Reference for Menachot 70:3
א"ל רב אחא בריה דרב יוסף לרב אשי מהו למיתפריה ועייליה לתפירה לגאו אמר פוק חזי מה עמא דבר
R'Aha the son of R'Joseph asked R'Ashi, May one sew it together, turning the seam on the inside? -He answered, Go and see how the people act.<span class="x" onmousemove="('comment',' And the people are not in the habit of sewing the straps together again; it is therefore forbidden to do so (Rashi) . According to R. Tam it is permitted since the people do sew the straps together.');"><sup>3</sup></span> R'Papa said, Curtailed straps<span class="x" onmousemove="('comment',' I.e., the straps which usually hang down after the head-tefillah has been placed upon the head, had been cut short and only stumps of them remained.');"><sup>4</sup></span> are still valid.