u/imjms737

Vivobarefoot recently released the Primus Flow Knits (link):

https://preview.redd.it/9w7hq39u9f2h1.png?width=1105&format=png&auto=webp&s=98b975bf4b04096ff3de8dc88e7df35849b0945f

I currently use the Primus Flows for shod road runs, and I really like how lightweight they are. They got me through a marathon, and I really like the midsole protection as road runners, but I was never the biggest fan of their upper material. Quoting the cons section of my initial impressions review of the Primus Flows:

>The insides of the heel are made up of leather-like material, which helps heel lock, but it catches your socks when taking the shoes off. These are the only pair of shoes where I have to tie and untie the shoelaces each time I take them on/off.

>The uppers are not as breathable as my knit shoes (regular Primus Knit and Primus Trail Knit), despite being almost see-through

I also enjoyed the two Vivo knit shoes I've used for their comfort and breathability, but I started preferring the non-knit versions for their weight savings. But the knit version of the Primus Flows is only 2 grams heavier than the regular Primus Flows (161g vs 159g), which is a pleasant surprise.

Given how new the shoes are, I don't see any reviews of the shoe. Has anyone tried the Primus Flow Knits, or does anyone have any thoughts on the shoe?

I attempted my first triple digit ultra using minimalist shoes yesterday and unfortunately had to drop at 70K due to foot fatigue.

I've done a 100K ultra before, but that was with HOKA maximalist shoes, and I wanted to try this ultra with minimalist shoes. I attempted yesterday's 112K with the Vivo Primus Trail 3.5 FGs with 5.5mm stack height (2.5mm tread + 3mm base), but my feet were not strong enough.

From around the 50K mark, my feet were starting to feel very tender, and from the 60K mark, each step was extremely painful. My IT band started to overcompensate from my bad form caused by the pain, and that combined with the foot pain was too much, and I simply could not go on. I think I could've grinded through an extra 10 or 15K, but another 42K was too much and I decided to drop out.

Extremely gutted, but I'll come back with stronger feet and maybe some more support for ultras - looking at the Altra Lone Peak 9+s right now.

For reference:

• I've been using minimalist shoes since 2013, but have only gone unshod a handful of times.
• My longest run with minimalist shoes was a 63K trail run. I'm happy I got up to 70K this time, but I wish my feet had been strong enough to finish the remaining 42K.

Some questions :

• What are your shoes of choice for 100K+ ultramarathons?
• Has anyone succeeded in running triple digits with minimalist shoes? I was trying to remind myself that the Tarahumara run 100 milers with the huarache sandals, but I guess I'm nowhere near that level of foot strength.
• What are some routines or exercises to enhance foot strength? I'm thinking of mixing in unshod barefoot runs in my training now.