Q factor (bike)
The Q-factor in the cycle the determined stability range (engl. Tread ) and refers to the lateral spacing of the mounting points of the pedals to the crank set .
The distance is made up of the horizontally measured distance between the outer surface of the left pedal crank and the center of the frame plus the same distance between the outer surface of the right crank and the center of the frame. Often these two distances are the same. Sometimes the right crank is a few millimeters further from the frame, e.g. B. to create space for a chain guard box. The Q factor is largely determined by the axle length of the bottom bracket and the offset of the cranks.
When walking, most people put their feet almost in a straight line. This suggests that a small Q-factor is more ergonomic than a wider pedal distance. If you ride in a standing position, increasing the distance between the pedals requires the use of the upper body and arms to compensate for the forces that are introduced to the side of the center axis of the bike when pedaling.
If the pedals are further apart, the risk of the inside pedal touching down when lying on the side in tight and fast corners increases.
For recumbents with full aerodynamic fairing, a particularly small Q-factor can be desirable because it enables a light, streamlined, narrow design.
development
In the past, it was not customary to specify the Q factor. The distance between the pedals was similar on most bicycles and straight cranks were used, so that the length of the axis of the bottom bracket roughly corresponded to the Q-factor.
Today, bottom bracket shafts from around 105 to over 135 mm in length are offered in order to be able to adapt the chain line and to accommodate an additional chainring on the left side of tandems, for example. In addition, the Q-factor depends on the shape of the cranks, which are now almost always cranked (curved) outwards.
The use of wider tires and a third chainring on mountain bikes increased the Q-factor. In the case of mountain bikes, the previously common installation width of the inner bearing of 68 mm is now often increased and 73 mm could establish itself as the new standard.
With racing bike cranks, a low Q-factor is still aimed for in order to enable efficient pedaling.
literature
- Hey Pal - What's you Q-factor? , Article in English, from the 1991 catalog of the bicycle manufacturer Bridgestone
Individual evidence
- ↑ Sheldon Brown : Sheldon Brown's Bicycle Glossary . Sheldon Brown. Retrieved November 11, 2009.
- ↑ Bike technology for professionals: Bike technology for professionals - http://radtechnik.awiki.org. In: radtechnik.awiki.org. Retrieved January 8, 2017 .
Web links
- Notes on the possible reduction of the Q factor for recumbent bikes (in English)