Disc Learning

Disc Learning

Of the many experiences it is possible to have on a bike, the one that seems most universally disliked is a loss of control. It—that loss of control—comes in as many flavors as jelly beans do. There’s the loss of traction that can come in the wet. There’s the inability to control the direction the bike is going that can happen after hitting a big bump. There’s the inability to carve a precise turn at speed if the frame isn’t stiff enough. A similar loss of input can happen when tires are severely under inflated. While I doubt many people have experienced this, riding a bike only to find have the bar move because the stem hasn’t been torqued sufficiently will definitely give you a jolt of adrenalin. Whether the bar is turned 45 degrees to the front wheel or is turned up like a 1970s 10-speed, the effect is not what I’d call recreational.

However, there’s a different subset of these that I want to address—poor braking. Pull the levers only to experience the bike slowing less than anticipated is a first-order horror, but not one John Carpenter will ever make into a movie.

I’ve been on descents with both rim calipers and disc brakes and decided it was time to prepare for a switchback by braking and discovered that pulling the levers did less than I needed. I’m fortunate that in every case the cause has been worn pads, never a broken cable or air in the hydraulic line. Those experiences have been instructive.

As the debate over disc brakes has raged among enthusiasts, pro riders and anyone else handy with an opinion, I’ve often considered how when I have little braking power, the only recourse I have is to start braking earlier and earlier, perhaps even just dragging my brakes because I don’t trust the bike to arrest my momentum once at full speed. On the other hand, as I ride review bikes with disc brakes as well as the latest calipers, I’ve yet to have the opposite experience—Oh my gosh, this bike stops too damn well!

Last year I spent an afternoon interviewing mountain bike pioneer Gary Fisher. It was a terrific reminder into the incredible insight he has had into what makes a mountain bike ride better. Bigger headsets, 29-inch wheels and longer front centers are but a few of his ideas. On the subject of disc brakes he took me back to Shimano’s early V-brakes. The engineers in Osaka decided they were too powerful. That’s not a thing, just as it’s not possible for a beer to taste too good. But they wouldn’t be dissuaded and in the next model revision, they included a cam they called Servo Wave, and they even included a little window in the lever so you could see it, proving that they were trying to make a bug into a feature. Servo Wave decreased braking power as you pulled harder. The logic (absence thereof, really) was that it would prevent a rider from locking up a wheel. What it really did was decrease control.

Shimano ditched Servo Wave after Fisher and others convinced them that better brakes was always the better way to go.

I’ve been on a half dozen different road bikes in the last month, plus several gravel bikes and a couple of mountain bikes. As I switch between them, the sensation I’ve been most interested to compare between those bikes has been how well they stop and what that means for my confidence and control. It’s no real surprise that the bikes that stopped the best are the ones I feel most confident on. However, I’m encouraged to report that thanks to running larger tires (28mm rather than 23mm) at lower pressures (75 psi instead of 100 psi) and the way Shimano redesigned the calipers on its top-of-the-line Dura-Ace group, rim calipers have never provided more braking power.

Here’s the strange part of the lesson: Without having ridden disc brakes extensively, I’m not sure I’d ever have attempted to pull on the levers for the Dura-Ace brakes as hard as I have on some of my local descents. Because I’ve ridden discs on all the big descents near my home, I’m aware that I can wait until right before a turn to begin braking and hit the brakes hard and not break the tires free.

For me the epiphany carries with it an inherent irony. I can accept that disc brakes present such a radical change to what road bikes are that some people just don’t want to make that big a change. And often, this resistance is posed as not wanting to buy a new bike. The crazy part is that combining the new Dura-Ace calipers with bigger tires run at lower pressure represents a huge gain in braking power, but to achieve these gains, a rider still needs to buy some new equipment. Buying new stuff is exactly the opposite of what some people want, but I can say that as more and more riders switch to disc brakes on their road bikes, for those who are doing group rides with people on discs, I’d want to make sure I was on a bike that had a shorter stopping distance than I could achieve on my old 10-speed Dura-Ace, or Campagnolo Record.

For anyone who has to use brakes to manage their relationship to gravity, I truly believe stronger brakes are a net gain.


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  1. Zed F

    As long as the brake response is roughly linear, yes. A brake that went from not enough to full lock would be scary, too.

    1. Author

      I’ve found that a completely linear brake response isn’t ideal. I want a very light touch initially for pack riding and speed scrubbing, but as I apply more force, I want braking power to increase rapidly. It’s a different sensation but I came to welcome it pretty quickly.

  2. Neil Winkelmann

    I have my first-ever disc brakes on my gravel bike. I’ll accept they are a step forward, but I feel that the limitations (wet-weather noise and pad wear) were downplayed, and I have been somewhat disappointed in the experience. But I’ve normalized that, and my expectations are now matching the reality. My next pure road bike will almost certainly have discs, but I’m not going to buy a replacement bike solely for that “upgrade”. My current road bike (C59 with SR) is 6 years old, and I anticipate a replacement in about 3 years (I think by which time I’ll be lucky to find a rim-braked high-end bike in any case).

