Modern Enduro Bike Geometry Compared, Analyzed, and Explained

Photo: Matt Delorme/Trek Bikes

Enduro bike geometry is often a source of debate or confusion, depending on how much you know about the topic. For example, some riders prefer the benefits of short chainstays for their flickability while others say longer is better because of the stability factor. Every rider has their own individual preferences. As it turns out, brands have their own take on “ideal” mountain bike geometry, which is one way they can differentiate themselves in the market.

Then you also have wheel size and suspension travel to consider. Do 27.5″ or 29″ wheels make a better enduro bike? How much squish is enough? While I don’t intend to settle those debates with this article, what I wanted to do was answer the question:

“How big are the differences in enduro bike geometry between brands and between wheel sizes?”

Strap in for a deep dive into the nitty-gritty of geometry figures for a vast array of today’s enduro bikes. And if you haven’t already, be sure to check out the companion to this article that compares geometry between the top trail bikes on the market today.

Definitions

Before we get started, it might be helpful to define what an enduro/all-mountain bike is in general. The term “all-mountain” has been around for at least a couple decades, but in recent years it’s been superseded by the word “enduro.” Basically, bikes in this category have relatively long suspension travel (140-180mm depending on wheel size), geometry that favors descending capability over climbing efficiency, and components that place an importance on durability above weight. These bikes are made to get you to the top of the mountain under your own power and then safely down the rowdiest of descents.

Initially, “enduro” was specifically a race format. In an enduro race, a rider is timed only on the descents, called “stages.” In between the stages you have untimed portions called “transfers.” A typical enduro race will have 3-5 stages, but they can also span several days and many more stages. At the end of the race, the rider with the lowest combined time on the stages is the winner.

The mountain bike enduro race format has been around for the better part of 15 years, but it wasn’t until the last five years or so that it became mainstream. And since it became mainstream, the enduro name has been slapped on everything from bikes to shoes to helmets to gloves to you name it. In my opinion, the most irksome application of the enduro label has been to trails themselves, and to rides. Like when someone says, “I’m going on an enduro ride,” or asks, “is this an enduro trail?” It’s just mountain biking y’all, same as it’s ever been.

As annoying as I find the enduro-ification of mountain biking, I’ve come to accept that it’s now just part of our sport’s parlance. While I’ll use the term enduro in this article, just know it’s interchangeable with all-mountain.

Geometry Terms

I included this glossary in the trail bike compare-o, but those not intimately familiar with all the geometry terms might find it helpful.

  • Head tube angle (HTA)  the angle, in degrees, of the head tube relative to the ground. Generally speaking, the steeper the angle is (closer to 90 degrees), the faster the bike will respond to steering inputs. A steep HTA also aids in climbing, as the front wheel will track straighter. A slack HTA puts the front wheel farther out in front of the bike, slows steering input, lengthens the wheelbase, and increases descending confidence.
  • Seat tube angle (STA) – similar to HTA, except this is the angle that the seat tube forms relative to the ground. A steeper seat tube angle brings the rider’s hips forward, over the bottom bracket. A slacker angle will move the rider’s weight back over the rear wheel. This angle also has an effect on the ETT: a steeper angle creates a shorter ETT measurement, while a slacker seat tube will lengthen it.
  • Reach – this is the horizontal distance between the center of the head tube and a perpendicular line drawn through the center of the bottom bracket. More and more, brands focus on the reach figure since it gives the rider an idea of how the bike will fit when standing on the pedals.
  • Effective top tube length (ETT)  the horizontal distance, measured parallel to the ground, between the center of the head tube and where it intersects the seat tube or seat post. As you go up in frame size, this distance will get longer.
  • Stack – this is the vertical distance between the top of the head tube and the bottom bracket. Stack is important because it will impact how high or low your handlebars will be.
  • Chainstay length (CS)  sometimes also called rear center, this is the horizontal measurement from the center of the bottom bracket to the center of the rear axle. Short chainstays are very much en vogue right now, as they can add a playful character to a bike. However, short chainstays can also detract from high-speed stability.
  • Front Center (FC) – this isn’t included in the illustration above, but I had a few requests to provide the front center measurement. The front center is the horizontal distance from the center of the bottom bracket to the center of the front axle. To determine FC, simply subtract the chainstay length from the wheelbase. Front center tells you how much of a bike’s overall length is located in front of the BB.
  • Bottom bracket height (BB) – the vertical distance from the ground to the center of the bottom bracket. A lower BB height will aid in cornering, but also increases the chance of pedal strikes.
  • Wheelbase (WB) – the horizontal distance between the front and rear axles. A longer wheelbase will increase high-speed stability, and a shorter wheelbase will make the bike more maneuverable on tight trails.

Conditions and Assumptions

With 160mm/150mm travel, you’d think the Rocky Mountain Altitude would classify as an enduro bike. Not so, says Rocky. (photo: Aaron Chamberlain)

Now that I’ve defined what an enduro bike is in general, I’ll let you know how I chose the bikes for the purposes of this particular discussion. Here are the requirements:

  • For 27.5″ wheeled bikes: a minimum of 150mm rear travel and a minimum of 160mm front travel.
  • For 29″ wheeled bikes: a minimum of 140mm rear travel and a minimum of 150mm front travel.

Granted, it’s not a perfect definition since many bikes blur the line between a trail bike and an enduro bike, but it’s more than sufficient for this comparison.

The Pivot Firebird pedals better than any 170mm bike has a right to, but their Mach 6 is a better choice for enduro racing (photo: Pivot)

Also, note that I didn’t always pick the longest-travel bike offered by a brand. That’s because a handful of brands offer bikes that are in yet another category above and beyond trail or enduro. Call them freeride or park bikes if you like, but these beasts have abilities skewed even further towards descending. While you could pedal them to the top of the mountain, you probably wouldn’t want to, especially in a race situation.

If in doubt, I tried to find out what bike a brand’s team used for racing. Most enduro races have plenty of pedaling and climbing, so a bike’s overall capability has to be taken into account. It’s not simply a matter of choosing the most travel and slackest geometry.

Additional things to be aware of:

  • Measurements below are taken for size-large frames.
  • For bikes with adjustable geometry, measurements are from the slackest setting available.
  • For bikes with only the bottom bracket drop listed, I estimated the BB height for the sake of comparison. I assumed a 352mm axle height for 27.5″ wheeled bikes and 372mm axle height for 29″ wheeled bikes. This roughly equates to a 2.30-2.40″ wide tire. The following bikes have estimated BB heights using those criteria:
    •  27.5″
      • Canyon Strive
      • Commencal Meta AM V4.2
      • Cube Stereo 160
      • Fuji Auric
      • Giant Reign
      • Jamis Defcon
      • Nukeproof Mega 275
      • Rocky Mountain Slayer
      • YT Capra
    •  29″
      • Niner RIP 9
      • Nukeproof Mega 290
      • Rocky Mountain Instinct BC Edition
      • Scott Genius 900

I would call this list extensive, but it is by no means definitive. There will always be bikes from smaller brands that are not on my radar. What I tried to provide is a broad, diverse cross-section of bikes from numerous brands.

On to the bikes!

Click to page 2 for 27.5″ Enduro Bikes.

Share This: