Running

In the short term I'd suggest spending 5-10 minutes twice a day opening up your hips/flexors with the normal driving lunges, sumo squats pressing back against your knees with your elbows and open/closing the gate rotations definitely some high knees drills as well. If your predominantly a cyclist i bet your hips and flexors are really tight and opening them up could add inches to your stride length. Sage Canaday has done some good vids on this area of improvement on YouTube. My hips certainly were tight when i made the switch from serious cyclist to multisport. You've clearly got the engine to go pretty quick which takes the longest to build all the the other things that could be slowing you down could probably be massively improved in 6 months. Not much help before the 20th but if your light with a high Vo2 I'd say longterm you could go closer to or even sub 1:15. My last vo2 lab test about 3 years ago i only scored 67ml/kg (yours must be a good bit higher?) end of season after a 3 week break at 66kg and 39 years old at the time. I've tested a fair bit higher when i was fit back in the day but last year still managed a 1:18 half following the 10k plan @doubleodavey uploaded. I've also work hard on my lazy passive heel lift, weak hamstrings, tight hips, reducing my ground contact time and generally getting more efficient. That all took 3-4 months of serious work then twice weekly maintenance but i assume your engine is way bigger than mine and chassis lighter so there must be something holding you back. My first half was 1:35 on a hilly course on no running training at all just 16h a week on bike training as i took a injured mates entry last minute. The last 25 minutes were hell and i couldn't walk for 3 days after. With your gas tank unless there's something really wrong with your stride I'd have thought you'd jog round a flat half in 1:30 no problem. And buy some super shoes because they are super. Good luck there's definitely a runner in there somewhere.