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December 15, 2017
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  • Farbar

    I still don’t believe a blunted edge (as shown in the photos) will make much of a difference. A screwdriver will puncture someone just as effectively as a knife. However, in a pile-up…and I’ve been in one or two…I’m more scared of a handlebar end taking a core-sample out of me.

    • James Huang

      For a relatively small and pointed object as a screwdriver, no, of course the sharpness of the edge won’t matter much. In my opinion, the potential of a disc rotor injury lies not in outright slicing but more in the edge’s ability to grab on the skin and tear. In respect, a blunted edge is far more likely to slide across the skin than dig in. Let’s just say my forearm was much happier with one vs. the other when I was putting this article together.

      • PsiSquared

        Another thing to consider is the possible tearing/cutting that wave-like edge could do. I think a disc with a constant radius and radiuses edges is the answer. The manufacturers may need to move to a thicker disc as some have claimed that putting a radiused edge on such thin discs introduces additional stresses in the disc.

        • Dave

          The ones with the sharp notches in the outside probably need to be done away with, they are useful for MTB brakes but not so much on road discs.

          I don’t see anything wrong with a gentle wavy profile. However, you can achieve the same effect (with respect to the pads, at least) without any concave sections at all by simply using a shape with 12 sides and rounded ‘corners’ – a shape I have seen already.

    • Ed Goss

      So, you’d be equally as happy to have surgery with a screwdriver as a scalpel? The sharper it is, the less pressure you need to make a cut.

    • Erik Van Bommel

      As a race commissaire in the 90s if I saw a rider on the start-line or pre-race in the carparks without h/bar bungs I’d pull him/her out of the race unless they could show me the bike with plugs before the start. It’s in the rules. If you have riders with a number on without plugs, they are illegal.

    • Eric Janik

      Handlebar plugs are supposed to prevent that.

  • Did you have to cut the steak to get the rotor to stick in there?

    • James Huang

      Absolutely. Stock rotors are sharp but not *that* sharp! I suppose I could have potentially sliced into the meat by mounting the rotor on a high-speed drill or circular saw base but that’s not really the point. At least in my opinion, injuries due to a rotor are more likely to be caused by the edge catching and tearing the skin, not when they’re spinning at high speed.

      • Dave

        Mounting the disc on a circular saw and attempting to cut the meat would simply have caused a friction burn on the surface of the meat.

        • jules

          mmm char grilled steak

        • mzungu

          While that can be true, it will be a little different if it was the knee, where there is a very thin soft tissue, but a hard bone underneath it to push it into the spinning rotor. At a crash where you decelerate form 20-30mph to 0 in a split second, I can see how it can slice the skin open.

          So far all the Youtube video everyone did in their garage all show people shoving something into the rotor gently, none have show anyone using their hand slapping on to the edge of a spinning rotor yet….

          • ebbe

            I think you’re misinterpreting this. It is not the point of these videos to show that it is IMPOSSIBLE to get hurt from slamming into a disc at speed. You can get hurt from slamming into almost every part of a bike… remember hitting the top tube with your soft parts when you were young and reckless?

            What these videos do prove however, without any shadow of a doubt, is that discs are no sharper then (m)any other parts on a bike. *Slamming into* (aero) spokes, chainring, cassette, chain, pedal, derailler cage (front and rear), rim brake arm/release lever, shoe buckle, quick release lever, computer mount, etc etc can also rip a piece of your skin off. Getting a handlebar logded in your spleen can kill you. Landing on a spinning tire can burn you. You just need a bit of bad luck.
            I would also not slam my hand into a (spinning or not) cassette, chainring, derailler cage, or even a rim brake lever *at 50km/h*. Would you? Or would you repeat these garage videos (merely touching, not slamming) with a spinning chain ring, cassette or aero spoke? I’d like to see that ;-) Actually, scratch that… no I wouldn’t!

            The “mortal spinning bladed razor knives of death by a million paper cuts” argument is debunked. Instead the reality is: Discs are about as sharply hazardous as (m)any other part of a bike. Not because *any* of these parts are inherently deathly dangerous, but simply because speeds are so high and most body parts of riders are barely protected. The possibility to severely hurt yourself slamming into *any* part of a fellow rider’s bike will never be gone, unless…

      • that’s a video I’d watch…

  • ebbe

    Not as sharp a people make them out to be. Some Scandinavian guy, so not me, but I did do the same experiment myself.


    Of course you can hurt yourself on just about any part of a bike if you crash into it at speed and/or with a bit of bad luck. Any man who’s ever smashed into a top tube with his soft parts surely knows how much that hurts. So yes, it is theoretically possible to hurt yourself on a disc. But that in no way proves disc brakes are inherently MORE dangerous then most other functional parts.

    • James Huang

      Nope, not surprised by that at all. I don’t see discs as dangerous due to their spinning motion. As you mentioned, they’re sharp but not *that* sharp, plus unlike on a circular saw or similar tool, there’s not much rotational momentum behind them. The perceived risk relates more to what happens if someone were to crash into a rotor at high speed. In that scenario (which is much more common in pro road racing), the more likely risk is the edge catching and tearing skin and/or flesh.

      Again, I’m not terribly concerned about discs myself (and I believe in the technology’s superiority enough that it’s extremely unlikely that I’ll ever buy another bike that uses rim brakes) but I’m not racing in a peloton. Regardless of whether Ventoso really was injured by a disc rotor, the reality is that any potential risk could have and should have been mitigated before the trial even began.

