The purpose of this thread is to collaboratively form a compendium of technical skateboard build knowledge. First off, I am by no means an expert on any of this; I'm simply a random nerd who enjoys skating and obsessing over tiny details of things. PLEASE DO call me out on any and every error, forgotten measurement, wrong fact, or bad recommendation in here. Hopefully with the help of some SLAP pals this thread can eventually become a complete resource for how each of these measurements affect a skateboard's performance and how they interact with one another. I will consistently monitor responses and update the following list with information. As for the recommendations, keep in mind they will be very generalized; there will obviously always be personal preference involved (especially on SLAP). There are no hard and fast rules for most things in skateboarding.
The loose format I've tried to follow is: Spec name, how to measure, unit of measure, performance effects, correlations, basic recommendations (which I know most here won’t need).
Last update: 12-26-21
Deck Width
Deck width is the horizontal measurement across a deck, in inches. It is generally measured aerially (does not include the deck's concave). This is by far the most common (and often times ONLY, for the lay man) measurement of a skateboard. With good reason; the width of a deck is critical for a riders comfort. It also directly affects the ability for the board to flip (wider decks flip slower than narrower decks). It also directly affects deck weight. It's generally recommended that riders who are taller/longer inseam or have larger feet ride a wider deck, and shorter/younger riders with smaller feet ride a narrower deck. Paul Schmitt says height is generally the most common factor influencing this decision. Once again, there will always be exceptions due to personal preference.
Wheelbase - Deck
Deck wheelbase can be measured independently of the trucks and complete board and is the measurement between the center of the inside bolt holes:

Taller street riders may prefer a wheelbase of 14.25-14.5", whereas a shorter rider may prefer 14" or even less.
Wheelbase - Trucks
Truck wheelbase can be measured independently of the deck and complete board by calculating the total increase in wheelbase for each model of truck, measured in inches. The following list offers some measurements of wheelbase change for each set of two trucks (list probably needs double checking/revisions):
Ace 44 (8.38" axle): + 2.75"
Film 5.5 (8.25" axle/6 Hole baseplate): + 2.875"
Film 5.5 (8.375 axle/4 Hole baseplate): + 3"
Independent 149 STD (8.5" axle): + 3"
Independent 169 STD (9.125" axle): + 3"
Independent 149 forged hollow (8.5" axle): + 3.1875"
Krux K4 (8.5" axle): + 2.625"
Tensor ATG Aluminium 5.5 (8.25" axle): + 3.0625"
Tensor ATG Mag 5.75 (8.5" axle): + 3.125
Thunder 149 team edition (8.5" axle): + 3.1875"
Thunder Hollow Lights 151 (8.75" axle): + 3.25"
Venture standard 5.8 (8.5" axle): + 3.25"
Venture 6.1 (8.75" axle): + 3.125”
Venture Lights 5.8 (8.5" axle): + 3.5"
Venture 5.8 Titanium (8.5" axle): + 3.4375
Venture 5.6 cast: +3.25
Thunder Ti Hollow Lite 148: +3.25
Independent 139 Titanium: +3.00 in
Thunder 147 Hollow Light: +3.3125 in
Destruco D2 Mids: +3.125
Thunder 161 (9.125" axle) +3.10" wb (52mm height)
Indy 215 Stage 11 (10" axle) + 3.00" wb (55mm height)
ACE 66 (9.35" axle) +2.65" wb (54mm height)
Film 6.0 raws: +3.13"
Venture 5.6 V-hollows: +3.38"
Tensor Maglight Low 5.5: +3.15"
Source:
https://www.slapmagazine.com/index.php?topic=108580.0 Wheelbase - Deck + Trucks
Wheelbase is the measurement from the center of one truck axle to the center of the other, in inches. Ultimately this is the only wheelbase measurement which gives complete information about a board. A shorter wheelbase will cause trucks to turn sharper, and bring the heaviest part of the board (the trucks) closer together, increasing the speed of spin tricks like shuvits, 360 flips, or 360 ollies. This is usually better for street skating. A longer wheelbase will turn slightly slower, but give the board more stability, especially at higher speeds. This is generally preferred for transition skating. This may be another measurement correlated closely with a rider's height and preferred type of skating.
Deck Length
Deck length is the measurement of a deck vertically across in inches. This is also usually done aerially (disregarding concave), although there is a distinct lack of measurement standards like a lot of things on skateboarding. This spec will have very similar implications to wheelbase including spin speed and stability, except obviously it does not affect turn. Deck length will marginally affect the weight of the deck, which as discussed further down is a critically underrated board specification. Deck length will also play a role in how a board pops, but not as much as nose/tail length and angle.
Deck Nose/Tail Length
*graph or a table on how a deck’s kick length & angle affect the angle of the board when it hits the ground
*Shorter & steeper kicks lead to steeper angle but how much would you have to shorten a kick to offset a 1°? How fingers of flat plays into this?
