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3T Ionic 25 Ltd seatpost



A smart looking seatpost with a unique mechanism that is solid and offers independent reach and tilt adjustment, but it's very expensive.

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The adjustment of the the 3T Ionic 25 Ltd seatpost makes it easy to get your saddle exactly where you want it, but you pay a premium for the carbon version.

3T updated its seatpost range this year and new is the Ionic, which uses the company's own DiffLock splined clamping mechanism which was on the Palladio post previously. This allows accurate adjustment of the saddle angle with independent reach adjustment, which makes fine tuning your bike fit very simple.

The DiffLock mechanism features dual interlocking splined barrels which allow very fine angle adjustment. It's easy to get the saddle in the desired position, though it does take a bit more time because you have to slide the inner barrel out every time you make an adjustment. I feared it might not offer the same fine level of adjustment of most other saddles, but I happily got the saddle just where I wanted it.

Once you've achieved your desired saddle tilt, two end caps bolt into place and secure the saddle firmly in place. The most appealing aspect of this design is that you can adjust how far forwards or backwards you want the saddle without having to worry about the tilt.

The supplied end caps are only compatible with round rails, though 3T do offer oval rail end caps. It would be nice if they were supplied with the post, considering the high cost.

The seatpost is made from carbon fibre, with a one-piece design, and is available with a 25mm setback that I've been testing or an inline type. The 200g weight is a bit higher than some similarly priced seatposts, the DiffLock clearly adds a bit of weight. It's available in 27.2mm (tested) and 31.6mm versions. You could always cut the post down a bit to save weight.

After a couple of months of use, including plenty of road racing, the seatpost has been solid in its service. With some carbon non-slip grease it hasn't slipped in the carbon frame it's been tested in, and once set up the DiffLock mechanism has proved solidly dependable. It's a smart looking post as well with 3T's usual discrete decals.

It's an expensive post, as most carbon components tend to be. The good news is there's an aluminium version of this post which is less than half the price, and according to the 3T website only weighs 235g. That would be the one I would buy, and pocket the saved cash


A smart looking seatpost with a unique mechanism that is solid and offers independent reach and tilt adjustment, but it's very expensive. test report

Make and model: 3T Ionic 25 Ltd seatpost

Size tested: 27.2mm

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

Ionic is a new seatpost design featuring the sophisticated and robust, 3T''exclusive DiffLock seat clamp. Ionic''25 places the seat clamp assembly 25 mm behind the seatpost's centerline. This gives athletes the option of a more rearward position on today's shorter framesets. The splined alloy DiffLock coupling is a highly-accurate method of setting saddle angle needing only lightweight clamping by side-mounted bolts. It is especially useful for fine adjustment of saddle setback, which can be done without impacting saddle angle. Ionic''25 Ltd is a monocoque in high-modulus carbon-fiber, finished in high-gloss black with the 3T Ltd silver stripe.

Tell us some more about the technical aspects of the product?

Material: HM carbon-fiber

Bolts: Stainless steel

Saddle Clamp: Alloy DiffLock™

Setback: 25 mm

Finish: UD Gloss Black

Certification: CEN

Rate the product for quality of construction:

Excellent as you'd expect from 3T and at this price.

Rate the product for performance:

Performance is excellent, once set up it offered no problems or required any attention.

Rate the product for durability:

Yes, very good, the finish is tough and doesn't scratch easily inside the frame.

Rate the product for weight, if applicable:

It's pretty light but isn't the lightest for this money, the clamp clearly adds a big of weight, so weight weenies might want to look elsewhere.

Rate the product for comfort, if applicable:

Didn't detect any discernible compliance.

Rate the product for value:

At £200 it is very expensive, but if you've spent £2,000 or more on a frame, you won't be skimping on the details now will you?

Tell us what you particularly liked about the product

The independent reach adjustment for bike fit setup.

Tell us what you particularly disliked about the product

The clamp takes a bit more time to set up.

Did you enjoy using the product? Yes

Would you consider buying the product? I would look at the cheaper aluminium version

Would you recommend the product to a friend? If they had the cash. If not, I'd point them at the aluminium version.

Anything further to say about the product in conclusion?

Nice, but very expensive. Unless you must have carbon, save your cash and buy the aluminium version.

Overall rating: 7/10

About the tester

Age: 31  Height: 180  Weight: 67

I usually ride:   My best bike is:

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, touring, mtb,


David worked on the tech team from 2012-2020. Previously he was editor of and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes

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David Arthur @d... | 10 years ago

I think they must have changed the mechanism Gasman because I haven't found that problem with this post. I'm using it with a Prologo Scratch saddle and it's been fine, no noise to report

Gasman Jim | 10 years ago

I had one of the carbon Palladio posts for almost 12 months, and while there was lots to like about it there was also one big problem: noise. The clamp mechanism forces the rails of the saddle towards each other from the sides, rather than just clamping each rail vertically, and I'm convinced that pushing the saddle rails together like that led to lots of clicking noises from the saddle rail / clamp area. I even tried a new saddle but to no avail. Switching the post to a spare Thomson I had lying around, but retaining the same saddle got rid of the noise. I ultimately ended up on a Syntace P6 and love it - quiet as a mouse.

The other annoying thing about the 3T was that they hadn't put the stripe up the back of the post perfectly symmetrically, which is rather unacceptable considering the price.

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