Been searching the bay of e, and have read the previous thread.

Can’t find anything in reasonable length / not too wide so as to waste min foam.

Also, how thick? 6mm? 10mm?

Anyone actually done this and followed through?

Cliffs; I don’t have a laser cutter.

cheapo camping roll mat?

Here’s who I used:

https://www.efoam.co.uk/closed-cell-polyethylene-foam.php?gclid=CjwKCAiA0IXQBRA2EiwAMODil0hA8bJHCp26KA9OPFCG7OuqPtqwYcYgdM1BQtWI8f6DXIdfmBjxthoCOQIQAvD_BwE

I ordered 15mm thick, 67mm wide strip by 2m (to go in 2.6″ tyres) and then just cut a few notches in. I believe this is exactly the same as the new stuff from MarshGuard, but cost under a tenner 🙂

I’ve used this place for work stuff, before:

https://www.anyfoam.co.uk/sheet-foam.php

width 58cm, length 400cm, thickness 1.5cm

For two tyres, that site wants £49???

You need to do 58mm, 4000mm! At the moment you’re sizing up a sheet 58cm X 400cm…… 😉

D’oh

If you want a simpler and easier alternative to a flat style Huck Norris, with the additional benefits of swanky pants Cushcore, watch this vid…

[video]https://www.youtube.com/watch?v=bCfRoxOBarw[/video]

Only problem is 50mm backer rod isn’t that easy to come by in UK; I’ve made do with 30mm (without having to split it down middle as video suggests) and it’s done a fine job so far, costs about £1 an end and weighs about 40g per wheel (I’m #26forlife mind)

Pool noodles are another option, but not sure how they’ll do on circumference for all you new fangled big wheel warriors.

Plastazote is a trade name for the material if you are googling

Thinking about it, it wasn’t that I couldn’t get hold of 50mm backer rod, it was more that I didn’t realize until I’d already got the 30mm stuff off ebay.

If you have wide rims, probably worth the upgrade and it’s still not gonna bankrupt you:

https://www.dortechdirect.co.uk/polyethylene-foam-backer-rod-50mm-circular.html

How’s that worked for you then andyrm?

Are people finding these foam inserts allow the use of lighter “exo” type rear tyres on rocky trails? Or do they not really prevent holes?

I’ve found it good so far, on a 34mm internal rim and 2.6″ Butcher Grid. You can see it’s taken some whacks but no pinch flats yet – including a full day at BPW a couple of weeks back. That’s at 78kg kitted up, 28psi rear.

Just bookmarking for reference

Thinking about it, it wasn’t that I couldn’t get hold of 50mm backer rod, it was more that I didn’t realize until I’d already got the 30mm stuff off ebay.

If you have wide rims, probably worth the upgrade and it’s still not gonna bankrupt you:

https://www.dortechdirect.co.uk/polyethylene-foam-backer-rod-50mm-circular.html

How did the 30mm work for you. I only run up to 2.3/2.4 tyres on not that wide rims. I’m thinking the 50 would be overkill.

The site you linked has it in all sizes but I guess the 30,40 and 50mm ones are the choice.

This is most excellent. I’ve just been umming and ahhing about what to do instead of procore, which has turned out to be just as much hassle as having inner tubes.

I wonder if there’s value in keeping it full size in the tyre.

Given how cheap that stuff is I’m going to give it a go. Only need 2m cut in half for my 26er wheels

I’ve just ordered some 50mm, let’s see how it does! I’m thinking that I’ll leave it full circular like a flat tyre defender.

What do we think then? Backer rod vs flat foam cut with holes?

And what width for 25mm rims and 2.3-2.4 tyres?

How did the 30mm work for you. I only run up to 2.3/2.4 tyres on not that wide rims.

I’m running it on rims that are 23mm internal, 28mm external with 2.4 tyres…

Main reason I went for it is because I always used to burp tubeless, so wanted the extra bead support, but also fancied more rim protection after a summer in the alps dinging more rims than a colonic surgeon.

My burping issues are cured and although our local trails aren’t that rocky, I’ve cased into tree stumps a few times and my rim is as pristine as if it’d been bleached…

That said, I’d reccomend going a bit wider if you regularly encounter mad rock and I’d like to try 40 or 50mm widths to see about the extra sidewall support.

How do u mount the tyres with the foam inside?

I’ve bought the 50mm for my 30mm IW rims.

Backer rod should be better at bead retention and over lapping the rim edge when the wheel is cranked over – I’ve seen Huck Norris fail in that scenario.

Basically as in the video…

Wrap foam around tyreless rim, cut to length, secure with zip tie, then remove from rim

Fit one bead of tyre

Insert insert, can be a bit of a faff feeding it around the rim and making sure the gap lines up with the valve, but it’s pretty simple really.

Pour in tubeless sealant of your choice.

Insert other bead of tyre, grimacing at how white your knuckles are as you manoeuvre the final portion into place.

Inflate and dance merrily at the combined achievements of saving money and weight in comparison to the commercial products on the market, whilst ensuring your rim is ready for a solid pounding.

ensuring your rim is ready for a solid pounding

Sign me up!

Doub-entres aside, I thought I’d follow this up.

The packer rod arrived earlier in the week and I’ve spent part of today on general bike up keep including the inserts.

First up, the packer rod foam is less dense than the Huck Norris foam. A 2m section weights 110g, so cut in half to mirror a Cushcore insert would reduce this to 55g. THats 4-5x less dense. It’s not sufficiently dense IMO to successfully mitigate against impacts if cut in half to be like cushcore.

At this point, I decided to put the entire packer rod in un-cut, which is more akin to the banger insert from Mr. Wolf.

I measured up and cut the extra length needed for my 29er wheels and attached it together with two cable ties looping through both ends.

