I’ve seen lots of misconceptions about mountain bike tires and tires in general. I can understand people trying to think outside the box, but most skip the point of learning the basics first. My personal opinion is that setting tires up properly is essential for any serious mountain biking. I often tell customers at my bike shop that going after expensive derailleurs and stuff like that is worthless unless you already have a perfect pair of properly set up tires and a good suspension. At the end of the day, that is what makes mountain bikes great.
Are MTB tires directional? How to pair MTB tires? Can you run MTB tires backward? Those are some of the questions I usually get from customers looking to make their bikes better at specific riding goals.
Are mountain bike tires directional?
Mountain bike tires are directional. Tire knobs are designed to give proper grip in one direction and allow decent rolling resistance in the other direction. Tires should be mounted as shown with the directional arrow on the sidewall to achieve the best riding performance.
With that being said, there are situations where you want to invert the rear tire backward. To answer when you should do this, we must go into details a bit.
Does Rotation Direction Matter on Bike Tires?
Of course, the rotation direction on mountain bike tires matters a lot. If you see tires that don’t seem to have a direction indicated and the tire pattern doesn’t seem to differ in each direction, those are bad tires, and they most likely won’t perform well on the trail.
When looking from above, the tire pattern is made to resemble sort of a v-shape towards the front. If not the v-shape, some knobs should have some v-shape or be ramped up towards the front while 90 degrees cut on their backside. What this does, is when the tire is touching the surface, the direction is reversed. The ramped-up knobs and v-shape are now pointed backward to ease up on rolling resistance and make you faster while increasing grip in the front direction. Especially when braking, now the rear end of the v-shape that touches the ground can increase tire-to-ground friction.
If you are not sure which is the right direction, remember that you can always see which mount gives more grip on the tire when you are holding the front brake and trying to push the bike forwards with your hands. The proper tire direction should better grip the surface and even prevent you from pushing the bike altogether on a hard surface.
I believe this to be the general logic behind any bike tire. However, while always the same in the front wheel, a rear-wheel can sometimes require the opposite logic. The situations in which this is true can be a little complicated to distinguish, so I want to explain some differences first.
Tire Requirements And Directions for Different Types of Bicycles
The tire direction and difference between slick and knobby don’t equally apply to all types of riding. I think this is best explainable when looking at riding on pavement versus riding on a trail. The logic is always the same, but there is something called diminishing returns that comes into play.
For example, a bike tire used on a dry road will have very little grip difference between being slick or having big knobs. This is because asphalt is purposefully made to achieve good grip with slick rubber. Therefore mountain bike tires have diminishing returns in increasing the bike’s overall grip while greatly increasing rolling resistance and slowing you down.
On a loose surface like your average trail, a bike tire has diminishing returns in increased rolling resistance with added knobs while greatly increasing grip.
I’m even explaining this quite an obvious thing because most people I encounter don’t have a good estimate of what’s worth and what is not. In other words, when playing around with tires, my customers usually want to spend an unnecessary amount of money because they believe it will result in something spectacular. The bad thing for my employer is that I’m usually honest, and I stop them from wasting money. They often want slicker tires for trails thinking they will get so much faster, while it’s proven by numerous tests that you barely gain a percent or two in speed while losing a massive amount of grip and braking power.
Can You Run Mountain Bike Tires Backwards?
When I’ve mentioned how diminishing returns work on bicycle tires, I can answer some of the more frequent questions on this topic.
Is running mountain bike tires backward okay?
Running mountain bike tires backward is okay only for the rear wheel. It can be used when there is a need to slide the bike’s rear end in corners and add extra torque on climbs. The cost of running the rear tire backward is reduced braking power and increased rolling resistance.
I consider this possible because when looking at two different trails, the surface can be quite similar, while the usage of those trails can be absolutely different. Because of this, you can sometimes ignore the diminishing returns you get by greatly increasing rolling resistance on the rear tire to add a bit of extra torque and playfulness to your bike.
To add a bit more detail, I would say this is applicable only when both tires are the same or have the same rotational logic. You will see that some tires are made to apply backward logic for the rear tire. That’s why you will see the same tire model in the front and rear versions.
The best and most known example is the Maxxis Minion II tire which comes in the DHF version for the front and the DHR version for the rear wheel. I noticed that this reverse logic is usually already applied on most downhill tires because the grip reduction on the rear tire is minimal due to knobs being massive and thoughtfully placed.
If you are using some toned down trail tire like Continental Mountain King or Trail King, you might want to test reversing the rear tire because, by default, they will be of the same properties for front and rear. These are made to apply less rolling resistance with a really decent grip where both tires achieve the same goal. They are great for casual riders, but I find them perfect examples to test putting the rear tire backward for more advanced riding techniques.
Directional Mounting Mountain Bike Tires
Directional mounting tires use the same tire but are made specifically to put in two different directions, front, and rear. The most known example is the Schwalbe Smart Sam tire.
They use the same logic I explained above. Some trails like more advanced cross country trails or just an average mixed trail can benefit from this type of directional logic for advanced riders.
If you think about it, that’s why almost all downhill tires use different tire models rear and back with this same logic applied to them. They expect downhill riders to be advanced enough in their skill to benefit from this while having no drawbacks. And this is basically how you can apply it on more casual bikes and trails.