I had an old OCR3 http://www.giant-bicycles.com/en-us/...ad/1243/29271/ which was 8 speed and had thumb shifters. You could look into what parts that one had? It came with a drop bar. I guess you would have been better off getting a Defy3? If your bike is still in like new (and re-sellable) condition, you could probably bring it back and ask to exchange and pay the difference.