A decent set of brake discs will improve your bike’s stopping power. If you ride a performance bike, the chances are the OEM discs are already very good and you’ll just be looking to replace them rather than upgrade. However, if you ride a budget bike, upgrading your bike’s brake discs will make a noticeable difference.
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The Different Types of Brake Disc
FixedThese are the cheapest brake discs to produce. As such, budget motorcycles and smaller-engined scooters are more likely to be fitted with fixed discs. They are made in one-piece, that is to say the rotor (braking surface where the brake pad makes contact) and the wheel mounting surface (sometimes also referred to as the hub, carrier or central rotor) are connected. These brakes perform well but the fact they can’t expand means they are more likely to warp or crack if subject to intense braking temperatures. However they are often coupled with brake calipers that are less capable of producing excessive stopping forces, therefore making warping in day-to-day use unlikely.
Semi FloatingBoth Semi-Floating and Fully-Floating brake discs are constructed in two parts. Often they are made with an aluminium carrier and a stainless steel rotor. The two are held together by rivets. When the brake rotor is subject to intense heating during the braking cycle, the rotor can expand in all directions and is free to do so as it isn’t directly connected to the carrier. Most of this expansion comes from the outside of the disc (larger diameter) expanding more than the inside and the floating nature allows this expansion. A 'floating' disc is less about its ability to be able to be 'wobbled' from side to side on its carrier.
Fully FloatingAs above, a fully-floating brake disc will allow greater expansion of the rotor. Also the fact the rotor can move on a fully-floating disc compared to a fixed disc means that the pads will be able to press directly against the rotors surface for maximum braking performance and as such, fully-floating discs are often used on high-performance motorcycles.
The Best Brake Discs for Road Riders
Brake discs that offer strong stopping power, feel and longevity. Perfect for road riders looking for improved braking performance over OEM brake discs.
Great stopping power, value for money
EBC’s X-Series brake discs are high-quality fully-floating discs which are a direct size for size replacement for OEM discs. The rotors are made from high-friction stainless steel and EBC claim they are up to 300g lighter per disc than the equivalent original discs. A great bet for all road riders and more than capable for trackday weapons as well.
Great stopping power from a trusted brand
Brembo is synonymous with racing and these top of the line brake discs are a great choice for both road and trackday riders. CNC machined, the rotors are made from high-grade stainless steel while the carriers are anodised aluminium. They’re the standard fitment for high-end Italian motorcycles and a great choice for fast road riders and trackdayers.
Brake disc jargon buster
Rotor – the surface that the brake pads clamp against to reduce speed
Carrier – the part of the brake disc that bolts to the wheel
Rivets – Used on semi or fully-floating discs to connect the two parts of the disc; the carrier and the rotor.
Rattle – This can occur or semi or fully-floating discs where the washers that couple with the rivets break or bend which can cause the disc rotor to move more than intended, causing a rattle.
Warping – This is when the rotor generates more heat than the material can carry without changing structure. The hot disc will warp when cooling, causing it to change shape.
Judder – Juddering is the feeling you get through your brake lever when the calipers are gripping onto a warped disc. This occurs on old discs where the material has been worn down or on discs that have warped. Older discs are more likely to warp as there is less rotor material to carry a given amount of heat and therefore the rotor will exceed its maximum operating temperature.
Brake disc thickness and the MOT
Your bike will fail its MOT if the discs are deemed too thin by the tester. There is no minimum thickness as all discs are different. However you are more likely to fail your MOT if there are defects in the disc, for example warping, cracks or scratches.
There is no set thickness that your motorcycle’s brake disc needs to be in order to pass, or indeed fail, an MOT.
According to the MOT tester’s manual, the following applies:
1.1.14 Brake discs and drums
A brake disc or drum must be significantly worn before you should reject it. Being worn below the manufacturer’s recommended limits isn’t a reason in itself.
Therefore it is down to the tester to judge whether your brake disc condition is a reason for your bike to fail. It is more likely that your discs will be picked-up by the MOT tester if they are heavily scratched, pitted, cracked or corroded to the point where the structural integrity of the disc is affected.
Brake discs only tend to become scratched or pitted if your pads are worn past their replacement markers, so that the pad’s mounting or backing material is then able to score the disc. Sometimes discs will crack from the edges of the perforation holes. These tiny cracks are caused when the disc expands and contracts and usually only occurs on worn discs where there’s less metal to absorb the heat generated while braking.
