A low-cost experimental-numerical method for the prediction of on-road comfort of city bicycles is presented. Experimental tests are performed by exciting the wheels of the bicycle with impulsive vibrations and measuring the frequency response functions (FRFs) between different sensitive points of the bicycle (i.e. seatpost and steerer tube) and the wheels. Laboratory tests are carried out with the rider on the bicycle, and the posture is carefully checked. A mathematical model is employed to predict the accelerations experienced by the rider on the road, considering tyre and wheelbase filtering. As a verification of the proposed methodology, comfort predictions obtained with the experimental-numerical method are compared with reference data obtained from road tests. A general agreement in terms of the root mean square values and power spectral densities is found.

Vibrations of two typical bicycles are measured by means of road tests in bicycle lanes. The analysis of experimental results in terms of power spectral density (PSD) of the acceleration components shows that most of the energy associated to bicycle vibrations is concentrated in a low frequency band (<30 Hz). Since piezoelectric cantilever harvesters achieve the best performance in resonance and the resonant frequency is well above 30 Hz, specific tuning strategies are adopted. A novel mathematical model for simulating the electro-mechanical behaviour of a piezoelectric harvester equipped with an auxiliary oscillator is proposed. Calculated results show the potentialities of this tuning device in terms of generated voltage and stress inside the piezoelectric layer. Prototypes of harvesters equipped with auxiliary oscillators are built and tested in the laboratory obtaining the frequency response function (FRF) of generated voltage. Finally, the average electric power generated by these harvesters (which are assumed to be interfaced to an electronic load by a power management unit based on synchronous rectifying technique) is simulated by using the measured FRFs and PSDs of bicycle vibrations.

The problem of frequency tuning a cantilever piezoharvester to the typical vibrations of a bicycle is here investigated. This is a key to optimize the energy harvesting performance. Road tests with a bicycle on a typical city track are first carried out to measure the power spectral density of bike vibrations. Both analytical and experimental methods are used to estimate the average electric power that can be harvested by a piezoharvester with a solid tip mass. This solution is compared with a tuning strategy based on a liquid tip mass by using a novel analytical method for simulating frequency response.

Cyclists are exposed to vibration due to road roughness. The levels of vibration that the cyclists experience have a major effect on comfort and depend on the bicycle, rider and road characteristics. It is known that the posture of the cyclist has a relevant effect on the bicycle-cyclist system vibration response. Nevertheless, this effect has been scarcely quantified. This study focuses on the measurement of the effect of body posture on comfort while riding a bicycle. A laboratory methodology based on the measurement of the impulsive response of sensitive points of the bicycle was implemented to predict the comfort of cyclists on the road. The posture on the sagittal plane was verified during the tests. The methodology was implemented to predict the comfort of two cyclists riding a city bicycle in two postures: upright and bent forward. Experimental results showed that in the bent forward posture the acceleration levels had a significant increment for the handlebar stem and a non-significant increment for the seatpost.

The correlation between the modal properties and the comfort characteristics of a utility, step-through frame bicycle are investigated. In-plane modal testing of the vehicle is carried out both without and with the rider, and the major differences between the results obtained with the two conditions are highlighted. In order to have an insight into the contribution of the various bicycle components to the transmission of vibrations, the frequency response functions (FRFs) between the main interface points in the vehicle structure are measured and studied. Finally, the modal characteristics are compared with road tests data, emphasizing the relationship between the in-plane vibration modes and the main peaks in the acceleration power spectral densities (PSDs) measured on the road.