up with this, I wanted a really clean look and rear lights sticking out on stalks sometimes ruining the flow of the bike. I like the dual side rear exhaust so I thought it would be cool to see how it would look with some LED's running around the exist of the exhaust pipe housing. The actual exhaust pipes run inside this housing keeping the high temperature parts away from the LED's. I'm sure it would be a technical nightmare to get these to work, but that's the fun of creating concept designs!
I wanted to follow the matt black look of the Night Rod Special but with a different colour for the tank, fenders and front light. I tried a few bright colours but when I hit the metallic grey and black I knew that completed the look I was after.
Solidworks 2011 was the CAD package I used to create the chopper design. The YouTube video shows the model in alot of detail. I work on the design as a single part file with multiple bodies as it is a much faster way to work and contained into one file. When I get to a point where the rebuilding takes too long and the file size gets quite big I export the bodies from the parent part file into their own part file. This method works really well, I can still go back and alter the geometry or other details of the bike and everything updates correctly. I then add more details to each part and then create sub-assemblies and then bring them together into a final bike assembly.
As I mention at the start of the YouTube clip a powerful “branded” PC is not necessary for a fairly complicated CAD model. I run an i5 2500k overclocked to 4.2GHz with a ASUS HD 6850 GPU (a gaming card) and Solidworks runs perfectly.
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