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Procave and Concave

written by Bubbles October 17, 2013

“Is the cave steep enough?”  “Which board has the best concave?”  “What is a progressive radial”

These are just a smattering of the questions we get every day from people who want to know more about what concave is and why it matters.  Well today, is your lucky day, ’cause we’re gonna hit pretty much all the basics to give you a good starting point when discussing the finer points of concave over a candle lit dinner with your longboarding boo.

First of all: what is concave?  Concave is the curve of the board that makes a cup for your foot to stand in so you don’t slip off the side of the deck.  Not all boards have concave but most do, so we’ll be assuming in today’s lesson that concave is the bee’s knee’s and that everyone does it.

NOT ALL CONCAVE IS MADE EQUAL!  That’s not to say that some is better than others, just that no 2 manufacturers are going to create exactly the same shape even though they may create boards with similarly steep or similarly shaped ‘cave.  Different shaped concave’s will feel very different and have different performance characteristics.  This leads well into the images that I uploaded below so let’s roll right into them!

Screen Shot 2013-10-16 at 4.32.01 PM

Radial Concave

(EX: Dimes, Cigars + Mission, Maestro Mini, Yofaces)

The first and most basic concave that we’ll address is known as radial concave because it draws it’s shape from the radius of a circle.  If you look at the image above of a radial concave you can see how it could be extended to eventually make a full circle.  “Radial” meaning that it is of or having to do with a circle.

Radial concave tends to feel very mellow, and is often used for boards where the rider is anticipated to be moving around a lot.  It allows the rider to comfortably change their position as they ride, making it ideal for freestyle and dancing boards as well as cruisers.

Screen Shot 2013-10-16 at 4.38.46 PM

Tub Concave

(EX: Ibach, BGDK, Royce; note: these boards all have a slightly progressive shape with a “w” that feels very much like tub cave but is not technically)

Tub concave is called such because it resembles the flat bottom and steep walls of a bathtub.  Perhaps also a consideration in the name is how difficult it can be to get out of either of them.  On a skateboard, tub ‘cave is used to provide an absolutely locked in feeling for the rider.  The sharp, steep rails on either side of the rider’s foot provide walls to push against and hold the rider in the board.  These locking features make boards with tub concave desirable for any type of riding where board traction and grip is the highest priority, primarily Freeriding and more specifically, Downhill skateboarding.

Screen Shot 2013-10-16 at 4.28.14 PM

Progressive Radial Concave

(EX: Sportster, EQ, Boombox, Mekanik, Ratmobile)

This leads us to my personal favorite and the general trend of the industry recently, Progressive Radial Concave.  Basically this is a combination of tub and radial ‘caves.  It seeks to provide the best of both worlds by having a steep wall on the rail while also having a gentle base to give you some guidance in the middle of the deck.  The name comes from the concept that it is radial concave, but as you get closer to the rails, the circle implied progressively grows smaller.

This style can be changed in a myriad number of ways, from different base’s slightly wider concave profiles, higher rails, etc etc, and (as was mentioned previously) provides a fantastic compromise between the comfort of radial boards with the performance of tub boards.

Screen Shot 2013-10-17 at 9.14.58 AM

“W” Concave

Now this is a somewhat interesting case, in that it is not a separate group of concave, rather a very common feature provided by many brands and manufacturers in their boards.  “W” can be added to basically any existing shape, and is exactly as described by the image above.  In the center of the board there is a small rise.

This rise provides extra grip in that it allows your toe and heel to dig into the space on either side of the “w”.  However, the bulge in the center of the board very often makes it uncomfortable when pushing as you have to balance on top of this ridge.  “W” is typically added when stiffness is desired as well as extra grip in the board, so primarily for DH and freeride purposes.

Well folks, there you have it, basically all I want to say about concave in one sitting, if you want to know more, leave your questions below or wherever I can find them and I’ll answer them just as soon as I get a little skating in!

Cheers and enjoy the ride!

-Bubbles

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