Front End Geometry On 29"ers: Set In Stone

Since the 29″er was first a reality with the introduction in 1999 of the Nanoraptor in 700c size, geometry for the wagon wheelers has been in flux. It was commonly known that the bigger wheel would automatically increase trail figures with the geometry carried over from the smaller 26 inch wheels. So, to gain back the quicker handling that had been honed in to perfection on the 26 inch side, various things were hit upon to make 29″ers more like 26″ers, at least in terms of turning.

Gary Fisher Bikes use a Fox fork with a 51mm offset, but don’t bet on that becoming the “standard” for 29″ers.

Of course, in the early days only a custom rigid fork would address the front end geometry needs necessary to get a big wheeler to steer in a manner that most riders craved. There were some early attempts to change suspension fork geometry for 29″ers, most notably Marzocchi with the special forks made for Fisher Bikes. Trouble was, at the time, most suspension fork manufacturers were loathe to make new forgings to reflect the offset needs desired by what was deemed a small, niche market. So other means were employed to gain some steering quickness back for 29″ers.

Until the 2009 Reba’s came out, all Rock Shox 29″er forks sported a 38mm offset.

Most commonly, the head tube angles were steepened. Most of the time 72 degree angles were used, but some bikes went as far as a 73mm head tube angle. While this worked in theory, the bikes tended to make suspension forks bend backward along the length of the legs instead of activating the damper. Finally the level of sales was attained that made getting fork manufacturers to make new forgings a possibility. The first salvo was launched by Gary Fisher Bikes, just like they did in the early part of the decade. They convinced Fox to manufacture a 29″er fork with 51mm offset. But not only this, Fox decided to also sell aftermarket forks with 46mm offset. This was actually the bigger story, as it turns out.

With Fox on board with 29″er geometry, the other 29″er fork makers were put on notice to make changes as well. Manitou changed their offset in conjunction with Fox, and then for the 2009 model year, Rock Shox announced it too would shed the old 38mm offset from the 26″er days. What Rock Shox did sealed the geometry for 29″er front ends for the future.

2009 Reba’s have 46mm ofset

Now with Fox, Rock Shox, Manitou, and the up coming Marzocchi 44 fork all having offsets nearly identical to one another, it is safe to say that the front end geometry for 29″ers is likely set. The time for experimentation is over. Gary Fisher Bike’s G2 geometry not withstanding, this is the future for 29″ers now. Sure, we’ll see things like through axles, tapered steer tubes, and longer travel forks down the road, but the offset issue for 29″ers is over.

The 2010 Marzocchi 29″er fork will feature a QR15 front axle and an offset nearly identical to the current crop of 29″er forks.

So, look for your 29″er to have some new fangled features in the future, but don’t expect too much change in the area of front end geometry anymore. Some folks will welcome that part with open arms, as just the mere thought of “offset”, “trail figure”, and “head angle” makes their heads spin. Others will lament the pasing of the “old geometry” for 29″ers, because they much prefer the way those early rigs handled. Whatever side of that coin you are on, one thing is for certain, this marks 29″er bicycles as being something that has come of age in the mountain biking world.