You are going to need a throttle for your EV. There are some decent and cheap throttles and some horrible and cheap throttles. I'll present the ones that I own and like and ignore the rest.
Before I use a throttle, I think about what it will go on. For something stand-up a thumb throttle is your best bet. The reason why is you are planted to the scooter by 2 things, your feet and hands. The more stability you have the better and on an over powered scooter like the Currie or what this Schwinn will be, you definitely want a good solid grip on the handlebars. A twist throttle, means your right hand is not planted on something that doesn't move. On my blue scooter, I started with a twist throttle. With the original set up it was weak enough that this didn't matter a whole lot. Then I upgraded to 2X the power and speed and then a twist throttle was a hazard. I want to be able to hold on to the grips solidly with no movement. My right thumb compromises my grip on the handlebars the least so a thumb throttle is pretty ideal.
This is the only thumb throttle I am currently willing to buy and as you can see it is really cheap. Despite that, they are pretty nicely made and I have 4 of them and given a couple away too. The LED's are the reason for the voltage. They are set for 36 or 48 volt battery packs. The top just pops off and then I replace the LEDs with a small 100 volt LED volt meter. I have no use for a couple of dumb LEDs to show me battery voltage!
https://www.ebay.com/itm/36V-Twist-Thro ... 0020!US!-1
This isnt the right LED meter since it's the .36" size, but you want the 3 wire meters since they work up to 100 volts. The 2 wire meters work up to 40 or 50 volts. You want the .28" size. They are a perfect fit inside the top of these thumb throttles.
https://www.ebay.com/itm/Mini-DC-0-30V- ... SwOgdYuNvr
You end up with something like this You can see the throttle in the right side of the picture on the Currie. And yes, there's lots of stuff crammed in here. Far left is a tire pressure monitoring unit. The sensors screw onto the valve stems on the tires. you can't really see them, but there's a couple of crappy switch clusters hidden by my phone that will get replaced with the below modded 7 switch cluster. The phone is mounted on a quad lock. The snap in back on the phone will come off before the quad lock lets go! Next to that is a TK15 watt meter. Above that is a GPS Bryton Rider 530 speedo. It has a twist lock mount. I pull it off whatever EV it is currently on and drop it onto all the others. One speedo does all my EV's. Next to the watt meter is a 1080P bullet camera and next to that is the thumb throttle.
People will look at my modded thumb throttle and say "Dude! you just built one of these (see below URL). While it is similar, the below throttle is poorly implemented, wobbly and doesn't work as nicely. I bought one and was really disappointed. The above thumb throttle is far better IMHO and I love modding so adding an LED meter to it is something I enjoy.
https://www.ebay.com/itm/36V-48V-60V-72 ... Sw1xpa1tGJ
Full grip twist throttles:
In twist throttles you have several options that I have personally tried and like that are cheap. I use twist throttles on sit down EV's such as mopeds, but NOT on stand-up machines. These are a few that I like a good bit and the build quality is pretty reasonable.
I have one of these that I use as a bench throttle. It has worked well for a number of years. mine has a rocker switch on it instead of the key switch. The 3 wire LED meter inside is good to 100 volts. I don't know why this auction says 72 volts.
https://www.ebay.com/itm/72V-60V-48V-36 ... 0005.m1851
This throttle and the above throttle are virtually identical. You get some variation in the grip style and a switch or key switch or a 3-way switch, but these throttles with a LED volt meter in them are effectively the exact same thing. They work well enough and I own several.
https://www.ebay.com/itm/12V-84V-Twist- ... SwCsBa-mQo
https://www.ebay.com/itm/E-Bike-Scooter ... SwGp1a5tF8
If the throttle has a few LED's that show you 3 or 4 levels like this, I just walk away. Give me a real voltage meter or don't bother at all. BTW, this is a crap throttle for other reasons, so never mind on multiple counts.
https://www.ebay.com/itm/48V-Ebike-Twis ... SwWGxazuPE
Since I use a watt meter and I strongly recommend you do too, there's really no need for a volt meter on the throttle. I've purchased a few "plain Jane" throttles that I like.
