Many years ago I remember venturing into a bike shop and checking out an all new 29" wheeled mountain bike. It was still a niche bike at the time and many people (including bike shop owners) said it was trash and would never take off. Little did we all know at the time, but it would be the start of the "wheel wars" that still rage on today. Once some people decided that 29" was too big and 26" was too small, 650b was thrust into the mountain bike spotlight as 27.5", the "tweener" size. As all this was happening the old 26" wheeled bikes slowly began to disappear. By the 2014 model year most brands had little to no offerings in the 26" size and it was declared dead. Wander into a bike shop today and find me a well spec'd 26" wheeled bike..... I bet you can't.
In recent years, during the time when all the fat and plus offerings were flying off the bike shop racks, Surly quietly introduced a new bike..... the Instigator 2.0. It came with 26" x 2.75" tires, or "26plus". As with most friggin-cool things from Surly it took a while for the idea to catch on (just like the Pugs fatbike, and the Krampus plus bike) and now people have noticed.
Over the last year there have been a handful of 26x2.8" tires come to market and wider 26" rims, all slipping in under the radar with me quietly watching things unfold. There were threads popping up on mountain bike forums with people stuffing these 26+ wheels into 27.5" bikes with enough clearance. It made sense after all, if you were on the short side for a 29er and liked 27.5 but wanted the traction and cushion of a plus bike you could build a 26+ (with about the same wheel diameter as a normal 27.5" bike) or if you just happened to prefer the smaller wheels it made sense too. Here is a nice graphic from Jamis breaking down the sizes.
Manufacturers have taken notice and now for 2017 you can buy a 26+ bike off the showroom floor. Norco has built a new line of Fluid hardtails with 26+ wheel options over three component levels. Haro is building entry level 26+ bikes. Jamis is building 26+ bikes in both steel (with the Dragon series) and aluminum (Komodo series). Just to name a few.
Its an exciting and confusing time to be buying a new bike, and it likely a nightmare for bike shops trying to stock all wheel platforms over a variety of component builds, let alone a decent tire selection. Some might not agree but I like the idea of a 26+ bike, it would be perfect for vertically challenged people (like my 5' tall wife) who want gobs of traction and cushion from a plus bike. I'm a holdout for my 27.5+ bike for trail riding and can see the advantages of 29+ for bikepacking / gravel grinding, but would love to try out a 26+ rig on some "Shred the Gnar" type trails. Horses for courses I guess, and with all the options... the choice is really yours.
The Bric...._ mountain biker, road rider, heavyweight gear abuser. Built like a brick sh*thouse. No bike is safe.