Altra Mont Blanc Carbon Review

Back in 2024 Altra released their first Carbon Plated trail shoe: the Mont Blanc Carbon. This is their flagship top end trail racer designed for tackling long distances, and if you look at any Altra sponsored athlete at UTMB they are all sporting these.

I wrote my initial review of the Mont Blanc Carbon here (along with a breakdown of the specs) if you want a better overview, however a summary is this:

• 251g weight (one of Altra's lightest shoes)
• 29mm stack height on a zero drop platform
• 3.5mm Vibram Megagrip Litebase outsole
• Full length "Carbitex Monoflex plate"

Now I've had a chance to test them across 2 ultras alongside some good training miles, hitting 290km usage, I'm keen to revisit my initial (pretty positive) first impressions to see if they still ring true.

Firstly, What Is A Carbon Plate?

A carbon plate is a long firm thin layer that is inserted into the midsole of a sole.

It is designed to act like a spring, tensioning up as you put force into it when your foot hits the ground, then releasing that force back out propelling your foot away faster.

Secondly, Is It Any Good For Trail Running?

Boy is that a question 😅. OK for the positives: I definitely feel this stronger sense of propulsion in two contexts:

• Running on hard flat ground where that plate can really act like a spring
• Pushing up a hill climb, that spring feel like it's kicking your feet forward

It feels like the plate gives back what you put in, the force your pour into it is multiplied

I'd also found that it really does act like a rock plate: most noticeably on descents over stony ground where jagged ground becomes muted underfoot reducing the fatiguing of your sole.

However, there are downsides. Notably the shoe is much firmer, you lose a good chunk of the cushioned feel underfoot for what feels like a harsher ride. You really can feel that firm plate under your foot.

You also lose a bit of flexibility in the shoe, not as big a deal on roads, but on climbs (when your toes are bending back on each uphill stp) and when navigating technical ground that flexibility (and to a greater extend the ability to feel the ground under your feet) is important.

The "Carbitex Monoflex plate" in the Mont Blanc Carbon has an additional feature which helps a little with that: it doesn't flex downwards but it does flex upwards, so you can flex the shoe how it would flex when climbing up hill, without losing that spring effect.

So, Is This Shoe Any Good?

In my initial review I was very excited about these, calling them the best trail running shoes Altra have ever made.

I was wrong.

So firstly yes, the Carbon Plate does give a propulsion advantage, that claim that it acts like a spring and boosts you forward is valid and you will feel that when running in them.

I will say too that descending in these felt good, they protected your feet and have a good deal of stability which provided confidence over technical ground.

And the grip is superb, you get real traction over a variety of surfaces, but that's true of most of Altra's range now they are almost exclusively using Vibram outsoles.

But as a long distance, ultra racing focused shoe, I've found they've got some real disadvantages that would put me off using these.

Firstly: that firmness, it is really fatiguing for the soles of your feet. I did a 50k in these with lots of hard surfaces and stony ground, and my feet were absolutely battered by the end of it. I was wearing thick wool socks too!

Notably I was sore in the front center of my soles where the plate sits, it had caused real aches there. I think if you were to want to race in these you'd need to build up to it, transition carefully to the firmer ride.

Next is the upper: the mesh and tongue are very "race oriented", by which I mean focus on weight reduction over comfort: this means you have to be careful of lace biting, the tongue is very thin, and even though the tongue is gusseted it shifts so it is often sitting off to the side rubbing against the top of your foot.

Then there's the plate itself. I don't know if I have a defect model or something, but the left hand plate, when it gets even a little wet, starts what I can only describe as "clicking". Instead of a smooth spring on my step instead it feels like it "clicks" up against my sole, exacerbating that firm harsh feel. It's also just annoying as heck, like a squeaky shoe that's also kind of hurting you on each squeak.

Finally: the cost: £220 is an astonishing amount of money for a shoe, an amount I wouldn't mind if this was a bullet proof highly durable shoe. I'm thinking like the Nike Zegama 2, a shoe that is expensive (but still much cheaper at £165) but feels like it's built like a brick shit house, you can tell they'd last you ages. That is not what you feel in the Mont Blanc Carbon, they feel very "race day" shoe, my haven't covered 300km yet and are already looking pretty beaten up.

All in all I'm not planning on using these for future ultras, I just don't think the comfort and durability is there, it's not worth it for the minor propulsion boost the plate gives.

Altra Alternatives

Altra recently release the Mont Blanc Speed. This shoe is very similar to the one above (same fit, same midsole and outsole), however:

• It has no Carbon Plate, but retains the 29mm stack height, so you retain the cushioning whilst dropping the firmness
• It has a more padded, cushioned upper
• It's £165, a full £55 cheaper than the Carbon version

I've been running in it during training and honestly I vastly prefer it. The underfoot cushioning is nicer, the more padded upper is comfier, and I don't get that fatiguing plate underfoot.

I'll be posting a review of this soon, until then that's definitely the one I'd recommend over the Carbons.