      • Anon N + 1

        People keep saying “crash into a rotor at high speed” but I don’t think that is an accurate representation of the situation. Think about it: The crashed bike is basically NOT MOVING because it is lying on the road. Further, the disc on the crashed bike is probably not rotating much either so its angular momentum is low (low mass rims and tires, low rotation). The following rider crashing into the crashed bike has some momentum when he or she hits the ground. But as others have said, brake levers, bar ends and spokes (those bladed spokes are thiner than discs) could also cause puncture wounds or lacerations.

        • Ed Goss

          The crashing rider has plenty of momentum – probably 85% of the bike & rider together. I’ve crashed at 25mph or so, and blunt bits of tarmac can take off your skin. A relatively thin, ‘relatively’ sharp and pointy bit of metal will do more than that. The spin of the rotor is a bit of a red herring – its the fact that there is an exposed sheet of metal to fall onto the edge of that I would be concerned with.

          • ebbe

            Of course a crashing rider has momentum! ;-) But let’s imagine that, in your scenario (which is completely different from the Ventoso COLLISION, where both riders stayed upright and facing forward, by the way), there was no disc. You probably would have landed straight onto the bladed spokes (since they are “below” the disc), or crashed into the quick release lever. These spokes or the QR lever could have ripped into your skin just as easily

            • Ed Goss

              I’m not saying that discs are the only issue. I accept QRs can cause trouble although it depends where you lock them in. Spokes though, bladed or not, you run along them, not into the end of them.

              • ebbe

                If a bike is already on the ground as you fall onto it? It’s very well possible to fall onto the spokes. On bladed ones you would fall onto the broader end, so that’s lucky. But still that end is not that wider than a disc brake is. Or you could even get a finger in between the spokes which would slam the ‘sharp’ edge into your finger at high speed, as the spokes are still spinning. Luckily, there is little momentum in a wheel, so they won’t rip your finger off, but a disc is attached to the wheel so it has the same momentum.

                The point is absolutely *not* that discs are soft cuddly teddy bears you can slam into at will… But when slammed into at high speed, they are about as dangerous as (m)any other part(s) on a bike. Back to Ventoso’s injury: This could just as well be caused by slamming into a pedal, cassette, derailler cage (front or rear), chain ring, etc, on the right hand side of the bike ahead of him. Ventoso admits he does not know, the UCI does not know, we don’t know. Yet, the UCI is taking decisions as if they do know. Initially I thought: What do I care? I’ll never be a pro anyway, and I can basically ride whatever I want. But now that several sportive organisations are jerking their knees following the UCI, this unsubstantiated decision is likely to start impacting me and many other consumers. That’s just wrong.

            • Chris

              Using two bikes (one with DB’s) I tried to reproduce the Ventoso accident, assuming that both riders were running a parallel course, one behind the other, but overlapping wheels, and both vertical. Assuming both feet clipped in, at no point could I get my leg any where near the other bike’s rear disc, without hooking my bars around a seat pin or saddle. Again two bikes running side by side, I could not get disc / leg contact, without other components clashing first, e.g. bars, pedals etc. Of course in an actual, riders down, crash the rules change.

              • ebbe


                I’ve tried the same… Even if you would unclip your left foot and manage to acrobatically wrap your left leg it around the rear wheel of the bike in front while riding and without completely losing control of your bike, you would only be able, with considerable effort, to get a cut along the tibia, never (perpendicular) across it and then up (which would require you to twist your leg 90º inwards, and then move it down several cm’s). It is much more likely that Ventoso hit a cassette (teeth), chainring (teeth), derailler cage (front or rear – both have sharp edges), right shoe buckle (sharp edges) or right pedal (sharp edges) at speed and that ripped into his leg. I’ve heard a rumour that a right side pedal with blood on it was found on a Direct Energie bike, but no confirmation as of yet. So that might just be a rumour.

                I find it absolutely astounding that nobody in the UCI equipment committee has realised the same we both did and at least started an investigation. I’ve actually tried to ask Bobbie Traksel (member of the UCI equipment committee, and a smart guy as far as I can tell) about this over Twitter (following his comments on this matter on Eurosport NL/BE), but after some initial non-answers which were clearly out of line with Ventoso’s letter, he just declined to respond. Amazing.

                • Chris

                  Just one small point: Pro’s run 4-5cm longer stems to mere mortals, such as myself, therefore making bar / saddle clash happen even earlier.

                  • ebbe

                    True! Although I am about as tall as Ventoso is (only 2 cms taller) and run a 130mm stem on my “old” (non-disc) bike, which is one frame size too small for me. I assume (but that’s all I can do) that my “old bike” set up is not that far off from Ventoso’s. Either way, for the UCI it should be fully possible to recreate the crash together with Ventoso, or at least get some additional info from Ventoso. I’m getting the uneasy idea that the politics of keeping riders associations happy is preferred over finding out what (f)actually happened.

                    Meanwhile, consumers wanting to ride sportives in France and Spain are currently being blocked from participating in the events, which they’ve already paid for(!), and refunds are refused. That’s £150 and a holiday down the drain for some people. That’s fully on the UCI, and it’s much more damaging to the sport than the (irrational?) opinion of a few pros, who – let’s be honest – basically have to ride what they are paid to ride. While I can understand the halt in the disc trial, if the UCI has the guts to do that without an investigation, then they should also have the guts to condemn the practices of these sportive organisers. Hard!

    • Alex

      That test would not simulate someone falling on a disc rotor of someone actually moving on the ground.

      • ebbe

        Indeed, as I said: If you hit anything at speed (which includes falling onto it, because the effect is the same: An impact shock) you could always get hurt. However, this experiment does prove that a disc (Note: a quality one! I would not just try this with any random disc) is not much sharper than many other bike parts. Ironically, nobody is complaining about (eg), bladed spokes, cassettes, chain rings, derailler cages (front + rear), pedals, and also the various parts of a rim brake. All of these, and anything I’ve forgotten, can either cut into flesh directly or catch and “rip/grind” a slab of flesh off (barely any sharpness needed in the ripping/griding scenario).

