The blurb at the top of this blog describes one of my interests as human powered vehicles.  

Human powered vehicles are – and aren’t – a longstanding interest.

Huh?

Well, in the same way I am interested in ultra-light and home built aircraft – but have never turned that interest into a reality – so for a very long time I have been interested in machines powered by pedals.  But having now started to build my own human-powered machines, I soon realised that I know nothing about cycling technology. I don’t know my Rohloff from my Schlumpf, so to speak. 

So I figured I’d better do some reading… 

Bicycling Science, now in its third edition, is widely cited as a brilliant book – a veritable bible for cyclists and bicycle builders that has answers to all their questions. Well, those people are right –and they’re also wrong.   

Bicycling Science is a very good book, but it should be so much better. 

The book’s genesis is convoluted; suffice to say that the current version comprises major rewrites of previous versions, incorporating corrections and a new contributing co-author. And the result rather reads like that – it lacks the integrated sweep of topics and coverage that would be achieved if it had been written from scratch. There is also a rather arcane air of acknowledging each and every variety of opinion – when as a reader, I’d rather just grasp the perspective that in the view of the expert author, is correct.  (The brief bicycle history chapter has lots of phrases like: “we might have been wrong [in a previous edition]” and when covering a historical technological development, “whoever deserves the credit”.)    

The main author of the current edition, David Gordon Wilson, is Professor of Mechanical Engineering Emeritus at the Massachusetts Institute of Technology.  That makes his engineering knowledge beyond criticism but it also has the unfortunate outcome that while lots of information is presented, exceedingly few conclusions are drawn. One gets the feeling that the professor expects lay readers to be able to make their own judgements on the basis of what they have just read – and I believe that is wrong.  

So for example, the front-end geometry of a bicycle is discussed in great detail. Fork offset, trail, mechanical trail, steering axis and so on are all covered. However, completely missing is what surely everyone reading the book would actually want to know: what differences do all these characteristics make to how a bicycle behaves? This is barely mentioned. The same applies to the design of bicycle wheels, frames and many other topics.  

In the bicycle aerodynamics section, Reynolds numbers are covered. In anyone’s language, a Reynolds number is a complex idea to grasp, but the reader struggles through the text to find at the end that the following statement is made: “Most everyday bicycling occurs in the Reynolds number range of 1-4 x 10⁵ , and the reduction in air drag through the use of some form of practical low-drag shape as an enclosure of “fairing” can approach 90 per cent.” In other words, variation in Reynolds numbers is largely irrelevant to real bicycle aero… Where was the book editor to guide and prioritise the knowledge presented? 

There are also some astonishing omissions. Bicycle suspension systems, surely the greatest technological development in bicycling in the last 30 years, are not covered at all. Frustratingly, the author(s) touch on some aspects of bump absorption when describing wheel diameters, tyre construction and frame design – but nothing is tied together and there is no coverage at all of springs and dampers. Nothing is summarised of the advantages/disadvantages of small wheel bicycle design (eg current folding machines) versus traditional large wheeled machines, and electric assist bicycles are barely mentioned. 

But there’s also plenty of excellent resource material in the book. For example, if you want to know coefficients of adhesion of various surfaces, aerodynamic drag (Cd) and frontal areas of different bicycling machines, power dissipated in braking, how a cyclist balances a bicycle, whether rolling resistance or aerodynamic drag is most important for different machines at different speeds, the fade of rim brakes when they’re wet – and a huge amount of other similar material – this is a brilliant text.  

So what specifically could be improved?  

Firstly, get rid of the constant author citations used on every page and table in the book. Turn them into numbered footnotes – the book would then read so much more fluidly. Secondly, at the end of each major section, summarise the content in bullet points, with particular reference to how the information affects real bicycles. Thirdly, analyse some production bicycles in terms of design strengths and weaknesses – exemplars always make for a far better understanding. Fourthly, include a chapter on suspension. Finally, use more explanatory diagrams.  

As a beginning builder of pedal powered machines, I’m glad I bought the book. But with the above improvements, it would be a book that would change the way I think about constructing human powered machines.  

Rating: 7.5/10 

Bicycling Science – ISBN 0-262-23237-5