What does your race warm-up look like?
Do you have a set routine that gets you in the zone? How do you balance getting your muscles ready while conserving energy for the race?
My race is 3 hours long and is gravel. The start is pavement and tends to be a little on the fast side.
PS No rollers or trainer will be present so the warm up has to be on the road.
The above advice is good.
If the start/finish is in the same location I like to ride a mile or 2 up the finish and back. This lets me know any surprises near the finish. Think logs trees rock gardens water crossing ect.
A cheap used trainer or rollers are a good investment if you plan on more racing.
One more note:
I don’t have power meters on bike yet. I could simulate them, but didn’t know if ya’ll had tips without a powermeter.
That is a good idea. I might check the pavement to gravel again as it is at pretty high speed.
I would like to race more in the future if this goes less than disastrous (like last year). But I think trainer road (and the FuelIn app) has me ready.
Use a heart rate monitor for zones instead of the power meter.
I like @mcneese.chad advice!
You could do the warm-up by rate of perceived effort.
Ride up the road a mile or 2 like @TrekCentury said, for about 15 minutes or so and then you can do a few sprints:
Progression-type ones, where you start easy and end fast, these can take about 30 seconds to 1 minute
30-second sprints at an effort you can sustain
10 seconds all out
Ive been following this 20minute warm up protocol for a while.
I have yet to see a correlation between warm up and performance. I’ve had amazing races with a warmup, and amazing races with no warm up. I’ve also had the opposite be true.
As I am introverted I find the “warm up” process to be a great excuse to just not talk to people.
I find more folk talk to me when I’m warming up 
I’m mostly in the same camp. Certainly in bunch races where there will be lulls in the racing to recover I find there to be no advantage to doing a warm up. As long as I can cope with whatever intensity there is at the start then I’ll be able to work my way into the race. Only exception where I always make sure I’ve done a proper warm ups with some efforts is for <1 hour TTs where you need to be putting out threshold power from the start and there’s no recovery. Guess other shortish, timed events like cyclocross or MTB would be similar.
In practice I usually end up doing some kind of spin before a race. Partly just to make sure the bike is working ok after getting it out of/off the car (especially if having done any bike maintenance in the previous 24 hours which I know I really shouldn’t do for races, but life doesn’t always work out that way!). And partly because there’s usually time to kill after registering and spinning the legs easily for a short ride is a good way to kill it and maybe check out a few course features if it’s not one I’m familiar with. But it’s nice knowing that I don’t really have to do a warmup, so that on the occasions where I’m running late, or race logistics mean there isn’t a suitable warm up area, or it’s pouring with rain, then I can just relax and know it’s not a problem vs being somebody who is getting stressed because they can’t do their usual warmup.
Depends on the race.
When running marathons I’d see Olympic runners jog 1/4 mile from the hotel to the start line, maybe a stride or two and then start off 5 min miles. (But to them, wasn’t that hard). Not much warm up is needed in a longer race. Why spend energy you’ll need later.
XCO? Better be ready to pop off at the start to get to the simgletrack first. It’s a 60-90 min race (for our local races). I prefer 20 min (or pre-ride the lap) followed by some accelerations. Nothing too crazy, you’ll cool down a bit waiting for the start anyways.
I’ve seen people go way too hard the day before and even in their warm-up the day off. They are great the first 5 min then are toast. I’m not going for the over-all at my age so riding smart has its advantages.
I rolled up to a Pro XC race, and realized I left my gear bag at home. I spent the entire couple hours I had to spare looking for a helmet, shoes, etc to borrow for the race and get set up. And of course last minute race plate because I left that at home too.
If you have ever seen a Pro XC you know that at the start you go full aenerobic and only hope you can recover on a downhill.
Probably my best race in that format to date.
Adrenalin the warm up of choice! 
I do the following, around 20 minutes max, finished 20 minutes before the race start.
11 minute ramp with 1 minute ramp up from low Z2 to LT2 numbers, 2 minute recovery followed by 30s mid MAP range sprint/hard effort, 2 minute recovery, with the last 5 or so minutes interspersed with three 12s sprints one minute apart with the last remaining time at low tempo.
It has helped me gauge where I am for the day physically and helps set mentally the starting pace for the race. For context, my races are 100 miler gravel events, racing for AG, anything from sub 5 to over 7 hours durations all dependent upon course profile and conditions.