I just built a ghetto version of a system like this in my house.
Its very simple if you are not worried about GPS tracking of the actual ride, IE not worried about whether people could cut corners or take out a section of trail, then you can use an iPhone with a 2d barcode reader at the start and ends.
Each rider has a unique barcode assigned to them (http://barcode.tec-it.com/, Select 2d barcodes, then enter your full name in the data box). This could be stored on a cell phone, printed and laminated like a WBP pass.
The rider would then get scanned at the start and end of the stage, and the app (currently fucking wiht one called Barcodes Scanner by Romain Pechayre) keeps a history of the data from the barcode (your name) and the time that it was scanned. I guess you could then collate that data and find your times…
simple, pretty much free, and pretty much ready to go. Would obviously need to do some proper testing first, but shouldnt be too hard.
looks like something very similar to the rfid just using barcodes instead
Why not just use number plates and use webscorer?