More holiday gift ideas for eXtreme sports addicts.
(In case you missed it, I posted five other ideas a little bit ago in eXtreme Sports Physics Gift List, Part 1.)
Hang Time!
When you catch air, you're in freefall. Another way to put it is that you're in a very low orbit that intersects with the ground. Either way, you're briefly weightless.
If you were to strap an accelerometer to your leg to measure the forces on your body, you would see it go to zero when you're in the air. If only there was some way to hook an accelerometer to a timer, you'd know how much hang time you pulled . . .
Actually, there are at least two companies making timers to record the duration of your monster airs. My favorite is the AirPod, but you might want to look into the slightly glossier (and pricier) HangTimer. Personally, I'm all about the data, bling means nothing to me. So I'll save a couple bucks and go with the AirPod.
I'm guessing a lot of folks will be disappointed to find out how little time they spend airborne. On the other hand, once you come to terms with the fact that humans really weren't meant to fly and you learn to appreciate the few precious seconds during each run that you get to enjoy free of our earthly bonds, you'll realize that devices like the AirPod and HangTimer are excellent tools for evaluating and perfecting your aerial skills.
AirPod - fly, be free, take data
$59 and up
In Search of a Fast Frame Rate
If you're a decent photographer, you'll always be a welcome addition in any eXtreme sports road trip. You might even get a free meal or two along the way.
As a rule, eXtreme sports junkies love to see themselves immortalized in high resolution action pics. One of the tricks to getting the shot is making sure you have a camera that can take lots of images very quickly. Pros spend multi-thousands for high frame rates. But you can do almost as well with a few cameras that slip in at just about a thousand bucks.
After using several digital cameras that deliver 2 to 3 frames a second, I found that I was going to need something faster, particularly in the skatepark and on the slopes. My budget limited me to the 5 frame per second and 8.2 megapixel Canon EOS 30D, which retails (with one lens included) at Amazon for $1025. Here's an example of one shot I captured of my son grinding the coping in a 10 foot deep pool at our local skatepark.
In order to get this shot, I actually took 6 pictures, as you can see from this sequence. The one I wanted is number 4.
The high frame rate is good for more than just photos, it also helps me do a bit of physics calculating. For instance, from these shots I can tell that my son traveled about 2 meters in the second that it took to fire off 5 frames, which means he was moving at 2 meters a second. The pool curvature is about 2.5 meters in radius at this point, so he was experiencing a horizontal g-force of about 1/6 the force of gravity. That's what was pinning him to the board as he carved around the pool. Cool, isn't it?
The 30D's older brother, the EOS 20D, has the same frame rate and resolution, but a smaller buffer, so you can't shoot as many shots in a row before stopping to let the electronics catch up.
If you're made of money, you can step up to the 10 megapixel EOS 40D at 6.5 frames per second. (The last time I checked, the EOS Rebels were all limited to 3 frames per second, so they don't make my cut.)
As far as I know, the Canon EOS line offers the fastest frame rate among the $1k cameras. If I find anything faster, I'll let you know.
Canon EOS SLRs
Just hold the button down, chances are at least one of those dozens of shots is going to be a keeper
$974 and up
Eye Witness
There's nothing like watching a crash from the first person perspective, and the best way to do that is with a helmet cam. (I'll post my own favorite crash as soon as I can get it downloaded from my son's PC.)
You can spend a bundle for a high tech, waterproof, shock proof helmet camera, or you can save money the way I did.
I bought a $99 camera that records straight to flash memory. Then I sometimes tucked it under the strap for my snow goggles (be sure to loop the camera's wrist lanyard around your goggle straps), velcroed it to my leading leg, or duct taped it to my skate helmet.
It makes for cool, low budget follow shots and gives a realistic view of what it's like to cruise down a mountain or thread your way through a half pipe. The crashes are the most fun to watch, complete with brutal crunching sounds and groans of pain. Just don't show them to your parents or significant others until a season or two has passed. Otherwise they'll beg you to stay off the slopes, rails, ramps, tracks, or whatever else you ride.
Helmet Cams - first person adventure and pain
$79 and up
First Aid - it's the best kind
Despite taking things to the edge, few extreme sports injuries involve compound fractures or head trauma. A few bumps, bruises and abrasions are the much more likely results of any given adventure. But the recent epidemic of coverage in the media of staph infections makes it clear that even minor scrapes need quick attention. Besides, you don't what your favorite eXtreme athlete staining his or her stylin' new jeans or jacket with unsightly blood stains.
I used to load up my backpack with a few Band-Aids and sterile pads, but it's a lot easier to just grab a prepackaged first aid kit and toss it in the trunk with the rest of my gear. REI offers a range of kits, from tiny sets that slip in the glove box to fairly comprehensive packs that include everything you need for most injuries, including a copy of "The Wilderness First Aid Manual."
First Aid Kits - 'cause your mom won't always be nearby to kiss the boo boo
$28 and up
Surfrider Gift Membership 
As the nigh-invulnerable superhero "The Tick" once said after being asked if he could destroy the Earth "Ye Gods! I hope not! That's where I keep all my STUFF!"
The Earth is a fragile place, and even if the Tick is no threat, without the work of groups like the Surfrider Foundation, you're likely to eventually lose all your stuff - and a lot more. In their own words . . .
The Surfrider Foundation is a non-profit grassroots organization dedicated to the protection and enjoyment of our world’s oceans, waves and beaches. Founded in 1984 by a handful of visionary surfers in Malibu, California, the Surfrider Foundation now maintains over 50,000 members and 80 chapters worldwide.
Even if you're not into eXtreme water sports, remember that most of this precious planet is ocean, and you can't have a healthy Earth without clean water.
So join Surfrider this year or give someone a gift membership - your great grandkids will thank you for it, and you get a cool bumper sticker.
Surfrider Gift Membership
$25
Holiday Gift Suggestions for eXtreme Sports Athletes and their Friends
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