The Dennis Kirk Blog
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When it comes to receiving attention, brake rotors tend to take the back burner. Riders are more concerned with how fast their bike can speed up, not how quickly they can slow back down. But still, after enough miles and years, all riders find themselves faced with the same task: Changing their brake rotors. If it’s your first time changing your motorcycle brake rotors, you have likely been left with some questions. Luckily, you are in the right place! We’ve taken it upon ourselves to predict what questions you might have and answer them before you even have to ask.
There are a couple ways to tell if you need new brake rotors. One way would be to test while you are riding, and the other is a simple test in your garage. We’ll give you a rundown of each.
If you found out you need new brake rotors while riding, it was likely because your brakes started pulsing. When brake discs are overheated, they will warp. This warping means that your brake pads can’t apply even pressure all the way around your brake disc, and the result is a brake pulsing that is both annoying and dangerous. If your brakes are pulsing, it’s time for a new rotor.
The second way to determine if you need new brake discs would be to simply get down and have a look. You’ll be checking two things: rotor thickness, and the surface quality of your brake rotor. All rotors have a designated minimum thickness, and by checking this with a micrometer or caliper, you’ll be able to tell quickly and easily if your disc is thick enough. It is important to remember that your brake pad doesn’t touch the outermost edge of your disc. This means that the outermost edge won’t be worn from your pads, so you will need to measure the middle of the disc where the brake pad touches to get an accurate measurement. When checking the surface quality of your brake rotors, you’ll be looking at the surface where the pads have been creating friction. You are looking for irregularities. It’s normal to see tiny grooves or lines, a tiny amount of texture on its surface, but any grooves or nicks that are too prominent should be considered a red flag.
As the name suggests, these rotors are made of a single piece of metal, usually billet steel. They are typically drilled or slotted for ventilation, and they are the cheapest option on the market! They are also the heaviest and the most prone to warping. But, this doesn’t mean that they couldn’t serve you well. Casual riders looking for an affordable brake disc will be perfectly happy with a one piece rotor, as long as they aren’t too hard on it.
Two piece rotors are for more performance-concerned individuals. Construction might vary, but generally, they start as a single piece of billet steel that makes up the outer ring of the rotor. The interior is made up of a lightweight aluminum, which is connected to the outer ring of steel with rivets. This design helps cut weight, and is great for those that are concerned with keeping their bike as light as possible.
This design is also utilized in floating brake discs, which can be considered the top of the line when it comes to motorcycle brake rotors. They utilize special rivets that allow the outer ring to expand freely when heated, eliminating the problem of warping. Floating brake discs are considered the best design in terms of performance, and if you’ll be riding hard, you’ll definitely want to invest in floating brake discs.
In short, it depends. If your brake pads are still quite new, and they are worn evenly, you shouldn’t have any troubles putting them on with your new rotors. They will perform just fine once bedded in. However, if your brake pads have been ravaged by your previous rotors and have been left uneven and gouged, you are best off starting fresh with new brake pads to ensure even wear patterns and maximum performance.
Bedding your brake rotors and pads is extremely important. Your new brake pads and rotors might feel smooth under your fingers, but they are actually covered in tiny little ridges and grooves. The bedding process helps synchronize these surfaces so that your rotor and pads are sitting perfectly flush, creating the most friction and stopping you as quickly as possible. The bedding process heats your brakes and spreads a thin layer of brake pad material across your rotor. Not completing brake bedding process can result in uneven distribution of brake pad material, which can result in brake pulsing. We’ve dug deeper into the topic, and taught you how to bed your motorcycle brakes here.
Well folks, there you have it. We’ve taken a crack at answering your questions before you could even ask, and with any luck, you’re feeling at least mildly impressed by our foresight. If we didn’t do as well as we thought and we didn’t answer your question, or if we left you with some new ones, post them in the comments below! We’d be happy to give you our two cents on your rotor-related questions.
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