Sunday, July 23, 2017

Nike Zoom Vaporfly 4% Detailed Breakdown Run and Race Performance Review: Sensational, A Game Changer!

The Nike Zoom Vaporfly 4% ($250) is the non customized version of the shoe worn by Eliud Kipchoge at the recent Breaking 2 attempt where he ran the fastest (unofficial) marathon time of 2:00.25. It was worn by both the men's and women's winners of the 2017 Boston Marathon.

The Vaporfly 4% is the product of extensive bio mechanics and materials research as part of the goal of  Nike's goal of breaking 2 hours in the marathon, the 4% representing Nike estimate of the potential improvement  in running economy, with individual runners varying up or down from the shoes. Added to running economy are the ideal training, course conditions and nutrition required to break the magic barrier.
Official Nike weight: 6.5 oz/184 g size 10, equivalent to approx. 6.2 oz size 9
My production pair in US size 8.5 weighed 6.56 oz /186 g, so a size 9 would weigh approx. 6.8 oz.
       -approx.1.6 oz/145 g less weight than Zoom Fly)
Stack height: 31mm heel/21 mm forefoot, 10mm drop.
       -2mm less stack heel and forefoot than Zoom Fly)

RoadTrailRun first tried on a single VaporFly 4% at the Boston Marathon here, tested and reviewed the heavier, "similar" Zoom Fly ($150) here and now have had a chance to take a first run in a pair of our own.
Unlike the Zoom Fly, with nearly identical stack heights and midsole geometry, the lighter weight (by approx. 1.6 oz), Vaporfly with its soft and bouncy ZoomX Pebax midsole foam and full carbon plate provided me in my first test run a similar but far more cushioned, responsive, shock free and fluid ride than the Zoom Fly.
The Vaporfly 4% is far more forgiving on the legs than the Zoom Fly and for sure the Zoom Streak 6, easier on the legs is part of the Breaking 2 goal of getting runners to the marathon's later stages with something left.
Time will tell as to durability of all these new materials but I would not hesitate to not only race but do all faster workouts in them.

First Run
I struggled at faster than my marathon paces in the Zoom Fly but not at all in VaporFly. While of course I was excited to try them, my 4 mile run at 6800 foot altitude on a fairly hilly course with lots of sun and temperatures above 85 F was a solid 15-20 seconds per mile faster than I would have expected for the effort, coming in at 8:17 pace.  It was my second run of the day, the first being a slower 4 mile run. The only place I struggled was on a very steep 600 meter hill, the stiffness of the carbon fiber plate, the Vaporfly being a completely flex free shoe in the conventional sense, requiring knee lift and drive something I do not have.  I walked away from the workout with fresh legs but a touch of soreness in the achilles.
First Impressions and Fit
  • Impossibly light and yet highly cushioned. 
  • Step in is soft and slipper like, a bit squishy up front. 
  • The "falling forward" I felt when I first tried them on at Boston is noticeable but not extreme when walking and becomes part of the flow when running. 
  • The sole is literally tacky and sticks ever so slightly to pavement.  
  • Trying them on with light socks at true to size I was initially concerned that the very minimal heel counter and collar would not stabilize the heel.  On my first run no issues or concern with heel hold so far and my test run had steep uphills, downhills and flats but it was short run so more testing is required
  • The fit everywhere was impeccable, roomy secure, and pressure free.  
  • This is not a race flat type such as with the Zoom Streak 6 or even I would say the Pegasus but a marathon fit, clearly designed for some foot expansion. The toe box has high vertical volume. 
  • The mid foot is eerily secure without any pressure as the VaporFly does away with Flywire and uses an internal underlay tied into the laces. I felt a touch of pressure under the arch trying them on but not on the run.
Fit was true to size with light socks. 
The upper is a single layer Nike's Flymesh with no lining and with lots of ventilation across the top. There is a touch of stiffener baked into the toe area to create a soft toe bumper and vertical volume.There is only one visible overlay, a strap running from the last lace hole to the rear and only on the medial side. It is bonded on the outside and stitched on the inside so this strap means business and is effective.
The mid foot hold does away with any Flywire, as the Zoom Fly has, adopting a similar approach to the fine Zoom Terra Kiger 4 trail shoe (RTR review).
An inner ventilated suede like "strap" is attached at the top of the midsole bucket seat side walls on both sides, the foot does slightly sit down into the midsole on both sides of the mid foot. It free floats up to the lace loops, wraps to the outer upper where it is attached becoming the lace loops.
As in the Kiger (which also adds a second inner stretch bootie sleeve) the wrap is consistent and pressure free.The sock liner is flat and securely glued down..
The heel counter construction or lack of it had me initially concerned as for sure I am a heel striker.
The far rear at the red "timing themed strap" is moderately firm down low then gets softer up to the heel tab. A thin wishbone of decently firm padding wraps the heel collar just below the top of the knit upper.
Part of what I initially felt, and which concerned me, was the fairly loose last rim of mesh. On the run the  hold action is down lower at the padded collar. While I might prefer a bit more heel counter especially given the pointy rear foot landing all has been just fine so far and in fact more securely held than the Zoom Fly, although I was a half size up in those which was not really necessary and maybe contributed to some of the instability I felt.
The bottom of the tongue is an extension of the forefoot mesh material with the top an asymmetrical plasticky but soft enough material covering most of the lace up and then lower down running down each side in strips on either side of the mesh to provide some structure to keep the tongue from bunching and folding.
Lace up was perfect. I found that over tightening the laces creates some top pressure as the tendency given the unstructured upper is to cinch down which I found was un necessary as foot hold is more than adequate without over tightening.

