I understand that tri bike fit can be a pretty exacting science, though like all sciences there will be slighly differing opions.
However, is there a bit more flexibility with road bike fit? Can you be made to be comfortable on a road bike that’s say, 1/2 a centimeter off in term of top tube length?
Despite all the threads dealing with fit, bike fitting is anything but a science.
I don’t know about road racing requiring less precision but road racers likely utilize more positions on the bike. We’ll be in the drops, on the hoods, on the tops, on the nose of the saddle, on the back of the saddle, standing to jump or sprint or just sitting and spinning along. I’ll say I’m much more comfortable on my road bike than on my TT bike. My TT setup is good for an hour tops. My position is agreesive for short TT’s and perhaps the odd 4Ok.
I can feel changes in saddle height and fore and aft of a couple of milimeters …I don’t know if that is due to the precision of my fit or the fact that I’ve ridden so many miles in that spot.
I personally don’t believe that it’s any less or any more. All bike fitting means is the mating of a machine with a certain degree of adjustability with a human body that has a certain degree of adaptability. It is important to get off to a good start with the correct frame size, crank length, seat height, cockpit length, etc but you can do all the measurements you want but any two people with the same measurements may have entirely different flexibility issues and therefore need completely different fit requirements.
Start with the bike fit section on the Colorado Cyclist site for the basics of road bike fit. Then read all Slowman’s articles and Tom D has a couple of good articles on his site also. If you study these articles the logic behind tri bike fit becomes quite clear.
Some people are quite capable of doing their own fitting whle others feel better about paying a pro to do it. But IMO, utlimately you have to be your own bike fitter with the fine tuning by listening to what your body is telling you.
Despite all the threads dealing with fit, bike fitting is anything but a science.
Ergonomics, biomechanics, anthropometry, anatomy, mechanical engineering and aerodynamics are all applied sciences. In many systems that I develop these disciplines (among others such as cognitive sciences, computer sciences and others) are taken together to build a model that will predict the efficiency and effectiveness of the interaction between humans and systems. Bike fitting can be a science. It is the people who deal with it that are not scientists but business minded individuals who cashing on scientific terms. For example, How difficult is it to become FIST certified?
In many cases, when fitting bikes, the fitter harness concepts from one discipline, compromising others. In other cases, the model does not involve the proportional contribution of each variable to the final outcome (speed, injury prevention, economy and so on).
One of the main issues is individual differences. The systems that I design aim at targeting the majority of the target user population. When fitting humans to bikes, each individual and each specific bike is a different worksystem with some unique constraints. Knowing how to extract these parameters is not a science but a skill. However, the process that underlines the specifications gathering process can be validated against quantified objective measures.
That the study of human performance and anatomy is a science, I agree.
That any fit system can use hard numbers to fit someone, I say no way, the systems are always open to human interpetation and therefore tainted by that human’s bias.
What I’m saying is that no math exists, no formula is available and no one system is the bomb. Much of bike fit is marketing hype and disinformation, all this from well meaning people.