It comes as no surprise to any mountain biker reading this that, when it comes to “standards” in cycling, the only constant appears to be change. Not so long ago, the industry transitioned from the 25.4mm clamp diameter to the so-called “oversized” 31.8mm diameter. Now 31.8mm is the norm, but the emerging 35mm diameter is poised to shake-up our cockpits once again.
There appear to be several sound reasons for going bigger. Handlebars have trended significantly wider since the adoption of the 31.8mm standard. Modern bars often range from 750mm to 800mm on gravity rigs, and 700mm to 750mm on many cross-country and trail bikes.
Shown here is the new Race Face SIXC carbon rise bar with 35mm the Atlas stem
The result - according to a growing number of companies - is that it is once again time to increase the clamp diameter to bolster the interface between the stem and our rangy handlebars. Race Face and Chromag are the latest companies to introduce handlebars with 35mm clamp diameters. They join Easton, Syncros, Kore and Nukeproof in supporting the size.
Easton claims its 35mm alloy Havoc bar has 15 percent greater impact strength, a 10 percent increase in fatigue resistance and a 10 percent decrease in weight compared to its 31.8mm counterpart. It remains to be seen if these weight savings and stiffness gains trump the burden of upgrading for the average rider. It's worth noting that these weight savings are made possible by decreasing the wall thickness — so pay even closer attention to the proper torque of faceplate bolts when stepping up to a 35mm handlebar and stem.
The question isn’t whether or not this new size will have staying power, but if it will become the new norm for all handlebars. Will 35mm become the standard for all mountain bikes, or will it be limited to stems and handlebars targeted at gravity and enduro markets?
Time will tell, but history may be the best indicator of things to come: there aren't too many companies producing high-end 25.4mm handlebars today.