## 1 Introduction  
People commuting to work, school, or hobbies are looking for alternative transportation to individual car transport because of the cumulative traffic density in, as well as out of, cities. It is in the interests of those who are competent to transfer the largest possible number of people to public passenger transport or to motivate them to use bicycles or walk for short routes.  
The bicycle is a strong alternative, which is becoming more and more popular, especially regarding transport within agglomeration. It is considered a sustainable and extremely convenient way for population mobility [1].  
For this reason, the emphasis has been placed on enforcing and supporting bicycle transportation in recent years. Some European countries, like the Netherlands or Denmark, developed their national strategies for bicycle transportation before the beginning of the 21 st century, and their bicycle-sharing system shows the success of these strategies. Slovakia belongs to the countries that need to expand infrastructure for cyclists to ensure a better flow of traffic, and especially, for the safety of cyclists [2].  
The introduction of shared bicycle systems (bike-sharing) is also a progressive tool for more sustainable mobility. Bike-sharing can be considered a type of public transport [3]that possibly reduces dependence on individual car transportation and subsequently also prevents air pollution and noise production [4; 5]. The fundamentals do not lie in profit but in the quality of improvement in life in the municipality.  
The aim of this article is to evaluate the efficiency of a bike-sharing service and identify improvement opportunities for this bike-sharing service in Zilina, a small urban area in northern Slovakia. First, the detailed description of the existing system will be provided based on the data provided by the company that operates bike-sharing in Zilina. For example, real data includes the number of bicycle rentals, the average time of the rental, or the time distribution of bike rentals individually per day. These data are processed in tables as well as graphically. Afterward, the sociological survey for city residents or commuters to Zilina was created, distributed, and processed to achieve important insights into the supposed extended bike-sharing system in the Zilina municipality. This study is guided by the research question: \"How can spatial and non-spatial analysis reveal the strengths and weaknesses of bike-sharing services in small urban areas like Zilina?\"  
The research proceeded from all available data and the characteristics of the municipality's area, and it is based on the following preconditions:  
* A comparison of the bike-sharing systems in European cities with similar areas to municipalities like Zilina;
* A spatial analysis based on the map's characteristics and availability of isochrone bike-sharing stations;
* The mentioned sociological survey was based on a questionnaire with 364 participants, where only 37% of participants stated that the bike-sharing station locations as ideal.  
Bike-sharing system expansion must be provided logically, and each proposed part of the expansion requires justification to avoid an unnecessary waste of funds as well as to simply ensure that the service is used sufficiently. Based on the determined preconditions, this paper presents a proposal for expanding the shared bicycle system in the city of Zilina with new stations and bicycles.  
The main originality of this paper derives from all the mentioned preconditions, from the connection of the spatial and non-spatial analyses proceeding from 5 years of real data, and from the sociological survey by questionnaire distribution. This research represents a unique investigation of the bike-sharing service system in a small urban area within Central and Eastern Europe.