String players devote a large part of their early training to smoothing out bow changes, from upbow to down-bow and vice-versa, in order to avoid any scratchy sound. The task is particularly arduous at the frog (lower part of the bow), where the musician has to use much more finger strength than at the tip. Playing bowed-string instruments requires a delicate balance of different control parameters in order to produce a consensual good sound, the so-called Helmholtz motion. Professional and experienced amateur players master this skill thanks to years of training ; however, they may prefer one bow to another depending on how it bounces on the string, the quality of the sound, the ease of playing or the clarity in the attacks, which they can relate to consonant-like sounds. Bow makers are aware of this, and are able to select the physical characteristics (e.g. camber or mass distribution) that best suit the musician’s preferences when making a new bow. In this study we focused on how the mechanical properties of the bow relate to the duration and properties of transients, and how players perceive them. For this purpose, we carried out different tests with different bows played by different musicians.We used a cello instrumented with piezoelectric sensors placed between the bridge and the strings, to measure the force exerted by the vibrating strings. We developed an algorithm to automatically detect and characterize transient regimes from the recorded force signals, in order to link the transient characteristics (e.g. duration or noisiness) with the mechanical properties of the bows and the perceptual evaluations by the players.