29/26 can accommodate the sizing demands of short riders with a lower standover height. Also, the shorter chainstays of a 26-inch rear end lend a different feel than those of a 29-inch out back, which some riders prefer from a maneuverability standpoint.
A 29-inch rear wheel has greater rotational inertia and therefore takes more energy to accelerate, and that's a difference you can feel in the pedals.
What You Need
- 26-inch wheel mountain bike frame, built around a 80 to 150mm travel shock.
Disc brakes will make things easier. Otherwise you'll need to find a 29-inch specific rigid fork with brake bosses.
New Parts You'll Need
- Rigid disc fork.
29-inch front disc wheel with tire.
29-Inch Fork Options
Here are some forks to choose from. Be sure to verify tire compatibility with the manufacturer before you start your project.
- Dimension: 413mm
Surly: 413mm, 447mm, 468mm
- Vicious: 438mm, 470mm
Salsa Moto Grande: 425mm, 468mm
Planet X: 425mm
On-One: 440mm and 468mm
Bontrager: 445mm, 465mm
White Brothers: 468mm
Measure your bike's axle-to-crown length: Take a pencil, a piece of string and a tape measure. Tie a length of string to the middle of the pencil. With the pencil placed in the fork dropouts, stretch the string taught to the surface of the fork where the headset crown race sits. Mark that point on the string with a pen and measure the distance from the center of the pencil to the mark in millimeters. This is your axle-to-crown length (L). If measuring a suspension fork, subtract roughly 10 percent of the overall travel from the overall length to account for suspension sag.
Measure the radius of your 26-inch wheel and tire in millimeters (R1).
Measure the radius of your 29-inch wheel and tire in millimeters (R2).
Use this equation to determine what rigid fork will keep your frame geometry close to the original setup.
(R2 - R1 = Rd); L - Rd = desired fork length
For example, when I modified my Dean Colonel SS (as reviewed in issue #113) to a 29/26, I used the following numbers:
Axle-to-crown length of existing Fox Talas RLC in 85mm setting (minus 8mm sag): 452mm
R1 = 337mm
R2 = 368mm
The equation revealed that:
368 - 337 = 31; 452 - 31 = 421mm desired fork length
The Surly 1x1 (413mm) fork was the shortest length fork to allow a 29-inch wheel and was also the closest available length, so I accepted the 7mm change in fork length, which translated to a minute change in head tube angle, with little noticeable handling difference.
When evaluating your modification options, consider that a shorter length will provide quicker handling for a more cross country feel, while a longer length will excel over prolonged downhills with higher-speed riding.