What are the benefits of an oversized road handlebar? 31.8 mm clamps on road handlebars allow for greater stiffness. Handlebars (especially carbon handlebars) with an oversized clamp don’t have to be built up as much to maintain structural integrity, so they’re often lighter than their smaller siblings. Bikewagon.com has a wide selection of 31.8mm handlebars to choose from, so you can save money and ride better.