{"id":20029,"date":"2026-07-16T22:33:39","date_gmt":"2026-07-17T02:33:39","guid":{"rendered":"https:\/\/nuxx.net\/blog\/?p=20029"},"modified":"2026-07-16T22:53:11","modified_gmt":"2026-07-17T02:53:11","slug":"kickr-core-2-tennis-ball-feet","status":"publish","type":"post","link":"https:\/\/nuxx.net\/blog\/2026\/07\/16\/kickr-core-2-tennis-ball-feet\/","title":{"rendered":"KICKR CORE 2 Tennis Ball Feet"},"content":{"rendered":"
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Tennis ball rocker feet on my KICKR CORE 2.<\/figcaption><\/figure>\n<\/div>\n\n\n

Last winter, after getting a Wahoo KICKR CORE 2 trainer<\/a> and designing some variable height feet<\/a> to level the bike I kept thinking about tennis ball feet. These provide a bit of give, allowing the trainer to rock and pitch a bit, reportedly making it more comfortable to ride. (And yes, for some reason I sat on this post for half a year before finishing it up.)<\/p>\n\n\n\n

I’ve never really noticed an issue with the static positioning of any of my trainers, but Kristen purchased a KOM Cycling Indoor Rocker Plate RPV1<\/a> while getting ready for AIDS\/LifeCycle<\/a> in 2021\/2022 and now finds she can’t really ride indoors without it. Her experience, and hearing nice things about tennis ball feet from others, has made me wonder how something similar might be for me.<\/p>\n\n\n\n

There’s a whole bunch of tennis ball feet available for trainers. From the well-engineered ones that my friend Jake \/ Cycl3dCo makes and sells<\/a> to a bunch of free designs on Printables<\/a> and MakerWorld<\/a>, there’s… a lot of options. Mostly because I couldn’t find one that was low enough profile to not require a riser block for the front tire (the inverse of the problem which prompted my trainer foot design), a bit of late-December poor weather boredom, wanting to get better at drawing stuff, and perhaps a bit of NIH<\/a>, I decided to try designing my own.<\/p>\n\n\n

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Detail of four of my KICKR CORE 2 low profile tennis ball rocker feet.<\/figcaption><\/figure>\n<\/div>\n\n\n

Here’s what I came up with. These are yet-another-set-of tennis ball feet, but they are designed so that with a 700c x 32mm front tire on the bike the axles are level during riding, and they replace the stock rubber feet and are held in place with the original retention screws.<\/p>\n\n\n\n

I restarted this design numerous times over a few days and learned a lot<\/em> about constraints and what not to do. I was originally going to make this a parametric design like the variable height feet, but realized it’s not as useful and stuck to a single height. This also allowed me to take some shortcuts in constraining drawings… Not the best practice, but not horrible for what I was doing.<\/p>\n\n\n\n

The final items were printed using the same filament and profile as the Riser Feet (Overture PETG<\/a> in black, 6 walls, 25% gyroid infill, printed hot and very slow), and they came out nicely. Because of the quantity of filament needed (estimated ~529g) I started on one spool and used the AMS<\/a> to auto-swap to the second when the first ran out. I was a bit nervous about how this would go, but it ended up working out wonderfully. While the second spool, purchased about two month after the first, had a more matte look to it, but it looked good once melted and deposited. My concerns about print imperfections during the swap ended up being for naught.<\/p>\n\n\n

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A very slow print job. This took ~34 hours.<\/figcaption><\/figure>\n<\/div>\n\n\n

I’m fairly certain I both designed and printed these more robustly (and slowly) than is needed, but as a beginner I’d rather err on the side of overbuilt (and spending a bit more on plastic) than have something which breaks and interrupts a ride.<\/p>\n\n\n\n

I’ve made this design available under the CC BY-SA-NC 4.0 license<\/a> and posted it here at Printables<\/a>.<\/p>\n\n\n\n

Included are .f3d<\/code>, .step<\/code>, .stl<\/code>, and Bambu Studio<\/a> .3mf<\/code> files. The .3mf<\/code> is as I printed it, including the print profile and imported .step<\/code> files. (The .stl<\/code> from Fusion, even exported at the High<\/em> setting, end up lower resolution than I prefer, but was included for completeness.)<\/p>\n\n\n\n

So how do they it feel to ride? Well, to be honest, they did what I thought they would and added some flex and give. But I’m not completely sure I like it. Just before spring I went back to my previous self-designed riser feet<\/a>. Next winter I’ll give these another go, though.<\/p>\n\n\n\n

A big, big thanks to Jake for providing a bunch of help and suggestions. He has a ton<\/em> of experience designing parts professionally and printing them for both prototype work and production and he shared a bunch of tips, tricks, and information that got me pointed in the right direction for this and many other designs.<\/p>\n\n\n\n

If you are looking to buy some tennis ball feet or other Michigan-made accessories for your trainer, give Jake your business over at Cycle3dCo<\/a>.<\/p>\n\n\n\n

(As I was finishing up my design and waiting on a test print, I came across Kickr Core 2 Rocker Feet for tennisballs<\/a> by punkti<\/a> over at MakerWorld<\/a>. A quick measure showed they have basically the same vertical as my feet, are physically narrower, but thicker. These likely would have sufficed and use roughly the same amount of filament, but I was nearly ready to do a final print when I found these, wanted to give my own design a try, didn’t really care for the appearance. These do look like a nice option, though.)<\/p>\n","protected":false},"excerpt":{"rendered":"

Last winter, after getting a Wahoo KICKR CORE 2 trainer and designing some variable height feet to level the bike I kept thinking about tennis ball feet. These provide a bit of give, allowing the trainer to rock and pitch a bit, reportedly making it more comfortable to ride. (And yes, for some reason I\u2026<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10,11],"tags":[],"class_list":["post-20029","post","type-post","status-publish","format-standard","hentry","category-cycling","category-making-things"],"_links":{"self":[{"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/posts\/20029","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/comments?post=20029"}],"version-history":[{"count":10,"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/posts\/20029\/revisions"}],"predecessor-version":[{"id":24787,"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/posts\/20029\/revisions\/24787"}],"wp:attachment":[{"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/media?parent=20029"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/categories?post=20029"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nuxx.net\/blog\/wp-json\/wp\/v2\/tags?post=20029"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}