As far as the running...taking 90 seconds off of a 10K is like taking about 15 seconds off per mile. Which is a lot harder to do than you realize, especially if you aren't religiously doing track workouts and tempo runs specifically aimed at reducing your 10K time. It's hard enough for me to run a mile or two at 15 seconds faster than my race pace - much less 6.2 of them in a row! Congrats on your work so far

I'm not very knowledgable about bike form, but as far as running, if you want to get faster you may want to have someone videotape you to see if you aren't running in a way that reduces efficiency. Slouching or bending forward at the waist, or pulling your chest up and back, overstriding, etc. Once your muscle memory is set it can be difficult to make the little adjustments to posture that make running easier, and we always feel like our posture is better than it is! Good luck!