Stopping Power: Why Hydraulic Brakes Make Sense for Road and Cross

Let’s start with a basic reality: disc brakes are coming to road and cross bikes, and hydraulic disc brakes are not far behind.

Fact 1:  Disc brakes are coming to road and cross bikes.

Volagi is but one of the manufacturers who are toying with or outright building and selling disc brake equipped road bikes.  They are certainly among the better known options out there, coming off of their recent bout of litigation with Specialized (where one defendant was ordered to pay $1.00 to Specialized.  Way to go there, Speshy!  That $1 verdict really justifies the amount you spent on legal fees in this case!)

Disc brakes are already in cross, and are now permitted in UCI races.  There are a multitude of disc-friendly cross frames out in production…and even more cross-possible frames out there, such as my Vaytanium.

(Photo credit to North Central Cyclery).

Frankly, they just make sense.  With technological improvements, the weight penalty for disc brakes is dropping, rapidly.  Disc brakes mean no need for brake reinforcement strips on rims.  They mean no overheating of rims or delamination of carbon rims in downhill riding.  No loss of braking power with ice/rain/snow.  No aerodynamic compromises to create a braking surface on the rim.  More stopping power and greater modulation.  Folks–I’m not the only one thinking this.  Disc brakes make sense for just about all bikes.  Ok–maybe not TT bikes or extreme aero bikes intended for flatland road racing…where the aerodynamic advantages of integrated braking systems overcome the advantages of disc brakes.  That brings us to point #2:

Fact #2: Hydraulic disc brakes are coming for drop bar bikes, and we should be excited.

Again–I’m not exactly cutting edge with the news that hydraulic disc brakes are around the corner for drop bar, STI bikes.  Heck, full hydraulic groups may be around the corner.  But why is that something to be excited about?  In my mind, there are two primary reasons.

First, hydraulic fluid can be non-compressable, and can be run in hydraulic lines with minimal expansion/contraction.  That means precise activation, no cable slop, no need to make adjustments over time to account for cable stretch.  The feel can be more consistent.  The difference here can already be seen in the feel of cable actuated disc brakes (e.g. Avid BB7) and hydraulic actuated disc brakes, on flat bar bikes.  Even a clean, well-tuned set of BB7s has a hard time keeping up with a moderate set of hydraulic brakes.

Second, and perhaps more importantly, hydraulic brakes can have a much greater force/leverage/pressure advantage.  That advantage can be translated either into more braking pressure, or more brake pad travel.  And it can be done with cleverly designed hydraulic master cylinders that don’t take up significant amounts of space.  (Sure, cable pull designs could have more leverage or more force, if you want huge, ungainly cable housings).  Why is this important?

The MTB BB7s on my Big Dummy and Mukluk function perfectly…with flat bar, Avid SD-7 brake levers.  They rarely need adjustment and they rarely malfunction.  However, the Road BB7s on my Vaytanium have not had as distinguished of a service record.  Why is that?  Road BB7s are set up for use with STI controls.  STI controls have a comparatively short cable throw, when compared to flat bar controls.  Short cable throw means that, to achieve good braking force, the calipers must ramp up reaction quickly.  That quick reaction ramp up design in the calipers means that the calipers are more prone to being out of adjustment.  One millimeter of cable slack on the Dummy is relatively meaningless and imperceptible.  (Heck–as long as the cable housings going to to the rear are, there’s undoubtedly more slack than that in the system).  The Dummy overcomes that slack with the long throw of the SD-7s and a slower ramp-up/responsiveness in the brake calipers.

Road calipers don’t have that luxury.  One millimeter of slack takes a perceptible amount of STI lever travel.  That reduces braking effectiveness.  That means that, for properly tuned brakes, you’re always chasing adjustments.  Too loose, and you lack braking force. Too tight, and you drag the brakes.  There’s no cushion in the system…so any imperfection in adjustment shows up in performance.  And with cable based systems, unless you’re constantly chasing adjustment, there will be imperfection.  If my SRAM Rival levers had more cable pull with the brake actuation, there would be less of an issue…but this isn’t SRAM specific…I’ve seen it on Shimano equipped bikes as well.  And for that matter, wouldn’t one expect that SRAM would work perfectly with Avid?

