https://www.prioritybicycles.com/pro...riority-apollo
Does the aluminum fork rule out a front hub? Does the belt drive rule out a mid drive and rear hub? Why would someone want to use a friction drive?

I would not recommend a motor on an alloy fork, especially a suspension fork, Nor would I want to hack into a sweet little bike with a belt/IGH to put in a mid motor. Friction drives roll a cylinder wrapped with sandpaper on your tire. Not so good when it gets wet.

It's not a suspension fork. Not a fan of steel, but that would do?

Convert to a Cr-Moly fork. About a hundred dollars.

The bike has a carbon fiber fork, which IMO disqualifies it for a front conversion. The belt drive makes it unsuitable for most/all rear or mid units. There is at least one individual here who has had excellent service from a friction system (if they respond). Otherwise, as above, you'll need to swap the fork. Make sure it has the same characteristics (rake & trail).

Bingo!

where can you find one? thanks

Universal Cycles, Amazon, ebay .............

ok, thank you. I am new here, so I do not know all the websites that sell bike parts at good prices

You have to get the bike first, so you know what kind of fork it uses.

[ ] 1. Threaded 1-1/8"
[ ] 2. Threadless 1-1/18"
[ ] 3. Threaded 1"

It's probably 2. Whichever one it is, verify the length of the steerer tube is long enough to fit your bike. This is the pipe above the fork. You will most likely have to cut off any excess length, You might have to move the crown bearing from the old one to the new one, or buy one at the bike store.

Suunds like too much work? What , you're converting to an ebike! This is the easy part. Any teenage kid working in a bike shop knows how to change a fork.

I have the bike and am weakly considering converting it.

You can use a belt with a Bafang mid drive motor

https://www.electricbike.com/gates-belt-bbs02/

Well don't. Just no. Why would you even think about it? I'm not even touching the fact that for half what that bike cost you could have gotten a Salsa Journeyman, oops I wasn't going to go there. Seriously, a friction drive on that bike? You're going to have to find a cheap Cruiser or MTB, 30ish years old, and throw your assist kit on that. The cheaper the better, because everything will be steel. Steel is real ... strong.

I wanted a belt drive.

I see. Weeel, belts are plenty strong, and quiet, and don't need oiling everyday. What's not to like? However, half the cost of that bike is the 8sp IGH final drive and they definitely are NOT strong and care free. I do believe it is possible to fit them with a belt compatible sprocket. But, don't do that. Seriously, if it was me, I would ignore the naysayers and put the motor on the fork, yes the CARBON FORK, and call it good. Select a nice (very nice) roll on of the power and TWO torque arms and you should be fine. I'm not sure why you need e-assist on a bike like that but, there you are. Good luck.

I should have been more explicit about two things 1) Sure you can have a belt drive with that bike if you have enough time and/or money; 2) Put a front hub on the carbon fork even though 95+% of individuals who have experience with ebikes will try to deter you, just make sure your health insurance is paid up and have good life insurance. JMO!!!

Priority makes or at least made the Embark which is belt drive and has a Bosch Mid-Drive if you are stuck on Priority if not a lot of other e-bike manufacturers use Bosch, Brose, Shimano STePS and similar high quality mid drive motors already designed into the bike.

Not stuck on Priority, but prefer belt drive

Then you have tons of great options for mid drive stuff. Gazelle has a couple Belt drive bikes (Enviolo and Nexus) with Bosch motors, R+M has most of their bikes available with belt and all Bosch (Enviolo and Rohloff), Specialized has the Como SL 5.0 with belt (Alfine) and their new Mahle SL motor, Tern does a bunch of stuff with belts (Enviolo, Nexus, Rohloff) and Bosch, Pedego makes one with Brose (not a company I normally recommend), Trek does belt (Enviolo and Nexus) and Bosch and there are plenty of others not mentioned.

any recommendations with drop bars? easiest way to go faster.

None I know of. Why not? Because the usual customers for belt systems are after reliability and freedom from the mess of chains, NOT speed and/or performance. You are a rare bird there. Another poster linked an article on how to make your bike belt compatible. That's as good as it gets. Drop bars are awful from a visibility, control and comfort standpoint. When you are blasting along at Class III speeds you should WANT to be using flat or riser bars. Drops are the best of a bad deal when there is no motor present. You don't need both. But, of course, you can have both. Most of Trek's and Specialized's high end road bikes (drops) come in e-assist versions. Chain drive thank you, and bidding starts at $9K.

Not with a belt! The Specialized Creo SL has drop bars and there are some other bikes with them but no belts. Honestly on my e-bike I probably don't want drop bars but then again I have a lot of drop bar bikes and really don't need another one. There are plenty of great alt bars which could be used for a similar position but I can get plenty of speed on my bike without much fuss and no drop bars on it.