Wednesday, February 15, 2012

Give me a brake...

In case you've been under a rock or all of your communication to the outside world is via carrier pigeon, you might not be aware that besides a certain Spaniard being stripped of his Tour De France title, the interwebs are rife with speculation about disc brakes coming to a road bike near you. There's been enough confidential information leaked (which grates my nerves and there may be something from these pages on that later) to know that disc brakes for road levers are coming to SRAM and Shimano's road groups for the 2013 model year.

I've got a couple of thoughts on this. First, just because they are coming out within a company's group that has traditionally been a "road" group, that doesn't mean they will show up on road bikes. Road components have been traditionally used on cross bike. It's my thought that they will show up sparingly on cross bikes first.

Second, disc brakes for road bikes have been available for years. However, they've, with very few exceptions, not been used on road bikes and have limited use on cross bikes. Avid's BB7 mechanical disc brake for road levers have been available for quite some time. For some reason, mechanical disc brakes get a bad rap. I personally like them. I've used BB7 brakes for both flat bar levers and drop bar levers for many years. They work great. Excellent power and modulation. What most people overlook in setting up mechanical disc brakes is the cable and housing. You can't just slap on a brake cable and brake housing. They have to be dialed in. Not going to get into that part here.

Off track. Get back on track. Back to disc brakes on road bikes. Disc brakes became necessary on mountain bikes as mountain bikes became faster. In the 1980's, mountain bikes were fully rigid with 26" wheels. Folks could ride them pretty fast and cantilever brakes worked fine to keep speed in check. Then in the early '90s, front suspension came about and folks could ride their bikes faster. The brake technology was slower to catch up and it took a bit for direct-pull brakes to make the scene.

A few years later, full-suspension started getting better and riders were able to ride even faster. There are a couple of factors that enable a rider to go faster. One is to keep the tires on the ground maintaining traction. Efficient suspension design accomplishes this. The other is to have the ability to control your speed more effectively. Disc brakes perform this task very well. This is why you had a subset of riders on rigid bikes saying they didn't need disc brakes.

So how does this apply to road bikes and disc brakes? Besides frame materials and shifting, road bikes haven't really changed since, well, since forever. A road bike today is not going to really descend any faster than a road bike of the '70s. As proof of that I followed someone down a wet, technical descent on a 1970 Masi and he absolutely killed the descent. There's been no real change in road bikes that enable them to descend faster like there has with mountain bikes.

I read this bit on and my doubts about the need for disc brakes were reinforced, even though the set-up in the article are a bit of a kludge, if you ask me. Because, after all, isn't it about need vs. want? Do you need disc brakes on your road bike or do you want them? Do you want them because they are powerful stoppers that are found on burly mountain bikes? Just because they are good on mountain bikes doesn't mean they'll be good on road bikes. Tire contact patches differ. Traction differs. Speeds differ. And more important, sustained speeds differ. Sure, there could be certain applications where they make sense, but for average Joe and Jane Road Rider, I don't think they'll do anything except add weight and complexity and, unfortunately, untimely failures. For me, I think I'll still with good old caliper brakes on my road bike. It's a pretty great, simple design that works darn good.

NR 005

(What's playing: KWMR Faultline Radio: Random Music Played Randomly)


Bushpig.vrc said...

The most compelling argument that I see for disc brakes on road bikes is that carbon rims don't make for good braking surfaces. While I recognize that you will pay a weight (and aesthetic) penalty for a hub that will be able to support disc braking loads, there will be an office from being able to focus rim designs on impact durability, aerodynamics and weight. Not saying I am in favor of disc brakes for for road bikes, since I am not, but I can see this one argument.

blackmountaincycles said...

I don't think that it's that carbon rims don't make for a good braking surface as much as it is that the tire to rim interface on carbon rims is not compatible with the heat. High performance race cars use carbon rotors which perform very well at high temps.

The problem with the carbon rim and tire heat issue is that the carbon rim/tire combo is simply manufacturers taking the aluminum rim and changing the material to carbon.

But yes, based on current technology, a disc brake with carbon rims might be a good application. However, if you are worried about heat build up at the rim from rim brakes because your descents are all long and fast and high heat generating, then you should have the same concern with disc brakes.

However, since roadies now have a taste for superlight carbon rims, there ain't no going back. The future will be interesting.

Jake Hess said...

The world would be a better place if we all used Superbe Pro brakes and Grand Bois Tires. Keep the faith because folks are listening.

Vince Gest said...

This might be an ignorant assumption, but I thought the reason one would use carbon rims is to shave grams. I realize rotational mass is more critical than weight found on other parts of the bike (otherwise I'd lose that extra 20 lbs around my midsection). It seems to me you'd gain that lost weight with the disc brake setup.

David O'Sullivan said...

I agree, I love my Calipers. So quick and easy to dial in.
I think where disks will be great will be on touring and commuting bikes where constant wet weather or more load is the main issue. Personally i think i would stay with road bb7 with brifters or thumbies but I will be interested to see what else the other two come up with.

RoadieRyan said...

Love the shot of the suntour superbe calipers

Wally said...

There are bigger two wheeled devices with motors that use disc brakes extensively. So there is knowledge and expertise on proper braking technique and use for fast or slow rides.
The bike rumor article only reinforces the role ignorance and common sense plays in making choices.
I use disc brakes on my road bikes and I use calipers too. Mine discs are all BB7's and I see no need to change. I personally prefer a well dialed in disc brake bike on the road but have no issue with good caliper brakes either. I've done some hefty descents on my fully loaded Vaya while touring where my speeds were well into the upper 30's and lower 40's and I liked having my disc brakes then.