How Long Do Road Bike Rotors Last?
Disc brake rotors on a road bike usually last so long that most riders (certainly at first) treat them as buy-and-ignore components. However, if you are achieving 50mph+ down a decline in a race, you’ll give a lot of thought to your braking system, which is why most manufacturers provide a minimum recommended thickness for their rotors.
Manufacturers of road bike rotors usually specify at what thickness to replace their rotors. Longevity depends on several factors:
- Braking style
- Rotor quality
- Environmental conditions (Dust, grit, water, ice, salt on the rotor)
- Amount of usage
The rotor lasts 2-4 years for the average rider.
The last thing you want to be preoccupied with in any race is your ability to stop as desired, and cycling is no different. Your bike’s rotors (or discs) are only rated to a certain thickness before they start to degrade and eventually fail. Shimano rotors, for example, are fitted to the bike at 1.8mm thick, and the bike giant recommends replacing them when the rotor’s braking surface has thinned to 1.5mm.
When Should I Replace My Road Bike Rotors?
Different manufacturers make different suggestions in this regard, but a good rule of thumb is to replace the rotors when a maximum of 15% thickness has been lost by braking. Tardiness in this regard can spell disaster!
How To Tell If Your Rotor Needs Replacement?
- Scoring on the rotor’s surface– Brake pads scraping against the rotor indicates that the rotor is scored and no longer smooth, which can cause failure.
- Cracks around the breather holes in the rotor – small cracks are not an issue, but they never remain small, so keep an eye on any deterioration.
- Warping – If you see any sign of warping, it’s time to go shopping for a rotor.
- Grind or screech – If you hear this type of noise when braking, there is a possibility that a foreign object has been trapped between the pad and the rotor, but it’s worth checking out.
If unsure, take the bike to your local bike shop for an expert appraisal.
Areas Where A Rotor Is Unexpectedly Damaged (Not Worn)
- Rotors heat up, and they are more prone to bending after a hard ride than when cold at the start. Any accident at this point might result in a bent rotor, so check carefully for damage when you get home.
- Placing any weight on top of your wheels when you transport your bike in a car boot is a bad idea. When the rotor is hot, this bad idea can cost you some hard-earned cash, as the chances of bending the rotor increase with temperature.
As an experienced cyclist quipped on a forum in the UK, a bent rotor makes the best windchime…
So-called ‘Floating Technology,’ where different materials are incorporated into the rotor, can help combat heat build-up. Take Shimano’s 160mm Ice Tech Brake rotor selling on Amazon for U$51.22, for example: Made of aluminum and stainless steel, the rotor promises to lower the operating temperature and resist power fade.
What Is A New Rotor For My Road Bike Going To Set Me Back?
U$25.00 – 90.00 is what you can expect to pay for a new rotor. These items are not cheap, but neither is medical care and all cyclists, regardless of skill level, know the importance of stopping when they need to. You can get decent rotors for as low as U$10.00, but remember; you get what you pay for.
What Happens If You Don’t Get Rotors Replaced?
If you fail to replace the brake rotor when necessary, you risk some form of brake failure, and no matter how slight, this can lead to an accident. The brake rotor absorbs heat and dissipates heat when the brakes are applied.
With a large amount of usage, the rotor thins, as discussed, resulting in more heat absorption taking place than it can release. Heat applied to metal can result in metal fatigue and warping – and in this case, a potential disaster.
Is Bigger Better Where Road Bike Rotors Are Concerned?
It seems logical to assume that since a thinning rotor (disc) heats up more quickly than it did when new (and thicker), a larger rotor should have the opposite effect, at least up to a point:
Larger Rotors For Improved Heat Management
If you take a standard 180 mm rotor and exchange it for a 200 mm model, you have an increased surface area of close to 11%. Go bigger and fit a 220 mm rotor, and the surface is now almost 25% bigger than the original.
Suddenly, the heat dissipation is far better and may add months to the rotor’s life before you need to replace the part, but there is always a downside – weight.
A larger rotor will naturally weigh more, requiring more energy to accelerate and stop. Still, the increase is minimal, and many experienced cyclists believe the improvement in braking and added longevity to the rotors is worth the effort.
Thicker Rotors Will Last Longer
A thicker rotor will naturally take longer to wear and will also be a little heavier. Not all manufacturers have the same thickness of rotor, and of course, calipers must be made to the correct size for the rotor. One example is Tekto: Their TR180-16 is 1.85mm thick as it rolls off the production line, and the TR180-17, which at 2.3mm, is almost half a millimeter thicker.
Conclusion
Brake rotors are an easy item to forget or ignore, much like the occasional pain in your chest, which you put down to climatic conditions or diet and avoid discussing. However, if you ignore these intrinsic parts for long enough, either one might send you to the ER via ambulance.
Take care of both, and never ignore warning signs. In the case of your brake rotors, they need to be replaced from time to time, and regular checking will ensure this is done timeously.