        Let’s also not forget that adding a disc brake also eliminates the need for a rim brake. Many many riders have hurt themselves (or their mechanics) while fiddling with the rim brake while riding, Felline style. Not saying I have proof Felline was fiddling with his rim brake, but these types of accidents do happen in exactly that way.

        All of this of course does not mean riders are not allowed their concerns about safety. But we should always strive to be fair and factual, even when voicing concerns. Discs are not “rotating knives”, so we should not use such terms, not even metaphorically to make a point. Should they put a larger radius on the edge? That won’t hurt the performance nor safety one bit, and the pros can certainly afford the surcharge ;-) So… Yes!

  • UnPirataOra

    Just so we’re on the same page:

    “bladed spokes in modern aero wheelsets — are not only half the thickness, but as pointed out elsewhere, more numerous and faster-moving”

    The spokes aren’t traveling any faster than any other part of the wheel. Unless I’m missing the wormhole generator that’s getting installed with seat-tube motors.

    • James Huang

      Sure, of course everything on the bike is covering the same amount of linear distance. More specifically, everything attached to the wheel will have the same angular velocity. However, the linear speed of any given point will vary depending on its distance from the axis. This article explains things nicely: https://aschooler6.wordpress.com/2016/04/13/debunking-the-disc-brake-rotor-fiasco/

    • ebbe

      The bottom of a wheel is touching the road, so it always (when riding) travels at 0 k/h. The wheel axle is attached to the frame and travels at the speed of the bike/rider. This can only mean that the top of the wheel moves at twice the speed of the frame/rider. This is the case with all normal wheels, until you find that wormhole somewhere ;-)

      What is relevant for injuries is of course the speed of the spoke *relative to* the speed of the rider. At the outer edge of the spoke (near the rim) that difference in speed is a bit under 1x the speed of the rider (no matter where on the wheel you measure). The outer edge of a brake disc moves at (very roughly!) 1/4th of that.

      More importantly: A spoke would in most cases cut at high speed perpendicular straight into anything introduced in the wheel. A “cutting” disc (which some people are afraid) would in most cases cut parallel to, but not into anything. Unless, which James specifically mentions, you crash into the disc from behind. However, at that point the spinning is nearly irrelevant, any injury is caused mostly by the collision and the resulting impact/penetration/rip/tear. That same collision and subsequent injury could happen with a cassette, derailler cage (front + rear), pedal, rim brake arms/cable/release lever, etc.

      And then we have the “pile up” scenario. In that case spokes are again a much more likely danger, since the area you can hit them at is much larger and at both sides of a bike, and they sort of “drag you in” through their motion. Luckily, there is relatively little mass on a wheel, so a spinning spoke on a fallen bike will only damage your hand or foot, rather than rip/cut/saw it off, but that same argument also then goes for a disc. The following does sound counter-intuitive, but is true nonetheless: Discs cover a portion of the spokes, so the total length of “sharp edges” you could directly land your (eg) knee on or finger in actually *decreases* with almost 75cm per bike.

  • DaveS

    Just put the damn calliper in front of the disc instead of behind. OK OK I know all about moments of inertia etc which matter on 200mph motorcycles, but bicycles? Seriously?

  • This does not just affect pros. There is also the considerable, global effect on amateurs racing. The rules were to change for amateurs next year, following a successful trial.
    Ventoso’s accident was not a pile up, but a coming together that thousands experience in their Sunday races ever week. Whatever decision is arrived at must take this into account also.
    Having inexperienced weekend warriors going at it in groups of over 100 has huge potential for calamity, both in lacerations, unequal breaking and otherwise.
    The only benefit in road racing is to the manufacturers. In other forms of cycling discs win hands down, but not in pelotons.

    • ebbe

      The mistake that is consistently made in this whole discussion is treating discs like something never seen before, with characteristics that are completely alien to the world of cycling, or road cycling at least. But that’s just wrong. There are hundreds of sharp edges on any bike, for riders to crash into. Should we add one? Well, if there is a clear performance benefit, and we’re *removing* a few others sharp edges at the same time, why not?

      Collisions (let’s not call it a crash if both riders stay upright, but a collision) as *allegedly* (no proof yet, and physically highly unlikely) happend with Ventoso are, unlike mass pile ups, certainly not unique to road racing. They happen all the time in MTB, and especially in CX. I’d even say they happen in CX a lot more than in road racing: The first guy misjudges a “climb”, or gets stuck in mud or sand, or hits a hole or a barrier and the next guy collides straight into the first guy’s bike’s back end. I see several of these collisions every CX race. Yes, the speeds are quite a bit lower in CX, but then we’d at least should have seen some minor injuries, right?

      • I rode XC MTBs when the tech was moving towards disc brakes. At the time I rode v brakes, so have experienced plenty of those types of collision you mention. It’s no harm, you get bounced onto mud, into a bush, or worst case onto gravel or rocks. But the speed is never the same, just as the harshness of the surface is also never the same. It’s completely incomparable.
        I now race on the road as a cat 1 and we go for hours at 40kph+. At speed when you are being propelled by your own muscles everything else mentally and physically takes second stage, especially reaction time. I have regularly seen crashes happen because guys anticipate something, slam on without a thought that the guy behind is going just as fast.
        It just doesn’t make sense to want greater stopping power for a shorter braking distance in those cases, unless it is uniformly adopted. You can’t rely on everybody having the same braking skills and capability. The only performance benefit from discs is shortening stopping distance, but the group’s compression at speed quickly turns this into a definite drawback. Braking swiftly is not always the answer to avoiding mishap, see brakeless track bikes for example.
        You mention that they are not alien to cycling. That’s true. Sharp edges also. But what is alien to road cycling is a rotating edge in close proximity to the pedalling shin of the guy behind. Pelotons cycle close together, amateur and pro alike.
        I can’t say that improvements in braking are not needed – anything that improves a bike should be welcomed. However, I also can’t see that any road racers will benefit from the tech as it stands, only the manufacturers.

