Nack rails nano carbon fibre rail carbon fibre kevlar and aluminium filaments in the seat post clamp area are treated with the production process called braided carbon rail bcr this is done in order to obtain the perfect fusion and uniformity of several types of fibres and materials for greater durability and long lasting properties pas technology pas technology perineal area system eliminates pressure spikes and numbness in the pelvic area the pas system is achieved thanks to a particu