For stand starting Kilometer... 51/50x15 at the most or the equivalent.
For individual persuit.... 50/51/52x15 or the equivalent like 54/53/52x16.
Kilo is such a short race that if u have the bad idea of use like 52x15 u wont be able to launch the bike fast enough, the idea is get the bike at full speed in the shorter period of time and keep it like that (thats why is important the strategy and the gear choice). Some sprinters use 47x14 other ones 50x15 (my case). But usually in Kilo u dont use an extreme heavy gear at all.
In persuit is like the same, but u have more distance to launch the bike so 1 or 2 extra Teeth sometimes help and sometimes simply kill u at 50% of the race. Btw u havent told us what do u use for TT, i mean if u want to put more multiplication means (at least for me) that u have a super high cadence and that u can keep it for long periods of time. But if u r using like 50x16 (6,60 meters per pedalier turn) and u r a 25 y/o guy with the strenght of a junior or a cat +2 makes a lot of sence that u feel like pedaling in the air when doing a TT race, u know.
What do u use for TT?
UM