The need for this project arose from observations I’ve made while working in the retail bicycle industry. As manufacturers adopted the use of carbon fiber steer tubes on both road and mountain bikes different installation procedures needed to be implemented in order to maintain a certain level of safety.
Manufacturers of carbon fiber steer tubes overwhelmingly subscribe to a specific way of installing handlebar stems. It is recommended that a threadless stem be installed with a small spacer between the headset top cap and stem. The size of this spacer can vary between 2.5mm and 5mm.
The installation method above shows the preferred way to install a handle bar stem on a carbon fiber steer tube.
The reason for this installation method is so the stem full grabs onto the steer tube, as opposed to the traditional way of installing a stem where the steer tube should sit about 3mm below the top of the stem. With a stem fully interfacing with the steer tube the user lessens the risk of damaging the top of the carbon fiber steer tube by applying uneven pressure between the top and bottom pinch bolts.
As a result of this installation method almost all riders with carbon fiber steer tubes use a small spacer under their top cap. I run this set up on 3 of by bikes.
This top cap design takes the function of a head set top cap and fuses it with a small steer tube spacer. It simplifies the set up process and adds some visual cleanliness to a bicycle.
The project is still in development at this moment. The model shown was a rough prototype that was 3D printed. The second version will be less bulky by using different hardware and slightly smaller.
