It seems you’re referring to the incorporation of folk elements in Franz Schubert's Piano Trio No. 1 in B-flat Major, D. 898. While Schubert's works may reflect folk influences, particularly in their joyful melodies and rhythmic playfulness, the specific references to "riding tumbling non-metrical rhythms" and instrumentation such as "clapping and yodeling" seem to evoke a more vibrant and perhaps improvisational interpretation of folk music.
In this trio, you can observe elements like changes in meter and varied rhythmic patterns which contribute to a lively character often associated with folk styles. Schubert’s ability to seamlessly integrate such rhythms into classical forms is a testament to his genius.
If you're analyzing specific sections of the trio or discussing its folk influences more comprehensively, I can provide a more focused response! Would you like to focus on a particular movement or theme?