    1. Marek

      There’s very little discussion about the downsides of road discs other than weight. Some of the aspects I’ve found fiddly are… fork / frame shudder (although this is probably due to the first gen bikes being modified for discs versus a ground up design), small fluid reservoirs resulting in dead-zone at the lever when pads wear, pad wear rates that I’ve not seen on MTB discs or rim brakes (probably not too bad per kilometer.. but you rack those up quickly on a road bike), road grime affecrts braking power more than MTB-mud, they’re also more fiddly to set up due to tighter spacing around the disc and a few other things. Do they have their place? Certainly, gravel, CX. Am I sold for road? Yes and no.

    2. Author

      I agree that some of the early road bikes had forks that weren’t stiff enough and they shuddered under even moderate braking. I haven’t run across that in a while. Pad wear is still an issue, but I’m comparing that to an era when I replaced brake pads every 10,000 miles.

  3. Mark H

    I’m not too sure I agree with Gary about the servo wave brakes being to weaken linear pull/V brakes.

    I was a bike mechanic when servo wave brakes first came out, and my recall of them (which Wikipedia corroborates- https://en.wikipedia.org/wiki/Shimano) is that at the beginning of the stroke they provided low mechanical advantage- but high cable travel- to get the pads to the rim quickly, then as you pulled the lever farther, they increased the mechanical advantage to get more braking power. I remember test riding newly assembled bikes and being able to (briefly) skid the front wheel.

    The flipside to this is that due to the high mechanical advantage, the pull at the brake lever was described by a friend as “mushy.” There’s the need to balance keeping the brakes from feeling too mushy or too wooden.

    Admittedly, I didn’t notice when or why servo wave got dropped, but I think I was out of the shop by then.

    Maybe what the problem at the time that V-brakes and servo wave came out, was that people weren’t necessarily aware that the v-brakes needed special new long-pull brake levers. Using old brake levers that used to work fine for cantilever brakes didn’t work so well with V-brakes- as everyone now knows. You’d get great power, but the pads would have to be set up really close to the rims, or the lever would bottom out. Servo wave gave great power with good pad travel.

    It’s the V-brake specific levers that came out after servo wave that were weaker than either cantilever levers or servo wave.

    The wikipedia article reminded me that Servo Wave is back for hydraulic brakes. Though I haven’t ridden a bike with them, just squeezing the brakes on the showroom floor felt weird, and I think I like the more linear pull of the lower end hydraulic discs.

    note: upon further research, it looks like the servo wave brakes with the transparent cover- M092- were for cantilever brakes, the servo wave brakes for the early V-brakes with the parallelogram pad mechanism did not have the transparent cover. But my recollection of skidding a front wheel with servo wave (with the transparent cover) still stands.

  4. Aar

    I accept that discs are more powerful and modulate better than rim brakes. I strongly believe that discs are a better solution for braking a carbon rim. I’ve also experienced failures with both cable and hydraulic brakes. The hydraulic failure was much closer to catastrophic. For that reason, I’ll be a late adopter of road disc brakes and that’s uncharacteristic of me. Finally, a bike company has released a disc bike that isn’t hideous but it will still be 5-10 years before I see myself riding road discs. My question is, Padraig, why are you so aggressively “selling” your readers on road discs? I mean, other than smaller chainrings which I finally accept, I don’t see you beating a drum like this very often.

    1. Author

      I’m not actively selling anyone on anything. The point of the post was to share some realizations relative to my experience with disc brakes. To some degree they were a surprise for me. I do see the landscape changing in terms of what’s available and what will make for harmonious group riding, but if someone doesn’t want to buy a new bike, that’s perfectly fine.

    2. Aar

      I can already see that rim brakes are an endangered species. That’s part of the reason I picked up a new ride last season. My experience with MTB hydraulic discs means two thing. First, I understand how much better disc brakes are when they work. Second, I want 5 or more generations of road disc development before I take that plunge.

      Thoroughly understand the different braking distances in packs. Willing to put up with it for as long as I can tolerate. Now, to buy my first (and second?) carbon wheels with rim brake tracks before they’re Dodo birds…

  5. scottg

    Riding in the rain a couple weeks ago on 28mm tires,
    thinking I’d be a little more relaxed on 38mm tires.

    As Napoleon said, “G-d is on the side of bigger contact patches”

  6. SternO

    I am now riding a disc brake bike. I love the stiffness of the front end with the thru axel. The stopping is no comparison. You can go deeper into the corner befor you apply the brakes. I was riding a Factor 02 rim brake and now the Factor 02 disc. There is nothing i don’t like about the disc bike.

    1. Author

      Some of my rain experiences with caliper brakes and big descents have inspired a similar curiosity in me.

  7. Rodd

    Convert to disc brakes for the road after 3 years on the CX/all road bike with different level of bodges (TRP Parabox, you were fiddly as regulating a mechanical watch), very happy now. And can now discern “character” between different products – Hope RX brakes modulate a bit less, but have more clearance than the more precise Ultegras. I do a weekly TT (and see no near future switching to a disc-brake TT bike) and it always takes about 10 minutes to remember the massive level of braking performance between “aero” calipers with carbon braking surfaces and discs.