        • ebbe

          Yes, I absolutely agree with your questions whether it’s such a great idea to have difference in braking power in a peloton (…specifically in the wet by the way. In the dry the difference is not really larger than a difference in weights between riders or the various different ‘horse shoe brake’ constructions could also generate). If *danger from differences in stopping power* would have been the reason to stop this ‘trial’, that would have been perfectly acceptable to me. Maybe a few races could be appointed to test discs *across all starters*. Something like Strade Bianchi, Tro Bro Leon or Paris Roubaix, or a race that typically has bad weather… in 2017, when all manufacturers have disc models?

          But that’s not the reason we’re given. We get a poorly substantiated and physically unlikely story, with at least one proven falsehood in it, of which the only eye witness has himself admitted he in fact saw nothing. If only in the interest of fairness, I think this story needs better evidence (any would be nice), or deserves to be debunked. Then, any decision made about discs in a peloton can finally be made *based on facts*.

        • Sean parker

          Disc brakes in the pro peleton aren’t for the benefit of pro riders. their development is for the benefit of non-pro riders.

          pro-riders only make up .01% of total riding time.; they should come second, bar safety, in concerns for any potential benefit for cycling. Effectively. we employ them, not the other way around.

          • ebbe


    • Rob Ferguson

      Agree with some of that, but in a group of wkend riders the disparity between different rim breaks is huge anyway, especially in the wet. You could have someone on dura ace and someone else on a 300£ bike. On the west coast of the UK disks not only work in the wet, but don’t destroy your rims. So definitely benefits wkend warriors
      Having said that just bought a rim brake group set as I can only afford one bike and it has to be race legal.

      • Carbon rims in the wet are also a concern with rim brakes. I run a wet weather set (I’m based in Ireland so we get your weather too). In general, as Ebbe says below uniform uptake is key. But, as you mention, cost cannot be factored out, as so many buy their bikes to be race legal, if that requirement changes it would be either piecemeal allowing users upgrade as their situations allow, or done en masse with safety benefits, but huge cost. Neither seems ideal, so as an amateur, for now, if something ain’t broke…

        • Dave

          I’m not convinced that non-uniform uptake really is the issue it is made out to be.

          Unlike with MTB where the extra stopping power is needed, with road bikes you go for disc brakes to get the single finger modulation instead of raw power. Properly set up rim brakes are already, in ideal conditions with a skilful rider, able to generate enough braking power to do an endo with the front brake or skid using the rear brake.

          If something appears which causes a number of riders in a tightly packed peloton to grab fistfuls of brake for a hard stop, there’s going to be a pileup regardless of the proportions of rim/disc brake users. That’s a function of reaction time, not brake type.

          • Sean parker

            not every amateur bike has their rim rakes set up correctly or recently.

            plenty of stretched cables, spongy brakes out their in the non-pro peleton. That may be the most tangible benefit for amateur racing – standard braking effectiveness.

          • Essentially that’s my point. If we already have these facets in place – powerful enough stopping, potential for compressed crashes etc, there is little argument in favour of adding new tech to the mix without benefit.
            The benefit, as you point out, is largely in modulation. But that modulation has to be possible across the peloton, or else you have two tiers of braking.
            Bottom line is I don’t trust anyone I race against 100%, nor do any other racers if they are honest. Having someone with more reliable braking in any given conditions within a group gives a potential for imbalance.
            FYI – I’m very much in favour of new tech, I run tubeless tyres on my road bike, aero everything etc. But there has to be a clear benefit for ALL the riders, and it can’t be at the expense of safety.

            • ebbe

              Indeed. UCI should have just appointed a few races where *all* teams/riders had to ride discs. Strade Bianchi, Ronde van Vlaanderen, Paris Roubaix, Tro Bro Leon, Arctic Race of Norway, these kinds of “harsh conditions” races pop to mind. A controlled test, but across the board, would have been a much better and safer “test”. This should be possible now that all frame builders and groupset manufacturers have disc (capable) equipment. (note: Canyon and Campagnolo were the last to join the party as far as I know… Wait, what does Ventoso ride?)

              While I do wholeheartedly agree with your point… For me it does raise a related question: What about some of the new aero bikes (used by pros currently!) that have notoriously *bad* braking? Let’s not name any names because we don’t want to get sued, but if you’ve read a couple of reviews on the newest top level aero bikes you know which specific one I’m talking about. Should that bike be banned because it has “imbalanced” braking compared to others? (In this case: Much less stopping power than others, which is even more dangerous then more stopping power than others)

              • Good point on 100% integration in sample races.That could be a game changer.
                I haven’t heard of the bad braking aero bike. Will Google now, instead of working

                • ebbe

                  There’s a “big S” on it ;-) Here’s a comparing review (against the directly competing Trek Madone) which specifically mentions the bad brakes: http://velonews.competitor.com/2016/02/bikes-and-tech/clash-of-the-titans-trek-madone-vs-specialized-venge_392763

                  • Ouch, that’s a major chunk of money to spend on something that frightens you going around corners!

                • jules

                  the aero brakes are more like cantilever brakes with the caliper arms pulled together with cable, rather than the solid linkage calipers used on conventional brakes. I have them on a TT bike and rate them somewhere between frightening and useless.

  • ridein

    What is needed is a 3rd generation fork/stay mount for a separate round guard for protection. Using a radiused edge on the rotor is just a partial stop-gap measure.

