4:30 hour ride in the hills (If possible). If not in a hilly area, then switch into the big ring and push a lower cadence (65-75) for a time during the ride. Try to get the feeling of riding hilly terrain. Let terrain and strength/endurance dictate pace and effort levels on hills.
Practice steady hydration and nutrition throughout, keep stopping to a minimum (bathroom & food refills only).
Make this hilly, but spin up the hills. Keep HR down, high RPMS, and just work on smooth pedaling.
WU: 300 warm up, then swim 8 x 50 on 20" rest.
MS: 100/200/300/400/500/500 all with 10-20” rest. Last 500 should be ~3-5” faster per 100, than goal IM Pace.
*For example, if the goal is 1:00 swim at IM - that would be 1:25/per 100/yd pace. So, the goal in the last 500 of this 2k set would be under 6:50 or 1:20-1:23 pace per 100yd.
CD: Get a nice easy 300 cool down.