Inside Adam Savage’s Cave: Improving a Cat Exercise Wheel

Adam’s friend Traci Des Jardins visits the Cave with a challenge: fix and improve her cat’s exercise wheel. With some tweaks and swapping out of parts, the giant wheel’s operation is greatly improved. It ended up a fun little project that required a bit of problem solving, and Traci’s cat got a great workout out of it at the end!

Shot by Joey Fameli
Edited by Benito Gonzalez

Comments (36)

36 thoughts on “Inside Adam Savage’s Cave: Improving a Cat Exercise Wheel

  1. How does one train a cat to use a wheel like that?

    Daxter-The-Hutt (pictured) could really use one….

  2. I wonder if you could even make it quieter by changing the side wheel that run along the edge. A bearing based wheel made of rubber would be smoother and quieter, they looked like hard plastic door glides. A fun video and wouldn’t have been complete without a shot of the cat using it!

  3. Finally!! A place on the internet where I can find cat videos.

    Actually, kind of a cool project…. I wonder how big I would have to make the loop for my 4 year old?

  4. Bengals are the only cats to own like a child with ADD dosed up on sugar lol, unlimited energy very fast very loud highly intelligent and they love water.

    This is mine his name is Kato he’s about 14lb lol I’ve been meaning to build a wheel for him for ages i might just have to get one designed now lol

  5. My cat is far too lazy and old now to use a wheel like that. But it was super cool to see the cat using it! There is justice in this world!

  6. It was all fine till Ziggy hit 88 mph and left a pair of flaming paw prints around the ring…

    Meanwhile in 1957 a very confused cat was found at a construction site of a new home…

  7. … Damn. Now THAT would be a project!

    A Back to the Future cat exercise wheel, with build in “working” Flux Capacitor powered by a dynamo attached to the wheel. I have geekbumps all across my arms just thinking about it!

  8. I just had a nerdgasm discovering I have geekbumps! A simple bicycle computer would be a nice touch to the thing!

  9. I’m impressed by the amount of improvement.

    However the skater and mechanical engineer in me cringes. That’s how sloppy skaters ruin bearings way before their time!

    As long as the bearing can easily slide sideways like that on an axle, the rotation is not taking place inside the bearing. The bearing seat is rotating on the axle which will work surprisingly well for a short time and then deteriorate.

    Effectively these ball bearings are now working as gliding bearings as well. Unlubricated and with the wrong materials and tolerances.

    A proper wheel assembly looks like this:

    The bearings are separated by a spacer and tightened by a but against a notch on their axle. The speed rings make sure the locking force only goes through the bearing seat and the spacer prevents any inherent side loads in the bearings from tightening them out of alignment with the wheel seat.

    However you achieve this, locking the bearings on the axle and using spacers in the wheel is essential!

    I would also consider softer wheels. Yes, high durometer wheels have less rolling resistance, but a softer wheel makes far less noise. A medium duro wheel might be the better compromise.

  10. Cool project! In the future you could rig up an optical rotary encoder on one of the axles and have an Arduino read how many revolutions the cat makes in the wheel. 🙂

  11. As another skateboarder, I was about to post a far-less-eloquent response about this.

    The inner ring of the bearing should be clamped in place by the spacers and a nut on each end of the axle, so the ball-bearing does the work. The spacers inside the wheels are key to proper operation.

    I wonder what duro Adam calls hard. In some of the other videos on Tested where durometer has been mentioned, the “hard” numbers mentioned for casting materials are still fairly soft in terms of skateboard wheels.

  12. brings up a good point, though in this case i wouldn’t be too concerned about bearing life.

    What i am concerned about is that Adam may have improved the wheel of death a little too much. There should be more resistance in the system than there presently is. All the smoothness additions are certainly better; the bearing/shaft tolerance, the the shaft rigidity, sanding the bump out of the wheel, all should reduce noise and vibrations. However, the hard skateboard wheels, when used on the smooth wood surface of the wheel, actually have too little rolling resistance. The wheel has it’s own moment of inertia, but as smooth as the wheel looks to be rolling, i wager it would feel much like running on ice, or with socks on exceptionally smooth flooring. The cat needs a little more resistance. Softer skateboard wheels should do the trick, providing enough resistance to slow the wheel down after kitty has gone for a jog, and also allow the cat to run at it a little harder with a little more stability.