The midsole is Nike new ZoomX Pebax foam with the embedded 100% carbon plate. The plate is located as illustrated by the pen line drawn on the midsole in the picture below.
Once the plate reaches the outsole it runs directly above the outsole, at ground level. The location of the plate appears to be the same as in the Zoom Fly with the Zoom Fly's is a polymer carbon composite and not full carbon.
It is clear the combination of 2mm less stack, ZoomX foam, removal of the full heel counter and carbon plate is where most of the weight reduction comes from compared to the Zoom Fly with its more conventional EVA and carbon polymer composite plate.

Essentially Nike has put a spike plate in the Vapor Fly. It is close to the heel at landing with 20 mm plus of foam below to cushion impact and provide 10mm of drop, accommodating for the fact that marathoners don't run on as much on the forefoot as track runners do but also cleverly given the plate near the foot even heel strikers won't linger long. As the foot transitions it sinks into the front foam which is effectively thicker over the plate than at the heel.

So from contact at the rear where the plate is close to the foot it is clear the design wants us
  • to not feel shock at the heel but also to move along, all that cushion below the plate at the heel, 
  • then get/fall forward as the foot compresses the front foam on the way to toe off. 
The front cushion is sublime  and when the foot pushes down and forces meet the plate at ground level the toe off is immediate but smooth and fluid quite unlike the firm harsh response of most road flats. So while response is not as instant as a firm midsole race shoe, even Zoom Air ones such as the Streak, or the Zoom Fly which relies on EVA, there is much less shock transmitted to the legs. The shoe is forgiving where it needs to be for long races and then just at the right moment.  Pop!
Usually saving such weight or putting a shoe way down below 7 oz means that in comparison the ride will be firmer and more responsive. Well here the Zoom X carbon combination is actually far easier on the legs than the Zoom Fly. The cushion is silky smooth and softer under load, softer, more forgiving but at the same time with far more bounce back when combined with the carbon plate which surely plays a role.  The softer yet more dynamic cushion and response upfront is particularly noticeable when compared to the Zoom Fly . There is a distinct sensation of  sinking into the foam on transition and "falling" forward to toe off.  While the stiffness takes some adjusting to, as the Vapor Fly is completely and totally stiff the stiffness is far less noticeable here than in the Zoom Fly. With my poor knee lift and drive I didn't struggle at all to transition and drive up and away expect on a very steep uphill where things went south.

Some have commented on the wrinkling of the outer midsole side walls as being a sign of compression of the midsole.  After 4 miles I see some wrinkles but think the midsole has an outer "skin" which will for sure wrinkle and something I have seen in other shoes. I have no idea yet how long this super light and lively new midsole will last. This is after all a race shoe.  Update: I have since applied Shoe Goo after every 10 or so miles of racing and all white heel foam wear stopped.

