27.5+ bikes are the next big thing in biking, and all of the major bike manufacturers are releasing their own versions this spring. But, is it worth keeping up with the trend and getting another bike? Read the rest of this post for everything you need to know about 27.5+ bikes to help you decide whether to purchase one (even if you already own a fat bike).
If you’ve already determined a 27.5+ bike is for you, check out our buying guides:
- Alloy 27.5+ Full Suspension Bikes
- Carbon 27.5+ Full Suspension Bikes
- Hardtail 27.5+ Bikes
- More coming soon!
Photo credits: Rocky Mountain Bikes
What Are 27.5+ Bikes?
27.5+ bikes are designed with plus size tires that fall between mountain bike tires and fat bike tires in terms of both width and tire pressure. In general, 27.5+ tires are between 2.8” and 3.25” wide, and they sit over a 40-50mm wide rim. This is about 25% wider than the traditional mountain bike tire, but still not near the width of 3.8-5” fat tires. 27.5+ tires also run with approximately 13-15 PSI as opposed to the 23-30 PSI of a traditional mountain bike tire and compared to fat bike tires that run as low as 8 PSI for soft trail conditions.
What’s the difference between 27.5” and 27.5+?
Because of the increased width of the tire, 27.5+ tires actually have about the same diameter as a tradition 29” mountain bike tire, so 27.5+ bikes will stand taller than a regular 27.5” mountain bike. The difference in tire width, volume, and pressure also make the handling very different from both traditional mountain bikes and fat bikes.
I Already Own a Fat Bike – Why Would I Want a 27.5+ Too?
27.5+ bikes boast some of the same features that attracted bikers to the fat bike craze: increased stability and awesome grip from the wider tire. Compared to traditional mountain bikes, the extra surface area of the plus sized tires offers 27.5+ bikes increased traction for steep or technical terrains. As with fat bikes, the wider tires offer greater stability, which can increase confidence of less-skilled riders on more technically difficult trails.
Compared to fat bikes, where 27.5+ bikes shine is in their decreased rolling resistance and lighter weight that make them more suitable for riding at higher speeds. For anyone who’s ridden a fat bike fast, you know that it can be hard to not only get up to speed but also to maneuver massive tires quickly. In comparison, the plus size tires can accelerate more quickly and handle sharp turns more nimbly even at a fast pace.
Does this mean plus size bikes could (or should) replace fat bikes? Not at all. Fat bikes were designed to take riders into terrains they could never have navigated by traditional mountain bike, especially soft conditions like snow and sand where the lower PSI gives riders necessary float. Meanwhile, 27.5+ bikes let you keep the best features of a fat bike with better handling at speed and on technically challenging terrains.
Can I Use 27.5+Tires on an Existing Frameset?
Plus size tires can only be used on bicycles with framesets and drivetrain designed to accommodate a larger tire size, so your surest bet would be to purchase a 27.5+ bicycle like the Rocky Mountain Sherpa (as seen in featured image of this post). Plus size bikes are getting easier to find (and afford) as more and more manufacturers jump on the trend and release 27.5+ bikes this spring.
That said, 27.5+ tires can sometimes be retrofitted onto a traditional 29” frameset, provided there is enough clearance between the wider tire and the frameset. Modifications may also be necessary to ensure proper spacing for the drivetrain.
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