Road Racing Flats for the Mountains (2012 Edition)

At any trail race you’re bound to see runners wearing all types of shoes, from traditional trail models with a great deal of protection to flimsy minimalist shoes lacking rock plates and traction lugs. Prior to the movement towards minimalist trail shoes, many top runners simply used road flats for training and trail competitions and thought little of it. Matt Carpenter’s years of using Nike Streaks to win the Pikes Peak Marathon, and Anton Krupicka’s use of everything from Puma H Streets to Nike Waffle Racers to win a multitude of tough mountain ultras come to mind. So I asked Joe Grant, ultra/mountain runner extraordinaire, what draws him to regularly select flats for racing and epic trail adventures. While Joe states that he doesn’t exclusively use flats, his experience and knowledge of running shoes was very much appreciated for this review, and his eloquent and generous replies are peppered throughout my shoe reviews below.

I set out to review several popular road flat models to see how they hold up on mountain trails, and I’d like to thank Erik Dube at Running Warehouse for providing me with several models to test on the trails.

Adidas Adizero Hagio

Adidas’ update to the popular Adizero Rocket, which was discontinued for 2012, continues in the same vein of providing a featherweight upper on top of Adidas’ firm Adiprene cushioning. At just over 6 ounces for my size 9.5s with a 5 mm heel drop, the Hagio ($90) offers a barely there feel with an excellent fit and pretty impressive traction.

I think Joe Grant sums up the Hagio perfectly with this take on the Adizero Rocket:

The Adiprene foam is firm and responsive and remains that way after many miles of use. The firmness helps with underfoot protection and stability when running more technical terrain. The responsiveness makes the shoe feel snappy on smoother terrain or when running uphill. I don’t ever feel like there’s much lost in the energy transfer when the foot strikes the ground. There’s no mushiness or “dead feeling” to the shoe which is quite hard to achieve without the help of a rock plate. While it supposedly has a 6mm drop, it feels flatter to me and the midsole thickness is perfect for pretty much any type of terrain.

The good news is that the midsole of the Hagio is identical to the Rocket as far as I can tell. I found Joe’s account of the Adiprene foam to be true, and I felt it held up for about 200 miles, which is astounding for a racing flat on tough terrain. The Hagio upper features well-placed welded overlays over a gloriously wide toe box, a fit not often seen in a racing flat. The heel cup is snug and the shoe seams to gradually splay over the course of the shoe. One complaint I had about the Hagio, is the stock shoelaces, which I quickly got rid of. Although thin and comfortable, they came untied repeatedly during my runs, and replacing them was an easy fix.

The Adidas Hagio.

Another benefit of the Hagio over the Rocket is that Adidas added fairly sticky rubber nubs to the forefoot area of the shoe that improve traction, especially in wet conditions. These nubs are small enough that they don’t really collect mud, and short enough that they don’t impede in the foot strike as explained by Joe:

Other than in mud and snow, I don’t like shoes with aggressive lugs. Lugs add weight, diminish the shoe’s responsiveness on hardpack, catch on things and more importantly cause too much breaking when running downhill. I like to feel a bit of “float” when running downhill, an ever so slight amount of sliding instead of the aggressive stick and breaking experienced with more pronounced lugs. Road flats are great in this regard with some outsoles with mini rubber “cleats” like on the Adios or Nike Streaks providing a perfect float/grip ratio.

The Adidas Hagio's outsole.

Adidas Adizero Adios 2

Could this road marathon world record holder make it on the trails? The answer is yes, absolutely. While the Adizero Adios 2 ($115) has a higher 9mm heel-to-toe drop than the Hagio, it proved to be a more durable shoe for long runs and the lightweight upper held up surprisingly well. I logged more miles in the Adios 2 this winter and spring than any other racing flat and although battered, beat, and torn, the midsole still has some life in it. Once again, the firmness of Adidas’ Adiprene was successful at protecting my feet from rocks, roots, and even cacti (don’t ask). While the upper of the Hagio is constructed of a single layer of synthetic mesh, the Adios 2 sticks with a more traditional dual-density nylon mesh and sewn overlays. The fit of the upper is fantastic which could account for the wide appeal of the Adios 2.