The outsole is full contact up front and patches at the rear with very thin sipes cut in to the material.
It is literally tacky and slightly sticky on the pavement. I could feel the slight stick both walking and running.  The heel rubber feels slightly firmer than the forefoot rubber which makes sense as that carbon plate is right under the forefoot rubber.  It is not particularly thick.  I do wish, as with the Zoom Fly that the rear of the heel geometry on the ground was more conventional less pointed and more rounded.  While the elites likely land further forward most of the rest of us could use more ground contact back there.
It is important to note that while the Vaporfly 4% is a very comfortable up tempo trainer this is a racing shoe which was not designed for trainer class mileage. Depending on your landing, foot scuffing during gait, etc... the outsole has significant areas of exposed midsole which can scuff and wear. I have seen some wear at one heel in particular. Use a layer of Shoe Goo as I have to protect these areas.

Initial on the Run Data from a Road Trail Run Reader
Road Trail Run reader Joshua Sun also received an early pair from Running Warehouse where I also purchased my Vaporfly. Joshua is a former avid cyclist who has run a marathon and several halves. He focuses his running on short fast efforts on the same loop and has also run the Zoom Fly. He was kind enough to share his first run impressions and comparative data using a Garmin Forerunner 935 and Running Dynamics Pod (see our article here) with us:

"There's a 3.25 mile route that I run frequently near my home.  I use this route to benchmark my performance and to test out running shoes.  Basically I run this route as fast as I can.  There's not much room for placebo effect because I'm pushing myself about as hard as I can without blowing up.  Over the years, I've developed a good sense of how hard I can push without blowing up and I run this route with a very consistent effort.  I track these runs using my Garmin 935 with RD pod.  Based on how much better the numbers were with the Vaporfly, I'm pretty certain that I would run faster in the Vaporfly than any other shoe out there.  I'm less confident in exactly how much better it is without a lot more data.

Here is some data about my runs in the Zoom Fly and Vaporfly - about 1 week apart so fitness level shouldn't be much of a factor.

Distance 3.25m
Pace: Vaporfly 7:18; Zoom Fly 7:33
HR Avg: Vaporfly 156; Zoom Fly 155 (However, both of these are about 4% lower than my average heart rate when I try to run this route fast - so it matches up well with Nike's claims.  I think the range is about 2-6% in Nike's testing.)
Cadence: Vaporfly 157 Zoom Fly 160
Stride Length: Vaporfly 1.39m; Zoom Fly 1.31m
Vertical Oscillation: Vaporfly 10cm; Zoom Fly 10.9cm
Ground Contact Time: Vaporfly 264ms; Zoom Fly 248ms

What this shows is that I'm running at a slightly slower cadence but that my stride has gotten longer and lower (more horizontal and less vertical, which is how better runners usually run).  You can see from the ground contact time that the shoe really takes longer to compress but then propels me forward longer and lower than with the Zoom Fly.  (And I've run faster in the Zoom Fly than any other shoe.  I ran about a 7:37 pace in the Zoom Streak, which is next fastest.) "

Ride and Conclusions
What more can I say the ride and performance is incredible. Vapor Fly is light, cushioned, dynamic and despite the stiffness of the shoe far more fluid than the Zoom Fly for me.  I ran 15-20 seconds faster per mile than I would have expected to for the course and effort in my first run. Can I sustain those kinds of improved paces over longer distances given the unusual stiff geometry? Update: the answer is yes, see below.

My Race Results in the Vapor Fly 4%
I have been racing fast, very fast in the Vapor Fly. Among, if not the fastest, times in the last 8-10 years over distances from 5K to the Half Marathon and I am 60!

Update: My first 10K in them went very well. 1st in my 60-64 age group at 7:04 pace on my watch which is certainly faster than my marathon pace and with no issues. The course was at altitude between 5100 and 4500 feet so downhill with about 1.5 miles of flats and the Vaporfly performed magnificently on flats, moderate downhills, and uphills. The first half mile was a very steep downhill where they did feel somewhat unstable at the heel. The combination of the outstanding cushion, fluid transitions, snappy response was outstanding and truly unique. My legs were none the worse for wear the next day.
Update: Ran another 10K race in the Vapor Fly, this time a flat course at sea level. I have run this race 3 times since 2013 and this was race was my fastest time by 7 seconds. Faster isn't easy at my age... 60.   The entire difference came in the last 1.2 miles. My legs were just fresher in the finishing stretch. I had no soreness the next day and the day after "ran" a very mountainous (over 4000 feet of vertical)  half on slick trails none the worse for the 10K race. While there may be faster shoes, even for me, for a 10K as race distances increase the advantages of the VaporFly in terms of performance also seem to increase.

