The first issue is the gearing. I am used to a high RPM sport bike with a six speed gearbox. I find that I am either hitting redline or looking for more gears on this bike. So I wanted a gear indicator.
The second issue is the speedometer. The factory speedometer is average size, not overly large. Being a larger bike, it is a bit further away, making it difficult to read. What makes it even more difficult is that the range is calibrated as 0-180, which makes around town speeds only about a quarter of the range. It's not easy maintaining 40 mph when the spacing from 40-50 is about 1/4" on gauge 3 feet away.
The following photo was taken from the driving position (click on images to expand):
View this in the original GIANT size to see the markings on the speedometer
So it is tough to read the indicators. However, one thing that I noticed (also visible in the picture) was a reflection of the top of the silver fairing reflected on the windshield.
I decided that the top of the fairing would be a great location for a heads up display, reflected in the windshield. First step was to validate the idea. I mocked up some ideas on paper, and it looked promsing. I tested both 7 segment displays and 5x7 LED matrixes in commonly available sizes.
The paper version looked good, so ir was time to test something a little closer to what the actual device may look like.
I mocked up some images I could test using my cell phone. I briefly considered using an LCD, but the available modules would wash out in the mid-day sun. I drew them as green on black so they would reasonably resemble the LED displays I am considering using. While I do not intend to use an LCD display, it was a good mock up of how the light would reflect.
I think that the larger sizes would work well. The speed and gear indicator will show up within the rider's line of sight, but down on the road where it would not interfere with visibility.