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Selecting a Mountain Bike for Off-Road Triathlon - Part 1

xterramtbimg.jpgWe got together with our friends at XTERRA and Professional Triathlete Cody Waite to bring you and informative two-part post on what you should look at when selecting a mountain bike for an off-road triathlon. Here are five factors that can help lead to success.

Part 1 covers: Suspension, Tire Selection and Wheel Size
Part 2 covers: Gearing, Weight and an overall Summary
(Look for Part 2 next week)

The bike leg of a typical off-road triathlon can make up over half of the overall race duration and often determines who will finish on the podium and who will finish at the back of the pack. Even more so than on-road triathlon, the bike leg in an off-road triathlon is critical to your success and the bike itself plays a big factor in this equation. Mountain bikes come in all shapes and sizes. Beyond fatter tires and flat handlebars there are several other factors to consider when selecting a mountain bike for off-road triathlon racing. The most important are:
 • Suspension
 • Tire Selection
 • Wheel Size
 • Gearing
 • Weight

Suspension: Less is More
The majority of mountain bikes sold today are full-suspension mountain bikes, meaning both the front and rear wheels have some form of suspension travel. Suspension has many benefits including increased control and comfort as well as improved traction and less rider fatigue. The amount of travel found on mountain bikes ranges from 3 to 8 or more inches of travel. Suspension travel refers to exactly how much your wheels can move up and down when going over rough terrain. As travel increases in bicycle design the geometry of the bike changes as well as rider position and an increase in weight of the bike. Many experienced riders prefer a bike with only front suspension and no rear wheel suspension (aka hardtail) claiming the lower weight and no rear wheel movement provide a "racier", more nimble feel compared to a suspension bike. This is purely a personal preference however, as it is all but proven that a standard 26-inch wheeled full suspension mountain bike is faster and more efficient than a hardtail.

mountain bike suspensionFor off-road triathlon racing you want to stay in the "cross-country" category of mountain bikes which includes bikes in the 3-4 inch travel range. This category allows for enough suspension for the types of terrain found on off-road triathlon courses while maintaining an efficient rider position for climbing hills, riding technical single-track and fast downhills. The next category up in travel is referred to as the "trail bike" category which is the largest selling category of mountain bikes today with 5-6 inches of travel. Trail bikes can work for the occasional off-road triathlete but the added weight along with a shorter and more upright rider position make for slower climbing and acceleration while also making them less nimble for faster riding over varied terrain. Instead, choosing 3-4 inches of travel for off-road triathlon is the way to go.

Tire Selection: No Tubes
The one word you should know is TUBELESS. This is the only option as far as cross-country and off-road triathlon racing goes, arguably the greatest advancement in mountain biking technology since the suspension fork. The tubeless tire setup has many advantages with pretty much no disadvantages (except maybe a little extra effort to install). The advantages of tubeless tires include the ability to run lower pressure, thus improving ride quality and traction, without the likeliness of pinch flatting a tube. Flats in general are limited to major tears in the tire since the sealant used with tubeless tires will seal most small punctures up to a quarter inch in size. Lower rotating weight can also be achieved if you can run lighter "non-tubeless" tires as tubeless with sealant. You can instantly drop 100 grams per wheel by removing the tube and replacing with two ounces of sealant. However if you are a heavier rider or ride very rough, rocky terrain you will want to stick with true "tubeless tires" that have reinforced sidewalls for greater protection and support.

Wheel Size: Is Bigger Better?
The big debate in cross-country mountain bikes these days is between wheel sizes. The long time standard 26-inch wheel versus the larger 29-inch wheel size. There are arguments for and against both and the official jury is still out. Either size works well for off-road triathlon racing. The 29-inch wheel is gaining popularity amongst both experienced riders and novices alike. The larger diameter wheels allow for better traction due to a larger contact patch with the ground as well as the ability to roll over trail obstacles with more ease while maintaining momentum. The larger wheel diameter performs similar to that of an inch or two of added suspension. A novice rider may find more confidence riding through technical terrain as it seems more manageable and requires less energy than a 26-inch wheel. Trade-offs with the bigger wheels are slower acceleration and increased weight due to the increase in mass of the larger wheels and tires.

mountain bike wheelsIf a 29-inch wheeled bike is selected, it is even more critical to keep the total weight of the bike in mind as they can become significantly heavier than a 26-inch bike. For this reason, many 29-inch riders opt for a hard-tail frame design (no rear suspension) to keep the weight down and "racier feel" high. It is becoming possible nowadays to have a 29-inch hardtail mountain bike under 20 pounds and even a full-suspension 29ʼer under 23 pounds, making 29ʼers quite possibly the ideal bike selection!

Author: Cody Waite, Professional Triathlete & Coach
About Cody Waite:
Cody is the founder of Endurance Performance Coaching and is passionate about endurance sports. He has raced Ironman and Ironman 70.3 races, multiple marathons and half marathons, off-road triathlons along with winter endurance sporting events. He currently races XTERRA triathlons and mountain bike races at the professional level. Cody has been coaching endurance athletes since 2003 and continues to develop his own philosophies on training through his own training as well as those he coaches.