Can You Put Mountain Bike Tires On A Road Bike?
A lot of people all over the world use their road bike off-road. But the first change you have to make, is to fit more grippy tires. Since mountain bike tires offer a lot of grip on loose surfaces, you might wonder: can you put mountain bike tires on a road bike?
You can’t put mountain bike tires on a road bike. There is not enough tire clearance and the rims are not compatible with the wide mountain bike tires. However, if you are in need of more grip for using your road bike off-road, you can convert your bike into a gravel bike and fit gravel bike tires.
In this article, we’ll go through the limitations of putting mountain bike tires on a road bike. After this, we’ll look at some tips and tricks to make your road bike off-road compatible!
Can You Put Mountain Bike Tires On A Road Bike?
The short answer to this question is simple: you can’t put mountain bike tires on a road bike. Factors that prevent this are tire clearance and rim compatibility. Let’s go in depth.
If you want to read more about the difference between a road and a mountain bike, have a look at my article: How To Convert Mountain Bike To Road Bike.
Tire Clearance: Frame And Brakes
Road bikes are aerodynamic and lightweight. To achieve this, a road bike has very narrow tires and as little clearance as possible between the tire and frame/fork. Ordinary road bikes have the narrowest tires; endurance bikes have slightly wider tires.
The width of a road bike tire is generally between 23-32 mm. A mountain bike tire on average, is between 2.25-2.5” wide, which translates to 57-64 mm. Not only the width of the mountain bike tire is a concern, but the outer diameter is also too big to fit a road bike frame.
There are additional clearance issues when you attempt to put bigger tires on a road bike equipped with rim brakes. The design of the braking system may lead to the tire coming into contact with the rim. It’s important to mention that this only applies to older road bikes. Newer bikes have disc brakes for more stopping power. However, you would still run into clearance issues when it comes to the frame.
Rim Compatibility
Even if there would be enough room on your road bike to fit a mountain bike tire, you’d still run into problems. First, let’s compare the tire size measuring system of road bike tires to mountain bike tires.
Road bike tire sizes are defined differently from mountain bike tires. A road bike typically uses ‘700C’ tires. This term originates from an old French measuring system that is now considered outdated. However, the bike industry has retained the term, and it refers to the wheel diameter. The width of the tire is then specified in millimeters, as seen in the notation 700Cx23.
The sizing in mountain bike tires is essentially the same but in inches. The designations 26”, 27.5”, or 29” actually refer to the outer diameter of the inflated tire. Among these, 27.5” and 29” are the most common rim sizes nowadays. The width of the tire is specified in inches; for example, 29×2.4 inches.
If we combine the two measuring systems, a 700C and a 29” tire would theoretically fit on the same diameter wheel. Similarly, a 650C and a 27.5” tire could also be considered compatible. However, in practice, a mountain bike tire doesn’t fit on a road bike rim. The rim bed, which is the space where the tire bead sits on the rim, is typically too narrow for a mountain tire.
Switching to different rims won’t solve the problem as there isn’t enough tire clearance.
Convert Your Road Bike Into A Gravel Bike
We’ve established that’s it is not possible to put mountain bike tires on a road bike. But to be honest, you don’t need mountain bike tires if you are in need for more grip. Knobby mountain bike tires are overkill and a road bike isn’t set up for mountain biking. But there is a good alternative.
The way to go is to convert your road bike into a gravel bike. To the untrained eye, a gravel bike might appear as a road bike with off-road tires. However, upon closer inspection, there are notable differences, including frame geometry and tire width (and clearance). Rather than investing in a new bike, you can make a few changes to your existing road bike if you want to use it off-road.
Gravel Bike Tires
The first step is to fit the widest tires possible. For an ordinary road bike, you will be looking at probably 28 mm. On an endurance bike with disc brakes, you can go up to 32 mm. For context: gravel bikes can fit tires as wide as 40-45 mm.
Frame Protection
With using your road bike off-road, comes some abuse to your bike. Stones will chip your frame and the chain may damage your chainstay by slapping onto it occasionally.
To protect your pride and joy, the second step is to wrap it in frame tape (or helicopter tape). There are also pre-cut frame wraps available on the market, but they are a bit more expensive. Pay special attention to the down tube, chain stay and behind the seat stay.
Additionally, you can get rubber bumpers for over the end of your cranks to prevent them from getting chipped.
Changing The Cassette And Chainring
If you are going to use your road bike as a gravel bike quite often, you might find that the gearing is not suitable for the purpose. The cassette of a road bike has less teeth, and is built for high speeds. Gravel bikes have a much wider gear range to be able to conquer steep climbs.
The third step is to look into changing to a cassette with a wider range and/or switch to a smaller front chainring.
Changing The Wheels
Although road bike wheels are very robust, they might get damaged if you hit a rock. You can often repair dings in aluminum wheels, but carbon wheels are usually not repairable. To replace a carbon wheel, you have to spend a lot of money.
That’s why the fourth step is advisable: get a second set of wheels, preferably in aluminum. Put gravel bike tires on the new set, and road tires on the original ones.
Switch To Mountain Bike Shoes/Pedals
The fifth and last step, is to switch to mountain bike shoes and pedals. The design of the pedals as well as the shoes, is more suitable for off road use. The pedals are less likely to get clogged up with dirt, and the shoes are great for walking. Walking on your road bike shoes will scratch the sole and damage the cleat.
