Mah.. un nastro da 21 su un cerchio con gola da 21 non andrebbe usato (io non lo userei anche se mi pare di ricordare che Notubeless lo accetti, poi vedo di trovare l'allegato, meglio un 24 anche un 25 tirandolo tantissimo.
edit. The result of blending a ZTR Race rim with a ZTR 355, the ZTR Crest is the best of both worlds. All the wall thickness and corresponding durability of a 355 with the next generation BST creating a wider rim cavity with shorter sidewalls.
Fully tubeless compatible with the 21mm yellow tape or the 25mm yellow tape and valve stem.
Crest rims are part of the history of mountain biking. Introduced in 2005, the Crest's design evolved directly from Stan's earliest ideas, including the legendary 355 rims.
www.notubes.com