Note that all of the boots described and weighed in this comparison are European size 41. This is approximately a USA size 7.5 to 8.
I'm a lifetime motorcyclist, but I've only been riding off road for over a bit over 10 years. Particularly as an "older" rider, I believe in wearing the best protective gear I can get. So I've been wearing a great pair of Sidi Crossfire boots for many years. These things are awesome:
Sidi Crossfire - size 41 - 4 lbs. 4.8 oz.
But they are HEAVY. They are about 4.3 pounds (1950g). Also they have a metal toe cap that is very slippery in certain circumstances... they can be deadly on tile floors. All that said, they are great protection.
Now it is important to note heavy boots won't protect you from everything. About 4 years ago I was riding in these Sidi Crossfire boots with EVS Web Pro knee braces when I caught my toe on a ridge on the right side of the trail. My foot was twisted around to the outside badly breaking my fibula:
I carry a satellite beacon but somehow I managed to ride out of the desert without using it... but it was painful.
So top of the line boots and knee braces won't protect you from everything! But maybe they saved me form worse or different injuries. My point is that while you want very protective gear, no gear is perfect.
At any rate, being older and slower I recently purchased a much lighter ebike and I plan on doing shorter, slower and less aggressive rides. And I have decided to get some lighter gear as well. The Sidi Crossfires feel like anchors to me, the pair is almost 9 pounds! So my goal was to find some lighter but still protective boots.
At the lightweight end of the spectrum, just for reference, I have a pair of Alpinestars SMX-6 v2. Alpinestars call these a "track and street performance boot".
Alpinestars SMX-6 v2 - size 41 - 1 lbs. 13.4oz.
That is LIGHT, 1.8 pounds (833g). But not nearly enough ankle support and protection for off road use.
So I purchased both the Sidi Adventure 2 and the Gaerne G.Dakar GTX so I could compare them. Note that I have seen some variation in the Gaerne boot's name: Dakar, G. Dakar, Dakar GTX, but they all appear to be the same boot. The Gaerne boot does seem significantly less expensive that the Sidi at this time.
Sidi Adventure 2 - size 41 - 2 lbs. 9.4oz.
Gaerne G.Dakar GTX - size 41 - 2 lbs. 13.8 oz.
So the Sidi Adventure 2 is about 2.6 lbs. (1174g) and the Gaerne G.Dakar is 2.8 lbs (1298g).
So the Adventure 2 is about 10% lighter than the G.Dakar.Note also the Adventure 2 is about 40% lighter than the Crossfire boot! That's about 3.4 pounds for a pair of boots.
The Dakar is about 33% lighter than the Crossfire boot, or about 2.9 pounds lighter for a pair of boots.
Here are some pictures comparing the linings of the boots:
Adventure 2 on the top and Dakar on the bottom.
Note the liner of the Adventure 2 goes all the way to the top and the Dakar ends a bit lower. I thought that might make the Dakar cooler in the Southern California heat, but in my short "try-on" the lightness of the Adventure made it seem like it might actually be cooler? Kind of impossible to judge by a 2 minute test in my living room.
Also note the brown colored areas of the Dakar are actual leather, where the Adventure is some kind of synthetic. I'm sure it's good, but I'd personally prefer the real leather of the Dakar.
Dakar
Above are pictures down into the boot. I don't have much comment on these. Both boots are made in Italy.
The ankle of both the Adventure 2 and Dakar felt similar in stiffness to me. The soles were also both stiff, but they ARE flexible, not like the totally inflexible Crossfire. This flexibility will make them less protective than a real motocross boot like the Crossfire.
Note the Dakar has a real stitched-on sole. The Adventure 2 sole has some molding that looks like stitching but is not and appears to be bonded. My understanding is that a cobbler can replace either kind, so this did not matter to me personally.
I did slightly prefer the Adventure2's buckles, but that may just be because I am used to the similar design on the Crossfires.
