For a summary before I start, check out the official Challenge GC bike course below on this really cool 2m video.
All three of us were on road bikes. I had my Scott Foil Premium (11 speed compact with 12/27 range), GB and Ew-dog both ran standard chain rings with 12/25 on the rear.
Ew-dog was keen to go moderate from the start so I enjoyed the scenery from business class on the first "finger". The first "finger" was exactly 20kms and was very uneventful. There was a slight natural uphill outbound with some mossy wet corners to note near the turn around. The turn around is at an Eden ..something wall sign.
We rode back much faster taking advantage of the slight downhill. There is one sharp curve around a U bend at perhaps 26km. Next is a left turn at the 30k mark. Then uphill toward the "pinch" which starts about 300m up the road. There is a lead-in hill that is similar to the bottom of Mt Gravatt which lasts about 150m (at 5%-8%) then a plateau before the pinch of 15-20% for about 80m before left and right turns where it pitches up a little more for another 50m or so. I managed to stay seated for the full length of the ride. Ew-Dog stood up and took off. It is not anymore difficult than perhaps Clear Mtn Road ~ if you head from E-x'ing road to Wynn Road direction. The decent from this side is safe.
Another 5-6km along (having passed through a round about) you will hit a T-intersection (at lights) then turn right. A couple more kms down the road there is a gradual hill (max grade 8%) followed by a sharp decent the other side (a little more fun on your way back in). The remainder of finger 2 (including the little thumb) was basically rolling hills. Continue on Finger 2. At the 49km mark take a left on Peitch Creek Road (may have the name wrong). After about 3km do a U-turn at the buss stop (just prior to the road significantly narrowing) and return to Finger 2. Turn left. Head out until 60km (basically it will be as far as you can go again before the road narrows. You will pass 2-3 narrow water courses. After this turn you return home (by-passing the little thumb).
The "pinch" from the other side is way easier as it is a series of inclines and flats. The decent is a little dangerous as you follow the switches at the top before the drop down the steep hill. Once you return to the T-intersection on the first finger turn left and return to the start (we started at the school pool).
This is unquestionably a TT course (so the Plasma wins ~ once the gears are fixed!) unless you are a beginner or out of condition in which case you may consider a road bike for comfort. For a challenge it would be fun to see your roll over in a penny farthing. We sore this guy driving around when we got back to our starting position. I am pretty sure he didn't do it but you never know.
We rode around moderately and finished in about 2hours 45ish. One thing we noticed was that we had pretty saw backs when we tried our 10m run off the bike.
The scenery was fantastic. Lots of rolling hills, sub tropical forest, water passes and rural properties. The roads are a little bumpy with some pot holes but mainly on the shoulder. On race day you will be able to take advantage of the main part of the road. We were all pretty impressed and look forward to having another go soon. For anyone interested here is my Strava. For Brisbane based guys one word "Brookfield".
Get out there have a go and enjoy the beautiful scenery!
*Nick names used to preserve privacy of campaigners (although known well to Red Dogs)