Hi all! I just got a strida a week ago, ride a couple of times with my son (him on his frog bike), and love it, started looking for upgrades (mine is a 5.2 with 18" wheels). I suppose I am just like any new-comer, wanting the curved handle bar, the spring saddle, even considering if it is appropriate to change one wheel into carbon. But of all, I really want to get the dual-speed Speed-Drive! I am no mechanics, and a bit concerned if I have to fix it myself if I buy it through ebay… Anyone could advise if there is anywhere in Hong Kong which they could help me install the ATS Speed-Drive? Many many thanks!!