TruTune active carbon airside inserts – any takes?

Well this looks interesting – a £120 insert that turns the feel of your air fork into a coil. There’s very much Science™️ behind what looks initially like snake oil.

MTB Air Fork Insert

Check out the video here. I’m surprised only PinkBike seem to have looked at this so far: https://carbonair.co.uk/

Anyone tried one?

I tried one and know a few people who use them. They definitely do what they say on the tin but whether or not it will suit you depends on your fork and riding style.

For trail riding it felt very good in my performance 36 and more coil like (much easier to use travel while maintaing ride height), and I’d say ground tracking / traction were particular strong points. Once i got onto bigger hits at our local freeride park it was too easy to bottom out though. Im a pretty light rider and the Grip forks arent super supportive though so I wouldn’t say I’m the ideal candidate for it.

I reckon it would have worked well in my previous older pikes where I struggled to get full travel / small bump compliance. Very light riders, those with overdamped forks or people who want jibby / supportive forks while being able to use full travel would be another.

Thanks @wr404 – would that be a case of going for the short one (as recommended for heavier riders/eMTB) and using 2-3 normal tokens? I run my Lyrik Select+ with no tokens at all, no issues bottoming out but would like things smoother. (enduro riding, 85kg/85psi as recommended by ShockWiz)

Correct me if I’m wrong, but wouldn’t using normal tokens with the TruTune defeat the purpose of the TruTune?

I clicked the link and was immediately confused by “Despite taking up space inside your fork, it increases its effective air volume” – which is a physical impossibility.

Soooooo…. I’m concerned about the sales pitch already! :o)

“effective” I would imagine is the key word. TBF, it sounds like the sort of thing that’s a nightmare to describe in text, but they do seem to a be a real thing and behave in the way they claim

The explanatory video is pretty rubbish at explaining it. From what I can tell it’s essentially a semi-porous Volume spacer. The thesis being the activated carbon somehow works at a “molecular level” to provide more volume with higher pressure/speed (?) and make the spring more “linear” for bigger hits. At least that appears to be their claim.

Not totally sure I buy it as a concept and I do wonder if you could achieve very something similar with some sort of open-cell rubber foam “volume spacer” or a screw in mini pressurized bladder/cylinder instead (which plenty of other manufacturers have done versions of before).

Ultimately £120 for a fancy volume spacer does just feel a bit steep, even if you manage to get the word ‘Carbon’ in there…

Its real scientific phenomena.

Whether it makes a difference to fork feel is open to debate.

I won’t be buying one – I reckon it’s ‘snake oil’ of the finest quality :o)

i saw them at Ard Rock. Spoke to the chap on the small stand with a pre-conception of this is going to be rubbish/a con/etc.

He had a large volume syringe with the end blocked off. Put the plunger in and you couldnt really compress it (obviously). He then dropped one of the volume spacers in, put the plunger back on and you could compress it a fair amount (maybe 20% of the volume of the syringe). So it definitely did what it said.

They were offering free demo’s. Just take you bike over and they would fit it.

Seemed good, but as mentioned, i am sure probably only for certain applications. And at £120, its not at a price worth dipping a toe for (IMO)

Its does seem a bit expensive compared to, say, the luftkappe.

What forks are people using these with?

My V1 Zeb uses the first two thirds of its travel very easily but has never reached full travel (it is at 190mm though).

This sounds interesting, but it’s £20 more than the 2023 airshaft w/buttercup thingy.

chakaping – if you read through the review of that really ugly Pole ebike over on Pinbike, Seb has used one on the 190mm Zeb on that.

https://www.pinkbike.com/news/review-poles-190mm-travel-voima-is-long-slack-and-high.html

chakaping – if you read through the review of that really ugly Pole ebike over on Pinbike, Seb has used one on the 190mm Zeb on that.

That’s what piqued my interest actually. It does sound like it might suit the Zeb. Slightly surprised he thinks the new Zeb still needs a widget adding, but perhaps it’s a thing with long-travel air forks? I’ve always had coil forks for 180mm+ in the past.

