I LOVED my Gel-Nimbus 19s that I had previously. They were getting a little rough after 450 miles, soles were worn smooth (or missing) in alot of places, and they were starting to feel a pretty dead like they may start to give my some knee problems soon. I was real stressed when I saw they had made some changes to this newest version in the 21 and was worried they wouldn't be as good as the 19s I had come to love. I could not have been more wrong.
The updated forefoot shape in these is amazing. I was skeptical when I put them on at first because they felt so roomy in the forefoot and toebox. There was no way all this room wasnt going to give me blisters or cause some other unseen issue. Again, I was wrong, they are SO comfortable and have been from the very first mile.
For my first run I just did 4 miles on a treadmill to make sure they were going to be ok, and I had 0 issues, no stiffness, no break in, no hotspots, nothing. The next day I took them out for 10 miles on the road and had the same experience, nothing but awesome comfort mile after mile and my feet felt great at the end of it. As of this review I have about 75 miles on including multiple 10 milers and still have not had any issues.
Lacing is great, it feels like it has more stretch or adjustment or something than the previous version. My other favorite small thing is that the tongue does not shift at all which was one gripe I had with previous versions. Its really easy to dial in your perfect tightness throughout and it stays once you have it where you want it.
Plenty of cushion for long run comfort while still offering good response for shorter faster runs, and never feels soft or spongy. Breathable mesh upper is going to be a nice feature on warmer summer days for sure, but I dont have any issues with it being too cold in the winter either.
I found the fit to be consistent with the 19, I sized up from my typical sneaker/street shoe size by a half size in both and they fit perfect. Do your feet and running a favor and pick yourself up a pair of these, you wont regret it!