Checking brake discs when buying a second-hand bike
If you’re buying a higher mileage second-hand bike, it’s well worth checking out the brake discs. If the bike’s done more than 20,000 miles and it’s on the original set of discs, then the chances are you’ll have to replace them sooner rather than later.
If the bike’s a classic but with low mileage the discs may still be past best, possibly showing signs of warping pitting or cracking due to metal fatigue.
A quality set of discs can cost £300, so it’s worth factoring this in if you’re buying a ‘bargain’ bike, as consumables like this can soon add up.
How to check your motorcycle’s brake discs
Your brake discs will have a manufacturers-recommended minimum thickness. If you’ve never replaced the discs on your bike, consult your manual for guidance. If you have replaced your discs, then check out the manufacturer’s website. For most discs, this figure is between 3-5mm.
When measuring this thickness with a vernier caliper, make sure you’re not measuring the very edge (lip) of the rotor as this is unlikely to have been in contact with the brake pad as much as the central part of the rotor.
OEM Brake Discs – Are they better?
If you’re happy with your bike’s current brake discs, then there’s nothing wrong with going for a set of OEM replacements.
The chances are these original discs will be made by a well-known manufacturer – their logo and the part number will be printed on the disc (usually on the side that faces inwards).
If you do want to improve your brakes when you replace your originals, a set of aftermarket brake discs are a cheap way of improving braking performance.
Wavy vs Normal Brake Discs
Wavy discs originated in motocross where it was claimed the shape helped them remove excess dirt from the brake pads to maintain optimum braking.
They were popular on road bikes in the 2000s when riders chose to upgrade their discs from OEM to improve braking performance and they went for wavy discs as they liked the look.
You’ll notice hardly any racing teams use wavy discs, as race teams will have a maximum rotor size (usually 320mm) and the waves in a wavy disc remove metal from the rotor, which in turn means the disc has less ability to remove heat and therefore less braking power.
Some manufacturers fit a type of wavy disc as standard (Kawasaki’s ZZR-1400 for example) but this design is know as a petal disc rather than wavey as the difference in height between the peaks and troughs of the waves is minimal but the wave design is retained.
For road riding there will be next to no discernable difference between a wave and standard rotor, so if you like the look of a wavy disc, go ahead and buy some!
Brake Discs for Classic Bikes
Most classic motorcycles were fitted with drum brakes, front and rear. Only the very cheapest modern motorcycles have drum brakes and even then, they’re rarely seen on bikes over 125cc. Drum brakes don’t offer as much braking power as a disc-brake setup and drum brakes are often cable operated, rather than sing hydraulic fluid.
However some classic bikes have a single or dual-disc setup, similar to a modern motorcycle. You can buy OEM-equivalent brake discs for classic motorcycles, some of them using iron discs (as used on early disc-brakes motorcycles) while some use stainless steel. The vast majority of disc brakes for classic bikes are fixed discs, although some do fit floating dics for track-ready classic bikes.
What brake discs do they use in MotoGP?
MotoGP teams use carbon brake discs. These discs run with special calipers and brake pads and offer the maximum braking force, with less weight than a steel disc, no fade and no warping.
The cost for a set of discs and matching calipers is in excess of £15,000. You could buy a brand new Aprilia RSV4 RF for that. However even if you have the money, you won’t be able to buy these discs as Brembo only sell them to MotoGP teams.
World Superbike and BSB teams use stainless steel brakes. However if you want to get as close to MotoGP brakes as possible you could opt for a set of ceramic brake discs.
Ceramic discs have been around in the car world for many years. Supercars often come with ceramic discs but some performance cars like Audi’s RS6, Porsche’s 911 and BMW’s M5 have ceramic disc options. They have yet to be incorporated on a production motorcycle, probably due to their cost and the fact that power figures not braking performance sells motorcycles.
There is one company that makes ceramic discs for motorcycles: Braketech. However getting hold of a pair might be tricky, so it’s worth calling them to see what stock they have. They’re approximately 50% lighter than a stainless steel disc and not only claim better braking performance but they’ll also save unsprung weight, aiding the motorcycle’s handling.
