Legendary Finnish running company Karhu got in touch with me via an Instagram post last month. They were looking for a shoe reviewer and so sent me a pair of the “Fast5’s” to take for a spin! Pretty cool huh?
So I have been testing them out on the road, off the road, up some hills and through some mud to really put them to the test and see how well they perform even in areas they were not designed to.
This review/measurements are based on a size 12 UK pair.
The shoes came in a bold, yellow, Karhu shoe box with the symbol of the Bear (Karhu means Bear in Finnish) on the front, looking pretty badass. The shoes themselves are nice looking and right up my ally, with nice clashing bright red and ink blue colours, a clean and simple design, a wide toe box and a comfortable fit.
Let’s get technical!
The drop – 10mm heal to toe offset
The weight– Pretty light weight with a UK size 12 coming in at only 366g/12.9oz
Toe box– wide, but when tightened correctly, a secure feel is experienced
Cushioned shoe? – Yes, The Fulcrum technology along with the materials used offer a soft, cushioned ride
Materials – Compression moulded EVA with EVA rubber sole and a light-weight, seamless, mesh material upper with a synthetic overlay
Give me some sole!
The midsole of the shoe is comprised of compression moulded EVA material which helps to promote a comfortable foot strike and, along with the Fulcrum technology, helps to provide a smooth ride. The sole is comfortably cushioned but not so much that you lose responsiveness from the ground. The heel is well padded and comfortable upon putting the shoe on. The heel works well with the materials in the midsole and forefoot to provide a soft, cushioned yet controlled foot fall.
The sole design to the Fast5 is unique in comparison to many other models. The newest and most significant update to the shoes being the integration of the full length heel to toe “Fulcrum”.
What is the Fulcrum?
The Fulcrum has arrived from Karhu working with the University of Jyväskyl in “Pursuit of efficient forward momentum”.
The Fulcrum is a full length compression moulded “cradling” layer that assists runners through the gait cycle. I have attached a diagram bellow to help explain how this works.
This is what Karhu has to say about the new technology:
- Feel (Easier) – The Fulcrum Technology lowers the foot to ground angle allowing for a more comfortable, smooth landing. The lower dorsiflex position reduces injury risk and eliminates wasted vertical forces.
- Ride (Farther) – The Fulcrum Technology reduces over-striding and promotes a more balanced body position with a gentle forward lean. The improved tibia angle at midstance eases stress on bones, muscles and ligaments.
- Stride (Faster) – The Fulcrum Technology activates the calf muscle for greater forward propulsion and increased forward momentum. At the same speeds Karhu Measures up to 7% higher calf propulsion compared to other footwear brands.
Ah, Suits You Sir – The Fit/ Upper!
The Fast5 has a very secure (locked in) comfortable feel that provides a sense of security. The upper is made of a lightweight, mesh material that is breathable and, after some vigorous testing, is still showing no signs of wear and tear. There is a synthetic overlay around the shoe lacing that, with some personal adjusting provides the stable, snug fit around the foot. The Karhu synthetic “M” logo on the side of the shoe is also connected to the lace section giving a strong feel around the sides of the foot and locking it into place. The whole upper is seamless mesh and, working together with the synthetic overlays, does a good job of giving you a feeling of comfort and control.
My experiences in the shoe!
Walking about town – Upon receiving the shoe I decided I would break them in a wee bit by wearing them to work and about the town. The shoe is super comfortable and looks good.
Road – The Fast5’s are marketed more towards the road and as you would expect, performed best here. I ran a few 10k routes and one longer run in the shoes and found them to be very responsive. I found that the Fulcrum technology does live up to its name as I found myself with a slight forward lean and felt as though I had improved footfall and gait. The cushioning was perfect for these distances on the road, with no obvious aches or pains stemming from any of the materials.
Light trail – The shoe responded similar to the road on these hard packed pathways. The sole offered enough grip to keep traction and still felt fast and secure.
Muddy trail – Starting to take the shoe out of its comfort zone, I tackled some muddier less road-shoe-friendly routes. The shoes were responsive, light and fast through the flat sections. Due to the tread being angled at road running, the shoes were a bit slippy on the steeper uphill section and felt less secure on the muddy downhills.
We don’t need paths! – Just for fun, I decided to take the shoes on a trip up the hill sides around argyll, following no paths and seeing how they would get on. The shoe responded very well on the dry areas, slipping a wee bit on the steep ascents and descents, yet still maintained that secure foot feeling. As you would expect from any road shoe, however the wet less hospitable areas proved to add more challenge with the soles slipping on the wet grass and stone.
Do I like them?
After having the shoes for nearly a month now, and putting them through various tests, I can say with certainty that I really like the shoes. They offer a comfortable and responsive ride when you get the adjustments right for you and they feel like a fast yet secure shoe. The shoe looks good, with a simple design and nice colour scheme. Karhu definitely tick all the boxes so far with this shoe. I feel as though this shoe will be more suited to shorter runs/races as I personally would require a bit more stability for longer, ultramarathon training runs.
I would definitely recommend giving them a bash if you’re looking for a cushioned, neutral, responsive and fast ride!
Thank you for reading!
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For more information and to purchase the shoe, visit – http://karhu.com/runningshoes/men-s-fast-5-fulcrum-ink-blue-bright-red.html