Penny Boards are in general always slower than a longboard. The components used to build a Penny board were selected to make it light and cheap, at the cost of stability, speed and control — on the other hand the components on a longboard are built to keep you safe and in control during higher speed downhill riding.
Longboards go faster than Penny Boards when ridden downhill mostly due to their components, even more importantly longboards are much more stable than Penny Boards — allowing better control at high speeds making them dramatically SAFER for downhill riding.
The only place a Penny Board is ever 'faster' than a Longboard is in instances where you are riding short distances, stopping to pick up the board to walk for a bit — before throwing the board back down to skate (
for instance in the airport).
When riding a Penny Board around the airport (or putting it in your backpack) the smaller size of the Penny Board makes it faster to swap from walking to skating (while not disturbing people around you if it's crowded) and vice versa.
Why are Longboards so much faster than Penny Boards down hills?
While some longboards are made specifically for going downhill, or even Downhill Racing, ALL longboards have a wider wheel base (and a wider deck width) which helps keep you in control at the higher speeds you will experience riding down hills.
No matter how many upgrades you apply to a Penny board to make it faster — the size of the deck will always make it an inferior downhill option. If you're trying to send it on a Penny board, you're going to have a bad time.
All Longboards have standing deck platforms that are bigger than a Penny Board. The distance between the front truck and the back truck (called 'Wheelbase') on these longer boards will be more stable at faster speeds and much more comfortable carving down the road.
Primarily that's because a wider wheel base allows you to stand on a longboard with your feet further apart. In the photos above (or video below) you can see how the small size causes a larger riders to 'squash' their stance placing their feet incredibly close together — which makes it impossible to balance at higher speeds.
Comfortable control of your board (on a Longboard) gives you the ability to confidently control your speed carving down hills, speed checking when you need to and drifting hairpins once you learn to slide safely.
A bigger board is also much more comfortable to ride longer distances — and easier for beginners to balance on when learning to push.
No Plastic, Stiffer Decks, Better Wood = Faster Speeds on Longboards
Even though it's easier to make plastic boards (like Penny Boards) very inexpensively in many colors, the downside is that Plastic is a really poor material choice for any sort of serious downhill riding due to it's dead fish, floppy, flexiness which reduces control. In direct contrast to the plastic Penny Board construction most longboards are made with 7-10 plies of the best quality maple (and many are further reinforced with fiberglass or carbon fiber) which is much stiffer than plastic — that adds to stability, increasing control and safety during downhill riding.
The Penny Board 'Longboard' is ALSO made out of plastic and ALSO performs poorly going fast down hills. Even though it IS longer, the other issues related to Penny Board construction and components still mean a wood, or even better composite / carbon fiber, longboard will work better on hills — and stay stronger longer.
Cheap Penny Board Components = Poor Speed, and Bad Downhill Performance
As mentioned above Penny Boards are designed to be cheap — many Penny Board options with wheels and bearings are less than $100. Part of that is because plastic is a cheaper material (albeit worse for the environment and for downhill riding) but the other reason Penny Boards are cheap is that the bearings and wheels are made of poor quality materials (just like the deck).
Small Penny Board Wheels are slower
Smaller wheels that use slower, less expensive, urethane formulas help keep the cost of Penny Boards inexpensive but mean that Penny Boards are slower than Longboards in almost any situation.
Smaller wheels use less urethane, and slower urethane formals are less expensive — Penny Boards use both.
Longboards use larger diameter wheels that have a higher top end rollspeed and most quality longboards ($150-$200+) come with wheels that will use the same high end urethane formulas that are used for downhill racing — but with customized wheel shapes to make learning to slide and control your speed on hills easier.
Longboards use Faster Bearings
Another place Longboards end up gaining ground and start out faster than a Penny Board is in the bearings. Bearings used for skateboarding & longboard are different than industrial bearings due to the fact they bearings used in factory machinery etc are designed to spin incredibly fast — much faster than our wheels spin when longboarding or skateboarding.
There are billions of industrial bearings produced each year — so even though they are not designed to work well for skateboarding, they are incredibly cheap. These are the bearings that Penny Boards use, which is another way they keep the price to below $100, and another reason they are slower than Longboards.
Most quality longboards use bearings that are built with higher quality more materials and custom designed specifically for longboarding. A good way to tell if a bearing is designed for higher speeds and longboarding down hills is to look for the Built-In Spacer which helps to stabilize bearings, reducing chatter for more controlled slides, like Cell Prime Longboard Bearings.
Quality longboard bearings are engineered to generate the most speed out of every hill — rather than being designed to spin at a million miles an hour in a machine which results in poor performance when used on a board (like Penny Board bearings).
Better quality bearings providing more stability, more speed, and more good times enjoying one of the oldest styles of skating. Speed wobbles not included.
Longboard Trucks are Built for Hills and going Fast
Small narrow trucks use less metal, so Penny Boards use these trucks to save material and (again) make the total board less expensive. The problem is that wider trucks are more stable and allow for more control at faster speed when going downhill.
Every longboard will always use a wider truck than a Penny Board. While those trucks are more expensive since they use more metal, if you are riding down hills having a truck built to handle higher speeds is critical.
Penny Boards are fun to mess around on - not so fun on Hills
All in all Penny Boards are fun and they are a great option for travel if you want the smallest possible board to carry around. That being said the small size is a major disadvantage when you are learning to balance & push as a beginner and even more so once you get on serious hills.
There is a cap on how far you can effectively commute on a Penny Board and really on how good / far you can progress as well — thats where Longboards really shine. Longboards are a piece of performance equipment where as Penny Boards are more of a cheap novelty deck to play with.