A system that had no slack…no compressibility…that would be a perfect system.  And that’s where the unique benefits of hydraulic come in.  Less adjustment needed.  More linear activation.  More consistent feel.  More resistance to accidentally being out of adjustment.  Mo’ betta’ braking.

In addition, there are fewer unsealed, exposed moving parts with hydraulic brakes…which means fewer parts to get gunked up with mud/gravel/sand/slime in cross, gravel racing and touring riding.

Does the new world order of hydraulic disc brakes for road/cross bikes have downsides? Sure.  Extreme-cold weather performance may suffer.  Road bikes will take on the indignities of hydraulic brake setup and bleeding (in lieu of the much simpler, albeit more often repeated setup of cable systems).  Potentially higher weight (remains to be seen).  Greater cost and complexity.  But those detriments will be worth it, I believe.

When they come, the Vaytanium will be an early adopter.

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8 thoughts on “Stopping Power: Why Hydraulic Brakes Make Sense for Road and Cross

  1. 1. There are Road BB7s designed exclusively around road/canti cable pull rates.
    2. Once again, let me adjust those brakes.
    3. Shimano Mineral oil freezes around -22f, and Dot goes well lower then that with people riding them to -50f. If Mike Curiak can use Hydros, anyone can. That guy is a maniac.
    4. probably forgetting something, but see you in 5 mins.

    • 1. Yup. The Road BB7s have a faster activation rate (what I called Ramp Up above). That means that the brake pads move more with less cable movement. That just makes them twitchier, and more prone to maladjustment.
      2. Next time they’re out of adjustment.
      3. Agreed–I don’t think cold is a practical issue for road/cross, given the bottom end temps at issue.
      4. Only briefly.

  2. I don’t need of want discs on all my bikes. I live in the PNW and I am not wearing through rims or having brake overheating problems with rim brakes. I’m also not having issues braking as needed. I think the whole rush to disc brakes on every bike is silly.

    Having said that for a Cross bike or a MTB discs discs do make sense and hydraulic discs offer superior performance to cable discs unless you spend the $$ on compression-less housing which few people do. It will be great to have a drop bar compatible hydraulic brake lever for those that want to use them.

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  5. Good article, I couldn’t agree more that discs on road is way overdue.

    I got sick of waiting for the manufacturers to come out with a good solution. My BB7s weren’t cutting it for me, not compared to my mountain bikes.

    I ended up making my own hydraulic road bike. I posted pics and how to’s over at http://hydraulicroadbike.com.

    It’s not the prettiest solution in the world, but it works great and I dig it.

  6. My BB7s both MTB and road version are firm, powerful, and don’t require “constant adjustment”.

    They are fit and forget with the exception of an occasional click or two to compensate for the pad wear (a 5 second job).
    Smooth cable routing is critical and so is using compressionless casing (which doesn’t cost $$$$ BTW).

    IMO hydraulic brakes offer marginal advantages (if any) and have their own problems and their popularity is driven more by their sexy high tech image than anything else.
    People automatically assume that the presence of hydraulic fluid makes the component superior.

    The biggest problem of hydraulic brakes (based on my own and workshop experience) is the issue of lazy/sticky pistons/rotor rub which most of calipers will develop sooner or later.

    Mountain bikers can live with a slight disc rub it but I can’t imagine roadies putting up with the slightest loss of efficiency 😉

    I won’t even start on internal hose routing, complexity and cost of brake levers… and what it means when something goes wrong or you decide to replace/upgrade your brake components…

    • My Vaya gets subjected to a lot of difficult conditions, with submersions, gravel rides, mud, snow, and various other muck. Add to that the fact that I’m a bit (a lot) A/R when it comes to bike maintenance…and it results in me constantly chasing the adjustment. Hydraulic brakes in that same context require far less adjustment. I do run high quality cable housing with logical and smooth routing–that isn’t the issue. And I do have BB7s in other applications where they serve without issue–on my Big Dummy, which sees less severe service, they work admirably. But for a bike that is going to see the service that the Vaya sees, in my opinion, a high quality set of hydros makes more sense…and I am hopeful that the coming crop of drop-friendly hydros are in fact good quality.

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