Update: On Oct 1st I ran the Travelers Beer New England Half marathon in the VaporFly, my first half in them. I ran the best time for the distance in 9 years 1:35.24 ,winning the 60 and over age group by 20 seconds after a 4 mile duel with the eventual 2nd place finisher. My legs were fresh and lively start to finish and I had minimal soreness and ran well the day after. Zero blisters, cramps, or issues of any kind. Truly an amazing race shoe! My full race and full gear report is here

Update: Subsequent to that fast half marathon I ran the BayState Half  two weeks later on more tired legs and a and came in 1:37:36, finishing 3d in my age group.  My mile splits were very even but slower right out of the gate and legs as before fresh to the end.  My Strava data is here

Update: on October 28 I ran a somewhat downhill 5K finishing in an official 21:18, 2nd in my 60+ age group.  Strava had me at 20:55 for the Garmin measured 3.19 miles. It was my fastest 5K since 2009 although I infrequently run 5K's.

Update: On April 8, 2018 I ran my first marathon in my original VaporFly with about 108 miles on them at the start. The race under cold (30-37F/-1-3C) on a very flat course and some winds went very well as I got a 14 minute Boston Marathon Qualifier, 3:40:48 and 2nd in my age group.

I was remarkably consitent maintaining even splits until just before mile 25 when I had some balance issues. My legs stayed fresh the entire race with no soreness during to speak of and not even a hint of any cramps. In a first for me in many marathons I was able to run 2 miles the next day and 6 miles on trail the day after as I had almost no soreness at all. Usually I am barely able to walk for two days after a marathon. Many others report similar fresher legs during, less end of race fade, and a rapid recovery.

Are the VaporFly 4% worth $250? Well sports "toys" can cost big money, just think bikes and ski equipment. Lighter weight and performance advantages claimed, real or otherwise, always come at a premium cost and some downsides as well.
Are they only for world record setting elites? Absolutely not!  These are very forgiving if unusual shoes. I think they will provide at least some of the advantages of Breaking 2 to serious recreational runners, not the least of which is the demonstrated advantages of lighter weight for racing shoes yet here with plenty of cushion. Here incredibly light weight is combined with outstanding bouncy cushion, plenty of it, and response.  All my runs and races (see below) have been considerably faster than expected.
Are they only for racing? I say for most yes.
While they are fabulous for up tempo training the exposed midsole under foot may see accelerated wear depending on your foot strike and scuffing patterns. I see some at 25 miles I am saving mine for races, their intended use, and will protect these high wear areas with Shoe Goo. To date apart from some creasing of the midsole walls the cushion and stability is intact.

Our frequent contributing writer Derek Li of Singapore recently ran a 20 second 17:36 5K PR in his Vapor Fly.

Camille Herron runs a world record 100 mile in the Vapor Fly  She trains in them daily too! Read her RTR World Record Racer Story here

Racer Story: Joost De Raeymaeker runs a 2:29 at Berlin in the Vapor Fly at age 49+ here

Reads my article about the Vaporfly 4% for Competitor Magazine here

The Vapor Fly 4% was a personal purchase. The opinions herein are entirely the author's.

Comments and Questions Welcome Below!
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Sam Winebaum said...

Luc, Thanks for calling this to our attention. Corrected.
Sam. Editor
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Unknown said...

Thanks Sam. I have been eagerly awaiting the Vapor's for months and you report has me drooling more than Homer Simpson over a donut. I missed out on getting some the other day but hopefully in August. We are of similar age. I turned 64 a month ago. I ran a 2:45 marathon last year and 2:50 3 weeks ago at a comfortably hard pace due to a virus (my coach would not let me do race pace). I bought the Zoom Fly's 2 weeks ago and love them. They are super fast for me with loads of free speed. I first ran in them on weary legs 10 hours after a hilly 6 mile morning run. Yet thanks to the Fly's an 8 mile "easy" run soon became a fast progression run with the first mile at 7:26 pace then dropping 5:42 pace by the end. Surprisingly my legs were fresh at the finish. They are 40% heavier than my regular Lunaracer#4 racers but you wouldn't know it. Now you know why I am drooling for the lighter faster Vaporfly 4% . I will be 65 next year so If I stay healthy an AG WR marathon is beckoning

Sam Winebaum said...