The Adidas Adios 2

The outsole is fairly simple, but Adidas uses Continental road tire rubber which is fairly grippy on hard/packed trail in addition to hard rubber nubs glued to fabric on the forefoot. Initially, I expected all of these nubs to simply fall off, but after 300+ miles most of them are still there. Although a bit heavier at 7.8 ounces, the Adios 2 proved to be the longest lasting of the bunch as far as midsole resilience and upper durability.

The Adidas Adios 2's outsole.

Asics Hyperspeed 5

Asics has a long heritage of making great lightweight racing flats, and the Hyperspeed 5 ($80, 7 ounces, 6mm drop) is no exception. A marked improvement in my opinion over the last update, the 5 uses Asic’s SpEVA foam which is softer than Adiprene, but still offers enough protection for non-technical trail. Again, a great fitting upper with an Asian last (wide toe box) is complimented by welded overlays on dual-density mesh. Joe describes what he looks for in an upper:

The upper is just what you need to hold you’re foot in place with nothing extra. There’s no extra padding anywhere. The overlays happen to be adequately placed so that there’s good lateral stability on varying terrain and also avoids blowing out the shoes in common areas on the lateral and medial side of the forefoot. Since road flats aren’t specifically designed for off road use, it’s never certain whether the overlays will be placed right.

The Asics Hyperspeed 5.

The outsole of the Hyperspeed 5 is absent of traction lugs, but is made entirely of sticky rubber without any plastic trusstic system making contact with the ground. It also has what seem to be drainage holes, similar to the Asics Gel Fuji Racer (review), which could help the shoe dry out quickly. I cannot attest to this as I only ran in the Hyperspeed in dry conditions.

The Asics Hyperspeed 5's outsole.

Overall Impressions

Some of you may be asking, what is the difference between these road flats and a minimalist technical trail shoe such as the New Balance MT110, Montrail Rogue Fly, or the La Sportiva Vertical K? The real differences are evident by what these road racing flats lack, such as aggressive outsoles, reinforced uppers, and rock plates. These absences can be a bad thing or a good thing depending on the type of terrain. On non-technical terrain, such as nicely buffed out single track, the smoother outsole and responsiveness of a road flat can feel superior to a trail running shoe. But, the uppers of these road racing shoes are what I appreciated the most. With the vast leaps in trail shoe technology, sometimes the uppers can get a little overbuilt and it is nice to lace up a simple and breathable shoe for a run.

With every shoe company out there touting their own trademarked EVA foam technology, I have to give Adidas’ Adiprene a big thumbs up for trail running. Their racing flats tend to have a firmer feel which also lends a bit more protection. My pet peeve for trail shoes is when any plastic torsion device is exposed in the midsole and the Hagio and Adios 2 both have exposed plastic on the bottoms of the shoes. This doesn’t really seem to affect performance or traction, but something about chewing up a thermoplastic device on the sole of a shoe makes me question durability. For a softer, but very responsive feel, the Asics Hyperspeed 5 was a joy to run in, and on smooth trails or for speedwork this shoe has grown on me increasingly over the past several months.

There are certainly exceptions, Joe being one of them, of folks who can get away with very little shoe on technical terrain and not seem to have sharp rocks stabbing them or hamburger legs by the end of a long run. I learned the hard way, after a particularly painful trail marathon this spring, that road flats only work for me on the least technical terrain or hybrid road/ trail courses. After repeatedly being stabbed by sharp rocks on the downhills I vowed to do a bit more homework on course terrain. But, I would encourage any trail/mountain racer to gauge the feel of a road flat next to their favorite lightweight trail shoe and ask themself what works best for their needs. You may be surprised.

A special thanks to Joe Grant for responding to my geeky trail shoe questions. Go check out his website for beautiful photography, soulful inspiration, and coaching services.

Call for Comments (from Bryon)

  • What are your thoughts on wearing road racing shoes on the trails? Do you ever do it?
  • If you do hit the trails in road racing flats, what’s your favorite model (or models) at moment? Try any that didn’t make the cut?
Tom Caughlan: is iRunFar's Minimalist Gear Editor. Tom’s passion for trail running and specialty running retail experience shine through in all of his highly technical reviews, which do range outside minimalist shoes.

