I am just replacing regular rack to a rack time on my st1. The rack time rack you have is awesome- a european stand, I hear.
It only works with the rack time adaptors that come on their baskets, etc. They snap on and off, once I figured out how that seeming worthless rack worked, I've made flatbeds, golf club carriers, shopping baskets, and fishing rod holder baskets, and can interchange them with a push of a little button. sweet. google rack time. Sierra trading post has a lot of their stuff at huge savings.
There are some really good options. I never got the city kit because it's not strong enough to support the 30-50 lbs. of stuff I sometimes take on long trips of 100 miles or more--tent, sleeping bag, Stromer batteries, charger, etc., etc.
So I looked around and opted for the Ibera Pak Rak RA5--fits the Stromer and its rear wider axle/disc brake perfectly. I added Ortlieb pannier bags that snap on to the Ibera and stay on--I've ridden on a lot of rough trails and they really hold up. The best thing about the RA5 is--it's really strong, and it's cheap--$39 or less on eBay. It includes a couple of extension arms that reach over to the seat post. You'll need to get a Salsa mounting collar (or other brand that fits the seat post) to connect to. Total cost should be $60-$70. There is also a bike rack/bag shop in Tucson that has all sorts of quality options too. I got my Ortlieb pannier bags from SierraTradingPost.com for about $100--way less than other places. Good luck.