HI John, Thanks for writing! What fabulous times. Long May You Run and Fast! I just couldn't turn the Zoom Fly. The Vaporfly a different story. The combination of light weight and the ZoomX midsole is amazing, especially in the comfort cushion department . Please drop me a line when you have the Vaporfly and have run them. Would love your comment and feedback.BTW what size are you?
Sam, Editor.

Unknown said...

Thanks Sam. Will do. I am a size 12. By the way I am a latecomer with running. In May 2012 I was 215lb and so unfit. Walked off 45lb in 3 months then started to jog, then run. Now a much healthier 150lb. Am keen to use the Vapor's for a 50km flat terrain event late this year where I will attempt to break the M60-64 WR (3:29)

Wobby said...

I took the ice blue VF out for its first run today -- even though it was 85 degrees and sunny at 5pm.
Schedule called for a tempo run of 9 miles, 6:50ish pace. I chose the same route I ran about a month ago for a 7 mile tempo, 1.5-mile loops.
Biggest difference? That day it was 6am and only 52 degrees.

I ran 9 miles at a 6:53 pace today, despite it being 30+ degrees warmer than the 7 miles I ran at a 6:48 pace last month. This is astonishing to me, since I went into this run dehydrated and hungry.
My HR was around 165 on average, vs. around 159 last month. Again, huge difference... compare to an 8-mile tempo last week, almost entirely downhill (in quite cooler temps, 70 degrees) when my HR averaged 169bpm.

Today should've been a super miserable run by all accounts. It wasn't. There were times when my foot turnover was almost more rapid than I could keep up with -- the stiff responsiveness and rebound of the shoe is real.
This is also perhaps the best ventilated shoe I've ever worn. In this weather, my shoes have been completely saturated by 6 miles on every run - these shoes held up over 10 miles. (I still need a better race day solution but goodness I hope its under 65 degrees for my marathon.)

I felt like the cushion over 9 miles was fine - other racing shoes (my current go-to has been Hoka One One Tracer) seem like the 13.1 mile mark is the upper limit. I am pretty confident these will hold up well over a 25km race, and probably pretty well over 26.2mi.

I'm totally on-board with the Vaporfly. I was prepared to not believe any of the hype, certainly. (Part of why you order via Runningwarehouse is no questions returns!) And this is not a "magic shoe", but my legs feel better than they should, and my run went so much better than it should've. I'm not totally sure it's worth an extra 40% more than any other running shoe...? But I'm pretty sure it's the best running shoe for racing I've put on.

Sam Winebaum said...

Hi Robert,
Thanks for your feedback on the VF 4%. I totally agree especially with the "legs feel better" part and I too am seeing considerably faster than expected paces for effort.
Sam, Editor

RotorHard said...

Great read just a correction: The 4% naming of the Vaporfly has to do with the average improvement of running economy when tested. The increase in performance to lower the current WR to Sub2 is closer to 2.5% but the new numbers are directly related.

RotorHard said...

*two numbers are not directly related

Sam Winebaum said...

Hi RotorHard,
Thanks for the clarification. Article is edited to reflect.
Sam, Editor

Gabriel Machado said...

Great Sam! I have used my VF4% for about 80 Miles so far, and I can see the outsole with a lot of excessive wear, specially the edges. And I never had any problems with excessive sole wear on other "normal" shoes.

I was wondering, are you planning to post a update for this review anytime soon? I'm very curious to know your opinion, even better if highlighting the durability of these shoes. Thank you

Sam Winebaum said...

Hi Gabriel,
I have a total of about 20 miles on mine and I am seeing some wear of the exposed foam surrounding the heel rubber. I expected this as I have one foot that wears hard there and have used some Shoe Goo to protect those areas.
While a fabulous ride for training to0 these are racing shoes and to get that light weight and other characteristics something has to give in terms of durability and the weak point is that exposed foam. I am saving mine for races. I am more sensitive to how the platform will hold up, the foam. I see some expected creases which are on the outer skin but so far so good on compression and stability but will be keeping an eye on it.
Thanks for reading and commenting.
Sam, Editor

tpd said...

