The rim brakes versus disc brakes debate for road bikes has been raging for almost half a decade now, but it has recently changed its course. It is not so much a debate anymore, rather a rider-by-rider preference. However, whether you like it or not, due to the fact most manufacturers are kitting their road bikes out with disc brakes, it’s a battleground you will have to enter when you next go shopping to indulge the n+1 formula.
Before we get on to the nitty gritty, let’s have a refresher of the two types of brakes. Rim brakes are the more traditional style: a caliper mechanism attached to the frame (or fork) at the top of the wheel houses two brake pads, and the braking force is applied to both sides of the rim to slow it down. Disc brakes work the same with a caliper and brake pads but are situated at the centre of the wheels and focus the force on a smaller separate rotor. Traditionally used on mountain bikes, they are now becoming the industry standard for all types of bikes.
As you’ll see from our recap, the first and most obvious difference is aesthetics with one being a unit on the top of the wheel and the other being a separate rotor in the centre. The main functional differences though, are where the braking force is applied and how the systems are operated. Rim brakes use cables to close the caliper on the rim, and while disc brakes can also use cables, the more reliable superior varieties use hydraulics. When you pull on the levers, the fluid builds and causes the pistons inside the brake to move the pads against the rotor to slow the bike down.
Bike manufacturers haven’t made the switch to disc brakes without reason – there is plenty of evidence to back up the choice. At first there was resistance to the look of road bikes equipped with “mountain bike brakes”, but over time the aesthetics have improved – that or we’ve got more used to seeing them at club runs and bike races. The main advantage of discs over rim brakes is that they offer greater stopping power. A rider can apply less pressure on the levers which reduces muscle fatigue on those long descents. This power also makes you slightly faster as you are able to brake later, meaning more time at high speeds and less time slamming the brakes on a long way from a corner.
The braking is also more consistent – at least once you’re used to them – meaning that over time you’ll develop an understanding of exactly how much pressure to apply for the desired degree of braking at different times and under different conditions. This is less consistent on rim brakes as the cables and pads start to loosen and wear.
Then there’s the question of weather conditions and unforeseen damage mid-ride. On rim brakes there is often a slight delay in braking performance in the wet as the pads have to first displace water on the rim. In comparison, due to the position of the rotors at the centre of the wheel and away from road, discs perform better in wet conditions. The units are more self-contained than rim brakes too, so performance is largely unaffected although more caution is always advised. Rim brakes are also massively affected if your wheel is even slightly buckled as they will catch on the bend with every rotation. This is not such an issue with disc brakes as the unit is well away from the rims so you can make do for much longer – this is particularly useful if you’re on a bike tour.
There is a long-term cost benefit with the use of disc brakes too as your rims do not sustain any wear or damage. Over time, rim brakes will wear a wheel, tire and inner tube much quicker than disc brakes as the combination of grit and heat build-up causes damage to the rim surface and puts greater pressure on the structural integrity of the whole wheel. Disc brakes also offer greater clearance so you can run a wider tire, giving increased grip on the road and improving rider comfort.
As we’ve previously mentioned, disc brakes are fast becoming the industry standard, but that doesn’t mean rim brakes are now obsolete. There is ongoing debate in the professional ranks with INEOS Grenadiers choosing to stay on rim brakes, and the last time we checked they aren’t half bad… The main advantage of rim brakes, and the reason many choose to keep them on their climbing bikes, is that they are the lighter system. They’ve also been proven to be more aerodynamic on test. When properly maintained and well set up, rim brakes can perform just as well as discs which is why when it comes to shaving weight off your road bike, the traditional system is the better option.
Another huge advantage is that on the whole, bikes that are equipped with rim brakes cost less than their disc-ready counterparts, and although disc brakes generally last longer than rim pads, the replacements are more expensive. Furthermore, rim brakes are far easier to maintain, adjust and check on a daily basis. Disc brakes are sealed units so if something goes wrong it’s more than likely the bike will have to go into the shop for the brakes to be bled. This is a long and costly process compared to a simple caliper adjustment, and it’s especially pertinent if the system needs a quick repair mid-ride – if you watch the pros, especially during the classics, you’ll have seen the sometimes painfully slow changeover of disc wheels. With cheap, widely available parts and brand compatibility, if you’re in the middle of a bike tour and having brake issues that need immediate attention, it may be worth sticking to the old faithful.
Although disc brakes are the newer option, the latest rim brake systems on mid- to high-end bikes are better than they have ever been. This means that they can produce just as much stopping power as disc brakes when properly maintained. Some riders in other disciplines like gravel and cyclocross actually prefer to have modulation and a less consistent braking force so as to adapt to the change in surfaces.
The choice is a personal one at the end of the day, but the points we have touched on above should help to inform your decision. If you’re unsure, it is best to stick with what you know, whether that be disc or rim brakes, as that will more than likely be the best fit for you. However, if you’re in the market for a new bike and have never tried disc brakes, don’t be too quick to dismiss them – maybe look for a chance to take a disc-equipped bike for a test ride. While they may cost more, the reason so many bike manufacturers are prioritizing their use is that they offer more control, stopping power and wet weather reliability and thus are safer for the average rider.