About Disc Brakes on Road Bikes.
By Tom Demerly.
On Wednesday, April 13, 2016 online publication Cyclingweekly.com reported that the Union Cycliste Internationale or UCI, the international governing body for the sport of cycling, has “issued a suspension” on the use of disc brakes for professional road racing events.
The new sanction against disc brakes on road bikes follows a trial period of disc brake use by pro cyclists before their permanent approval for competition.
According to Cyclingnews.com this “second testing phase [would have permitted] every rider in a team to use disc brakes in 2016 and in every major race. This is expected to spark widespread use of disc brakes during the 2016 season.”
But today’s suspension of disc brake use in the pro peloton raises a few questions about disc brakes on road bikes specifically, and about cycling technology and its role in the consumer market more broadly.
The cycling industry is a consumer industry. It relies on interest in new products to drive bike sales. Every season new features need to be released to keep customers interested.
But not every new feature has an attendant benefit.
Some features are just… new.
To a degree disc brakes fall in this category, but only to a degree.
Let’s consider a balance sheet of disk brakes on road bikes:
Pros:
- Disc brakes remove the braking surface from the rim, allowing new flexibility in rim shape design.
- Disc brakes usually have better stopping performance in wet and dirty conditions than a rim brake.
- Because a bike frame designed specifically for disc brakes does not need caliper brake mounts frame designers have new latitude with frame design not available with traditional caliper brakes.
Cons:
- Disc brakes are heavier than caliper brakes.
- Disc brakes are more expensive than most caliper brakes.
- Disc brake equipped wheels take longer to change in a race-service setting.
- Disc brake equipped bikes are less tolerant of interchanging wheels from bike to bike; the brake disc spacing on the wheel must be exact for it to work on a given bike and this often varies from bike to bike. Caliper brake equipped bikes are easier to change wheels on.
- Disc brakes have different stopping power than caliper brakes. This can create different braking performance on group rides where some riders have caliper brakes and some riders have disc brakes, potentially creating a hazard.
- There are not as many wheel options available aftermarket for disc brake equipped bikes as there are for caliper-equipped bikes.
If you weigh both sides of the balance sheet you see that disc brakes offer some advantages, but not necessarily advantages in a professional road race setting.
As with aerobars, disc brakes are not well suited for riding in a group, especially if some riders are also using caliper brakes.
Aerodynamic handlebars are similar; in an individual, time trial and triathlon setting they offer proven performance benefits, but they aren’t optimal for use in mass-start bicycle racing.
The bike industry may not have ever intended disc brakes to be a replacement for caliper brake racing bikes. Instead, the disc-equipped road bike may have been targeted for an emerging demographic of recreational cyclist who rides in all-weather.
I use the word “may” because the cycling industry seldom plans such things, but rather throws new ideas against the consumer wall to see what sticks. The impetus is to constantly release something new, if not necessarily better.
Because consumers seem to want “new”.
Disc brakes aren’t bad. They stop a bike adequately in all conditions and better than caliper brakes in wet and dirty conditions. On mountain bikes, cyclocross bikes, dirt road bikes and randonee’/touring bikes ridden in bad weather they are better than caliper brakes.
Recall the time when suspension forks were installed on road bikes used for the cobblestones in Paris-Roubaix. The trend didn’t last, and riders quickly returned to mostly conventional road bikes with rigid forks and caliper brakes at Paris-Roubaix and in the other Spring Classic races.
Suspension forks didn’t go away. They found their own best application on mountain bikes and some recreational hybrid bikes. And there they remain, because they are a feature that provides a tangible benefit on those bikes.
Do disc brakes belong on road bikes? On some road bikes they do. Not all, and they are not a replacement for caliper brakes. If you ride by yourself on dirt roads and in wet conditions, disc brakes offer a benefit. But disc brake bikes aren’t a replacement for the caliper brake equipped road racing bike. They were never intended to be.
tomdemerly 
In this article, the author nicely brief in details about disk brakes on road bikes. There are necessary tips, resource, advantage, disadvantage for using disc brakes on the road bikes. The road bike user may choose the perfect brakes for their bikes.
Why are disc brakes so expensive? (about three times more expensive than equivalent mtb offerings)
Why don´t manufacturers make frames and forks that have fittings for both disc and caliper so that the riders can decide?
Hi Brendon, Thank you for these questions Sir, both of them are good. Disc brakes are more expensive than cable actuated caliper brakes because there are more parts to them, they require more steps to manufacture and assemble and install and they are relatively new compared to caliper brakes. As you know, “early adopters” of new(ish) technology are usually willing to pay a premium for the perceived “latest and greatest”. Disc brakes on road and triathlon bikes are relatively new compared to caliper brakes. That has also contributed to higher prices.
There are likely two significant reasons bike frames aren’t usually configured for both disc brakes and caliper brakes, one is cost. It would add expense to build a frame with both mountings, and it may not necessarily be a selling point to all customers. The second reason is that it would be somewhat unsightly (ugly) to have brake fittings for two types of brakes when only one type was installed on the bike, especially on lightweight road and triathlon bikes. It wouldn’t seem like elegant engineering.