What the Wheel Size
What the Wheel Size
An unprejudiced look at the various wheel sizes and why it doesn’t pay to play favorites.
A popular mountain biker trope is “to pick a wheel size and be a dick about it.” That means to choose a side and furiously argue for its superiority over all other options.
How does wheel size fit into this mythical decision making matrix? Well, every wheel size has its merits, it’s own characteristics, and depending on who you are and what you want to get from your riding there’s likely going to be a wheel size that most suits you.
29" - Fast and smooth
29-inch is the biggest wheel size, with the largest range of benefits and with it a sizable number of unique traits that will make or break your heart.
When they were first introduced few people believed 29-inch was appropriate for mountain biking but that’s partly because the bikes they were mounted to weren’t quite finished. If people complained about more flex (from longer chainstays, forks or spokes) or an unwieldy feeling that made it hard to make the bike turn on tighter terrain then it was likely because the geometry, frame and chassis of the time weren’t optimized. Even our founder Rob Roskopp once said we’d never make a 29-inch bike, but then in 2009 we released the Tallboy and many people had to reevaluate their previous experiences.
You see, 29-inch wheels are surprisingly maneuverable when paired to the right geometry and chassis. It was clear larger wheels would provide monster trucking ability to roll over more trail debris with less effort, but what wasn’t obvious at first was that changing fork offset, bottom bracket drop, and any number of other geometry numbers could actually allow big wheels to feel not just fast in a straight line but able to carve lines down any shape of trail.
The reduced rolling resistance and larger footprint of 29-inch wheels does inspire confidence and helps riders cover ground efficiently. So for people looking to maximize their speed for chasing podiums or bragging rights, 29-inch is the obvious choice. But also for relatively novice riders who want more trust when terrain is unpredictable 29-inch is a fantastic choice because it can provide a more stable base of support.
Mixed wheels - a mix of both worlds
A relatively new option is mixed wheel (also known as ‘mullet’). This is when a 29-inch wheel is used for the front wheel and a 27.5-inch is used on the rear. The leading 29-inch wheel creates a large contact patch that generates a lot of traction and lowers the rollover resistance. While the smaller diameter rear wheel gives more butt clearance (a factor for some shorter limbed riders) and creates a quicker handling bike. The result is a bike that still feels composed like a 29er but requires less input energy to lean the bike over or place the rear wheel where necessary.
One thing that’s overlooked in all this wheel size debate is the axle height, both wheel axle and BB axle. 29-inch wheels, if paired with a frame with good BB drop, can feel very stable because the rider feels ‘between the wheels’. However the mixed wheel setup means that the reduced BB drop (BB to rear axle) at the rear allows the rider to pivot over the rear wheel and unweight the front end more easily, which might aid in getting over obstacles at short notice (lifting over roots or manualing, for example).
Mixed wheel has been something our downhill racers on the Syndicate experimented with and found to be beneficial. Some riders find it to be a good balance of traction and agility, as well as giving them more butt clearance. This is why it’s well suited to a bunch of our trail bikes which blend fun at speed.
One note about mixed wheel setups is that we’ve found that “bodging it” by putting a wheel into a frame designed for a different wheel doesn’t work too well most of the time. As we said earlier, wheel diameter is just one variable and how the wheel size is integrated into the geometry is vitality important. Not just for frame clearances but for creating the right dynamics. A very small difference in any of the geo can have a big effect, so putting a smaller (or larger) wheel in your frame will change the geo a lot, and that changes the character of the bike.