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Exotic Carbon Matrix II Seat Post

27.2x300mm 165g £54.29

The eXotic Carbon Matrix II from Carbon Cycles is a happy compromise between materials and comes in at a very nice price. I have enjoyed using it, as have others, on a mix of bikes ridden over different terrains. A bit of a traditionalist, I have been enlightened.


Pros: aesthetically pleasing, nice price, functional, well-built.


Cons: nothing significant, but a few quid more will take you to a monocoque sibling.

xotic carbon seat post test review cycling
seat post test review carbon cycling

Spec/materials 4.25/5

It is worth remembering right at the start that all carbon fibre is not equal. Different densities, additives, and processes will have an impact of how strong, light, rigid, the components made form it become, as well as how well it may absorb impact. Having said that, the main properties remain consistent in general. Highly specialist disciplines may require deeper examination of the material. In this review I have avoided getting bogged down.


The eXotic Carbon Matrix II is a composite seat post. The top 29mm of the seat post are reinforced with aluminium – Matrix refers to the process of bonding the two materials. An aluminium seat-clamp with a carbon post offers combines light-weight rigidity and a weightier flexibility. As such it promises a happy marriage, even if not one made in Heaven. The 3K weave of the carbon fibre puts it very much at the ‘softer’ end of the carbon fibre spectrum – which make sense for a seat post as it offers more flex than weaves with more filaments.


Carbon Cycles aim this post at the road and cross-country rider, but do not recommend it for aggressive mountain biking. However, it promises a good deal to the weight-general rider as well as the cut-down tourist. It is an in-line model, so your pretty much directly over the pedals for max power transfer. Whilst this suggests more competitive riding, light-weight tourers might well appreciate it too.

tst reviw cycling bicycle seat post carbon
tst review cycling bicycle seat post

The bolts on the clamp are stainless steel.


A dual seat-tube clamp is recommended by Carbon Cycles. Spreading the load is a good idea with carbon, as is getting the loading right. I have used a single clamp without any ill-effects – however, that may impact on any warranty let alone an unpleasant injury should you get things wrong.


Size options for tube diameters range from 27.2 to 31.6 calling at 30.9 – all round, no aero. Length – measured form the base of the post to the middle of the seat rails - options are 250, 300, 350, and 400mm. Combinations are not offered across the range of sizes, with only three lengths for the 31.6mm diameter – there’s no 400mm. There should be something to suit most geometries – bicycle and human. Exotic suggest the use of a shim for fine tuning the diameter if necessary, but only for road riding, definitely not for off-roading. Exotic point out that it is worth checking carefully before ordering, as returns will incur a charge. 


The Exotic Carbon Matrix Seat Post has been inserted in the down-tube of Mrs Steve’s compact geometry road bike, a friend’s all carbon flying machine, as well as my tourer and gravel-hack-commuter. In fairness, whilst the weight may be noticed by sinewy racing snakes, it is less likely to draw gasps of awed admiration from sturdy tourers: weight is not the only arbiter. Having said that, my speedster mate was very happy on training rides and a couple of time-trials. I’ve ridden over gravel trails and the pot-holed subsiding surfaces of local city roads.

Size/fitting 4/5

Made to a high tolerance fitting should be easy on. Carbon gripper paste is a definite. There should be no issues marrying it with carbon, aluminium, steel, or titanium frames. Keeping you seat post looking dandy will be easiest on carbon frames or chamfered metal – although ours survived less favourable insertions. Give your seat-tube a clean first.


The clamp looks simple enough with a cupped base that allows adjustment to suit. The two bolts are simple and the rails slide easily along for a good fit. I found things a bit fiddly when fitting the saddle. Success came by getting things finger tight to hold things in place before final adjustments and pinching up. 


6nms torque is what you are aiming for. Invest in a set of suitable tools with a newton meter, if necessary – certainly a good idea of you are going down the carbon route. If you haven’t then you may be risking things, especially if you overtighten; To spread the load, as recommended, I bought a double seat-post collar – remember this needs to have the lower collar fitted to your seat tube and the upper collar fitted to the seat-post.

test review sat post cycling

Performance 3.75/5

Starting off on the road. Pretty good was the verdict when chasing personal bests. Were comfort a bit more important than speed, the aluminium offered a nice bit of flex when things got a little bumpy and when adjusting seating position. This fitted in with the feeling that on longer day rides on road there was a good compromise between power transfer and weight on the one hand and comfort on the other. My previous experience of carbon seat posts has been that they do not deal with frequent small bumps, important for touring and gravel, as opposed to bigger lumps. Thus, the aluminium-carbon composite mitigates this to some extent.

test review carbon seat post
test review cycling bicycle bike sat opost

Away from asphalt and I’ll admit to premonitions of my aging bones receiving the sort of rattling they could happily do without. I’ve been using  Ultimate Vybe Suspension Seat-Post (not carbon, of course) for a while when hitting gravel and the mixed surface commute, so decided, to be fair to do some mileage on rigid seat-posts before trying out the Matrix II. Well, I was impressed finding that even I noticed that things seemed lighter and that power seemed to be well-directed. True, the gravel did feel a bit bumpier, but this was compensated for by the rolling along more easily.


Strap-on seat packs have not impacted on the smart look. SQR type seat packs or beam racks are very much a no-no on carbon.


In short, this is a bit of kit that, as you’d expect, does not deliver the super-powers of a monocoque design, but makes a good compromise when the going gets rough without adding much in the way of weight.

Value 4.5/5

Frankly, paying just short of £55 for a carbon seat post - alright, composite- seems like very good value – especially an aesthetically pleasing one. Of course, you may wish to add the cost of a dual seat clamp if you decide to stick to the manufacturer’s recommendation. This may set you back from a tenner or so upward (I got one for £25 from Clee Cycles). The same might well apply to any carbon seat-post.


Brand X offer a carbon seat post for £35, although the aluminium clamp is less likely to rival the happy marriage of carbon and titanium. The Cannondale Topstone is fifteen pounds pricier than the Exotic Matrix but only comes in one size. After that the sky is your limit with models ranging upward into the hundreds of pounds


Michael liked the Carbon Cycles Ti Seat Post – a monocoque model with titanium bolts. Marginal gains for an extra £20?


Tifosi's carbon post (£29.99 officially but seen cheaper) but limited to one diameter and length. (although Michael ran one on the Holdsworth for several years. There's the WCS Carbon Zero Offset MTB seat post from Ritchey for £140. 


As ever, pick the right horse for the right course depending on your preference and your budget. I have come to like Exotic Matrix Seat Post a lot, after initial misgivings about carbon and ‘my type of cycling’ – informed by a good deal of old-school steel is real prejudice. However, I can see me using it for long day rides and for touring, although I’ll avoid clamping on seat packs to it. You might pick it for gravel ventures and speedy road trips, to0, if you want to cut-weight without breaking the bank.

Verdict 4/5 Value and sound functionality with good performance for a variety of cycling activities.


Steve Dyster





Ryton On Dunsmore

Coventry  CV8 3FH


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