Putting the insert in was a bit more involved than regular tubeless, but un-eventful and not excessively long. maybe an additional 5-10 minutes per tyre.

The technique of pushing the tyre bead under the insert into the rim well with a tyre lever to get enough slack absolutely must be applied otherwise you’re never going to get the tyre on the rim without breaking something.

Pushing the tyre bead down and in like this does result in the bead sitting on the top of the valve and allows air to short-circuit when trying to inflate, so be aware of that. Its a simple matter to drag the bead back over the base of the valve, but its not obvious at first.

Otherwise, inflation was uneventful, as was topping up the spooge which I did via the valve and the bead.

Its clear that the insert is compressed by the tyre pressure. I did two today, and one rattles in the tyre where is circumference has reduced and is no longer tight on the rim. After I noted this, I made the second insert a tighter fit and that one is fine.

Its obvious that I need less pressure to get them feeling the same. I’m hopeful, given my preference for low pressures that the higher volume insert will behave a bit like a rockshox air token and increase the progressiveness of the tyre compression as well as providing physical bottom out resistance. Air volume in the tyre must be reduced by at least 60% I’d have thought.

Proof will be in the pudding. First ride out tomorrow, but on the soft soggy Mendips, I’m doubtful the riding its going to test it that much.

Details are:

LB 35mm 29er carbon rims
50mm packer rod
Schwalbe Nobby Nics 2.35.

According to teh data sheet for the high density foam @andyrm linked to, it compresses by 50% at 170 kPa, which is about 24 psi. So it’s going to get half the size. But can’t do that circumferentially so it may get even thinner than half size because it is being kind of stretched. But then @Scienceofficer says the round stuff rattles, so that appears to be compressing in two dimensions but not in the third. Which is a bit weird.

I am not sure tbh, what this stuff does when in the tyre. If you pinch, will it spread teh load out a bit? Not much, I’d have thought. If it is acting as a “tyre within a tyre” then perhaps.

I’m going to try the 50mm packer rod a bit later too, arrived yesterday.

So far, the high density foam I’ve used has been all good, I run 28-30psi rear anyway, so probably pinch less than others.

Greyspoke – cheers for the actual numbers, that helps. Wonder if I can now go searching for foam by compression figure??

Given that the rod is very long and very narrow, I’m not really surprised to see it get baggy under a bit of pressure. It’ll be more subject to compression changes in its shorter dimensions. Given the relative differences of OD/ID over its 50mm width, it wouldn’t need to reduce its sectional area much before becoming loose. The material is a bit stretchy and its under slight tension to make it a close fit on the rim. The second one I made tighter was only about 40mm shorter and its remained tight enough on the rim to not rattle.

Bear in mind that the backer rod is also a different product from the one andyrm linked to. Density is 35kg per m3, but I can’t find any expression of compression under pressure.

Any of these inserts should behave along the same lines as the products actually sold to prevent puncture and provide rim protection. The question in my mind is whether they will work sufficiently well to reduce pinch punctures and help protect rims for a fraction of the cost.

I’m hoping my experiment will provide some cut resistance via sacrificial damage to the insert like Huck Norris (and cushcore, and Banger in fact), as well as function as a damper due to its thickness providing physical resistance to tyre compression, and ramping up air pressures in the air chamber under larger tyre deformations.

Given that the insert is squishy and the tyre carcass is stretchy, I don’t know how well its going to be work or what behaviours I’ll see, but the point is, if it does, its £2 per tyre, not £35 in the case of Huck Norris, £75 in the case of cushcore or £95 in the case of Banger.

Actually thinking about it, I’ve no idea if the quoted figure is linear compression or all round compression, and I’d have to purchase a copy of BS ISO 7214 to find out. Zote say they do harder and denser grades thant he LD45, but they may not be available in small quantities.

any update thoughts on this.  I’ve been playing around with tyre pressures and likely to get some the dortechdirect rod either 40mm or 50mm for 30mm OD rims

Just switched rear tyre at the weekend – 50mm backer rod all good! Few little nicks in it suggest it’s done it’s job properly but no pinch flats, burps or bashed up rims so for the tiny price, I’d say it’s a resounding success 👍👍👍

Actually, yes.

The backer rod has been pretty effective, but it’s certainly susceptible to damage. I’m not really surprised, since it’s less dense than either the Huck Norris or Cush Core and I’ve been running 20 psi on 2,35 tyres.

<span style=”font-size: 0.8rem;”>Now the drier weather is here, I’ve just whipped mine out to see how it’s doing. It’s riddled with cuts and slices, but my carbon rims are both fine. I was pretty sure it was doing something after hearing some funny popping noises on some heavy hits over the duration.</span></span>

Interestingly, the one ride I had without the insert at the weekend made the tyre feel really pingy and I thumped through to the rim twice on roots.

The up shot is I’ll be continuing to use it, but it seems like it needs replacing every 6 months for my riding preferences and low pressures. Still, it works out at about £3 a year as an insurance policy for my rims, and I prefer the way the tyres feel too.

.

Those are the most severe cuts by the way, plenty of other minor cuts around the circumference.

Awesome stuff, thanks for the update.

I found some 75 kg/m3 foam to use.

hi , im struggling to get hold of this stuff in sweden. any ebay link or alternatives to dortechdirect?

ooh, poah, got a link?

http://www.easycomposites.co.uk/#!/core-materials/closed-cell-foam-and-3dcore/easycell75-closed-cell-pvc-foam-core.html

will need to cut and shape but should do the same job as huck norris

What thickness were you thinking? I note the 10 and 25mm thickness ones are stated as being ‘difficult to bend by hand’

Book marked as this might be useful for an upcoming Morzine  trip.