Deck Nose/Tail Angle
Deck Nose/Tail Shape
For traditional popsicle shapes, a nose/tail can either be pointier or more full/square shaped. Full/square kicks are nice for sitting on nose/tailslides and having less foot drag on the feature. They can also feel a bit more stable if you’re setting up for a trick and your popping foot is off center in the pocket. Generally, they’re considered a bit worse for scooping tricks as it's harder to wrap your toes around for leverage. Nose/tail shape will also affect your flick depending on how far off the nose or side of the board you tend to flick for your flip tricks. Really full/square kicks can also make the board feel wider.
Deck “Fingers of Flat”
Fuck I hate this term. It’s a rudimentary and inaccurate way to measure the flat space between the outside bolt holes and the flat part of the deck before it begins to curve up into the nose or tail. It’s “measured” using the pointer, middle, and index fingers (How many fingers fit on the flat?). Paul Schmitt suggests that longer legs generally prefer more fingers of flat. If a deck’s total length and nose/tail length stay the same but the deck wheelbase decreases, this will naturally yield more fingers of flat.
Deck Concave Steepness
This is currently a very qualitative characteristic of a deck which refers to the depth of horizontal curve. Steeper concaves can mean more board stiffness and board longevity. It can also help increase board feel, especially with thick soled shoes. Too much concave can be uncomfortable to some people and seems highly based on preference.
Deck Flex
Another highly qualitative characteristic. Probably has much to do with materials used in construction. For example, Powell Flight decks are known to have high flex. Need more info on the practical effects of deck flex.
Deck Symmetry
Nearly all modern popsicle decks are asymmetrical, with the nose being slightly or significantly taller than the tail. "Twin tail" decks are bucking this trend with a symmetrical nose and tail. Proponents of this deck style comment that it's more balanced than a traditional asymmetrical deck, and also removes the concern for ever thinking about which side of the board you're riding. Of course this would only work if you ride trucks at even tightness. But even if you don't and you still only ride one end of the deck, it could still just feel more balanced. Paul Schmitt seems to be in favor of traditional asymmetrical decks, referring to them as "Swiss army knives" with two blades. He suggests trying to pop with the nose instead of the tail if you're having trouble landing certain tricks.
Grip Coarseness (Grit)
The coarseness of grip tape is measured in grit. The lower the number, the more coarse it is and vice versa. The majority of grip tape is around 80 grit. This will affect your control over the board while riding and manipulating tricks.
Wheel Diameter
Wheel diameter is exactly that; the measure of the diameter of the wheel in millimeters. Every millimeter difference of diameter raises or lowers board by 1/2 millimeter (radius = diameter divided by 2). Larger diameter wheels (55-65mm) will be heavier but will roll over uneven ground more easily than smaller diameter wheels. They will have less acceleration, but carry more momentum. Smaller wheels (48-54mm) are lighter weight and will have faster acceleration, but carry less momentum. Smaller wheels are generally more desirable for technical park and street skating, whereas larger wheels are better for cruising and transition.
Wheel Durometer
Wheel durometer is the measure of the hardness of a wheel using the Shore hardness scale. A book could be written about this topic, but most people agree that durometer ratings are pretty inconsistent across brands, and hardness ratings over 100 are technically impossible based on the scale itself. Also, it sounds like durometer would need to be measured in a temperature and humidity controlled environment to be consistent. In general, a harder wheel (99+ durometer) will roll faster on smooth ground, and slide better as well. Medium wheels (92-97a) will be more grippy and forgiving on uneven terrain. Soft wheels (85-92a) will be great for the smoothest of riding and cruiser boards.
Wheel Width
Wheel width is the total measure of width across the wheel in millimeters, including the edges which don't make contact with the ground. Wider wheels will be heavier but generally have a larger contact patch (see below), which lends them to producing a smoother and grippier ride. Wheel width will also affect grind clearance.
Wheel Contact Patch
The contact patch is the portion of a wheel's width that actually makes contact with the ground. This is the width of the wheel that a rider will actually feel when pushing a board around. Surprisingly, a wider contact patch does not affect the board’s ability to grip the ground. Based on science, it has no effect whatsoever. Heavier rider and total board weight will increase the grip of the wheels. Subjectively, some argue that there is a grippier feeling with wheels that have a wider contact patch.
Wheel Shape
Wheel shape refers mainly to the side profile or “cut” of the wheels. A rounder profile such as a Spitfire Classic will be easier to get into and out of grinds, but not lock in as well as a Spitfire Conical/Tablet shape. However, the flat profile of the Conical/Tablet shapes could produce more drag when sliding against a feature. Round profiles will also generally be easier to flip, but truck axle width and total truck/wheel width (see below) will factor into this as well. More squared wheels like the aforementioned Conical/Tablet shapes will naturally have a wider contact patch, which can provide a more smooth ride on rough terrain.
