The “time trial specific training” I mentioned means steady output over your target time. For example, if you aim for 32km/h for 20k, which will take about 40 minutes, considering the short climbs, the ultimate goal of your bike training should be riding at a steady pace for 40 minutes. But I prefer power rather than pace when talking about cycling. If you got a power meter, you can calculate and estimate an finishing time. And you specific training should focus on how output higher power within the target time. Thus as your season progresses, you interval length should increase, but keep shorter than the race, and the intensity should be around your target power or effort.
I forget the duathlons consists of three consecutive parts. There’s 7.5k run and 20k bike. According to your goal, the length should be around 70 minutes, including about 30 minutes run and 40 minutes bike. The intensity should be a little bit higher than your half-marathon, according to your previous PB. I don’t know about your race strategy, full effort for both run and bike or use bike as a little recovery. No matter what you choose, you should set your target and gradually transition to your target, from intensity and time during the two key months. Following is a brief example:
Warmup 3x 15min target power or a little bit higher of your race 5min recovery at z2/z3 or 2x 20min target power or a little bit higher of your race 5min recovery at z2/z3
There’s a another example for the bike considering the climbs: 5min your target power 2min around ftp (just an example, the intensity here should be your plan for the climbs) 2min a little bit lower than your target power (try to get recovery from the climb) 3min your target power 4min recovery at z2/z3
The intensity of recovery session is up to you, but should be not too low or too high. As high as possible only if you can keep the quality of the next interval. You can freely set the length of the interval, but from my point of view, it should not be longer than the target time.
The long, low-intensity bike rides are always beneficial, but the point is do you need it. The long, low-intensity ride is good for your aerobic basis. The more, the better. But the load and the time you can sustain is limited. So when it’s far away from your race, you can do many if you wish. But if you’re close to your race, I think more specific courses maybe more helpful.
I’m not familiar with duathlon and triathlon training, so I don’t have much idea about the brick sessions. My suggestion is that the training should be similar to your race.
Hoặc