Why Did We Choose STT 3DMA?


t Primo Cycles, we have made a big investment in our fitting technology by installing the STT 3DMA system. But why did we choose this system out of the many that are out there and why should you get assessed with this for your next bike fit?

Let me get one thing off my chest before I get started: I have a gripe with the bike fitting industry. I feel that it has become very “branded”. People say that they have had a “Retul fit” or a “Guru fit” or a “X, Y or Z fit”. All you are doing is naming the tool that the fitter used to measure the angles. It would be the equivalent of saying that your bike got a “Park Tools service”. The tools do not do the job for you. The expertise come from how you interpret the data that the tool provides. I have been fortunate to have worked with many different tools during my time as a bike fitter and have got used to their limitations. It started out with simple static methods with goniometers and plumb bobs but these were often not representative of what was happening when actually riding. Next were dynamic video based software which had the limitation of being two dimensional and often having to guess where the bottom of the pedal stroke was and where the joint lines actually were. Finally I started working with the Retul system 6 years ago which, at the time was head and shoulders better than anything else out in the market but things have now moved on.

In my opinion, the STT 3DMA system is the best on the market. It uses four cameras placed in the ceiling which fire out infra red light and then times how long the light takes to reflect back to at least 2 cameras. With this information, the system can triangulate the position of that reflection in 3d space and track it’s movement. We position super reflective balls on each part of the body that we’re wanting to measure and the system can quantify the angles between joints at every part of the pedal stroke.

It creates a virtual 3d skeleton than we can rotate and look at from multiple angles. This allows us to visually show our clients things like excessive hip rotations, if the client is sat off centre on the bike, dynamic knee tracking and back posture. With Retul, it often felt like staring at the matrix, there were a bunch of numbers flashing up on the screen that, while I knew what they meant, the client often looked dazed and confused. With the 3DMA graphics, a layman can instantly see where problems are and how things have improved. Retul was great, however it only recorded the mechanics of one side of the body. For riders that had imbalances left to right, we had to spin them round to quantify the other side. Often we then found that the other side was out of range, particularly if the rider had a leg length difference. This lead to the fitter having to continually spin the rider around to find the best balance between left and right which took time and limited how many adjustments that could be made. With the STT 3DMA system we get the angles from both sides and can therefore quickly find the best balance between the two.

The system can be used to measure for both road and time trial and even mountain bike positions and after the fit also measures the bike contact points with the same accuracy. Because the system is measuring to the same points on the bike, it is very easy to replicate the position to other bikes. Global Triathlon Network did a good video recently with their experience of the system.

A STT 3DMA fit on your current bike takes 2 hours and costs £200. In addition to quantifying your riding mechanics with the 3DMA system we will asses your flexibility, cleat placement and shoe support, saddle and bar width. In addition to leaving with a correctly adjusted bike, your will also be sent a PDF report with the bike set up. Drop us an email at bikefitting@primocycles.co.uk for more information on our bike fitting and to get yourself booked in.

Recommended Posts

Leave a Comment