But if you want MotoGP-style carbon brake discs, you’re out of luck.
- In the first stages of braking make sure you transfer the weight of the bike over the front wheel by braking progressively. If you just grab a handful of brakes, even with ABS fitted, you won't be able to brake as hard as you would if you allowed the bike's weight to help push the front tyre into the road surface.
- Get the bike upright to ensure you have the tyre's maximum contact patch gripping the road, to reduce the chances of your tyre losing traction.
- Change down the gears to ensure there's engine braking helping to scrub off speed.
- Practice braking with the rear brake as well. Applying the rear brake helps keep the bike more level, meaning you can brake harder with the front and not end up going over the handlebars.
Motorcycle Brake Disc Manufacturers
There are lots of brake disc manufacturers on the market. If the EBC and Brembo offerings above don’t float your boat, then why not take a look at the following brands that also produce discs for a wide variety of motorcycles.
ABE – UK firm that makes discs for hundreds of bikes. Especially good for older models.
Armstrong – Specialise in wavy brake discs.
Brembo Brake Discs – Quality high-end discs that are fitted to most superbikes.
EBC Brake Discs – Arguably the UK’s most popular motorcycle brake disc manufacturer.
Ferodo – Far better known in the car world than in motorcycles but a quality brand none the less.
Galfer Brake Discs – Famous for their wavy brake discs, Galfer are quality items.
ISR – Swedish brake specialists and manufacturers of calipers, discs, and brake lines.
JT – They only produce brake discs for motocross bikes.
NG – Spanish company, supplies some Moto2 teams and is German TUV certified.
SBS – Arguably better-known for their brake pads than discs but they produce a wide range.
Tsuboss – Greek motorcycle disc manufacturers who specialise in wavy discs. All products are German TUV certified for quality.
Highway Code Braking Distances
The Highway Code’s stopping distances were established in the 1970s, so you’d be forgiven for taking them with a pinch of salt. Modern tyre technology, more powerful brakes and ABS have all helped reduce the distance required to stop your motorcycle.
The Stopping Distance is comprised of the Thinking Distance and the Braking Distance. You could argue that while the Braking Distance for cars and bikes has reduced over the years, the Thinking Distance might well have increased due to people paying more attention to what’s going on inside their cars these days, rather than outside of them.
Official Highway Code Braking Distances
20mph – 12m / 40ft
30mph – 23m / 75ft
40mph – 36m / 118ft
50mph – 53m / 174ft
60mph – 73m / 240ft
70mph – 96m / 315ft
Only a fool breaks the two-second rule. This saying was part of a UK Government’s advertising campaign more than 20 years ago and it referred to the thinking distance. If you’re sat right up behind another car and they suddenly brake, you might have better brakes but you’ll have next to no thinking distance.
Comparing the Highway Code to real-world figures
The world has moved on since the Highway Code’s Stopping Distances was introduced. To give you an idea of how a modern vehicle stacks up, check out these figures for approximate stopping distances from 60mph, which includes the 18m Thinking Distance:
Highway Code: 73m / 240ft
Honda Accord: 59m / 193ft
Harley-Davidson Electra Glide: 63m / 206ft
Ford Focus ST: 54m / 177ft
Kawasaki ZX-10R: 57m / 187ft
Audi R8: 47m / 154ft
If you’ve ever been unfortunate enough to have a car anchor-on in front of you, you’ll know that, on a motorcycle, it takes a lot of braking force to not run into the back of the car.
Also as a general rule, the Braking Distance at 80mph is almost double that at 60mph.
Brake Disc FAQs
What else can I do to improve my brakes?
If you want more braking power and more bite, then upgrade your standard brake hoses to braided lines. Braided brake lines are stiffer than standard lines and transfer more fluid to the brake pistons compared to standard brake lines which have a slight amount of bulge when you brake hard.
Can I fit the same brakes as MotoGP riders use?
No. Brembo only sell their MotoGP products to official MotoGP teams. If you want to source them yourself, you’ll need to have the right contacts.
Do I need to use the same brand of brake pads?
You don’t have to, although most disc manufacturers will recommend a pad to go with their disc, for your type of riding. Different pads will react differently to different discs but you are free to use any brand of pad with any brand of disc.
Thanks to the following websites which helped us research and write this article