"I can’t go to far into reviewing a 650b tire without a quick note on the tire/wheel size itself."
A few years ago 650b was on the fringe of the bike world. Despite existing for decades there were few options for tires and rims and even fewer bikes that utilized this size. 650b sits between 26” and 700c and just like the shared rim dimension between 700c and 29” (622), it shares the 584 rim size with 27.5” trail tires. The general idea behind a 650b pavement or gravel tire is “more tire/less wheel”. A 650bx42mm tire gives almost the same tire circumference as the 700x23mm standard road tire. What this means is clever builders were able to make bikes that can utilize the same tried and true road bike geometry we all enjoy but pair it with a tire that rides incredibly smoothly over rough pavement or dirt.
It literally took the mainstream bike industry 40+ years to catch on to this. However, with the shift away from drop bar bikes to being either purpose-built for road racing, cyclocross or heavy touring to more versatile “gravel” or “endurance” drop bar bikes the time was right for 650b to move into the spotlight.
"While this size is still far more esoteric than 700c it is quickly gaining popularity thanks to two particular tire companies."
Compass laid the groundwork and continues to innovate, but in the past year, Wilderness Trail Bikes (or WTB for short) has played the biggest role in bringing 650b to the masses.
I have been using 650b tires on my own personal gravel/endurance road/yolo bike for over two years now and I’m always on the lookout for bikes that can have their potential unlocked by converting from 700c to 650b.
"The two tires in particular that offer the best overall performance across a variety of criteria are the Horizon and Byway from WTB."
I first installed a set of Horizons on my own bike in early fall of 2016 before setting out on the longest ride of my life, an offroad adventure from Pittsburgh to Washington DC. The 650bx47mm tire casing proved perfect for the task.
The Horizon combines a 47mm casing with a tubeless compatible tire bead and a thick (yet fast rolling) rubber compound to make an incredibly durable, yet efficient tire that proved nearly impossible to flat or wear out. After over 5000 miles of commuting, bike camping, dirt, gravel, urban pavement, and even some single track they were still going strong with zero flats along the way.
When WTB launched its second tire in this size, the Byway, I actually put off trying them because I was so happy with the Horizon tires.
In November we had a big ride planned with lots of pavement and lots of dirt so it seemed like the ideal time to try the new tire. The Byway uses the same basic casing design of the Horizon but tweaks it with a bit of knobby tread on the side and a bit thinner rubber in the center.
I mounted them up on a Saturday and rode home to make sure everything was good. The next day I met up with people at the shop and set out on a fun 85-mile ride through some really cool spots that would be a great test for the tires.
My assessment of the tires after the ride was 100% positive. The updated center tread and thinner rubber proved to roll noticeably faster on pavement and the knobs on the shoulders of the tire were absolutely appreciated off road. At around 35 psi they felt perfect the entire ride.
"This faster on road and more capable off road tire doesn’t render the Horizon obsolete though."
My take on things now is that if you’re going to be off road a bit or want the faster tire the Byway is the right call. However, if you’re going to be commuting/touring or just want a tire that is going to take what seems like forever to wear out the Horizon is the smart choice. The minimal decrease in performance from the thicker rubber is a reasonable tradeoff for what should be an appreciably longer lifespan.
"While these tires unfortunately are not for everyone due to many bikes not having the necessary clearance to fit them there are a wide range of bikes out there that work great."
We have installed either of these tires on quite a few bikes we have sold that were originally designed for 700c. A few bikes in particular that now seem better suited for 650bx47 than 700c that we have sold or stock are the Marin Nicasio, Fairdale Weekender, and Soma Wolverine. There are even some really great carbon endurance bikes, like the Norco Search XR, out there that take either by a stroke of luck or design that are perfectly suited for these great tires.
We always have these on hand to test fit if you’re curious if your bike can take advantage of either of these tires.