I have this exact throttle on the XB-502 moped. It has no bells or whistles...just a throttle and looks pretty. It operates smoothly and makes 1/4 turn.
https://www.ebay.com/itm/Ebike-Throttle ... Sw8IJZjLZd
I have one of these throttles. The throttle works great. I can't complain about smoothness or operation, but the 2 switches laid out like they are makes for this odd looking thing hanging down off the throttle. Still, if you need controller enable and 3 speeds on the throttle, this works pretty well for that use. I wish the writing on the switches didn't exist and instead they said 0/1 and 1/2/3 or something else a bit more universal than Chinese squiggles.
https://www.ebay.com/itm/Speed-Control- ... FvmHdYD-4g
Enough of throttles...Onto switch clusters.
In a switch cluster I want 3 things as a minimum.
1. Head light switch that can handle some decently powerful LED lamps.
2. Directional switch that is very clicky and tactile so I can feel it strongly go into left, off or right positions without looking down.
3. A decent horn button that my left thumb just falls on without needing to look for it.
This is the only 3 switch cluster I will ever buy from now on. It has a nice metal shell and is very small. I haven't seen one, but beware of someone duplicating it in plastic! I have probably 10 other versions of 3 switch clusters. They all work, but pretty much suck by comparison to this one. Get this switch cluster and don't look at anything else. Trust me on this...this is the one you want! I have various other 3 switch clusters on my EV's and pretty much hate them...mostly for the directional switch and pathetic head light switch. This one just destroys everything else. For people that need headlights, directionals and horn, this is the best option and it's cheap. If I have a complaint about it, it's the toggle for the head lights is so close to the horn button. The directional switch is uber clicky which is perfect. You can easily feel the 3 positions without ever looking down.
https://www.ebay.com/itm/7-8-22mm-Alumi ... 0#viTabs_0
If you are wanting just a few more switches and don't mind modding a bit, then this is a good option. You can find them with an aluminum or plastic shell in 7 switches. The unfortunate thing about them is the plastic version looks identical to the metal version so beware. The metal shelled ones are a far better switch cluster than the plastic shelled ones. I have both and know this for fact. In either shell only one button locks. This switch cluster was intended to control a motor cycle computer, not turn on lights and other peripherals. You need to get locking switches and toggles to turn it into something useful on your EV.
https://www.ebay.com/itm/Universal-Moto ... SwBp9abtkI
These little locking switches are uber cheap on ebay. They are rated for .5 amps so double up the 2 sets of contacts to get 1 amp out of them. They are a perfect fit for the plastic gromets that hold the switches.
https://www.ebay.com/itm/20X-8-5mmx8-5m ... xyI8lR-dYN
These toggle switches provide 3 positions or ON-OFF-ON. For lights, double up the contacts so you have 2X current handling or 6 amps. They are pretty clicky and tactile so for a directional switch, they are not too bad and they work well as a 3 speed switch too. They are a tiny bit snug in the plastic switch gromets, but they do fit.
https://www.ebay.com/itm/10pc-Sub-Minia ... xy4t1SiNW4
This is the insides of these switch clusters after modding.
I kept one momentary push button for the horn. Commonly that's the green button so I used the green switch cap for the lower position on top. The rest of the buttons I replaced with locking switches. The toggle is for directional lights.
I later got a couple more of them and modded them a bit differently so that I had a second 3 way switch for 3 speeds. I only needed 3 locking switches for all my lights (headlight, side lights and battery box lights) so that left me with 2 button switches that I didn't really need. One got replaced with the second 3 way toggle. Later I realized that one of them could be used at the handle bars to turn on and off a USB power port. That used up the one remaining push button locking switch. One of the switch clusters was advertised as aluminum, but I got this plastic switch cluster instead. GRRR! Be sure you get what you are expecting to get! OH well, I was giving it away to a friend anyway and the ebay seller has refunded me my money. The aluminum shell is a lot nicer than the plastic shell and it's a bit smaller too.
In the above switch cluster, green is horn.The yellow toggle is directional lights. The yellow button is head lights. Red is side lights. Red toggle is low, medium and high speed. Blue is battery bay lights and grey is aux (USB power). The metal version I received will go on the Currie and the plastic one will go to my friend. I'll get another of these switch clusters to put on the Schwinn S1000 and do this exact thing to it. I might replace the yellow button with another small off-on toggle so I have more amperage for the head lights.