Understanding Brake Rotor Sizes: The Benefits of Larger Rotors at the Back

We've used this setup for mountain bikes since years. You're best off with the same sized rotors front and back. We think that having a big rotor at the front, and a bigger one in the back would be even better. Why?

You want to be sure that you can stop just as fast if you enjoy riding quickly. Mountain bikes disc brakes are often not up to par with the extreme loads they face. Manufacturers try to reduce weight by reducing rotor size and specifying lighter brakes. Comparing SRAM G2s with SRAM Codes we discovered that the SRAM code is the best option for nearly every rider. A few extra grams can make a big difference in performance, safety and fun. Fitting larger brake rotors can be a cheaper and easier way to boost the performance of your brakes.

A heavy rider on steep terrain is a bad combination

The brakes that come with most bikes are usually adequate for lightweight riders. If you weigh more than 80kg, and you frequently travel downwards for more than a few hundred meters, or longer, there is one more detail to bear in mind: the color of your brake rotors. Usually, the rear brake rotor is the one that gets to ‘take the hit.’ It can overheat and become discoloured after cooling. The front disc, on the other hand, usually maintains its silver color.

How do you brake really?

Many riders argue that they need more brake power up front. In principle, it's correct that if you brake hard before a turn, your front rotor will have a braking power of up to 70% and the rear rotor can only reach 30%. Short hard bursts of torque are not a problem; it is the braking force that causes the rotor to overheat. The brakes are the only mechanism you have when you’re cycling and you are on the downward slopes. This means that they must lose energy and turn the energy into heat. We use our rear brakes to keep up speed because the front wheel is easier to handle and can generate more cornering grip. Normaly, locking up the front wheel is not recommended unless you are doing a stoppie in order to raise your rear tire around a turnback. This constant friction causes the temperature to rise, which can lead to brake fade or discolored rotors.

Why bike brands don't like speccing large rotors

Large rotors are not without their disadvantages. They have an advantage in that they can deliver more brake power, but also build up less heat. The first is weight. Bike brands hesitate to sacrifice because a larger rotor weighs more and customers are still weighing bikes when buying a bike. ACCEBIKE has long held the belief that bikes should not be weighed. We have written about this. Large rotors tend to warp easily and cause rubbing pads. Dealers can face a serious problem if customers are constantly returning to their store to get the rotors straightened.

If all other factors are equal, switching from 200 to 220mm rotors will reduce the temperature of the brake pad by 39 degrees Celsius, resulting in an increase of 10% in the braking force!

Larger rotors for improved heat management

The braking surface increases by approximately 11% when you replace a 180mm rotor model with a new 200mm model. The increase in braking surface is around 11% if you go straight up to 220mm. The brake can dissipate the heat more efficiently. Weight difference is largely determined by the rotor. SRAM's 180mm Centerline rotor is 151g. It is 37% heavier than the 200mm version at 207g. However, there is only an 11.5% difference in weight between 200mm and 220mm. Temperature at the pad of a brake is an important factor when determining its stopping power. SRAM claims that the temperature decreases by 39 degrees Celsius when switching from a 220mm to a 200mm rotor in the same circumstances. According to SRAM, this 39degC reduction in temperature is responsible for 10% of the braking force.

The smaller the rotor at the front, better is its modulation

After choosing the right type of rotor, some of the issues you may consider include your weight, your riding style and the area of riding and cycling. And he added that someone always ends up buying the biggest rotors possible in his experiments. The relation upgraded itself from 200/180 to 200/200 and then upgraded to a 220/220 kind of relation. More massive rotors offer more power, but at the same time reduce the load on the forearms or shoulders because you don’t need to apply as much force to stop the bike. This allows you to be more active and ride for longer. The large rotors can make it difficult to modulate, but depending on your terrain, they may be overpowered. They decided to reduce the size of the front rotor because a powerful brake with four pistons and a 200mm front rotor is usually enough. Many of the forks currently on the market have not been officially tested with 220mm rotors. They struggle with these forces and creak. He rides with the 220 mm rear rotor and the smaller 200 mm front rotor.

More power, better modulation and additional tips

There are many other ways to increase the brake performance, besides choosing the correct size of rotors. For example installs sintered brake pads in the back and organic pads up front. The organic pads are easier modulable and have a better bite due to their soft structure. Metal pads are heat-resistant. Properly bedding-in pads is an important factor for increasing power, regardless of the rotor's size.

What companies offer 220 mm diameter rotors for sale?

ACCEBIKE is currently offering 220 mm and 223 mm ebike rotors. SRAM, Trickstuff, and GALFER are also available. It is essential to ensure that your frame and fork are approved and compatible with the size of the rotor before installing them. FOX's 38 fork (which we have already reviewed separately in) is compatible with 220 mm brake rotors.

Conclusion

We have ridden almost all brakes on the market and tried every combination of rotors you can imagine over the past few years.

• Many bikes are equipped with brakes which are not powerful enough. This is especially true for larger frames intended to accommodate heavier riders.
• You brake more quickly and harder at the front. The rear brake is dragged to control the speed and generates a great deal of heat.
• Upgrade to 220mm rotors for heavy riders or aggressive riders who use large wheels of 29.
• Powerful brakes are also beneficial for trail bikes. We would never use 200mm brake rotors unless you have powerful brakes like SRAM CODEs, or four-piston Shimano models.