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Cycling: Build Your Own Bike Mounted Video Camera

Web Wombat Staff - 24/Apr/2007     Live Cycling News Feed

Bike Video Camera
Specialized bicycle similar to the one used

CA533A
Sunplus SPCA533A based WombatCam

1GB SD memory
1GB SD memory card and Lithium camera batteries

WombatCam Mounting Hardware
Rubber dunny washers 9mm hole

Seatpost Mudguard
Seatpost Mudguard - only clamp is used

WombatCam Tripod Bolt
Filed bolt head replaced original in knob

WombatCam Mounting Assembly
WombatCam Mounting Assembly

WombatCam Side View
WombatCam Side View

WombatCam Screen View
LCD Screen on and ready to record!

Inspired by the dropping costs of video camera technology, one intrepid member of the Web Wombat team has taken to mounting a You-Tube compatible video camera in his bike. Take a look at the pics from the video:

Attack!

Attacking the C-grade bunch!!

Brighton Rd. 6am Tues ride

Garbage truck forces 40k riders into RHL. Cars move into oncoming traffic lane - 6am Beach Road ride. Good driving! Things were tight and no warning.

Judging by the interest created by this simple camera, our Wombat Cyclist has shared the technical ins and outs of exactly how you can build your very own WombatCam and where to obtain the parts and their cost. A full inventory of parts is shown in the right hand panel.

How cheap can a CamCorder get?

Amazingly enough the price of a video camera recorder has plummeted to an astoundingly low level. You can get your own 320x240 pixel (QVGA) camcorder by performing a search for "camcorder" on eBay. The cheapest unit at the time of writing is sub $50 Australian.

After pondering the possibility of creating race-day cycling videos for a week or two, the bid was placed! The project was born.

Research on the web produces an incredible array web pages showing all manner of very costly camcorders. These are attached to all sorts of jigs mounted to various bicycle parts and in one case even on a bicycle trailer.

Fortunately, the Chinese-made camcorder (based on the Sunplus Technology SPCA533A IC) used here has no moving parts. All video is stored on an SD flash card (limited to 1G max - cost $17 at www.msy.com.au). No moving parts makes for a vibration resistant solution which is a must for bike use. Racing bikes, in particular, run on very high pressure tyres (145 psi in this case) and have no suspension other than flexing of the carbon fibre frame components.

Experience from WombatCam's first outing reveals that a recording of more than one hour of exciting CCCC criterium racing (only C-grade so don't get too excited) produces a 390Mb file. Sunplus have certainly done their homework on video compression. More than 2 hours of racing can be crammed into this tiny handlebar mounted unit.

Editing the resulting file proved to be challenge as the file format (Microsoft .avi format) used the new Motion JPEG or mjpeg codec (different from mpeg). Most flavours of Windows can play the video directly though, as can Linux. However, most current video editing software will send the would-be director scurrying to the search engine to find that new encoder.

Sound recorded by WombatCam is completely useless however. All you get to hear are the wheel bearings, road noise, and the freewheel hub sounds which are transmitted up through the frame and occasionally broken up by the Shimano DuraAce shifters changing gears. Even those loud uncontrolled outbursts other cyclists are prone to only barely register.

Would a professional cyclist consider this? Well the camera weighs in at 135 grams!! (without batteries.) Look carbon Keo pedals weigh in at 115 grams each. So, perhaps.

Mountings

Mounting the camcorder turned out to be far simpler than anticipated. In a remarkable stoke of luck,  it turns out that the Chinese manufacturer provided for a tripod bolt mount on the base of the camera.

In a further stoke of luck, your Wombat Team Cyclist discovered that the type of bolt used on a standard tripod is coincidentally within half a millimeter of the bolt used to secure an aftermarket mud-guard. It just turns out that the seatpost and the handlebars are similar in diameter and both are carbon fibre making this a perfect solution. 

Simply unbolting the guard and using the mount together with a 1/4 inch tripod bolt produces a very solid professional looking camera mount. A slight reaming of the bolt hole with 6.5mm drill produces a perfect fit.

Supplied by Bentleigh Bicycles this mudguard has two "elbows" with knurled knobs. With a bit of filing it is possible to get the camera bolt hex head to sit neatly into the original plastic knob recess making for an even more professional finish.

Stopping the camera from rotating on the plastic mount was overcome by using a pair of thick rubber dunny washers. These grip the bottom of the camera and also the plastic mount allowing the camera to move and spring back into place. Bunnings Hardware supplied the camera tripod bolt and the washers (from the plumbing department).

Results

Racing video promises to be an invaluable training aid if discussion at Cafe Racer in St. Kilda is any indication. Those far more experienced in the art were able to identify strategic moments in the race where your Wombat Team member allowed emotion to overcome racing common sense.

Essentially, in a criterium race, the rider must conserve as much energy as possible, only using it when opportunity presents itself. Those skilled in the art are able to see the tell tale signs of vulnerability in a peleton where we lesser riders obliviously pedal on. At the moment of weakness (and only at that moment) brains give way to brute force (provided the rider possesses such a power) and propels himself in to the winning position.

Landing to theorise on tactics over coffee

Landing at Cafe Racer where "The Coaching Panel" deliberates err perhaps pontificates over these videos?

And therein lies the true value of WombatCam. It's one thing to theorise about strategy over a coffee, but it's entirely another to have the wiley old medalists (or "The Coaching Panel") point out actual examples of what to do and when (also over coffee however). And in the case of this Wombat Team member, what not to do...

Where to from here?

The next most obvious step is to superimpose data from the Polar Cycle computer onto the image (heart rate, road speed etc). Polar data is also time-coded so that matching it to the video time-coding on the computer after the race should be possible. 

Heart rate, cadence, speed, lap-times, power and more can all be sub-titled on the screen for later viewing and analysis. Once this data is available The Coaching Panel will recognise that your Wombat Team member also needs a significant amount of fitness training to capitalise on peleton weaknesses. But does one do interval training or strength training and in what proportions? 

The data mixed video may be able to reveal all.

Technical (Geek) Stuff

"The SPCA533A is a highly integrated solution for DSC (Digital Still Camera) application. It consists of image processing engine, image compression engine, the storage interface controller, TV encoder, LCD interface controller and USB interface. The SPCA533A supports a wide range of sensors, including most-commonly used CMOS and CCD sensors. Flexible control of the internal buffer allows the SPCA533A chip to support up to 4-mega pixels image resolution. It also supports many flash memory card interfaces, including CFC, MMC, SMC, and SD. The SPCA533A can also interface to both TFT LCD panels and STN LCD panels for preview. With full support to a DSC's major peripherals, customers can realise a DSC system with the minimum cost." from SPCA533A datasheet - General Description. For dummies, that means a single Integrated Circuit or IC for the whole camera that does all these wonderful things - and it's so darn cheap!
See also How to repair a carbon fibre frame


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