Tightening torques when clamping carbon components must always be strictly followed. Carbon's benefits of making lightweight and rigid components are enormous, but carbon is very sensitive to pressure. Overloading is to be strictly avoided !
The use of a torque wrench is therefore absolutely necessary and belongs to the basic equipment of every owner of a carbon bicycle.
Unfortunately, there are no uniform values or tables from which one could read off a flat rate. As individual as the construction of carbon frames, so different are the torques.
First, the specifications and assembly instructions of the manufacturer must be considered. In this case, the respectively lower torque of two components is the decisive variable, the maximum value to be applied.
If one component made of aluminum or steel, the value for carbon is basically, because this will always be less.
Before assembly, the tolerances must be checked; Of these are particularly affected stems, handlebars, seat posts, front derailleur clamps and barends. If the two components to be connected are laid loose, no pressure edges or gaps should be discernible, which leads to increased point loads. A uniform surface pressure, the uniform distribution of clamping forces is the alpha and omega of a secure and stable connection.
If this is not adhered to and controlled, a damage is inevitable even with the correct torque.
The use of mounting / assembly paste for carbon can reduce the required torque (previously determined value to be set maximum value) again by up to 30%. The paste increases the frictional forces and can even compensate small tolerances.
Therefore set the maximum value reduced by 30% on the torque wrench and tighten the previously greased screw until the torque is reached. If two screws are to be clamped, tighten them alternately one after the other so that no jamming occurs and a uniform surface pressure is ensured.
If, after a test drive, it turns out that the connection is not tight enough, gradually increase the torque without ever exceeding the maximum value.
The ideal case is to get the firm connection with the smallest possible torque and thus protect the carbon structure sustainably in use.
Nm = Newtonmeter
lbf = pound-force-inch
1 Pound-force-Inch [lbf·in] = 0,112984833333333 Newtonmeter [N·m]