I did prefer the plastic under the lower buckles on the sides of the Sidi Adventure 2... it seemed more protective if the side of your foot was smashed by something. The lower buckle on the Gaerne Dakar seems to sit right on the leather and might be a bit more injurious in an impact? On the other hand, I preferred the hinge area on the inside of the ankle on the Dakar, as it was nice and smooth. The pivot point on the inside of the Adventure 2 bumps out a pit. These two pictures show these differences:
Adventure 2 on the top and Dakar on the bottom.
After trying them both,
the Sidi just fit my foot better. It didn't feel appreciably narrower to me, although it definitely was narrower if you examined the sole. But in size 41, the Gaerne was a bit short on my foot, it felt more like a size 40.
But I was sure going up to a 42 would be too large. So the Sidi fit me better and was lighter, and that decided it for me; I kept the Sidi Adventure 2. (See below addendum 2)
All, that said, I really liked the Gaerne G.Dakar GTX. If it had fit me better, I would might have kept it instead. I liked the leather construction, the real stitched on sole, and that it was less expensive.
ADDENDUM 1:
Once I picked the Sidi Adventure 2, I wore them a bit more, and immediately noticed a "hot spot" on my ankle right above the ankle bone. The boot was just a bit tight there and pressed against my ankle just above the inside hinge point. Looking at the boot I noticed that the cross section of the boot around the upper buckle (around the upper ankle) was very oval, with the long axis being from the front to the back of the boot. It was almost as if it had been stored a long time with the boot being a bit squished from the side. More likely, the base molding of the plastics in that area was just shaped that way. I could probably just have worn the boots a while and it may have "broken in". But in my experience it can take a long time for plastic boots to adjust to your feet, sometimes they need some help.
I carefully heated the plastic of the boot above and just in front and behind the pivot, and then clamped the boot just a bit to make it a bit rounder. And then I heated the boot a again. Be very careful not to heat the plastic too much, I just do it until it is hot to touch, no more. You don't want to damage the plastic! After cooling overnight, the ankle area was a bit rounder and the fit was perfect... but, it didn't last..
ADDENDUM 2:
The plastic ankle on the Sidi Adventure 2 kept recovering to it's narrow original shape. Also, it didn't seem like there was much padding around the ankle bone. At this point, I had only worn these boots around the living room... and at $450 I became concerned they would always hurt my ankles. If you remember from above, I did really like the Gaerne Dakar, they were just a bit too short and I feared the next size up might be too big. But it seemed that I should return the Sidi's and try the larger Dakar. So I brought the Sidis back to my local Cycle Gear and I purchased a pair of size 42 Gaerne Dakars from Brian at Atomic Moto (great company!). This time a received them in my preferred "all black", as I ordered.
Gaerne G.Dakar GTX - size 42 - 2 lbs. 15.1 oz.
I have happily found that the size 42 fits me well! I find them also a bit snug around the ankle bone, but they seem better padded and don't cause me the same pain there.
Here is some revised weigh data comparing to the new size 42.: So the size 41 Sidi Adventure 2 is about 2.6 lbs. (1174g) and the size 42 Gaerne Dakar is 2.9 lbs (1335g).
So for the sizes that fit my feet, the Dakar (42) is about 14% heavier than the Adventure 2 (41), about 0.7 pounds for a pair of the boots. Conversely, The Adventure 2 (41) is about 12% lighter than the Dakar (42).
The Dakar is about 32% lighter than the Crossfire boot, or about 2.7 pounds lighter for a pair of boots.
Note also the Adventure 2 is about 40% lighter than the Crossfire boot. That's about 3.4 pounds for a pair of boots.
Having spend a bit more time now with the Gaerne Dakar boots, I do really like them. I like the leather construction and the real welt sole. They do feel a bit softer than the Sidi and maybe provide a bit less protection for rolling your ankle to the side. There is certainly more plastic in the Sidi's construction (which might be a good thing protection-wise?). The Gaerne sole is a bit wider, and feels a bit more stable walking around.
So in the end, I still think these are both good boots. What is important is finding the pair that fits you best!