Did a test run today, Clayton to Fed Square mostly along Gardiner Creek Trail, some 23km in all supposedly.
Left home at 0910, arrived at Fed Sq 1040, so 1hr30'. However, I stopped many times to check directions, a few times to adjust my bike - you can fiddle as much as you like when you put on new tyres, but really you just have to ride and see - and got two phone calls, too. So I think I could probably do it in 1hr15' without busting my arse.
A few lycra-clad greybeards passed me. Those guys are the Volvo drivers of the cycling world - going too fast for safety in case of pedestrians or obstacles, pretty oblivious of others, and with more money than sense.
Three times a guy would be dinging his bell and pass me, then 600 metres on he'd be struggling and I'd pass him in my stately way... I cycle the same as I used to march in the Army, slow but at a pace I could do for hours and hours.
Then it was another 10' across the city, and 5' to park my bike, go to the loo and change my shirt. In all, 1hr45'. I think I'll allow 2hr in all, means I'll be setting out from home at 0700 or so.
Doing that 4-8 times a week should help with the pre-wedding cut