well i need help pretty bad, so here's whats wrong with it. i rode it toay and i noticed that it didnt engage at the begging of the day it slipped through a turn, and as the day goes on it got worse and worse so i decided not to ride anymore. tohught id try it again when i got home and it did the same, its like its not engaging, so basically could anyone tell me whats wrong with it and how to fix it? the spring hasnt been strecthed or nothing. is it possible for the spring to slip so it doesnt engage? i dont really understand, and my local bikeshop dont even no how to fix a punture so useless going to them. any help is appreciated! if there is a certain problem could you tell me step by step on how to fix it as i dont have no money what so ever and i really dont want to miss this london ride! thanks alot.