  • mzungu

    The Tektro/TRP rotors edge don’t look like it’s rounded to me…

    • James Huang

      The picture doesn’t do it justice. They definitely don’t have 45° chamfers or 1mm-radiused edges but they’re far less sharp than the other ones shown.

      • mzungu

        So small an radii, wouldn’t normal wear just sharpen it up again?

        • James Huang

          With substantial wear, yes, but keep in mind that rotors last quite a long time and at this level of the sport, they’re apt to be replaced fairly often. Shimano Ice Tech rotors also use a unique three-layer construction with stainless steel ‘skins’ over an aluminum core so they can only get so thin before they’re useless anyway.

          • mzungu

            That’s true, but is there a reason they don’t want to go for a full radius or a bigger chamfer on that edge? more $$ than their current deburring process for sure…

            • James Huang

              My understanding currently is that a more substantial chamfer or radius would add an extra process and, thus, extra cost. Aside from that, I haven’t heard a good reason why it isn’t done already.

              • mzungu

                The deburring process for that tiny radius on the Tektro rotors is pretty standard for sheet metal parts that are stamped and can often be done with the same vendor very cheaply or free, but adding a chamfer or radius is a different machining or grinding process that often done elsewhere at a machine shop.

                My guess is that it can prob double the price easy, unless you are a big manufacture that are set up to do all this in house with a good set up.

                • ebbe

                  As an industrial design engineer, I highly doubt one additional step in the manufacturing process would be double the price, but it could be. However, having said that, to get a “safe for peloton use” label, even double the price would be worth it. Pros don’t pay for their stuff anyway.

                  Also note that double the *manufacturing price* does not need to be double the *retail price*. Manufacturing price is always only a portion of the final retail price. A big part is also shipping, brand margins, shop margins, tax, etc ;-)

  • Brad

    Full radius that rotor edge.

    • ebbe

      They could even do a larger radius on the “outside” edge. It’s impossible to hit the “inside” (facing the spokes) edge anyway.

  • Neuron1

    Is that Kobe or wagyu beef and is the rotor hot enough after an alpine descent to properly sear it to medium rare?

  • Al Storer

    Can journos start acknowledging that Ventoso is just plain wrong about Maes- the video evidence is enough to show that no Lampre-Merida or Direct Energie riders were in that pile up. And it seems no LAM or DEN rider thinks they were involved in Ventoso’s incident (though of course in the chaos of a race memories become confused plus “they would say that”)

    • James Huang

      Mat Brett at Road.cc put together what appears to be a nice debunking of the Maes injury (http://road.cc/content/tech-news/186146-have-disc-brakes-really-led-injuries-peloton) but so far, I haven’t seen anything to either support or refute Ventoso’s claims. As I mentioned, though, it doesn’t entirely matter if Ventoso’s claims are true. What matters is that the risk exists – however small – and that more should have been done to mitigate them before the trial began, even if only to calm the nerves of the riders.

      • Dave

        Etixx-QuickStep themselves confirmed that no disc brakes were involved in the crash of Maes.

        Journos should, in my opinion, be making better efforts to make it clear they are commenting on Ventoso’s allegation and not endorsing it as fact.

        • James Huang

          I’ve tried to make it as clear as possible that I’ve regarded Ventoso’s claims as just that: claims. I’ve also stated clearly that I don’t think the veracity of his story matters. The fact that the possibility remains is ultimately the issue.

          • transalpen

            James I think that is the point. You’ve jumped on the bandwagon by stating “disc rotors, as they are currently manufactured, can be very sharp and there is the potential for rider injury in a mass pileup”. There’s been a great deal of hype since the PRB reports, but very little critical analysis of whether rotors did, or even could cause the alleged injuries. I’m simply not convinced that the ‘possibility’ has been reasonable established and your article doesn’t adequately address this point. In fact, you’ve simply perpetuate an assumption. I’m not against taking reasonable steps to reduce potential risks, I just wish that discussion could be taken forward from a more informed position.

            • James Huang

              I did do a lot of thinking about how Ventoso’s claims could have happened and while I still find it unlikely, it’s not impossible. Without available evidence to refute or confirm the story, the only remaining option is to present it as such: an unverified claim.

      • velocite

        On the contrary, what matters is the extent of the risk, not that it exists at all. And of course the extent of the risk will be some kind of estimate before widespread usage. So although it’s hard to disagree with rounding the edges I think it was entirely the right thing to allow discs on a trial basis. And I think it’s quite odd to say it doesn’t matter whether Ventoso’s claims were true or not. Surely the trial was stopped on the basis that it proves discs are too dangerous – with no inquiry.

        I do wonder about the ‘trial’ aspect of the introduction, though. Was any trial observation protocol put in place? Was a successful result defined? Based on the knee jerk response to one unlikely story I fear not.

        • ebbe

          Agreed! Risk = probability x impact. If something has not ever happend, even if the potential impact is enormous, the probability is still relatively low. Eg: The risk of crashing from being hit by a moto in the race is much^3 higher than the risk of being cut by a disc. Both the probability and the impact are far worse.

  • Conscience_of_a_conservative

    Not sure how unbiased a piece is when it begins, ‘Professional road racers have a long history of resisting change, and safety hasn’t always been a paramount concern; many riders opposed helmets before the UCI mandated their use in 2003’.

    The position of cyclists in the past on safety issues does should not and does not change the legitimacy of current concerns.The argument comes of as a type of strawman.

    • Michael_Fink

      It’s an article; not a legal submission. ;-)

      And at the risk of being a pedant whilst it might be perceived as evidence the journalist’s apprehended bias, it’s not not an example of a strawman argument.

