Icebug - ACCELERITAS4 RB9X Review

29th July 2015

Icebug - ACCELERITAS4 RB9X Review

It's with great delight we welcome a new brand into Front Runner ... Icebug.

Who are Icebug?

Icebug are a Swedish brand perhaps best known amongst the orienteering world for their grippy, hard wearing and super lightweight shoes. However, in recent months they have become exceptionally popular with Obstacle Course Races (OCR) and fell runners. 

They're a family run business and were the first company to develop shoes specifically for winter traction. Iceberg have gone from strength to strength and in an effort to develop shoes for summer use they've introduced shoes such as the Acceleritas4 and Zeal-L. 

After much research and product testing of the Acceleritas4 and Zeal-L around the Peak District and Snowdonia we found these 2 shoes couldn't be more perfect for the demands of the UK terrain and are without competitors to shoes from Inov-8, La Sportiva and Salomon. 

Acceleritas 4 Review.


  • Purpose - lightweight, aggressively studded fell / off trail shoe.
  • Weight - 200 grams (UK8)
  • Drop - 4mm
  • Last - Racing (feels quite broad for a racing last / high volume toe box)
  • Very flexible forefoot
  • Upper Material - Ripstop nylon. Non absorbent and very hard wearing.
  • Mid sole - Compression moulded EVA
  • Outsole - Rubber 9 Extreme

How does it fit?

I'd really expected the Acceleritas 4 to feel much more narrow than it does. I've a large 'D' width foot and have plenty of room in the toe box and adequate space down the sides of the shoe. The lacing on the Acceleritas 4 reaches further down towards the toe end than most fell shoes enabling a real good range of adjustment and a snug fit for the full length of the shoe. The heel counter is supple and moderately high, cradling the foot nicely but not digging in or rubbing. There is very little give to the Ripstop Nylon upper, I'd half thought the robust nature of the upper might make the Acceleritas 4 crease into the foot however I've not had any issues with this at all and have the material is as tough as the come!

The sole is very flexible allowing for a very natural foot movement and responsive ride, I could have sworn the Acceleritas 4 felt like it had some underfoot protection (rock plate) as despite it's flexible and low profile design you don't feel every lump and bump however after some research it doesn't appear to. 

I'd have said the sizing is a little out as I'm take the Acceleritas in a smaller size to what I am normally and even then it still feels roomy.

Icebug Acceleritas

Photo. Men's Acceleritas4.

How does it run?

As I mentioned above, the Acceleritas 4 feels light and fast, being low drop and very close to the ground gives you great ground feel agility. It's not a shoe I'd like to run too far on the road in but when I have been on the tarmac it's a bit like  racing flat! 

The Acceleritas 4 has 2 stand out features... the grip and the upper.

To cut a long story short, the traction from the RB9X rubber is nothing less than remarkable. A shoe that grips on oily, wet quarried grit stone slabs is a shoe to shout about. 

We've all had the shoes we love and after 100 miles you rip through the upper or your little toe pokes his cheeky face out the side.... I'm 100 miles into the Acceleritas 4 now and the upper is a little grubby but 100% intact and not showing signs of tearing wearing through anytime soon.

Icebug acceleritas4 grip

Photo. Ripstop upper and aggressive cleats. A shoe built to last! (pun intended)

icebug acceleritas non absorbent

Photo. The materials used with in the Acceleritas4 are all non-absorbent. Meaning the shoe stays light even when wet. 

What shoes is it comparable too?

I'm a firm believer that shoe variety in terms of drop, stiffness, shape and cushioning is paramount in helping prevent injury and reduce overuse niggles. The Acceleritas stacks up pretty well against a number of popular fell shoes.

Icebug - Acceleritas 4 VS Inov-8 - X Talon 212

  • Acceleritas is 12 grams lighter
  • X Talon has a high drop (6mm)
  • Equal lug depth
  • Similarly hard wearing uppers
  • Acceleritas has a more supple midsole
  • Both have gender specific fits

Icebug - Acceleritas 4 VS La Sportiva - Anakonda

  • Acceleritas is 80 grams lighter
  • Equal drop (4mm)
  • Anakonda is more structured, particularly in the heel
  • Acceleritas 4 has ladies and gents fits
  • Acceleritas has a broader toe box

Icebug - Acceleritas 4 VS Salomon SLab Fellcross 3

  • Equal drop (4mm)
  • Acceleritas is lighter
  • Acceleritas 4 has ladies and gents fits
  • Fell Cross potentially has a slightly more aggressive outsole
  • Word on the street is the RBX9 rubber is stickier


Like any shoe, if it doesn't fit your foot then you probably won't like it. Having said that the Acceleritas4 has all the components of a great fell running shoe. The grip is great, the materials are hard wearing, it's light, it's comfortable and it is responsive... what's not to like.

The Acceleritas4 and Zeal are available in store and on our webshop > Here

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