The issue I have with all of the Brooks shoes I have ordered in the last two years is the tongue of the shoe. Full disclosure: I'm not a runner, but I am a shoe wearer who wears these Brooks shoes all day long for comfort and stability. I noticed a strange aching discomfort at the end of the day on the top part of my foot in the upper ankle area. This has gone on for so long that I went to see a doctor and got scans only to finally come to the conclusion that it's these Brooks shoes I've been buying/wearing all day. The tongue is especially long in the center and also can slide to the side leaving the corner poking into that part of your ankle. The design department needs to revisit this issue because previous versions of this shoe along with other lines like Adrenaline had shorter, flatter tongues that did not cause as much of an issue (see pic comparison). I love the shoes, hate the unnecessary pain, and the fact that I spent a lot of money for an unnecessary doctor's visit w/diagnostic testing (since my insurance is so terrible). Since you may not be able to tell what I'm talking about based on the online pictures advertising this shoe, I'm posting my own pics to show this tongue which is found on the latest versions of the shoes of Glycerin 21 along with the others I mentioned. I bought Ghost Max because tongue piece appeared in the ad pic to be a little straighter, lower, less angular than these, but it still causes an aching discomfort when I remove my shoes at end of day just not to the degree that the Glycerins do. I didn't get an Adrenaline version this year because of ugly colors/design. Aside from the tongue piece issue, which sadly is proving significant or I would not have sought a dr and been willing to pay the medical bills, the shoe feels great. It has a similar Ghost Max cushiony sole (without the heel drop feeling that Ghost Max has). Brooks please reduce the size of the tongue pieces! You did before 19 versions and prior, I know you can do it again. If this is a runner enhancing design, can you make a shoe with a removable tongue piece and sell an alternate piece for non-runners that could be attached?

Ok... so I switched from the Ghosts to try the Glycerin's as I've been needing more cushion and wanted to try a lower heel/toe drop. I got the coconut in wide and love the pale blue/orange color combo. Traditionally, with my flat feet and wide toe-bed, I like to feel more of the ground when I run and was concerned the cushion on these would simply be too high and too soft. Well, in a way, they are a little. Let me explain: I first ran on the treadmill with these (while away from home) with a 0.5 incline. They ran beautifully, no issues. Then I ran on the road and it felt a bit too think and heavy. Then I returned to NYC where I run on a gravel trail in Central Park and on my first run, I found it VERY awkward with zero toe-off to propel myself and a lot of fatigue. On the plus side, my knees, hips, back and neck were not in pain after my run which can sometimes happen (I'm so misaligned, lol) so I allowed myself to recover and then ran again today and it felt very different than the first difficult run. This time, while there still was little toe-off and the leg fatigue hitting me faster than I'm used, I realized that I could feel my calf muscles more elongated and my butt muscles activated and realized that the fatigue might have more to do with a different part of my body being activated that wasn't activated before. And a part of my body that I WANTED to work out more anyways, so maybe this was actually a good thing! Also, the run was far easier than my first attempt on the gravel trail. Then I ran on NYC concrete back to my apt and noticed how wonderful the cushion was this time, allowing me to run longer than usual when on concrete.

So... all this to say: I think my body is simply adjusting to the lower heel/toe drop, the higher cushioning (which may be harder for me to run in when I'm already physically exhausted, but it's certainly more protective) and I want to give this a few more weeks of running in Central Park to see if I stick with this or return to the Ghosts... Thank goodness for their 90-day return policy that allows you to actually try out the sneakers... Very grateful, Brooks!

I was compelled to give a review based on an excellent customer service experience I had with a problem with a different shoe (and I would give the customer service 5 stars, or more if possible), I felt very well taken care of by Brooks and note the company and customer service agent went above and beyond to help me. As for this shoe, I picked it as a replacement to the now-defunct Levitate line as I needed a neutral support shoe with which to replace it. The Glycerin 21 certainly avoids a blister problem I had previously on the last iteration of Levitate#6 (sadly! The prior ones I tried including Levitate #2 and #5 were perfect) and this model is also quite roomy in the toe box (maybe a bit too roomy for my narrow feet). It also has an abundance of cushion. My critiques of the shoe (which I knew going into purchasing it but chose it anyway) are that in comparison to the Levitate, there is perhaps too much cushion and so it is a little clunky and I lack sensitivity of the ground. It's more of a walking than running shoe in this regard, I think it might hamper my speed if using for running, but I use it exclusively for long walks and at work, and it will fit my needs just fine for the season. It also kind of looks like a "clown shoe" due to so much rubber on the bottom/sides - I don't care about this myself, but just to note for those ordering this online. I'll probably end up gravitating toward a different pair for the future, but it will work well for me for now. Thanks again Brooks for your spectacular customer service!

I always thought Brooks' midsoles were too stiff and firm for my liking. However, I was sent a pair of the Brooks Glycerin 21s which meant I had a risk-free way to change my mind. And change my mind they did.

The Glycerin 21s have became my number 1 walking and training shoe. The upper is plush and comfy, The outsole has never posed as problem. But the midsole is something I haven't experienced before. While I was right about it being firm, the firmness was actually a positive. The midsole is cushioned and protective but light and responsive.

I mostly took this shoe on super easy runs but during the few times I used it for strides it was surprisingly fast and responsive.

Overall my favourite aspect of this shoe is how it disappears on my feet when I run. Its the only running shoe that allows me to completely focus on my run and not think about what's on my feet and how I should be landing. This quality has made it my favourite trainer but its so good for walking and general athletic use that I use it for pretty much everything now.