Mountain bikers need both riding stability and steering precision for optimum control off-road. The decisive component for high precision is the stiffness of the individual components, including tyres, wheels, fork, cockpit and especially the frame. One might assume that greater stiffness is always better. However, factors such as fatigue, riding feel and the need for forgiving handling in demanding terrain also play an important role.
System rigidity
Tyres, wheels, frame and fork together form a series of springs that connect us to the ground. The wheels are the stiffest components (100 %), followed by the tyres (40 %), fork (20 %) and frame (15 %). Theoretically, variations are most likely to be felt in the softest component of the chain - i.e. the frame.
Robert Krauss, Propain design engineer
As with so many things, the solution lies in the middle. Not too stiff and not too soft. We measure the whole bike and aim for a target value based on feedback from our racing teams. Different applications require different stiffnesses. The desire for different stiffnesses, depending on the frame size, has not yet been expressed by the racing team or customers.
Philipp Friedrich, Park Chief Mechanic, Geißkopf
I weigh 110 kilos ready for use and can clearly feel when the rear suspension is too soft. This feels unsafe and inhibits downhill riding - especially on berms. Tyre marks on the seat stays are a clear sign of a lack of stiffness. I also take a critical view of forks that are too soft. Conversely, I know of light riders who get arm pump more quickly from forks that are too stiff (Rockshox ZEB).
Peter Nilges, BIKE Test Manager
When it comes to frame stiffness, many manufacturers are still in their infancy and are wasting valuable potential. Our measurements and ride tests show huge differences, even within the same model range. In the future, the design of stiffness will be even more of a focus in the development of bicycles - because it has a major influence on ride quality and fatigue.
Laurin Lehner, BIKE test editor
I admit that I often guess wrong whether the frame is stiff or soft. This is probably due to two things: 1. components that falsify the impression. 2. with a body weight of 75 kilos, slight deviations in stiffness are hardly noticeable anyway. Then there are individual preferences: For example, I like soft upside-down forks that find their own way through nasty rock gardens. In short: Yes, a frame can be too stiff or too soft, but that is an exception.
Laurin Lehner
Editor
