Concave - General discussion

[Beau]

Concave - the curve in the board from side to side - can vary quite a bit between decks. I'd like to make this thread a spot to share feedback about skating difference concaves and how they affect board feel.

A few types of "common" concave include:
- Radial (circular arc)
- Progressive (elliptical arc - the concave gets steeper towards the edges)
- Flatcave / tub - flat base with "slanted" concave - like a ditch, rather than bowl
- Flat / no concave - totally flat
- W-concave - like circular or radial, except with bulge in the middle, so the cross-section of the deck looks like the letter "W"
- Variable concave - a combination of any of the above styles

Skateboard concave infographic:

Here's some general info I've gained from skating and talking with other skaters:

Steepness:
- concave makes a board stiffer (think about folding New York style pizza so it doesn't flop down) - good for board pop and responsiveness.
- flat is more flexible, and can act as shock absorption (typically used on boards with camber) - good for cruising.
- concave creates more leverage for easier flip tricks, and flat decks are easier to for doing flat spins (like shove-it variations).
- concave creates pockets, which some skaters like for sliding the board or resting their foot in for downhill.
- flat creates a more even surface for freestyle / dancing footwork.
- concave helps reduce chance of wheelbite.
- boards with more concave will be slightly heavier than boards with less that are the same width, because more material is needed to make an arc than a straight line.

Shapes:
- Most of what I've ridden in recent years has been radial concave, though I've been considering experimenting with progressive concave, which would lower the deck's center of gravity, making flip tricks easier, since less force would be required to flip the deck (more leverage).


- W-concave is popular with some of the downhill/freeride skaters I have met. Seems like it may provide some nice pockets for standup slides.
- Flat cave is nice for wider boards, since it rises linearly - helpful if you want concave on a wide board but don't want something very deep.

What do you like to skate? What sorts of things would you like to see pertaining to concave?

[skrrrp]

Been longboarding since 2k8 and I thought I'd add my 2 cents to the discussion on concavity.

My favorite deck to ride to date is the Landyatchz Bamboo Drop Carve 2011. The deck has W concavity. Specifically I would like to note that the deck (unlike the description above) has W concavity from truck to truck.

As a freestyle rider and skateboard commuter I find this type of curvature ideal for pump-carving and superb for doing frontside and backside stand-up slides. The trenches give the foot just enough of something to grip to when whipping around.

Unfortunately, the top ply cracked last January at which time I retired the board. This is largely what brings me here to board building as I am finding it very very difficult to find a deck with all bamboo plys which follows the same concavity design.
Fortunately, I came across the technique for cloning board shapes using vacuum prior to the board starting to snap and stopped riding it before it was in 2 (or more pieces). My hopes are to copy the deck shape after I get my hands on some bamboo ply.

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Last year I made my first homemade deck out of a 1x4 of Padauk wood of which I essentially just cut it to a good length and slapped grip-tape on it. As such it is of flat concavity. When trying to get fancy I find that the flatness makes it easy to slip off, especially when I ride in wet conditions. I am thinking about hand-planing the center of it to get something close to radial concave. That being said, I still have lots of fun on it and with the deck being only 4" wide I am able to "monkey grip" it which typically overrides the need for any concavity.

On a final note, many moons ago I tried a friend's deck that was convex. For me, it was like a bucking bronco constantly trying to kick me off the board. I wouldn't recommend it unless that is your cup of tea.

[Beau]

By "W" concave from truck to truck, do you mean be camber? (Camber is the opposite of rocker, and boards with camber have an elevated mid section that gradually goes down towards the ends - which would make a "W" from end to end if the board also had kicks).
Also, is it 100% bamboo? Most of the bamboo boards I've seen are maple/bamboo hybrids. Let us know how your build goes!