Tech Talk
Welcome to Tech Talk. Short and to the point, our monthly articles aim to keep the average cyclist informed on how to keep their bikes running smoothly, longer.
Bike Fit – Road Racing Bikes
As a professional bicycle shop one of the things we are expected to do and do well is fit people to their new bikes. This is sometimes a difficult and contentious task. With one or two exceptions whichever system is used and whether it is a manual or computerized system it all comes back to the basics of the old knee over pedal system (kop).
As long as your bike is the correct size a good fit “with room to move” is easily achievable. However there are problems arising from the fact that there are finite restrictions to good bicycle design. If a bike does not fit within these parameters it may not handle well, particularly at high speed, it may accelerate poorly and it may climb poorly. In round figures a 54cm bike will have a 54+cm top tube, a 57cm will have a 57cm+ top tube but when you get to extremes of size a 50cm will have a 52+cm top tube and a 62cm will have 60-cm top tube. This is to keep then within acceptable parameters. This can create a problem with short or very tall people.
The fairer sex (women) cause problems because they are generally not tall and the majority of bikes sold to females are 52cm and under. Given that the bone structure/muscles in women are different to men and given the limiting parameters for an exceptable bicycle design it makes it difficult to get correct kop fit. This is so much the case that in racing when a bike/rider is being scrutineered, for knee/bottom bracket setback, special exceptions are made for women. Having said that it can be equally difficult to set up men on small bike frames.
This often results in the set up position being slightly forward of the ideal. What this actually means is that it is easier to spin but you don’t get as much power as you would if you were set backward of the ideal. Unless you’re contesting a Sun tour or Tour De France it’s not usually a problem either way. If your seat height is correct and your knee is pretty much correctly positioned and you are not overly stretched but are having problems such as a sore neck, knees or back you may need an experienced hand to help you.
Please note that doing a two or three day coaching course and being able to ride a bike does not make one experienced in bike fit.
Because we are all physically different one set of rules cannot apply to everyone. For example two people may have exactly the same bone lengths but one may have different muscle size and shape and different flexibility to the other. On the other hand riders may be of the same height but have different proportions.
If you are having problems you should seek to work through them with an experienced member of a good reputable bike shop (preferably the one you were smart enough to got your bike from), Good bike shops see and set up a lot of different people of differing sizes and from different walks of life giving them the experience necessary to help you.