View Comments (48)

  • I actually prefer a less protective shoe on the trails than I do the roads, since trail running demands greater agility and proprioception. The more technical the terrain, the more stable and comfortable I feel, when allowed to interact with it. I won't pretend to be anything like elite, and Joe Grant is certainly a lot faster than me. That said, I've logged basically 100% of my miles in the same pair of Saucony Hattori (a zero drop running slipper, basically) for the last 13 months, with many on pretty technical trail. In that time, I've run a 5:10 50K and 3:46 marathon, both on trails scored a 3/3 by Ultrarunning magazine. Again, I'm no world beater, and I am quite new to this (and to running in general). So it's possible that I'll end up with more on my feet in the future, or an injury, barring that. But for the time being, I'm happy to keep my feet level, close to the ground, and free to respond to the varying terrain. I think it's faster for me, but even if it weren't, it's a lot more fun.

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  • I've worn Nike Lunaracers at Hardrock and had zero foot issues. Typically I don't take them off my feet during a race, if my feet are going good I don't want to mess with a good thing. The Lunaracers have very little tread which was a bit of a disaster last year going down a steep off trail grassy section in the pouring rain at night. I like the combination of cushion with minimal upper and minimal control. I actually tried to transplant the LaSportiva X Country sole onto my Lunaracers. Guess how that went.

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    • DIY sole transplant - I like your style, who cares if it worked ;-D

      I've only ever changed shoes mid-race once. I completely agree with you: if it ain't broke, don't fix it.

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  • "Back in the day" before there were many trail shoe options, especially minimal trail shoe options, many of us ultrarunners (by that I mean roads & trails ;) ) wore road racing flats on ALL terrain. Imagine that! Think Eric Clifton among others. I wore the Adidas Adios on many a trail & road ultra including several 100 mile races. Light and fast has always been true; just the shoe technology has changed. I more modern times I've worn Lunaracers at a 100 as well (Leanhorse) and had no foot issues. I wouldn't dare wear them at a mountain 100 as I don't think the traction is near good enough and you're taking an awful risk with those flimsy uppers (have bashed my feet up pretty good in them running trails). Over the long haul though I think I'm better off with a bit more shoe, especially one with a rock plate (depending on the type of terrain of course).

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  • I'm UK based. I've been going down the minimalist road for 3 years now. I've run the 2009 Ridgeway Challenge (85m trail race) and 2010 West Highland Way Race (95m trail) in Inov8 F-lite 320 PKs, which are minimal compared to standard shoes: a lot less cushioning than normal road shoes, but with a fairly substantial upper, which is handy when you kick a rock you didn't see!

    I've since gone even further down this road, doing half of the 2011 RW Challenge in a pair of Merrell Trail Gloves: my feet got tired because it was extremely wet that year and the effort of staying upright in anything without a really deep tread was very taxing, so I changed into my trusty 320s for the second half.

    I've also ran 40 miles (mixed road/trail) in a pair of Vivobarefoot Neo Trails and 30 miles in a pair of Inov8 X-Talon 190s.

    I'll be running trail/mountain races up to 100 miles over the summer and will be using TGs, Neos or X-Talons, depending on conditions.

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  • The Brooks PureConnect also deserves a nod here. For fast and smooth trails, it's a great shoe - light and responsive with a unique 'pod' style sole. I just ran a 5K PR on packed sand trails wearing these and never felt lacking for traction or protection. With a 4mm drop and weighing in at 7oz, I'm surprised more minimalist runners haven't adopted these for racing or daily use.

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    • Matt,

      Agreed on the Pure Connect. I picked up a pair of those when they came out and they're a very cushy ride in such a light package. Different feel than the Pure Grits which I also liked and held up well. Don't know if I'd want to wear them on rocky trails though. Packed sand would be perfect.

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      • I've always been really into Brooks shoes: I use Pure Grit when the trails are technical (pretty common here in Italy) and/or wet and muddy... But when the conditions permit a better footing, on anything 50k +, I love the Green Silence: I actually like 'em better on trail than on road.

        Pure Connect are nice, but to me, they lack some of the overall comfort Green Silence offer

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        • Just what I needed to hear to convince me to wear my Green Silence on a 50K trail run this weekend like I was thinking about. I have worn them on a 44 mile road/gravel race and they kept my feet in great shape, I've been wearing them so much and haven't been in my MT110's on trails lately so I know they'd give me a blister at higher miles.

