I found a presumably 3rd party Speed Drive upgrade kit on a Taiwanese auction site. It includes not a genuine Schlumpf but an ATS Speed Drive, a sprocket (which looks like a deadly ninja weapon 
), an eccentric bottom bracket, and a belt. The item goes for TW$16500 (about US$516) but sadly the seller does not ship oversea. If this thing actually works well, I hope someone can import it to the US and sell it here.
tw.page.bid.yahoo.com/tw/auction/1205605125
If the auction page gets removed after the auction is over, check out the photos here:
strida.kuso.com.tw/modules/xcgal … -Kit-1.jpg
strida.kuso.com.tw/modules/xcgal … -Kit-2.jpg
