Herewith the routes for the 200 and 300 Dirtdax events. They are both derivatives of the canals loop so you will be getting to know that quite well. On the 200 there are two sections on the R511 tar road. The first is at about the 107km mark and is about 5km long. On this section there appears to be a good gravel shoulder for most of it. The second at about 147km and is about 3km long. There is no shoulder on this piece but there does appear to be a service road between the railway line and the R511. I cannot see clearly enough to be sure. This is a bit long at about 208km but you could shorten it a bit by starting and ending at the pub down the hill from the start. That would knock 2km off.
200 — ridewithgps.com/routes/5404422
300 — ridewithgps.com/routes/7009068
This is similar to the above but tacks an extra loop on the top. Distance looks ideal and maybe you could run this backwards for something a little different.
For more information on the Gauteng gravel events contact gerrit@law.co.za.