Total Truck/Wheel Width (Truck Width + Washers + Wheel Width)
Wasn't sure what to call this measurement. If there is a better or existing name please let me know. This is the measurement from the outside edge of one wheel contact patch to the outside edge of the other. This is affected by truck width, wheel width/contact patch, and how many washers are on the inside of each axle. Total width will correlate with your deck width to make a board flip easier (if deck is wider than total width) or grind/lock in more stable (if total width is wider than deck). NEED MORE INPUT
Truck Height
A higher truck equates to more time spent popping the tail, and a steeper board angle when the tail hits the ground. This can translate to a higher ollie, or it can generate "ghost pop" if the deck is too high off the ground for a rider's preference. Riser pads can be used to increase the height of the trucks. Alternatively, a rider can increase their wheel size (The board lifts 1/2mm for every extra 1mm of wheel diameter). Both of these options increase total board weight. Risers essentially increase the truck weight marginally, while larger diameter wheels increase wheel weight.
Truck Axle Width
This refers to truck axle width, measured in inches. Probably not as useful as measuring total truck width including wheel width. Generally, a wider truck axle will directly correlate with a wider hanger. Wider trucks will turn slower than narrower trucks. Smaller trucks can produce better leverage for flip trucks, especially when paired with a deck that is wider than the trucks.
Truck Hanger Width
Wider truck hangers yield more grindable truck surface, which can make it easier to cross pinch a round rail.
Truck Turning Radius
This is difficult to quantify as not many brands reveal this type of information, and not many skaters are out there making scientific comparisons across truck brands/models.
Truck Tightness
Tightening or loosening trucks obviously affects how quickly they respond to a rider leaning into a turn. It also affects a board's wheelbase. The tighter the trucks are, the shorter the wheelbase will get, although this has a marginal impact. If a truck has an inverted kingpin, tightening trucks will increase the kingpin clearance.
Kingpin Clearance
Truck Alignment
This will only really be felt if the trucks are grossly misaligned. Paul Schmitt recommends placing a long metal ruler that can span across both trucks lengthwise when installing the trucks. Put two bolts in each truck diagonally across from each other and tighten then gently. Use the ruler to ensure they are in alignment before fully tightening them and adding the other bolts.
Truck Weight
Truck weight is measured in grams and will significantly affect pop, flips, and spins. Some prefer a heavier truck for a more solid/stable board feel. Some prefer an extremely light truck light Tensor Mag Light ATG's for making technical tricks easier. Truck weight impacts total board weight the most of any part (DOES IT? ARE 2 WHEELS + BEARINGS HEAVIER?), and they are distributed on either end of the board, significantly affecting flip and spin speed (moreso spin).
Bushing Shape
Bushing Durometer
Wheel Weight
Wheel weight can be measured in grams and should include bearings and bearing spacers. Larger, more dense wheels will be heavier and slow down flip and spin speed (moreso flip). Most bearings probably weigh about the same, but wheels themselves will vary.
Deck Weight
Deck weight is a spec that nobody talks about. Assuming every single other characteristic remained exactly the same, I believe everyone would perform more optimally on a lighter deck/board. However, this is never the case. Lighter weight parts will almost always be a tradeoff. For example, Tensor Mag Light ATG's are made of magnesium which wears extremely quickly, and is less rigid that aluminum. This means more bent axles, especially for high impact skaters.
Total Weight
A lighter board will pop, flip, and spin with less effort. It may, however, also feel less "solid" or stable.
Weight Distribution
Truck and wheel weight will generally have a larger impact on flip and spin speed because so much weight is concentrated near the nose and tail of the board. Deck weight will be perfectly distributed across the board is it is a twin tail (symmetrical deck), otherwise most popsicle decks will be front heavy with a larger nose.
Rail Plastic Type/Durometer
Unlike wheels, rails are made from a couple different types of plastics. Paul Schmitt’s famous formula, now found in Welcome’s Candy Bars, are made with a “super high-molecular-density extruded plastic” which is a type of polyethylene also used in cutting boards.
Deck, truck and wheel specs make the biggest difference
Hardware is almost completely irrelevant, just use 7/8" without risers or 1" with 1/8" risers to minimize extra weight. Nearly all skateboard hardware will be stainless steel and within the same tolerances.
Bearings are mostly irrelevant, they obviously affect speed but wheel specs and riding surface will make the most difference. Ceramics will probably be marginally lighter, but generally most bearings will weigh nearly the same. Either buy Mini Logos, Quantums, Bones Super Swiss 6, or Bones Ceramic.
Overall I realize this is highly incomplete but I wanted to get it out there so I can start editing it with SLAP feedback when I get time.
Non-measurable board setup and maintenance tips (To work on in the future):
Bearing Spacers
It’s always advisable to run bearing spacers. This nerd explains perfectly:
Bearing spacers reduce the axial and torsional loads subjected upon each bearing while in use. In a perfect world the bearing spacers will match the measurement of the inner core of the wheels perfectly, but this is usually not going to be the case. Regardless, I think it's still better to run them than go without.
Bearing Shields
Bearing Cleaning and Lubrication
Deck Slickness
Shoes - Vulcanized vs. Cupsole Contruction