      Personally I find the conservative culture of road cycling quite interesting. Most innovations (be it carbon, sloping top tubes, integrated headsets, ergo bars, electronic gearing, tyre width, etc) seem to be met first with horror, then grudging acceptance, until within a few years they are defended as religiously as all the other ‘Rules’.

      Based on this my guess is that the latest development is just a hiccup, and that in the absence of real evidence of increased safety risks, everybody will be on discs soon enough.

      • H20

        Lots of sports get branded with the “conservative culture” label. When that label is thrown around so often, and so rarely with detailed justification, one has room to think it’s not valid. After all, “conservatism” in the form of restricting technology is the very essence of sport if it wasn’t for restrictions on technology we would be in F1-style cars. Not only that, the charge of conservatism normally completely fails to account for issues like the fact that making every current club-level bike obsolete in some way is not necessarily good for the sport, therefore resistance to change may not be conservativeness as such, but simply the right decision on a cost/benefit analysis.

        While one rider’s account (which we have read only in the form of a short letter in what may not be his native language) is not conclusive evidence of increased risk, on a purely objective basis such an eye-witness account would surely be seen to be better evidence that there is an increased risk, than the claims of forumites who were not there any say there is no risk.

        If “everybody” is on discs at club level then the sport already often seen to be too expensive and obsessed by technology will become even more expensive. People will have to discard perfectly good bikes and spend thousands replacing them. Is that actually a good thing for a sport? And while you’re at it, can you please provide evidence that electronic gearing etc has been met with “horror”?

      • Bärlach

        Well said!

  • Berne Shaw

    If we can send a person to the moon, figure out how to make an atomic and hydrogen bomb and that map our DNA, we can make a carbon cover for these brakes blokes! C’mon mates, it cannot be that difficult to shield them. The forces involved in falling on them at speed when they are hot and rotating and that one could sever an artery like the carotid means death so why not just make them safe and enjoy the benefits which are real. Or let us ban them until the industry wakes up and gets over its greed. As a researcher, it is a truism that even low probability events with enough trials will occur 100 percent so that we will see fatalities for this. And they are not the same as a round spoke due to the forces inertia and mass involved here.

    They can bend them to be closer to the spokes, cover them. They can innovate internal hub brakes. There are ways. We can even use carbon rims with aluminum braking surfaces if they resist covering them. This will speed and motivate them I bet.

    • James Huang

      I agree that this doesn’t seem like an overly difficult problem to solve – which is partially why I’m so frustrated that it wasn’t properly addressed in the first place. I don’t personally think the risks associated with disc brakes are quite as bad as some have made them out to be (especially with the burn risk, given that mass pile-ups rarely occur on long descents where that heat build-up is likely to occur) and at least to me, one of the possible solutions is technically very simple. More to the point, I’m not part of the user group that needs to be convinced. I remain firmly of the opinion that discs are vastly superior to rim brakes in terms of overall braking performance (and no, I’m not just talking about power).

      • Kerr Avon

        If that implies shorter stopping distances, then no. In dry weather, discs stop the same as properly setup rim brake. In the wet, they have the advantage over a wet, rim brake. However, if the road is damp and the rim surface is dry, the same as disc. Of course within the traction limits of the tire.

        The manufacturers know this and that is why you don’t see data or anything from them to compare both systems. All they talk about is modulation/power and the ability to stop powerfully with just a weak pinky.

        • ebbe

          The only test I’ve seen is this


          I will immediately agree that this is not very scientific. But still, it also confirms my own experience so far, moving from rim brakes on alu rims to disc brakes: Slightly better in the dry, MUCH better in the wet and other difficult conditions.

          That is, if you know how to brake properly. If not, rim brakes are just plain dangerous because they block too easily if you squeeze hard at once. Disc brakes actually don’t block that easily, in my experience.

          • Sean parker

            You’re right – this is completely un-scientific but it doesn’t have to be scientific to demonstrate your point.
            If you ride on wet roads discs are the better braking system. The type of reader who peruses this site probably trains wet or dry – which baffles me when i see so many comments stating that discs and rims are the same ‘oh, except for the wet’.

            Do drivers only throw their doors open into your path in dry weather?

        • Sean parker

          ‘… properly setup rim brake.’
          there’s the problem. many punters are riding on spongy, ill-maintained rim brakes. it’s easier to neglect disc brakes and still have a very effective brake. How do I know? – I am a neglector.
          Comparing rim brakes to discs in the dry is apples and apples when you are talking about pros but apples and oranges for the great unwashed who do not/can not maintain their equipment properly.
          Some riders also ride in the wet, by the way, so i don’t know how pertinent your argument really is to cycling.

          • Kerr Avon

            It’s their problem if they are too lazy to turn a barrel. For you or anyone else to neglect your brakes, you a re foolishly riding on borrowed time. Being that hydro disc brake components are much more complex and exposed, it’s wise to inspect your disc setup every ride.

            • Sean parker

              Yes it is the punter’s problem to maintain their brakes. Which is why many don’t do it well. It takes practice and knowledge. An engineering solution to a ‘human factors’ problem is ideal.

              Moreover, cable rim brakes get worse perniciously. Check out the number of newbies riding onsquealing, spongy poorly maintained cable brakes in any sportive. They don’t want to have crappy brakes, they just don’t realise they are because the problem evolves slowly over months.

              But I suppose if you only ride in the dry it makes no difference anyway.

      • tanhalt

        James…have you got any objective data to back up that opinion? It’s my understanding that publicly available data on the subject (especially comparing “best vs. best”, i.e. NOT using carbon as a braking surface) is pretty much rare as hen’s teeth. That sort of data would be key to convincing those who aren’t so stridently in the “vastly superior” camp.

