take a beating. If you look closely at the inside edge (biting edge)
of a worn front tire’s shoulder knob, you can usually see excessive
wear and likely chunking (cracking) starting at the base of the
shoulder knob. Most people don’t even notice this because they are
only focusing on the remaining tread depth. This type of wear has a
huge effect on front tire traction and steering.
MBA: Obviously, MTB tires affect ride quality. How would you
recommend riders experiment after they burn down their stock,
original-equipment tires? How should they evaluate their current
tires and upgrade them?
FS: I always say, “Right tires for your terrain.” In many cases,
the OE tires may not be the proper tread for the terrain where the
rider lives, so the rider will need to determine what terrain he or she
rides and then select the tread that best suits that terrain.
The other is the casing structure/rubber compound. An OE tire
may have the tread pattern that works in the rider’s area, but the
casing structure and rubber compound may not be the best option
for their riding. The casing structure (i.e., ply material, cut/puncture
resistant layers and rubber compound) completes the “recipe”
when making a tire. The proper casing structure is very important
to achieve a high level of durability.
My suggestion is to invest in a stronger casing structure to get
the most out of your tire’s performance and improve durability.
Upgrading the casing structure may add some weight, but in the
end, the rider will be happier. Stronger casing structures allow
for lower tire pressure and thus more traction, stiffer sidewalls to
minimize tire roll-over when cornering, improved tire sealing when
running tubeless and extra rim protection, all adding up to a win-win.
MBA: Which is fastest—high volume, low weight, low tread
pattern, better traction or all of them?
FS: We have ongoing tests to prove these types of things,
especially with the movement to wider rims and plus tires. Here are
a few things we’ve determined so far:
—Higher-volume tires and/or heavier tires, once they are in
motion, have almost equal rolling resistance (within a few watts)
compared to a lightweight tire when all other things are the
same—same tread, same size, same casing structure, same
compound, same rim, same inflation pressure, etc.
—Low-tread-depth tires almost always roll the fastest.
—Better traction (using the same tread pattern and size)
typically means the tire has a softer rubber compound. If you have
two identical tires—one with a harder rubber and one with a softer
rubber—the harder rubber typically will roll faster.
I’d like to mention that most tire brands test rolling resistance
one of two ways (both provide usable data):
—Rolling resistance can be tested in a laboratory using a large
rotating metal drum and attaching a wheel/tire assembly to roll
against the drum. This measures the contact area friction in watts.
—Rolling resistance can also be tested by riding the bike on
pavement using an SRM crank. This also measures contact-area
friction in watts.
MBA: Why do the most expensive tires wear down so quickly?
FS: Typically, these tires use high-quality, high-traction rubber
compounds. If you want them to grip at a high level, they’re going
In the pits: Frank Stacy working with Trek racer and World
Cup champion Rachel Atherton of Trek World Racing, cele-
brating the right tire choice for the day.
No matter which
style of riding or tire
size you prefer, the
Bontrager line of
tires, heavily influenced by Frank
is available to
hit the trails