  13. Adam made her kitty a car wheel hot rod!!!!

    You guys should attach a generator to it. I bet it would at least charge cell phones maybe power a night light XD

  14. Really ladies and gents ?! (why can’t I use an interrobang here??) I’m sure the bearing setup will be perfectly adequate and a vast improvement over the original. I suffer from over engineering syndrome too, though I’m trying to curb it. Sure we could make a better one…maybe with carbon fiber composites and aluminum honeycomb cores, and of course then we need to make a lathe large enough to turn that giant wheel on so we can ensure it is perfectly round, and then maybe…

    Let us not forget the intended purpose, it is a cat wheel.It has been improved by a significant margin. I doubt this video was shot as part of the core content and think it was more of a friend helping a friend with materials on hand, might as well roll some footage kind of deal. Thanks for sharing an unusual example of problem solving Traci and Adam.

  15. If it helps any, Mathijs A. van der Paauw made an optical tracker for his hamster wheel years ago, and used it and a few other sensors to monitor his hamsters’ health. Here’s a link to his site, though he hasn’t updated his blog in over two years now:

    Here’s a sample graph:

    Going off-topic, he also came up with the idea of making tiny versions of human food for hamsters and wrote a book on it 🙂

  16. My first “real job” was working in a machine shop, specifically on a manual lathe (some mill and CNC work from time to time), which I gave up to pursue a career in audio production. Watching videos of Adam and the team building and modifying projects in the shop makes me a bit sad that I stepped away from that path. I think it’s about time I find a project and book some time in a local shop.

    My first project on a lathe was at 16 machining a lightsaber hilt which I gave away…May have to make another.

    Great video, as always!

  17. That’s a big kitty, I think he’s saying he needs a bigger wheel. That could be a One-day Build, right? Get Jeremy to put some lights and counters on it too. 🙂

  18. As a long time resident of the Richmond…only in San Francisco will a cat have its own gym equipment.

  19. First I want to say Adam did a great job upgrading that cat wheel. Thanks for sharing this video!

    I do agree with the other comment posters that talk about the best practices with skate board wheels. But I want to point out, this is not a skate board. There is no side load on this cat wheel so if they is a little play in the brass spacers and no spacer in the skate wheel that’s ok as there is no side load or side pressure, there is no nut pressing on the bearing. This is only a linear load. Adam’s fix improved the engineering and function on the cat wheel significantly. Could it be even more over engineered sure, but does it need it for a 18lbs cat? no.

  20. I totally agree that the way Adam mounted the wheels should be totally fine, but it is worth noting how the bearings should be mounted in case someone watches the video and gets inspired to use skateboard wheels for another project that might require a bit more longevity and bear a heavier load 🙂

  21. Right so then i guess it begs the question. What if you were building an exercise wheel for a Tyrannosaurus Rex? What would you use for bearings? How would you construct the wheel?

    Bonus question: The T-Rex has a cousin who has evolved to live quite happily on Venus. He would like to purchase a similar wheel for his cousin. How would you build it and transport it?

  22. Awesome! Adam, could you please come over to Germany and fix my DIY Cat-Wheel too? It’s noisy and wobbly! 😉 Our bengal Obi-Wan would love that 🙂

  23. Is that wheel directly influence by 2001: A Space Odyssey? Every time I look at it I think Kubric.

  24. Nice gadget !

    I would just have put a drop of green loctite between the bearings and the shaft to hold their position. As there is no side loading you don’t really need the spacers inside the wheels. And you probably could have left out the inner of the three wheels as well as they do not do much, if anything but add friction.

  25. Aren’t those bearing supposed to sit closer to the center of the wheel? I’m fairly certain that you can push them farther into the wheel than that. I feel that after a while they’ll wobble out of the wheels. If you push them all the way in I dont think that’d happen.

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