Rim brakes are still king right now, but disc brakes are the future declares Zipp

One of the big debates in professional cycling this year will revolve around disc brakes. As you know, the UCI has extended the short disc brake trial it allowed at the end of last season for the entire 2016 race calendar, allowing any rider and team to race a bike with disc brakes whenever they want.

So will we see the entire peloton switch over to disc-equipped road bikes at the Tour Down Under later this month, the now traditional curtain-raising event on the pro calendar?

It’s unlikely. The majority of the teams don’t even have a suitable disc road bike and any team sponsored by Campagnolo doesn’t even have a disc brake it can use, even if it had a suitable bike to fit them too. So that means most will still be racing rim brakes for the foreseeable future.

Which leads Zipp wheel product manager Jason Fowler, in an interview on the Zipp website, to concluded that “...the rim brake is still king for road bikes at the moment.”

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That’s despite the fact we’ve seen disc road bikes flood the market in the past couple of years.

“This has been partially limited by the number of disc brake bikes available. However, with more disc brake bikes coming to market each year, we expect to see a big jump in the next one to two years,” adds Jason.

So choice, or lack of it, is the hurdle for any team or rider wanting to make use of disc brakes at the moment. Aside from choice, there are of course many well-documented arguments against disc brakes, and one of the common lines we hear against the use of disc brakes in the pro peloton is the aerodynamic issue. And the drag difference between a regular race bike and one with discs is quite significant.

“Current road disc brake setups create more drag than rim brakes, and the difference is on the order of 6-9 watts at 25mph,” explains Zipp Advanced Design Engineer David Morse.

That’s largely because the first systems, from Shimano and SRAM, owe a lot to the mountain bike disc brakes that both brands produce. It’s partly why Shimano and SRAM have been so quick to market, and why Campagnolo, which doesn’t make mountain bike groupsets and so has less experience with disc brakes, has been slower than its two rivals to market a road disc brake.

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“All of the disc-brake hardware found on road bikes is more or less a “copy-paste” from the MTB realm, which is a great starting point – that hardware is already excellent at stopping your bike and improving control. The drawback is that it isn’t focused on aerodynamics,” adds David.

But the next generation of road disc brakes could be better optimised for road bikes, and possibly reduce, or eradicate, the aerodynamic disadvantage at present. If you’re a sprinter like Mark Cavendish, you’re not going to be interested in a bike that produces more drag at high speeds are you? There have been some big aero developments in recent years as well, with aero frames, helmets, handlebars and wheels no common sights in the peloton.

“As road disc brakes become more popular and mainstream, road disc-brake setups will have to stray a little bit from their MTB heritage in order to tailor a product that offers matching or superior aero performance and better braking performance than rim brake options,” concludes David.

One of the benefits often flagged up for disc brakes, however, is the opportunity to improve wheel technology. With the brake system moved to the hub there’s no longer any need for a brake track. So could the rim be made lighter and overcome some of the extra weight with current disc brake systems? Zipp’s David Morse thinks so.

“The choice of resins used in a carbon rim is made much larger if the structure of the clincher hooks does not have to deal with high braking temperatures. This opens up the potential to increase strength and decrease weight by sourcing resins that have excellent strength and toughness properties but otherwise were not suitable for rim brake wheels because they lacked the tolerance to high temperatures.

Make no mistake, SRAM as a company is committed to disc brakes on road bikes. You don’t need me to tell you that. “The road bike sector is seeing a shift to a relatively uncharted braking technology, which is exciting for the fact that we have an opportunity to drive road disc-brake evolution and improve on the current shortcomings,” declares David.

“Down the road, we want to be able to allow the end user to make a win-win decision when they switch away from rim brakes. We’re headed that direction as fast as we can.”

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