When it comes to capturing and transferring bike fits, little technological progress has been made. VeloAngle showcases several vital innovations including how the relative position of reference points are described. The traditional method of defining position of the handlebars relative to the saddle would be to measure how far forward the handlebars were, and then how much higher or lower would require gathering the X (horizontal) - Y (vertical) measurement.
X-Y Measurement Approach
VeloAngle defines the X-Y relationship by the length and angle of the line connecting the two points. Referred to as a polar measurement, this approach is obviously different, but perhaps not as clear as to why it is the ideal process.
The main reason is that you are taking measurements in one step rather than two. In fact, up to six separate measurements are often made for each X-Y measurement:
- Transfer the saddle (1) and handlebar (2) position to the floor with a level or plumb bob
- Measure the X distance between the two points with a tape measure (3)
- Repeat the same procedure against a wall using a level to transfer the saddle and handlebar heights (4 - 6)
With each step, there is a potential for measurement error. In comparison, VeloAngle utilizes direct point-to-point measurement, with the distance between the two points read against a clear reference point and the angle of that line displayed on a digital inclinometer or smartphone app.
This raises the questions as to why X-Y measurement was adopted in the first place. Mainly, it is a reflection of the gravity-based tools available at that time. A simple weight on a string (a plumb bob) can establish a vertical line, while a carpenter’s level can provide both horizontal and vertical references.
An often overlooked requirement of accurate measurement is that the item being measured must be aligned with the measurement system. With traditional X-Y measurement, this means the bike must be level. While the error varies somewhat with size and geometry, for a typical road bike with a 56cm frame, one degree out of level results in saddle position errors relative to the crankset of 13 mm in X and 5 mm in Y. This would be quite noticeable for the vast majority of riders attempting to duplicate their fit. VeloAngle’s angle-based system allows the level plane to be set based on the bike’s position, thus eliminating the need for bike leveling.