Is the Q-factor in transmission bikes worse than in conventional bikes?
The Q-Factor is defined by the maximum distance between the outer edges of the crank arms ( Pic 28.1 ). The distance is measured at pedal height and is easiest when both crank arms are pointing in the same direction. An optimum Q-factor is relative, as it is dependent on the rider’s physiology and the intended use of the bike (street, cross country, downhill). It is influenced by the shape of the cranks and the width of the inner bearing. Pic 28.1 Current mountain bikes with derailleurs have a Q-factor range from 173mm to 176mm. Modern downhill and freeride bikes have Q-Factors between 188 – 192mm, this is due to wider tyres and the rigidity required in the rear swingarm resulting in a larger width. Recent gearbox concepts create similar values as mentioned. To prevent collisions from the chain line it is important to pay attention to the width of the Q-Factor, the chain line is explained further in question 25. Chainline attention is even more relavent when sloping the gearbox forward
