I've been known to acquire a pair of running shoes with a specific race in mind, as with La Sportiva Bushido for Transgrancanaria, it was with the Thames Path 100 in mind that I purchased the Helios SR.
TP100 is a 100-mile foot race along the river Thames in England, from the Richmond suburb of London to Oxford, with a cut-off time of 30 hours.
Helios SR is La Sportiva's lightest, most minimal offering. The flat, mostly dirt track and often paved nature of the route made this an ideal match between the task at hand and the tool. As things turned out, I wasn't far off the mark but the shoes fell short of being a masterpiece that they could have been.
Typical terrain on the Thames Path
La Sportiva Helios SR Specifications
Out of the box, the shoes surprised with their lightness (480 grams per pair of Men's US 9) and their flexibility. The plushness of upper and forefoot height of 23mm belied their low drop of 2mm. They looked and felt comfortable, just sitting in my hands.
La Sportiva Helios SR- The Looks
Initial shorter runs with the shoes were promising too. True to specs, the shoes were light, flexible, well-cushioned, and comfortable, with a slipper-like fit.
Much like Bushido, the other La Sportiva shoe I had experience with, the shoes sized small and I needed to go up a full size from the usual for other brands. (For reference, I am UK10 in Salomon, Adidas, and New Balance, and 9.5 in Brooks and Asics. The Helios SR I needed was 10.5.)
Flexibility & The Wave Sole
One feature which provides the shoes with the lightness and flexibility is the "wave" sole, with 9 crests. The dips consist of an exposed midsole and in my view the biggest "sole" reason for the shoe's downfall – I'll explain.
Midsole is composed of responsive injected EVA
According to La Sportiva, the injected midsole (as opposed to standard compression molded EVA) provide for a higher degree of cushioning and better elasticity. I can attest to the fact that the feel is definitely more "springiness" than "mushiness," and that to me is a good thing, particularly on the drier, harder surfaces.
I can attest to the fact that the feel is definitely more "springiness" than "mushiness," and that to me is a good thing, particularly on the drier, harder surfaces.
The wave sole
I did my longest run, 30 miles, along with an earlier section of the race route a month out from the race, and came away with no doubt that these will be the shoes I'll use on race day.
The shoes felt comfortable, and aside from the usual discomfort that comes from a long run and many hours out, no obvious alarm bells. Such was my confidence that I opted not to pack a back-up for either the 50-mile or 80-mile drop bags.
Comfort & the Upper
A big contributor to the comfort is the gusseted tongue, which works somewhat like the Endo-sock feature in some of the higher-end Salomons and serves to provide a wrap-around fit as well as keeping debris out.
The Gusseted Tongue
The Rockplate or Lack Thereof
The one immediate point I did notice about the shoe, however, was the lack of a rock-plate or similar forefoot protection, as would have pretty much been the norm in off-road shoes, particularly since La Sportiva markets these as their "sky running" model.
This was ostensibly to allow for maximum flexibility and lightness but nevertheless was surprising given the mountain running heritage of La Sportiva, which is based in the Italian Dolomites region.
As things were, every once in a while, even on well-groomed dirt track and grass that I was predominantly running on, I'd trod on a small stone right on the groove where the only thing separating my foot from the object was mere millimeters of midsole material and sockliner, and the sharp resulting pain was certainly noticeable.
I made a mental note to not take these out on technical trails where there was a high likelihood of debris and sharp rocks.
Frixion XT dual-compound outsole
Durability & the Outsole
The other point to note is the use of sticky rubber compound in the outsole.
La Sportiva actually has 4 different rubber compounds ranging from very "sticky" as in grippy (and non-durable) to very durable (and non-sticky) and combinations of the compounds are used in various parts of the outsole to maximize traction and durability.
What it amounts to is that the Helios SR employs a dual compound outsole where the black section in the fore- and mid-foot is the sticky rubber (explaining the SR part of the name) and a harder wearing yellow compound is used on the heel.
It's a great idea but, ultimately I was left wondering the point of it all since the lack of a rock-plate meant I was unlikely to be using the shoes on highly technical terrain where the grippy sole compound would really have come into their own.
As things stood, the sticky rubber just meant a quicker wearing outsole with no tangible benefits for the type of terrain that in my view the shoes were best suited for.
Nice Italian design touch
In summary, I liked the Helios SR for their lightness and flexibility which was conducive for "natural" running while at the same time providing decent cushion and responsiveness.
The shoes are very comfortable, breathe well, and the 4mm Ortholite sockliner adds to the plushness. They were well-suited for the non-technical, dry trails that I used them on, and served me well on the 100-miler along the Thames River.
I won't hesitate to reach for them next time I do a long run on a well-groomed single track. The lack of a rock-plate, however, is to me a major oversight for a trail shoe, particularly if it is being marketed as sticky-soled and for mountain running, and one should seriously be considered for the updated version, even if it comes at a slight cost to weight and flexibility.
As for the upper, nothing needs to be changed there. As things stand, the shoe is a near-masterpiece, which is a great shame.