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  • Brooks Pure Connect are easy on the eye, but fairly poorly build...Parts of the sole fell out after less than 30 miles on well groomed trails... My strong preference in this category is for the Mizuno Wave Musha (preferable 2, but 3s/4s) are fine as well... Completed 2 marathons (sub 4) and a 50k trail (sub 5) in those, and they are still going..... Great fit on the Mizuno's as well.. 4mm toe/heel drop (i think)

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    • I have the Mizuno Ronin 4, and with a more traditional drop 9mm, and a nice wide toebox, it has been a great shoe for me but I have yet to try it on a real trail run.

      That is strange about the Pure Connects? I've not had that problem.

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  • So far this year my favorite shoe for trails (when I'm not wearing sandals) is the Merrel Road Glove. The Hagio has been on my radar, but I was holding out for some word on how closely it resembles the Rocket. I still don't know if a road flat is going to work well for me on a 50 to 100 mile technical run, but like Alex I'm reluctant to give up dexterity for more protection.

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  • Thanks for another great shoe review, Tom. Good to know that the Hagio and the Hyperspeed have roomy toe boxes, something absent in other racing flats I've tried (Saucony & Brooks). I'm not of the light and fast set, but I like running in more minimalist shoes and flats that have a roomy toe box. The New Balance 703 (fit is very similar to MT110 or original Minimus)is also one to consider. It has 3mm drop and is very light. I picked up a pair to use for road and smooth trail running, although most of the running I do is on technical or cow/game trails.

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  • I'm working on my braking on the downhills. I am changing the way I think about traction in shoes because of injuries sustained from braking. Some lesser traction shoes like cushioned racing shoes have helped. Lately I have been wearing my Scott T2C's. They seem to work for Italian Marco de Gasperi in dominating the world mountain running scene. They weigh about 8oz, have firm foam that lasts for high miles and enough overlays in the upper to lock down the foot for screaming downhills.

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  • When I lined up at the start at this year's Chuckanut 50K, which has both flat and fast "road" sections and muddy, snowy steep climbs, Hal Koerner was in front of me wearing some Adidas racing flats. I was wearing some regular road lightweight trainers. Hal crushed me, and I think was entirely because his shoes were a bit lighter than mine.

    In any event, except in the most extreme conditions, I think the majority of bulky "trail" shoes are overbuilt for the purpose. Having said that, though, this is one of those issues on which everyone is correct -- about their own feet. Go with whatever is going to get you through the run.

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  • What's not mentioned very often when discussions of minimalist trail shoes arise are spikeless cross country shoes like the Nike Zoom Waffle Racer and the New Balance 507 ( there's more to the name of the 507 but I can't remember it.) The advantage to these shoes is they offer a lot of protection in the forefoot. I just completed Promise Land 50k in my NB 507's and despite the fact that they are an extremely light shoe they have enough protection that I was able to hammer the rocky east coast downhills with no concern for getting impaled on a sharp rock. Unfortunately these shoes are apparently out of production. One of the only bad things about spikeless cross country shoes is that they tend to have narrow toeboxes but if you just don't pull the laces too tight you should be okay.

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    • I love my 507s! You're exactly right: spikeless cross country shoes are light, minimal, built to handle the lateral forces (mostly), and have rock protection. One of the other advantages is... almost no one outside of cross country buys them. That means that if you buy them off season, they're super inexpensive. I picked up my 507s for my rotation a bit over a year ago for $42 including shipping!

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  • I think for east coast trails, you really need to get relevant experience in lightweight shoes to make sure they work for you. I run and race in several models of very light inov-8's that are great for sub ultra distances and work for non-technical ultras. For technical eastern trails, I do tend to go with something with more protection. To confirm that light shoes work for you in ultras, you need to do long runs at race pace on similar terrain. You could just try them in a race, but this is risky, and frustrating if it doesn't work out. For many, the advantages of lightweight shoes evaporate in the latter miles of an ultra if they have not similulated their races in training. I think one of the most important considerations is pace. I used to be surprised by the shoe selection of some runners at very technical trail races, but often these were runners that were racing a moderate pace. The need for more protection and/or cushioning is more apparent the faster you race. You generate more impact force, especially on downhills. A shoe that works great for a midpack runner might be not be enough for someone up front. There are obviously examples of top runners who don't wear much shoe, but this is more common in non-technical terrain. I used to amazed by the shoes worn by guys in the Pacific NW, but then I went out and ran on the trails. The soft surface, lack of intense rocks and roots, the 8oz shoes for a 50-100k made perfect sense.

