Monday, January 27, 2014

GT Bicycles - Development of the STS-1 - Carbon Fiber LTS

GT Bicycle's STS-1 Carbon Fiber Bike

This is the carbonfiber version of GT's high performance LTS dual suspension mountain bike I designed in the mid nineties. The design process started of with a series of side view hand sketches. As with a number of in house design departments the sketches are just black and white, no time to add color. To speed things up just the frame is drawn on photo copy paper with the wheels, seat, handlebars and already copied onto the page.

After the first few rounds of sketches, a few concepts were selected to be prototyped into models. I did a few more detailed sketches of just the frames to nail down the forms for a reference as I hand built the models.

Then, I got to work building the prototype models. Using metal, wood, bondo, screws, glue and even some very rough welding I created the models.

Having completed developing the frame forms the concepts are ready for paint to make them look more real.

At this point there was a management review and there was a feeling that the designs were too far away from the traditional straight tube look. Compared to bikes now, these concepts are very tame but back then they were a bit edgy. So a more linear concept was developed and a prototype model built to show how it would look in real life.

As is common with most development projects the initial designs are a result of working with a certain premise of how things are going to work. Any of these designs were going to be complicated to manufacture and we were learning more about the molding process which was not going to be easy. This is the point when assumptions are challenged and a fresh look is taken on how to design the product. In this case a handle bar using the same manufacturing process was being looked as a method of making our design easier to make. The bar had metal sleeves that the carbon fiber tube ran through in the center and at the ends where the stem and barends would clamp.  If we did the same thing with our problem areas, headtube, seat tube and bottom bracket areas, things would be a lot easier.
Time was passing by and we needed to get it done. So I sketched out a quick design of how we though it was going to look and we ran with it.
In the sketch you can see where I drew what the cross section would look like in various ares of the frame. You can also see the straps from the cnc machined parts that the carbon fiber tube was threaded through. A model was quickly made but never built up. Instead it was cut up to use for reference when modeling the frame in the computer software.

Below is the finished bike, some detail shots of the cnc parts and the bike as it looked as when GT developed it into a down hill bike.

If you are interested in seeing more of my work or are interested in the design services I offer please click here to go to my website, Bullseye Design Worx. To see more bike design related projects click on the label tags to the right.

The GT Bicycles STS-2

GT Bicycle's STS Head Tube
GT Bicycle's STS Seat Tube and Upper Pivot

GT Bicycle's STS-DH - Down Hill Bike