I have a 21-speed mtb with an e-bike kit on it. I have bought a new rear-wheel derallieur which needs to be fitted. I bought a new rear revoshift 7 twist grip shifter the inner cable will have to be cut to size when threaded through the new derallier. Also, I might need new inner brake cables for the front and rear brakes. I am not sure what size they are for my ebike brakes. How much would this cost to do the work. Thanks in advance Jay