The Ins and Outs of 650Bs
When we heard about another wheel size just over a year ago (650B or not 650B), we swore, shook our heads and banged our fists. Please, we don’t want to stock more tyres, tubes, rims, rim tape, spokes, wheels and bikes… please no more bicycle options! We have been through this before with 29ers, and now the 650B wheel standard (aka tweeners or 27.5ers) threatens to confuse things a little more.
But when Nino Schurter won the opening round of the 2012 XC MTB world cup on a prototype Scott 650B mountain bike, the success of the 650B standard was kick started. And now that he has won a silver at the London Olympics and overall 1st in the 2012 World Cup XC Series, the 650B revolution has begun. So what do you need to know? What is the situation NOW? Where are 650B, 29ers and 26ers going to be in 5 years?
Let’s get the simple stuff out the way, what do you need to know?
– the 650B wheel is commonly called a 27.5er but this is misleading because the rim size is not equally in between a 26″ rim and a 29″ rim. In fact it is more like a 27er, or about 1/3 the total difference between a 26″ and 29″ larger than a 26er and 2/3 smaller than a 29er. Maybe sanity will prevail, and people with call the different sizes 26, 27 and 29.
– the implications of the wheel being closer in size to a 26er means that some 26″ specific frames will fit 650B wheels and tyres, so this is a “cheaper” way of keeping up with your mates on their 29ers.
– a little bit of good news… all 26er tubes WILL WORK on 650B!
– 26 and 29 refers to the imperial measurement standard called inches, so a 26×2.125 tyre is 26″ in diameter and 2.125” wide. However, like road bike standards, the 650B is measured using metric units so a 650x57c tyre is 650mm in diameter and is 57mm wide.
– 26″, 29″, and 650mm aren’t the actual wheel or tyre diameters. The measurement actually falls somewhere between the rim outer diameter and tyre outer diameter. For example, a 650B rim has an outer diameter of 584mm, and a 650x57c Schwalbe tyre has an outer diameter of about 698mm. Why? It is complicated so Google it.
You want to convert your 26er to 650B?
– first, you will need to test a 650B back wheel and tyrein your 26er frame to check clearance and if you have a full suspension you’ll need to empty your rear shock of air so that it is fully compressed.
– you will need a Lefty 26er or Fox 26er fork (note that Fox does not endorse this conversion and it won’t work on tyres bigger that 2.1” wide), or buy a 650B specific fork.
– and then if all goes well, you will need to purchase a new set of rims, new spokes, new tyres and a new tubeless conversion
– this will cost you between about R4000 if you buy the good stuff.
– or you can rather buy a whole new set of wheels with the extra rotors, hubs and cassette for about R6000-R8000
– finally, when converting your 26er to 650B wheels and tyres, the angles in the bikes geometry won’t be affected if you convert both wheels, BUT the Bottom Bracket (BB) height will increase by approximately 16mm. The impact of this upgrade is better clearance over obstacles, but a higher centre of gravity. The improved rolling momentum of 650B tyres and improved approach angle should outweigh the sometimes negative impact of a higher centre of gravity.
What is the situation NOW? Niche brands such as Pyga, Santa Cruz and Intense have been rolling out 650B bikes and a few of the mainstream brands (such as Rocky Mountain) have already jumped at the opportunity. More importantly, the 2 largest bicycle manufacturers (in the world) have decided to replace their 26er line-up with 650B bicycles. Along with their current very successful 29er range of bicycles, Giant and Merida have decided to hang their hats on the 650B standard. Some brands, such as Specialized, haven’t jumped on the in-betweener wheel size band wagon but are further reducing their 26er offerings in favour of more 29ers. 650B tyres are still difficult to find with limited widths, brands and tubeless options plus inflated prices.
Where are 650B, 29ers and 26ers going to be in 5 years? Here are our predictions. For XC bikes and Trail bikes (ie travel up to 140mm}, we agree that 29ers are the best, but for Freeride and DH bikes (travel over 150mm), the 650B standard might be the ultimate choice. The 650b wheel allows better rear end travel designs for longer travel bikes where the large 29er wheel would just get in the way. The alternative approach is basing the tyre size choice on the riders height, or in other words, treating adult riders like children, and we say “why not?”. Kids have been sized according to tyre size and not frame size for decades… 12″, 16″, 20″, 24″ and then onto 26ers when they hit puberty. So why not build Extra-small adult bikes as 26ers, Small and Medium bikes as 650B, and Large and Extra-large bikes as 29ers. We predicted this a year ago and it is actually beginning to happen.
So we end how we began, will we need to stock more tyres, tubes, rims, rim tape, spokes, wheels and bikes? Yes, but we don’t expect 650B to be “the next big thing” because we still genuinely believe that 29ers are the best for the majority South African riders. But for riders who are vertically challenged, or want more than 5″ of travel, or don’t like the feeling from the larger 29er wheel, 650B will offer improved approach angles, grip and rolling momentum when compared to 26ers, and better handling, lower weight and longer travel when compared to 29ers.