Yesterday I was able to demo the Jamis Dakar AMT Pro with 650b wheels. Before I tell you what I thought of the bike, it is imperative that you know my background and thoughts about 650b wheels (or 27.5” for you nerds.) I am tall-ish (6′ 1.5”) and once I rode a bike with 29” wheels, I thought that there was no need for me to ever ride smaller wheels again. That was great for a couple of years until 650b wheels gained popularity and people started arguing with me about how great they were. I thought, “Nah, they’re just a fad that will go away soon.” I couldn’t have been more wrong.
When I first mounted this beast, I was impressed with the geometry. As an All Mountain Bike, I expected it to be very slacked out and climb like this. (Poorly if you don’t feel like clicking the link.) The front wheel did feel slacked out, which added a lot of control and handling, but the bike climbed great and didn’t feel like it was robbing me of much energy up the hills. This was not by any means a cross country race bike, but the up hills were all certainly manageable.
But the downhills make me want to write this like a teenage girl… OMG!!! This was one of the most fun bikes I’ve ever ridden. On a descending or flat trail this bike takes off like it has a jet engine. Rocks, roots, switchbacks; the Jamis AMT 650b rolls over everything with speed. The geometry and suspension are set up perfectly so that you can get through everything quickly, comfortably, and with a smile on your face. At least that’s what I did for our entire ride at Ringwood. The Sram X0-1 shifted incredibly smooth, and the chain never came off of the front chainring. The three-point adjustability worked flawlessly on both shocks which made climbing or riding on fire-roads a lot easier.
Now for the 650b… The hype is real, as this is the do-all wheel size. I rode right over big pointy rocks with the same confidence I would on a 29er, but was able to really lean the bike over in the corners which enabled me to go faster than if I were riding a 29er. The conclusion that I came to about these 650b wheels is that they are the ultimate all-purpose wheels if you want to have fun on a mountain bike. The only time I though that 29” performed better is at slow speed in large rocks. Does this minor drawback really outweigh the benefits? No not really. In those circumstances a 650b wheel is much more maneuverable than a 29er which enables you to choose your lines and put the front wheel where you want it to go. In my opinion, 650b is the only choice for an all-mountain style bike.