He had the wheels custom made, it would cost $$$ to get that done.
Solid rubber wheels are more economical and suited for a battlebot. **broken link removed**
You can have a motor assembly with a bunch of motors for a central drive chain, and drive the bot like a tank. You then hook up the motors to each of the wheels via chain or belt. Then do this for the other side. You can hook them up with belts and gears to get some major torque. That is how many FIRST robotics work. It is guaranteed to work well. You could also make a crab drive bot, but would probably break, but amazing maneuverability.
i know i am doing tank drive but im going to make it belt drive attached to the wheel to give it extra torque and im also attaching chain and sprockets
Or you could buy a featherweight kit (or its drive module separately) from these guys where the chain and all is already taken cared of http://www.battlekits.com/
Even though you said you want 4 wheels, I just point out featherweight because it's way way cheaper (and comes with armor!) than the other larger (4-wheel) kits.
THe drive you linked though would get smashed to bits in a battlebot (and cost magnitudes more to replace). It is possible to get flatproof, belt/chain driven tires without having to go to all that trouble.
Personally I prefer gearboxes over belts and chains...just because.
Our half million dollar automated plating line uses standard bicycle size chain for both of it's main drive wheels and heavy duty double chain from the main motor to a reduction gear. You might want to re-think your chain prejudice dk as it's unfounded =) Chains are signifcantly more robust than gears in many situations. The smaller chain has broken only twice and that was because of a worn sprocket, and the double wide heavy duty chain has never needed anything other than occasional greasing.
You can get battery operated mountain bike transmissions which you could use as a microcontroller controlled automatic transmission. If the motor starts to work too hard and draw too much current then you change down a gear to give you even more torque and if it's not working hard enough you can change up a gear to give you more speed. This will give you both speed and pulling power.
If you need something compact I'd recommend an RC car transmission. A mountain bike's derailer is pretty bulky. A visit to your local hobby shop should present you with some sollutions.
Probably not. But it would probably do quite well in a SOZbot compettion (so would a lot of other affordable methods). RC transmissiona re cheap though.
Make a small Robot and see if it works. If it does, then move on to the bigger stuff. Every Hobbyist wants to just jump into the final stage and say "I built a Giant 20 foot tall walking robot with dual gatling guns!" But if you cant complete a single module of it, then all is lost. If you can get one module at a time to work, then you may just be able to do so.
Sorry to interject here so late in the game, but Bill: what's the scale on the first photo you posted on this thread? I've been looking around for some small pillow block bearings, but there's no Princess Auto in Saint John. All they've got around here are some massive, industrial size ones! Does anyone know where I can get some small ones, even if only online? Sure, there are plenty of manufacturer sites out there, but I like pictures and price lists!