Prolonged hospital waiting times are linked with increased patient mortality and cause additional financial burdens on institutions. Efficient point-of-care diagnosis would help alleviate this, but is hampered by a lack of cost-effective devices capable of rapid, in situ, wide ranging analyte detection. Lab-on-fiber technology provides an answer allowing for diagnosis, treatment, and monitoring in situ with real time feedback. Here, a device is demonstrated that harnesses motor-protein-driven-microtubule molecular detection assays to optical fibers. By developing a new method for microscope-free microtubule gliding speed determination, proof of concept is demonstrated in the detection of Monomeric Streptavidin and Neutravidin, which initiate a decrease in speed in biotinylated microtubules as well as bundling in the latter case. Utilizing antibody functionalizsed microtubules label-free and microscope-free detection of the heart attack marker Creatine Kinase-MB, as well secondary antibodies in nm concentration is demonstrated. This detector has the potential to be used in situ, providing rapid, low-cost, multiplex analyte screening and detection.