As increasingly more bicycles are equipped with electrically powered pedal assistance, they can become the solution for the continuous congestion that threatens Europe. Pedal assistance decreases the effort, though cyclists often experience sores that occur at the low back, knees and bottom area. The risk of injuries is predominantly determined by the pedal technique, which is highly dependent of bicycle design, seat type and cycling posture. The optimal cycling technique and the relation to the bicycle characteristics needs to be discovered to create guidelines for bicycle construction and usage. This paper presents the design of a low-cost measurement system to analyse three-dimensional pedal loads in function of the pedal cycle by an instrumented pedal and an absolute encoder fixated on the crank. The pedal proposed is a combination of a unique steel sensor with twelve sensor regions, organized in four full Wheatstone bridges, installed on a standard pedal spindle. The pedals are calibrated with the Global Regression method acquiring a calibration matrix with a standard error percentage of full scale of maximum 0.5%. The instrumented pedal distinguishes itself from state-of-the-art techniques through (i) compatibility: it fits on every conventional bicycle, (ii) compactness: not influencing the cycling kinematics, (iii) broad applicability: it is applicable for in-situ measurements with extreme manoeuvres and (iv) accuracy: it delivers a relative high accuracy in relation to the production precision and production costs.

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Measuring lower extremity joint angles during cycling is interesting to derive joint loading from contact forces at the pedals and to determine the cause of cycling injuries. Traditionally, joint angles are determined in a stationary setup with high-resolution cameras that track marker movement in a lab environment. Alternatively, joint angles can be estimated mathematically in-situ: the lower extremities, bicycle frame and pedal arms are presented as a 5 bar linkage system which is fully defined by the lower extremity segment lengths, seat height and pedal position. As most instrumented pedals for power measurements include pedal orientation measurements, the bar linkage system demands no special equipment to derive joint loadings from pedal loads. The aim of this study is to validate the bar linkage system for joint angle estimation in the sagittal plane during in-situ cycling. Ten subjects cycled on a stationary bike while the hip, knee and ankle angles were measured with a Vicon optoelectronic motion capture system and simultaneously calculated with the bar linkage system. The results were averaged to subject-specific and method-specific ensemble average curves in the function of the phase in the pedal cycle and compared by a correlation analysis, Bland Altman plot, and Spm1D paired T-test. The hip and knee angle estimation of the bar linkage system showed no statistically significant difference from the optoelectronic system. Moreover, the ankle showed a statistically significant difference in the last half of the recovery phase of the pedal cycle. As the difference was maximally 3°, it has no clinical significance when deriving joint loading from contact forces at the pedal.

In many city centres and some large urban areas, access restrictions are imposed on trucks and vans. On the other hand, the number of e-commerce packages to be delivered daily is increasing rapidly, and service companies of all kinds also have to serve their customers in these areas. The use of cargo bikes is seen as a possible solution. The direct reason for this research is the observation that there is still room for a new type of cargo bike that meets the needs of the outlined target groups. This article summarises how the quality function deployment (QFD) method has been used for the systematic development of an electric cargo tricycle that meets these needs. The developed tricycle distinguishes itself from existing cargo bikes mainly by its loading capacity, stability and manoeuvrability. The prototype tests performed by professional couriers were so positive that a pilot series was built.

Traditional instrumented seat posts determine context-induced seat loads to analyze damping properties. This paper presents an enhanced instrumented seat post able to measure all six load components to resolve user-induced seat loads. User-induced cycling loads consist of all loads the user applies to the bicycle during cycling and is measured at the steer stem, the seat post, and the pedals. Seat loads are essentially uncharted territory, as most studies only address pedal loading to study cycling technique. In this paper, a conventional seat post is redesigned by equipping it with a u-shaped component and strain gauges. The instrumented seat post is straightforward thanks to (i) the simple design, (ii) the gravitational calibration method, and (iii) the permitted clearance on the strain gauge alignment. Analyzing mean seat loading in function of the pedal cycle can provide extra insights into cycling technique and the related injuries. It is an interesting addition to the universally adopted method of utilizing singular pedal loads.