Probably going to talk myself into a coil conversion instead anyway.

i saw them at Ard Rock. Spoke to the chap on the small stand with a pre-conception of this is going to be rubbish/a con/etc.

He had a large volume syringe with the end blocked off. Put the plunger in and you couldnt really compress it (obviously). He then dropped one of the volume spacers in, put the plunger back on and you could compress it a fair amount (maybe 20% of the volume of the syringe). So it definitely did what it said.

Ditto!!
It blew my mind – really!
It deffo worked to make the a 50CC volume feel ‘more’…
I guess it’s like having a larger +ve air chamber in your fork.
But, TBH, I make my chamber SMALLER with tokens, so could save £120 and remove a few tokens!

DrP

Ah, a damper which takes volume but also has ‘give’ when it comes to compression and rebound damping levels.
I wish someone had thought of that before.

I’ve not heard of this fork tuning device, I do have a DSD Runt which I got second from a local rider, sounds similiar, coil like feel and better nmid stroke support.

I’ve been running it for a month or so now and it has let me run lower pressures whilst the fork remains high in its travel.

Ah, a damper which takes volume but also has ‘give’ when it comes to compression and rebound damping levels.

Unless I’ve got it wrong this is an air spring modifier, not a damper.

I have a DSD Runt too, which is pretty versatile, but comes with its own tuning challenges as a result.

as above, it’s an air side adjuster, not a damper.

essentially the carbon sorbs air onto it, the amount of sorption increases (I think) with pressure therefore removing more ‘air’ molecules from moving about as a gas and creating pressure.

its a technology that’s used in analytical instruments like specific surface area measurements, using micro decreases in pressure to measure sorption of a gas of known properties onto the surface of a sample material.

it’s perfectly feasible that high surface area activated carbon will have a measurable effect on the small volume of air in a fork, or a shock.

So, being seeing this for a while and very intrigued. I get the science. Makes air chamber bigger but also makes it linear. Not sure if people know, Audi invented this idea. They had it patented for a while and use the concept in their suspension in some cars. Patent had a limit, it expired, and now others are using it.

If it is ‘increasing’ the volume, how is this any different to just decreasing the pressure of the fork?

The fact their graph showing the impact of the effect does not have a scale on it doesn’t fill me with the warm fuzzies.

Not exactly the same idea, but Formula’s Neopos are roughly similar in that they are “squishy” volume spacers which make things more linear than hard volume spacers. They are under £30 a set, so a fair bit cheaper to play with.

If it is ‘increasing’ the volume, how is this any different to just decreasing the pressure of the fork?

Google Boyle’s Law then consider that if you increase the volume of the air spring your forks travel has a lesser effect on the volume. If you reduce the pressure you’ve just got lower pressure. First case = more linear spring rate. Second case = soft fork

“If it is ‘increasing’ the volume, how is this any different to just decreasing the pressure of the fork?”

Also I believe this sorption is a dynamic increase of effective volume, so when the pressure is increased by compressing the fork a certain proportion of the molecules in the air attach to the surface of the carbon, freeing up volume for the other molecules to move in. It’s quite mindbending science!

Holy thread resurrection Batman.

If it is ‘increasing’ the volume, how is this any different to just decreasing the pressure of the fork?

Imagine a 150mm long air piston with a 1″ square cross section, filled to 10psi. To get 150mm travel would then require an infinite ammount of force.

Imagine that same piston but in an infinitely long cylinder, the force required to move it would be 10lbf (any distance, doesn’t matter it’s always the same).

Air springs don’t obey Hooke’s law, where a 10lb/inch spring would need 10lb for the first 25mm, and 60lb to bottom out.

So an air spring is a compromise between making it ramp up enough to actually resemble a ‘spring’, and not so ramping up that it doesn’t bottom out ever.

And in the case of this product the pressure required to make the fork sag to the correct level won’t change (much), but it will then be easier to bottom out.

Anyone pull the trigger on one of these +

I’m intrigued by them but what they offer isn’t something I’m aware of needing.

