I've logged some long days in these shoes, and the Ultra 100s feel like the perfect shoe for "big days up high." Burly, comfortable, and able to dance through technical terrain. Similar to Sportiva, I feel Dynafit shoes have a bad rep for being small/tight fitting for our big 'ol American hooves, but I've found the fit of the Ultra 100 to be very comfortable. I'm a 12 in La Sportiva, 11-11.5 in Saucony, and a 12 in the Ultra 100. There's some wiggle room in the toebox, but in a good way. I appreciate that room on the 7+ hr days.Soles are impressively grippy, and wearing well. While I wouldn't want these shoes for 5th class scrambles, the tacky rubber is more than enough for a smear here or there.If I had one qualm, it would be the stretchy laces. I've found the ... MoreI've logged some long days in these shoes, and the Ultra 100s feel like the perfect shoe for "big days up high." Burly, comfortable, and able to dance through technical terrain. Similar to Sportiva, I feel Dynafit shoes have a bad rep for being small/tight fitting for our big 'ol American hooves, but I've found the fit of the Ultra 100 to be very comfortable. I'm a 12 in La Sportiva, 11-11.5 in Saucony, and a 12 in the Ultra 100. There's some wiggle room in the toebox, but in a good way. I appreciate that room on the 7+ hr days.Soles are impressively grippy, and wearing well. While I wouldn't want these shoes for 5th class scrambles, the tacky rubber is more than enough for a smear here or there.If I had one qualm, it would be the stretchy laces. I've found the need to adjust laces a few times through the day. I think I would like a flat, static lace more.

High comfort shoe for more technical terrain

O am enjoying these shoes on technical trails, they offer good comfort, traction and stability. By nature of the terrain their life isn’t as long as I’d get out of a less plush shoe, however I accept that is a trade off.

Mid-stiff sole, uncomfortable across the laces.

Fits smaller then sizing - so size up 1/2. No cushion under the lacing - so will grip the foot better but be less comfortable.

Much more than a simple update

I'm really impressed with this shoe. It feels much different than the original. In my opinion it is far more stable with a much better fit. The sizing is similar to the original. I like a tight shoe and sized up a half size. If you like a roomy toe box I think you'd be well served to size up a full size. I put hundreds of miles on the original Ultra 100 but almost all were on treadmills because I felt the original was too unstable on trails. This new version is completely different in that regard, feeling much more stable on trails. In fact, this shoe is a joy to run in on trails. I'm also impressed with the shoe's performance in deep, slimy mud. The tread pattern is quite spread out so it doesn't hold on to mud too much and it is relatively easy to clean. I was ... MoreI'm really impressed with this shoe. It feels much different than the original. In my opinion it is far more stable with a much better fit. The sizing is similar to the original. I like a tight shoe and sized up a half size. If you like a roomy toe box I think you'd be well served to size up a full size. I put hundreds of miles on the original Ultra 100 but almost all were on treadmills because I felt the original was too unstable on trails. This new version is completely different in that regard, feeling much more stable on trails. In fact, this shoe is a joy to run in on trails. I'm also impressed with the shoe's performance in deep, slimy mud. The tread pattern is quite spread out so it doesn't hold on to mud too much and it is relatively easy to clean. I was concerned that the spread out pattern of tread would yield an uncomfortable ride on hard pack trails but the stack hight and relatively firm cushioning creates a very smooth ride. All around a great shoe, more than a simple update.

Not good for my feet. Yours may be different.

For reference, I usually find Salomon size 11.5 running shoes to fit my feet well. Size 12 in Dynafit felt at least half size too short. The toebox is on the narrow side but this might have been resolved by going half size up. Otherwise the fit seems to be decent, even if not on par with S/lab.

Quality construction but runs small

Nicely built trail running shoe. As the Dynafit website mentions, they fit small so size up.

Trail Pillows

I bought this shoe to get back into trail running after a 4-year hiatus. Living in Northern AZ, the trails range from slimy mud to jagged decomposed granite. These shoes tackle everything I throw at them with unparalleled stability and cushioning that rivals a Hoka (without looking like a clown). I have put well over 400 miles of running with an additional 400 miles of hiking on these and they are holding up amazingly. I will be ordering another two pairs soon, as it is usually my luck that when I find something that works, someone changes the mold - I hope they leave this one right where it is! It's perfect!!

Ultra Fun

These shoes are a blast! Used them on a recent 100k and they excelled wonderfully, very comfortable shoe, still very responsive, they are not too plush, a really smooth and fun ride. They look heavily cushioned, but they don't feel like it apart from making them super comfortable over really long distances, still have enough ground feel, very light, not too bulky. Shoes are very durable as I come to expect from Dynafit, outsole is very grippy, great ride on every surface. They are wider/bigger volume than other Dynafit models or the previous Ultra 100, also the lacing system is much better with a better heel lock than the Alpine or Ultra 50, so great improvements. Shoes look awesome, the black and white racing colour is dynamite!

Why did I try other shoes...

I ran in the previous Ultra 100s last year. They were super comfortable, but just needed to size up a full size. This year I thought I'd see what else other brands offered, specifically Salomon, Nike, Adidas, and North Face. After getting nagging injuries I decided to get the new Ultra 100s. My first run in them was a 30-mile, 9k foot run in the most wild conditions here in the Rocky Mountains - dry roots and rocks followed by overgrown wet vegetation, then rutted out switchbacks, a sudden hail storm, wet scree up to Capital Peak, a dry descent through the fields, and a terretial downpour through the rocky/rootie woods back to the car. I left the run with a smile on my face and while the feet were tired, it was a tireness of conquering vs defeat.I'm buying another ... MoreI ran in the previous Ultra 100s last year. They were super comfortable, but just needed to size up a full size. This year I thought I'd see what else other brands offered, specifically Salomon, Nike, Adidas, and North Face. After getting nagging injuries I decided to get the new Ultra 100s. My first run in them was a 30-mile, 9k foot run in the most wild conditions here in the Rocky Mountains - dry roots and rocks followed by overgrown wet vegetation, then rutted out switchbacks, a sudden hail storm, wet scree up to Capital Peak, a dry descent through the fields, and a terretial downpour through the rocky/rootie woods back to the car. I left the run with a smile on my face and while the feet were tired, it was a tireness of conquering vs defeat.I'm buying another pair this week. If you try size up a full size and be ready for trail happiness.