        • James Huang

          Do you have data to refute it? ;)

          In all seriousness, you and I have had this discussion on numerous occasions so I know we both can agree that ultimate braking power is always limited by tire traction. That said, I know how I am able to ride with rim brakes (of all different sorts) vs. disc brakes and I’m comfortable leaving it with the two of us disagreeing on the relative merits of each.

          • tanhalt

            The original SRAM hydro data showed that the braking torque (for a given lever force) for their hydraulic rim brake operating on an aluminum braking surface was within 10% (IIRC) of the hydro disc brake using a 160mm rotor, with basically the same “curve shape” (i.e. modulation). This implies that this particular hydro rim setup would actually be more powerful for a given lever input than the same disc with a 140mm rotor. Add in to this the improvements in power, modulation, and wet weather consistency found with surface treatments such as the Hed Turbine features, and it’s looking like “integrated aero rim discs” have some life in them yet…but, nobody seems to want to take up the task to get the data. I may just have to do it myself ;-)

  • jules

    I think people are missing an important factor in assessing the risk of various components cutting riders in a crash.

    What cuts skin is essentially the stress imposed by a contacting object. Stress = Force / Area.

    A reason why spokes and chain rings do not cause frequent, severe injuries is that other bike components – including the frame – tend to guard against contact with them. You can still contact those components, but the Force will be less due to load burden shared with other ‘guarding’ components.

    A problem with discs is that they are positioned in a relatively outboard position that means they are less guarded. In other words, it’s more possible to fall on a disc with the full weight of your body, or body part (leg, etc). I’d argue this is a factor making discs more risky than chainrings etc. – that simply comparing the shape of the components doesn’t account for.

    • Dave

      I disagree about the discs being easier to contact than the spinning spokes of death. You just need to image search for bike spoke injuries (bucket recommended) to see that.

      Discs are also largely guarded by other components – the fork and caliper at the front, the stays at the back, and the whole wheel from the right hand side.

      Put it this way – if I was to blindfold you and tell you to walk over to a bicycle on a repair stand with your arms stretched forward, the chance of a brake disc being the first bit you hit would be very small – even if I did double the chance of it happening by first checking the left hand side of the bike was facing you.

      If the shape of the outside is round without notches (can be done, my old commuter HTB/hybrid had round discs with holes instead of notches) and the edge profile treated, it easily becomes something you would be happy to have because it would present as a guard against hitting the spokes if you land on it in a crash.

      • jules

        I agree on the risk posed by catching body parts in spinning spokes – that’s pretty clear. I meant the risk of spokes in a blunt impact with them (not getting caught in them and sliced as your fingers etc. are jammed against forks/chainstay/etc).

        I sort of agree that discs are not deadly and that there are other risks attached to your bike. But I reckon if you fell on one with your full body weight at speed, they could do damage. There is some risk of serious injury there.

        • Dave

          If you’re falling on a disc with a fair portion of your body weight, you’re almost certainly falling onto the outside surface of it, not the edge, and quite likely guarded by the fork/stays as well. The edges still need to be treated better (those Shimano ones just look cheap, no way would I buy those) for the ‘scratch across an arm/leg’ type instances.

          If the edge is rounded, that’s still better to hit than the thin spokes underneath (although other parts of the body will probably hit them. Even the outside end of the through axle, or even the fork/stays would be more uncomfortable to land on than the disc from the side.

    • Sean parker

      In a cycle collision there are more things to worry about than the unlikely event of hitting the disc.

      Things like fractures and head injury.

      i would like to get excited discs but just because they are novel doesn’t mean that they have tangibly increased the risk of injury to cyclists; when real tangible actual risks are already accommodated, if not dismissed.

      So a a bloke got a laceration that may have caused by a disc…. how many lacerations requiring suturing occur every week by hitting the road?

      I am not waving away the ban, actually, but lets keep it in perspective.

  • Conscience_of_a_conservative

    I’ve been riding road bikes for close to four decades. Other than during periods of rain or snow I never once thought my caliper solution was inferior, but now there’s a whole bike industry out to prove otherwise. That said, nobody is arguing that disc brakes are not a valuable tool for the right applications. The cyclist union is not against disc brakes in general, but they are concerned about their use in their current guise in road race events where cyclists ride aggressively in close proximity and where crashes can and do occur.

    • Dave

      People said exactly the same things about having hollow tyres filled with air, about using bikes made of fibre-reinforced plastic and everything else that came along in between.

      • That’s pretty facile. Carbon fibre bikes are with us since the 80s. It’s only the last decade they have been accepted universally. Sometimes things take time to get right, which is what Conscience of a conservative said “they are concerned about their use in their current guise”

        • Kerr Avon

          And discs far longer… More than 50yrs for the cable units and 45yrs for Shimano hydraulic units.

    • ebbe

      I would like to agree, but now we’re seeing sportives in France and Spain ban disc bikes, following the UCI decision. This, to me, really is a huge step backwards for getting the consumer interested in cycling. Let’s put it this way: If a friend would like to take up cycling and came to me for advice: Two weeks ago I would have recommended they get a bike with disc brakes (and comfy geometry, and clearance for wider tires, etc) 100% sure! Now, I still support that recommendation, but I would have to tell them to play it safe and go for rim brakes instead… In case that they might ever want to go to France or Spain to join a sportive.