Hi Sam! I was looking at purchasing these Vaporfly 4%’s, but can not find anywhere. I tried your links to the RunningWarehouse. Site does not even list them. I’ve looked at Jack Rabbit, and Marathon Sports...any ideas? Need size 9.5.
Thanks for presenting honest reviews for anything running related! I check/read your Blog daily!
Thanks again! TPD

Sam Winebaum said...

Hi Tpd, Thanks so much for reading RTR! Much appreciated I see that the listing for Vapor Fly has been pulled from Running Warehouse. Thanks for calling this to my attention and I have noted on the link Not sure what is going on but do know that pairs after launch have dribbled in to various outlets a few at a time. My understanding is that the manufacturing is very difficult and slow. I will try to find out what the ETA may be for more pairs, likely again a few at a time.
Sam. Editor

Unknown said...

Hi TPD. On Tuesday the VF page on Running Warehouse was advising new stock would be available on Sept 24th. On Thursday the page was blank. The new stock was also to be the black model; not original blue. I am in Australia and the Nike website released new stock 3 days ago. The blue shoe sold out within hours and there are only a couple of black ones left. No size 9.5 though. Feel for you but at the same time ecstatic as I got my order in

Anonymous said...

Hi John and Tpd,
Thanks for your update John from the other side of the Pacific! I just heard that new stock of the VaporFly should arrive mid to late October. It was supposed to be available Sept 24 but is delayed.
Sam, Editor

tpd said...

Ok, Sam. I will look at the RunningWarehouse mid/late October. Plan to run a Spring marathon, so I have sometime. Just want to train in them for a while and decide if they are the right shoe for me.

I am Jo Rupp’s husband.


Anonymous said...

Check Gazelle sports or Sole Sports. I just got a pair of size 12 from Sole Sports. I've been checking every day and it seems like some stores are getting a few pairs at a time.

Jon said...

Hi Sam - just read your review and updates. Thanks for the detailed observations. Can’t wait for the next drop of this shoe. I’m 63, regular runner, and usually take a 9.5 regular width in a running shoe. I’ve heard the Vaporfly 4% fits on the wider side. Just wondering if you’d recommend that I purchase a half size down.

Sam Winebaum said...

Hi Jon,
Thanks for reading and writing. I was true to size with a relatively narrow foot. I tend to wear thicker socks as a rule so size works out but it is surprisingly roomy shoe. If I wore thinner socks I might size down a half. If I had a very narrow foot I might size down a half. I know women with narrow feet have sized down a half size. Most I know have stayed true to size.
Sam, Editor

Calvin said...

Hi Sam,

Great review! I would like to get some opinion on the sizing. Normally I wear medium socks, in that case, should I size up considering the toebox is shallow?

Sam Winebaum said...

Hi Calvin, I would not size up even with medium socks. I wear medium socks and plenty of room everywhere. Very narrow feet might size down
Sam, Editor

Calvin Saw said...

Hi Sam,

Thanks for the advice!

Unknown said...

thanks for the review and I love them for marathons and road races, but have a 1/2 marathon this weekend, on very forgiving dirt trails, should I use them or something with more tread?? i hate running in the dirt just have to get this race in!! thanks for your info

Sam Winebaum said...

Hi Vanessa,
Thanks for asking. If the dirt trails have any kind of unevenness and/or lots of steep I would use something else. This said Camille Herron set the world 100 mile record in hers on a rail trail but the dirt surface was smooth and level.
Sam, Editor

Anonymous said...

I am running my 22 miler tomorrow in Nike zoom flys, I have a pair of vaporfly being delivered in a day or so. After tomorrow I will start a three week taper. I do most of my training in Hoka Cliftons and used my Zoom Flys for my tempo runs during training to keep the mileage off of them so they'd still be fairly fresh for the race. My question is, is it to late to try to break in the vaporflys for this marathon?

Sam Winebaum said...

Hi Anonymous,
You should have plenty of time to determine if Vaporfly is right for your marathon. I found them far far superior to ZF as they are faster, softer, and far easier on the legs than ZF. I suggest some tempo runs as your marathon pace to get a feel for the "groove" a somewhat forward drive down towards toe off, to adjust sock weights etc.. Doing tempo is important as they are not a great easy slow run shoe. What is your goal time? Best of luck!
Sam, Editor

MechaDriver said...


Like the previous poster, I just received my Vaporflys FK and going into taper. How many miles do you believe should be good enough for break in before the first race? Thanks.