I know the temptation is to upgrade but my advice is to sell your S1 and buy a used multi speed Boardwalk. These are my 2 and I have a bit more than $125 in them with all the up grades. The bikes are nice riding but you are looking at a lot of money put into a frame that is not designed for multiple gears. It doesn't have all the small fittings needed. These are my 2. Roger