There was a time when it seemed like the 29er’s ultimate form would be a steel hardtail. The fringe wheel size was considered too heavy to merit carbon and too big to merit full suspension. And anyway, the counter-culture appeal of 29ers seemed to work well with the punk-rock appeal of steel. So for a while, bikes like Niner’s SIR 9 waved their freak flags on the front lines of the wheel size wars.

The new SIR 9 got boost 148 spacing, allowing for shorter stays and 27.5+ compatibility

Although there will always be a few soldiers out there who think there’s still a battle raging, the rest of us are at peace with the fact that big wheels are here to stay and here to party. And once again, they’re breathing life back into the steel hardtail. New trends in geometry and componentry are inspiring some really fun bikes, even for those who don’t consider themselves the hardtail type.

Niner’s eccentric bottom bracket lets you drop your gears if simplicity is your thing

Niner’s iconic SIR 9 is the most recent to take advantage of those trends. Now built around a 120 millimeter fork, the new SIR 9 got, you guessed it, longer, lower, and slacker. Boost spacing and a refined bottom bracket / chainstay junction shrank the rear center to an impressive 430 millimeters while the reach lengthened by a much-needed 12 millimeters.

The head angle went from 70.3 degrees to a more reasonable 68, and the bottom bracket dropped by about 3 millimeters. As we’ve seen with a few of Niner’s other new offerings, the SIR is compatible (and available) with 27.5+ wheels and offers a myriad of braze-ons for racks, fenders, bottles and bags.

Both the 29 and 27.5+ SIR 9 are built around the same frame and same 120 millimeter fork.

A few things haven’t changed. The SIR still uses Reynolds 853 tubing, and still allows you to go single-speed with Niner’s eccentric bottom bracket. And like all of Niner’s bikes, it’s available in a wide range of build options, or bare naked, ready for you to have your way with it.


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