I saw a video of the British cyclocross racers putting foam from a hardware store into their tires. This foam is used in construction to fill joints before caulking. All those joints on the concrete interstates in the US are filled with foam backer rod covered by caulk. FYI, CX magazine has a writeup on their experience here. Here is a forum discussion on TrainerRoad about DIY CX tire inserts.

Do DIY tubeless inserts like this work on gravel bikes? If so, how well do they work? I ask because cyclocross tires are wider than traditional gravel tires.

Additional questions might include:

  1. What should I look for in a foam tube? I fear that the backer rod used in the CX Magazine article above will be too narrow for a gravel tire. Foam inserts for MTB tires will be too large. FYI, there's some discussion on MTBR here.
  2. How well do they perform long term?
  3. How easily do they install, and are there any tricks to getting them installed?

There's not a lot of info online but from the video it looked like it did work. The DIY section of this article is probably the best description I found:

  • 2
    Reviews are off topic on this site, however you are welcomed (and encouraged) to answer your own question. If you could formulate this into a question that other people may find knowing the answer to useful (and avoid product recommendations and such) you are welcome to post it up here.
    – mattnz
    Commented Oct 29, 2023 at 23:33
  • Concur with @mattnz Juggle this around so it is a question, ("do ghetto foam inserts help in tubeless tyres?") and the bulk of this would form an answer-post.
    – Criggie
    Commented Oct 30, 2023 at 1:24
  • Well, you kind of already given enough information for people to be interested in it. If it does really work, then it would be a bit like lube your bicycle chain with wax, it really works and it has it's own energy to take off all on it's own, but it can take time because, as you said with foam tyres, it takes time to do it properly, and that's the key for success. There are already airless tyre products that have a patent, and are in development at a commercial rate. Look at Gecko Rubber youtube.com/watch?v=SXAkzNTL2tc
    – MindDBike
    Commented Oct 30, 2023 at 13:34
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    I didn't think the write-up would fit the format of the site well but since there is interest and I'm being told to go ahead, I'll edit it and post as an answered question soon.
    – user66598
    Commented Oct 31, 2023 at 18:23
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    See the edited question for an example of how you might phrase this as a question. If this doesn't work for you, you can undo the edit.
    – Weiwen Ng
    Commented Oct 31, 2023 at 18:48

1 Answer 1


Answer: Yes it is possible to make a foam insert for your gravel bike's tyres.

Downside: It’ll increase the wheel weight. Mass does affect the angular velocity. It will slow you down especially when climbing where you have to accelerate that weight.

  • This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review
    – Ted Hohl
    Commented Dec 9, 2023 at 20:59
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    Could you expand on "how" and perhaps some of the sub-questions in the original post ?
    – Criggie
    Commented Dec 9, 2023 at 22:14
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    How is the weight of the DIY-insert a downside compared to the ones that the OP would purchase? Do you expect ta DIY insert to weigh significantly more than store-bought insert?
    – Paul H
    Commented Dec 9, 2023 at 23:53
  • Ok, logically speaking you have narrowly answered. If the question was “ can I jump off a bridge?” Would you tell the OP that yes it is possible. Not mentioning the physics which says it isn’t advised? HVAC
    – HVAC
    Commented Dec 10, 2023 at 1:40
  • The OP did ask if this method would work on gravel bikes. If the question is answered narrowly, it will miss the point entirely. Certainly I “can jump off a bridge.” Or ask you to suggest a series of bridge heights. The answer is absurd without mentioning the physics involved. If that’s off subject, well that’s just silly. Who does that ?
    – HVAC
    Commented Dec 10, 2023 at 10:35

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