Part 1—The making of a really great bike

They may not seem it but bicycles are actually fairly complex machines and the various dynamic coordination chains required to ride one are even more complicated.  This is often forgotten because almost everyone finds it pretty straightforward to ride one, in fact it is quite difficult to make a bike that cannot be ridden. However, anyone who has ever ridden more than one will appreciate that every bike feels slightly different and some are better than others.  More often than not the reasons for these differences are not clear and so bikes are increasingly judged by parameters that are easy to understand and evaluate.  Unfortunately many of these parameters are almost irrelevant to what really makes a good bike.  

I will assume at this point that cycling is something that we all do because we enjoy it.  The reasons that we all enjoy it may be slightly different for each individual but whatever your reasons the experience that you have on a bike is governed by the interaction between machine and body, the ‘ride feel’ if you like.  It is this ride feel that is at the heart of my design philosophy and what sets a ‘Sturdy Cycle’ apart from the masses.  I have spent a long time refining my understanding of the interaction between man and machine and in this post hope to explain how this can be broken down in order to design a better bike.

When I first started my quest to improve a bike’s soul I soon realised that it would be nearly impossible to interpret what was needed from the rider's opinion.  I have learned from years of bike fitting that there can be misleading differences between what a rider thinks they are doing/feeling, what they say they are doing/feeling and what they are actually doing/feeling: A bit of experimentation soon revealed that, for example, a rider saying that ‘this bike was better because it was stiffer than that bike’ was a load of rubbish because I knew from testing that the opposite was in fact true (more detail on the specific example of bottom bracket stiffness follows in a separate post).  Instead I started to look at what was going on biomechanically and then relate that back to the mechanical characteristics of the frame.

At this stage it is important to understand a little more about the biomecahnics of cycling, specifically the way in which the legs generate useful movement to turn the pedals.  I won't go into too much detail here as I run the risk of delivering a sports science lecture.  Suffice to say that there are several large muscle groups involved in transferring useful energy to the pedals of a bicycle.  Each of these muscles contract in a coordinated chain to perform the required action and, as with most movements that we perform, the vast majority of this coordination is subconscious.  In order for our bodies to coordinate actions subconsciously they use proprioceptive feedback and reaction forces to get the timing of the movement right: For example when you stand still on a springy surface your body knows that its is on a springy surface because of the reaction forces coming up through your feet and keep you upright by constantly adjusting the position of your centre of gravity according to those forces. So we can see that, given that the action of pedalling remains a constant, the forces experienced by your body can be altered by changing the reaction force that is transferred to it through the bike.

This approach of examining the reaction forces is particularly useful when trying to break down what is going on mechanically in the bike to create a certain perception for the rider.  The dynamics involved remain extremely complicated and I do not have the time or means to fully quantify the relationships. The fundamental principle, however,  means that I am able to isolate key structural properties of the frame and their role in generating a certain ride feel.  By way of example I found that riders reported a different perception of bottom bracket stiffness on a carbon fibre frame vs a steel frame despite both frames having almost identical bottom bracket deflection in industry standard tests.  Isolating the key structural members responsible for the reaction forces highlights that because of the inherent mechanical properties of the two materials being different (i.e. steel has a much higher young’s modulus) the ‘stiffness’ of the bottom bracket is provided in a different way by each frame: The steel chainstays provide a greater percentage of total ‘stiffness’ than the carbon chainstays. This results in a different ride feel that I will elaborate on in a post to follow.

This type of analysis as to how the structural performance of a frame can be used to optimise the relationship between man and machine can be applied to many different areas of the bicycle. This allows me to build up an understanding on a level that is far more poignant than rider feedback or structural testing alone. It is this understanding that goes into creating the ‘soul’ that makes a bike really special.

In posts to follow I will use more specific examples to explain why my frames have certain features and why many are at odds to the trends evident in the wider industry. For now though I hope this has given you an understanding of what is going on behind the scenes, before I even touch a file, in the making of a truly great bespoke bike!