New for 2011, this is the 13th iteration of one of Asics flagship models.
If you have run in Nimbus shoes in the past, you will find the new model to be very similar to the Nimbus 12 with two minor, but significant functional improvements over the previous model: (1) increased side-to-side stability and (2) slightly lower profile heel. More on each below.
For anyone new to Asics or the Nimbus line in particular, it is one of Asics franchise shoe designs. At $120 plus dollars it is also at one of the higher price points, but worth it if you are a distance runner. The shoe is particularly well suited for those with a "neutral" gate and slightly higher arches - there is greater cushioning for the arches. If you are a high-mileage runner (running 25 miles or more a week) optimizing for comfort over absolute speed, this is an excellent shoe to train in to avoid injuries. Running on a treadmill or anything short of hard cement and you will feel like you are running on soft earth.
For background, I am 6'1", 175, and run three to six miles several days a week - primarily on city streets and paved running trails, sometimes on the treadmill. Some seasons I kick up the miles for a marathon, but in general running is part of a cross training program. The Nimbus 13s are probably my 6th or 7th iteration with the Nimbus line.
With respect to the specific changes for 2011:
(1) The improved side-to-side stability is a significant improvement. While not recommended, I wore the shoes to a boot camp-style class that included lots of left-right motion. Having previously tried this in the earlier Nimbus 12, my foot slid precariously around the footbed. In the new model the shoe feels significantly more connected to the foot. This translates well to straight-line running as invariably the terrain will have its uneven spots. In the past this meant jerking up your leg quickly to avoid a twisted ankle, but with the new model comes increased confidence.
(2) Another contributing factor to the increased side-to-side stability is the slightly lower-profile heel. Compared to the previous model the heel feels just slightly lower. This may be an influence of the current trend towards natural running in the foot-shaped webby-feet shoes. (For the record I own a pair and like them for walking on soft surfaces, but still like the cushion of a running shoe for the typical hard surfaces encountered in running.) Whatever the reason for this slight change, I would rate it an improvement as there is no noticeable loss of cushioning.
Looks-wise the new model is much more "fashion forward" with higher contrast colors than any previous models, which may be a plus or minus depending on your point of view. Both new combinations are slightly plasticy looking - more inline with Nike and others, though Asics is always about a step behind in this respect. The silver-fire color is the safer choice, but the new white-blue combination, looks better in real life than expected, though the white makes your foot look a little larger.
Two asides: (a) if you are new to Asics, most people order one size larger than their street shoes - ie, if you wear a 10 in regular shoes, you may need to order an 11 and (b) as in most running shoes, the stock insoles are barely better than cardboard - depending on your running style, distance, etc, you may want an aftermarket insole. But almost all running shoes suffer from this issue, so I am not deducting a star for this.
In sum, the new model builds upon the tremendous improvements made in the previous iteration (the improvement from Nimbus 11 to Nimbus 12 was dramatic), but the differences are iterative, rather than groundbreaking. This continues to be an excellent overall shoe for the neutral runner.
Hope this review helps you.