    Incidentally – what is that lever on the photo? Thru axle or QR?

    1. Author

      It’s the Naild thru-axle which is also semi-quick release. I know how to work it, but I can’t explain it to save my life. It’s a really cool design if you can learn to operate it.

    2. Rod

      Very neat, similar to the RAT system but “internal” instead of poking through the side of the frame/fork. Thanks!

  8. Hautacam

    Wait, are you saying my canti brakes aren’t up to snuff??

    … sorry, i promise i’ll retire this threadbare gag now. I just couldn’t resist.

    I know my equipment is old old school. Happily i am slow and out of shape so my ground speed matches my braking capabilities just fine. I hear those disc thingies are the bee’s knees though.

  9. Tominalbany

    Your first paragraph reminded me of the time my cousin went off the ramp we’d made on an old bike. He pulled up as he left the ramp in order to get that special wheel lift that makes 14 year old guys look mega-cool. The handlebar and quill stem came out of the headset. He did NOT land gracefully. Thankfully, he wasn’t going that fast and managed to not land chest-first on the headset.

    I think I’ll send him a message to remind him of this spectacular feat!

    Thanks, Padraig and to the commenters for the pros and cons of disk brakes.

    1. Tominalbany

      My first sentence is a grammatical mess! He went off the ramp while riding an old bike. Ugh..

    2. Author

      Only RKP readers would express a concern about the grammar they used in a comment. You kids rock.

  10. Dan

    Brakes need to do three things. First, scrub speed with the ability to modulate the degree of the scrubbing, second, stop without locking up the wheels and third, lock up the wheels. As long as the brakes can do this I don’t care if they are caliper, cantilever or disc. Since 90% of my braking is scrubbing speed, that component is the most important to me, give me the less powerful brake, it will modulate better. Now, what type of brake would I use. For for a road bike it would be caliper but if I was descening big mountains I might want discs for fade resistance. For for a touring bike, cantilevers or disc. If I rode in the wet and mud I would want discs. If I wanted tires beyond 32c I would want discs. I wish center pulls hadn’t all but vanished. I road those for my first 20 years of riding, I really like them. I wish I could find a reasonably priced road frame for 32c tires with post mounts, that would be perfect. I will have to suffice with my Black Mountain Cycles Road frame that will arrive this week.

    1. Author

      Congrats on the purchase. Given the sort of frames they are known to do, I’m guessing it’ll take post mounts and has room for at least 32s.

    2. Dan

      I meant post mount center pulls. They don’t do that but I will be happy with the mid reach calipers. Their road frame is built for Jack Browns and can even fit a little larger depending on your brake calipers.

    3. Author

      Very cool options. Every now and then I pine for a frame that can take the ones from Paul Components.

  11. Gabriel

    After 10 years off of Campy I built my steel bike up with a new Chorus group last summer. I remember their brakes lagging distantly behind Shimano and even the new-at-the-time Sram. 10 years on they’ve moved from poor to mildly terrifying. The window of finger pressure between slightly slowing down and sudden, lurch-inducing near lock-up is shockingly small. It’s a pain in the ass to have to think about the brakes so much on a technical descent rather than just letting it rip and have fun. I can’t imagine all the skidding that would occur in a crit; and the justified cursing of the riders behind.

  12. Seano

    Having ridden mtb discs extensively for the past 6 or 7 years and comparing them to my Dura Ace equipped road bike, I would suggest some of the real braking preference is terrain dependent.

    Living atop a 9%, 3.5 mi climb/decent has given me a perfect a/b comparison on brakes – from bone dry to pouring rain and standing water. Back to back days on different bikes and sometimes different bikes on the same day. While I do enjoy the benefits of 28c tires @ 80-85 psi on the road bike, the rim brakes just don’t stand up to my mtb setup (which, btw is XTR calipers, no fin pads & 160mm discs… cross country setup, not big mountain).

    Here’s the thing – I’m consistently faster descending from my house on the mtb with only 28psi in those tires and I’m far more in control and have significantly less hand fatigue.

    Has pad wear been an issue? Yeah – I’ve worn out a set of disc pads in one-day mtb races. I’ve also had mtb pads last many, many months in the dry. But I also chew through road pads in the winter time/wet weather ~ every 3-4 weeks.

    Hammering the two setups up and down my hill has brought me to one simple conclusion: my next road bike will be disc equipped and I’ll probably never ride a rim brake bike again – including my absolute love of a custom steel cx bike!

    1. Author

      The current traditional mount brakes are terrific. The direct mount? Even better.

    2. Lucien Walsh

      got it. I’ve been making incremental improvements to my now 14 year old Seven steel road bike; Upgrading the brakes woudn’t be too hard on the budget. On the other hand I’ve never owned a carbon bike and a persistent case of N+1 fever leads me to the Allied Alfa build site and to the Tarmac site….and now thank to you the Orbea LOL. So the larger cost/benefit discussion in my head regarding discs rages on. (here in MD we don’t have descents like you do out there!)

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