In the following series of blog articles, we would like to explain the various factors which provide resistance in moving forward with your bicycle and how we at Vélobsessive are addressing these factors, to make our customers riding faster.
A moving bicycle with its rider is a highly complex matter when it comes to analysing the factors of resistance and how to calculate, measure and improve them. As outlined below, there are many different factors, and they keep on varying all the time, especially if you are riding outside under changing weather conditions and on real roads.
There are already many studies and experimental examinations from scientific institutes and manufacturers of the cycling industry. Most of these studies and experiments only analyse a certain portion of the overall picture. For example, wheel manufacturers are analysing aerodynamic drag of their wheels, but ignore the rolling resistance of the tire or some experiments in wind tunnels are done without spinning wheels, ignoring the rotational drag of the wheels. We are not trying to do another scientific study in this area, but we would like to point out where to best address improvement efforts, also under a cost/effect perspective. Is it really worth spending 300 Euro on a high-end bottom bracket with ceramic bearings and what would its effect on the overall performance be? – or should you better invest this amount in a bike fitting which optimises your cycling position?
Let’s look at what is causing resistance when riding a bicycle:
In this total resistance diagram, you can find approximate numbers in percent for the resistance caused form the various components. It assumes riding at an average speed of 30 Km/h over a longer course which has climbs and descents.
There are five main categories which provide resistance when riding a bicycle:
Aerodynamic drag, consisting of:
Aerodynamic drag of rider
Aerodynamic drag of wheels (both transactional and rotational drag)
Aerodynamic drag of bike (without wheels)
Gravitational resistance, consisting of
Weight of rider, including clothes, shoes, helmet etc.
Weight of wheels
Weight of bike
Weight of extras, such as tools, bottles, cycling computer and lights
Rolling resistance, consisting of
Rolling resistance of tires
Rolling resistance of hub bearings
Mechanical friction of drive train
Chain, jockey wheels, free run body, bottom bracket
Depending on the course, braking and accelerating cause a considerable portion of the overall resistance
When thinking about improvement measures it is essential to consider all aspects of the entire system, including the rider. It is also important to separate moving parts from static parts, for both rotational drag and gravitational resistance reasons. Saving 100g on a frame does not have the same impact than saving the same weight on a spinning rim. Off course the numbers in this diagram are only approximate and only true for a certain condition. They were estimated, assuming a speed of 30 Km/h. If you ride faster aerodynamic drag will be a bigger portion of the overall resistance and if you are riding on rougher roads, the rolling resistance of the tire will have a bigger impact. However, this diagram may help you estimating the overall impact when improving a certain component. For example, if you were reducing the friction of your drive train with an expensive oversized jockey wheel by 20%, it would only have a minimal effect for the entire system of less than 1%.
Herer are some measures you can apply to improve these factors, ordered by impact they may have on the overall performance:
Aerodynamic Drag of Rider
Improve your position on the bike with a precise bike fitting
Use aerodynamic clothes, helmet, socks
Therefore, Vélobsessive offers comprehensive bike fitting services. It can have by far the biggest impact on your cycling performance at an affordable price.
Gravitational Resistance of Rider
Lose weight. Low cost, easily said, but sometimes hard to achieve.
Rolling Resistance of Tires
Choose the right tire for the given road type
Adapt the tire pressure for the given circumstances
Aerodynamic Drag of Wheels
Use aero wheelsets, aero spokes, internal nipples
Aerodynamic Drag of Bike
Use an aero frame set, aero fork, aero seat post
Choose internal cable routing
Mechanical Friction of Drive Train
Keep the drive train clean and well lubricated
Choose a stiff frame design to avoid loss of pedalling power
Use ceramic bearings in bottom bracket and jockey wheels
Gravitational Resistance of Bike and Wheels
Choose lightweight material for frame, rims and spokes
Improve your cycling skills. Exercise balance and riding through curves at higher speeds
Rolling Resistance of Hub Bearings
Use ceramic bearings in hub. However, this is not a recommendation as it only has minimal impact on improving the overall performance
In upcoming blog articles, we will investigate the details of these topics. In the next article, we look at environmental factors which influence your cycling performance and why it is important to choose the right bike for the specific application - keep tuned!