      I did a sportive just this Sunday (related to the start of the Giro) on open roads. The weather was… barbaric to say the least. I did see quite a lot of disc bikes (varying from road, to MTB, to trekking/commuter bikes), including my own (officially a CX, but I use it for road as well because it’s awesome). We were in a group of 6, picking up and losing other small groups all during the day. And I can tell you with 100% certainty: When the hail/snow/rain started pouring, I could easily drop my friends without any effort at all. Not because I’m a stronger rider, because I’m not, but because my braking was far far superior. I could basically ride as you would in normal weather, without being afraid to crash in every corner or slip on every brick. And no, nobody crashed into the back of me ;-)

      • Conscience_of_a_conservative

        That’s where we differ. I tell them to consider how they’ll use the bike. Good weather and road bike I never thought disc was necessary just adds cost and weight, commuter or gravel bike get disc. CX bike disc or cantis.

        Sprotive in hail and snow. no thanks. i did a fondo in 8 hours of rain back in 2013. its an accomplishment i’ll give you that, but not a fun one. I’d rather skip next time.

        • ebbe

          Good weather? Over here it’s a given you’ll end up in rainstorms every now and then ;-)

  • Dude pedalling


  • zurp

    Having raced at an amateur level for a few months now and ridden several more with Shimano road discs, I can’t tell you how many times it has come in handy already. You can’t convince me anymore that braking using two pieces of rubber coming in contact with the actual carbon wheel that you’re riding on which is some cases has a tire *glued* on is superior to taking that power to an aluminum rotor. If discs were here all along and that technology came out now, it’d be the laughing stock of the industry right?

    Looking at my bike, it’s still hard for me to wrap my head around how Ventoso managed to cut himself where he did. But shit happens so added safety isn’t a bad thing. After all, that’s why we wear helmets right?

    • jules

      if you’re constantly thanking your brakes for saving you while racing then you’re doing something wrong, or someone else is :)

      • zurp

        Long bumpy descents? Way more control. Later braking and smoother cornering, huge advantage especially the more extreme the turn. Avoided crashes on a few occasions, slammed brakes with no need to skid. And this is all in dry conditions

        • Kerr Avon

          You should have some podiums or did I miss the tactical advantages you’ve just implied?

          • Bärlach

            haters gonna hate

  • Bmstar77

    Get rid of the wavy disc fashion thing and move to round rotors. Then manufacturers can more easily chamfer the rotor edges. Just looked at a Ducati 1299 Panigale S. No wavy discs on that baby and they don’t have problems braking from (near) 300kph.

  • Matthew McArdle

    Round off the edge profile of the discs and make them solid (no spiders). Discs then cease to be a safety issue in the bunch, and we can all move on.

    You are correct, this has been a very poorly handled trial.

  • Eat More Lard

    Hardly science but check out this video from GCN around the 2:50 mark with the chorizo vs the rotor and the spokes. https://www.youtube.com/watch?v=JplymlruPZ8

  • Conscience_of_a_conservative

    Honestly, A lot of money has been invested in gearing up to sell hydro disc brake bike to the masses. I expected some silence after Roubaix and then for the marketing guys to start hitting social media to rebuild the case to bring disc to the peleton and more importantly convince us we all need to switch and buy the shiny new thing.

    • Sean parker

      You’re right. I’m going to take the disc brakes off my mtb and use my foot to slow down. just because ‘The Man’ sold me something i didn’t need.

  • Bones

    I think the discs will only be dangerous if the rider forgets to switch off the motor during a crash :)

  • Bryan

    Rim brakes are just big disc brakes. Get some hydraulic calipers and go forth! I’m not a fan of disc brakes. I see it as little more than the industry trying to part us with more money, as it makes bikes start to cost even more. Hopefully prices fall a bit as the technology matures.

  • PB

    I am going to point out for what seems like the 99th time that Ventoso didn’t see the accident and that he has no idea how he got cut. It could have been a brake rotor, but there are a lot of other sharp things flying around in a bike crash that could have also caused his cut. There may be reasons that disc brakes don’t belong in pro road racing quite aside from allegedly sharp edges and the alleged cutting of one racer, but Ventoso and the UCI are jumping to conclusions based on poor evidence.

    • James Huang

      No arguments here at all, especially in regards to what feels to me like a knee-jerk reaction to the incident in question. As for Ventoso, I’ll reiterate the comments I’ve made below. Without any evidence to either refute or support his claim, I can only present it as his account of what happened and I’ve made that status clear in the article. Either way, that the potential for injury from a disc rotor exists at all is an issue and one that should have been more properly addressed before this trial began.

  • Eric Janik

    I tend to agree with the author on this point: disc brakes do work better. On the other hand, for the kind of road riding I’ve been doing (rain or shine; I tried snow once and said never again) for the last 40 years, I don’t see the gains as surpassing the losses: expense, weight, and bother.

    As for the pros, yes, the rollout was premature. Let the manufacturers try again, after they’ve answered the questions about safety. And although I have no personal stake in the outcome–I don’t care if the pros aren’t riding the same equipment as I am–I’m still betting against widespread adoption.

  • Altimis Nuel

    Its a damn metal piece and any metal would harm your skin regardless of how its blunted or thickness

    If its goes your head or legs or arms, its hurts as hell.

    End of story.

  • Mick

    As someone who has had their hand cut open by a spinning rotor I think the UCI and most of you are are all bloody mad, it’s one of those things that sounds good until you get hurt and in this case more people will until they (the UCI & vendors) really fix it.

  • Pete

    Who cares if they’re sharp or not – the point is that the beneficiaries of disc brakes are the manufacturers. What other new ‘standard’ requires you to completely change your frame, groupset and wheels? Have not read one article saying rim brakes needed more power… and I’ve never ridden a road bike from 2007+ that I felt required better ‘modulation’ in the braking department. I maintain the slow take up of disc brakes is because people don’t see the benefit. I’ve had way more problems with disc brakes (screeching discs, improper bleeding, rubbing) than I’ve ever had with rim brakes. I buying a new road bike within the next month, I tried a disc brake equipped road bike – I am buying a rim brake road bike.

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