During the Cape Epic series (great series by the way) I know you need to ride on a smart trainer/power meter and wear a HRM, I do not think this requirement is clearly stated upfront and it seems to catch a lot of riders out.
The requirement is stated on the Zwiftpower description but not in the ZC ride description (well aware not a lot of people read this anyway) and also the web site states open to all with no caveats. At the very bottom of the web page it does state you need a smart trainer which you could interpret as no ZP riders.
I feel making this requirement a lot clearer upfront would cut down on the frustration being expressed on the forum posts when the riders finds out post event.
On a more humours note if that means less people are entered into the final draw and that increases my odds of winning, bonus