    Even in non-technical terrain, I don't think the benefits of extra cushioning should be overlooked. The first year I ran the Headlands 50k, I ran in very light road flats, and my quads were destroyed by the last few miles. The next time I ran out there, I chose a heavier shoe with more cushioning. There wasn't a huge improvement in time, but I did run faster and my legs felt much better over the last 8k. In addition, the last 8k of my road 50k's have been faster in races where I went with a little more cushioning. Part of fatigue is accumulated impact. I really think you need to practice the abuse of race day to really know if a flat will work for you over the entire race.

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  • socks or no socks with these shoes?

    I went no socks for a mountain 50k in mt110s and i'm missing quite a bit of skin on my ankles / heels. There were a few muddy and gritty creek crossings right before a climb that left me super blistery and just plain rubbed raw (never happened in clean water crossings during training).

    Just wondering if these shoes caused any blister or rubbing issues while wet

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  • About to do a 40km starting at 1200m asl with 1800m ascent + 1800m descent in New Balance RT 1100...will have a verdict on racing flats as trail shoes on Monday!

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  • Ben I think the reason you lost so much skin has nothing to do with socks. It's because the 110 suck!!! I have had 2 pairs. Both feel completely apart in under 100 miles. The second pair did not even get to 30 before the outer skin material started falling apart. Not sure what the folks at NB were thinking. I have actually seen a few pictures from Joe Grant that look like mine, I guess I am not the only one.

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  • I have been using the Hyperspeed for road ultras. According to me it is not an ideal shoe for these distances. First if there is any water in your way your feet will get wet because of the holes in the sole. Also stones will get stuck in them (very irritating!). Although the width is ok the toe box is a bit too narrow which gives me black toenails. Further I find that I could use a little bit more of cushioning in order to feel better towards the end of the race. For this season I have bought the Adios 2 for the ultras in hope to improve on these parts. The Hyperspeed is now used for the shorter 10k races.

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  • Would anyone use for example the Hagio for UTMB or Hardrock ? What´s the difference between for example, the MT110. The roadies gor more cushion I suppose ? How´s the fit if you´re running a steep traverse ?

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  • I used to wear Hyperspeed 4s on trails and they were great, unless the terrain was muddy or particularly covered with sharp rocks. They were super-light and drained well, as you hinted at here. The only thing was the little holes in the outsole used to trap debris - and the fact they blew out too quickly for an expensive pair of kicks. Now I can't go past the MT110, mainly for the reason that I can run to the trails, on the trails and home again without wanting to switch shoes.

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  • I am not quite sure why you would need to wear road racing flats on trails anymore since trail shoe makers have filled this niche. I run road and trails from 5K to 50K (will do my first 50 miler this fall) and I find the lack of traction on road shoes to be a deal breaker. Maybe if you are running on some rail-to-trails type deal it would be ok, but not on technical, rocky, rooty trails (which is what I have here in Virginia). If an biomechanically efficient runner is looking for light weight shoe to run on the trails with then they should look at the Montrail Rogue Racer (8 oz) or the Rogue Fly (7.5 oz). Another option would be the New Balance 101 (7 oz) or the 110 (7.5 oz). All of these shoes are light weight, flexible and give a racing flat feel, but have some sort of rock plate and decent trail traction.

    I ran 2 50K's this year in Rogue Racers and 1 50K in New Balance 101's and have also used the 101's for various other race distances as well. I also have owned many road racing flats (my current ones are Brooks T7's) which I have run in up to the marathon, but I wouldn't consider them a viable option for any type of technical trail.

    Maybe the author mostly runs well groomed trails, but I just don't see why you would give up the traction and the rock shield when there are trail alternatives that weigh about the same.

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  • Jason,

    I run mostly technical singletrack in Colorado, and for the record I wear trail shoes 90% of the time. I recently ran a 50 miler during which I wore road shoes but it was very non-technical jeep track.

    The idea for the article was to highlight why some runners may enjoy road flats for trails due to the "float" on the downhills rather than the grabbing traction of a rugged trail outsole.

    What I've learned is some runners don't like rock plates due to the decrease in flexibility and would prefer dense EVA foam for protection. It is often enough for some runners its important to know what works for you.

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    • Traction is the most overrated feature of a shoe.

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