The Niner SIR 9 Steel Hardtail Mountain Bike Frame blends modern trail geometry with the timeless ride quality of steel. Built from supple yet durable Reynolds 853 tubing, it delivers a smooth, compliant feel that softens trail chatter without sacrificing responsiveness. The frame is designed around 29-inch wheels and compatible with 120mm suspension forks, giving riders flexibility to tailor it for cross-country efficiency or trail-capable fun. With Boost spacing, internal dropper post routing, and mounts for racks and bottles, the SIR 9 balances performance and practicality. It’s a do-it-all steel hardtail built for riders who appreciate craftsmanship, versatility, and the unmistakable feel of steel on dirt.