I’ve just bought 200g of activated carbon from Amazon. First experiment will be with a syringe of air, and if that works as expected I will have a go at 3D printing a bottomless token to hold the carbon granules to see if it makes a difference to the fork’s behaviour.

wow dhague , ambitious, how will you get the token to hold the carbon without it falling out,but still be porous enough to allow airflow?

The carbon I ordered has particle sizes from 0.6 to 2.3mm, so I plan on printing something with lots of tiny holes – say 0.4mm in size.

You could probably buy a sheet of carbon matting/foam and jam a chunk in there?

Well Ive gone an ordered one

was recomended the short one with a luftkappe and for my husky physique

Will see how it goes, snake oil still lubricates forks, right?

I’ve been trying the TruTunes in a variety of forks (well, Fox 36s or 38s) on differing bikes. Full review to follow soonish. Suffice to say, the main thing you notice is the improved off-the-top sensitivity. Similar to fitting a MegNeg to a rear shock. But more so. Forks sag under the just the weight of the bike etc. Even after putting in the recommended extra PSI of pressure. As regards the mid- and end-stroke behaviour… more riding required still. Soz!

You could probably buy a sheet of carbon matting/foam and jam a chunk in there?

Doubt you’ll have the surface area.

so I plan on printing something with lots of tiny holes – say 0.4mm in size.

Proof of concept could just be a mesh bag attached to the bottom of a spacer no? Or a 3d printed basket that you can but a mesh bag into.

So, first experiment done and… I’m not sure it was a success.

I took a 150ml syringe and with 150ml of air in it I pressed down on some digital scales until I got a reading of 4kg. This resulted in the syringe reading 128ml.

Next I put some activated carbon into the syringe, about 25ml worth. I set the syringe to read 150ml and once again applied 4kg of force. Once again the syringe read 128ml.

So on the plus side I got the same deflection even though I added the carbon “volume spacer”, so some of the gas must have been adsorbed. On the minus side, adding carbon didn’t actually lead to more piston travel for the same force, so had no overall effect.

So, being seeing this for a while and very intrigued. I get the science. Makes air chamber bigger but also makes it linear. Not sure if people know, Audi invented this idea. They had it patented for a while and use the concept in their suspension in some cars. Patent had a limit, it expired, and now others are using it.

Hi endorium, just to clarify: the technology was developed and patented by TruTune’s parent company, Carbon Air. Audi fit high end models with our Carbon Air technology and their Tier 1 supplier bought a license from us.

Here’s another link introducing the technology:

https://trutune.co.uk/pages/technology

So, first experiment done and… I’m not sure it was a success.

I took a 150ml syringe and with 150ml of air in it I pressed down on some digital scales until I got a reading of 4kg. This resulted in the syringe reading 128ml.

Next I put some activated carbon into the syringe, about 25ml worth. I set the syringe to read 150ml and once again applied 4kg of force. Once again the syringe read 128ml.

So on the plus side I got the same deflection even though I added the carbon “volume spacer”, so some of the gas must have been adsorbed. On the minus side, adding carbon didn’t actually lead to more piston travel for the same force, so had no overall effect.

Control test of something roughly the same volume as the activated carbon but incompressible, like water, is needed.

I really like this and kind of want to get it, purely because it seems to really work and yet my brain just can’t believe that it does. That’s almost the definition of sorcery.

Got a quick night ride in this evening
160mm yari with a luftkappe

I just took out my 2.5 tokens & put in the trutune and added an extra 5% of psi. Not touched any dials.

Off the top not sure I felt much difference, still pretty firm over chatter at slow speeds
Over faster stuff felt nice,
– now my local trails running almost perfectly but really felt like had more grip than nornal, at the bottom of the descents I was surprised to see how high the o-ring was.

I’ll need to get out to some longer steeper trails to see how it fares, as I’m no lightweight, I find getting the balance of support vs plush on steep stuff is hard.

Just to add I’ve got some z150 bombers on a hardtail and this doesnt give the yari that same squelch, squelch plushness, but the grip feeling was similar