I am listening to NPR and they just said the the UCI had approved the use of disc brakes on road bikes for racing. That is a pretty unusual way to hear about bicycle racing rules. I haven’t seen that in print anywhere, but I have to assume that is going to be true.
I don’t really like the whole idea of disc brakes on road bikes. I actually pretty much hate it. I don’t see it as an innovation. I see it as a hassle.
Putting together bikes nowadays is a hassle. There are too many options for everything to really keep track of what parts you actually need. There are numerous different bottom brackets. Same with front derailleurs. Now brakes.
Shops can’t keep replacement parts in stock for everything. So, you have to wait to fix your bike on any given day. It isn’t like when you crash on a weekend, you can go down to the local shop and get the part you need to make your bike work the same day.
Specially, disc wheels are a hassle. I don’t understand the wheel change issue. It is nearly impossible putting a different wheel in a bike and not having to adjust the brake caliber. So when you flat in a race, how is that going to work?
And the spacing is changing too. 135 to 142. Thru axle, quick release. How many different rear wheels do you need to compete? Too many.
Flying with a bicycle is a hassle already. Now with disc wheels, unless you have a hard wheel case, you’re going to have to remove your brake rotors so the airlines don’t bend them up during travel. I guess it is fine if you don’t have a 6 bolt mounting system, but it is still 2 extra things to do disassembling and assembling your bike during travel.
I haven’t ridden disc brakes on the road much. But, nearly every time I pull my brakes, I stop. That is the case off-road too. Catherine was all concerned about riding V-brakes on her bike in Chequamegon. I asked her if when she pulled her bike didn’t stop? She answered that it did. What more do you need? Pull the brakes and the bike slows and/or stops. Seems that simple to me.
The one upside I can see to discs on the road is getting predictability when braking on carbon rims. Especially at speed, descending. Or even better, at speed, wet.
But the majority of us, really aren’t racing down mountain passes, on carbon rims, in the rain. And if we are, we most likely understand the capabilities of our brake systems. If you don’t, then you probably shouldn’t be doing it.
And how about having a bunch of guys in the field with different braking capabilities. One guy pulls his brakes and stops in 15 meters, the next guy 20. I guess it is no difference than someone with aluminum rims compared to carbon.
Plus, according to this article at Velonews last year, disc brakes on road bikes take up to 8 watts extra power, due to wind resistance. Don’t think a tt rider or triathlete would want to use these. Or any of us.
So, all our road bikes are becoming obsolete once again. If you don’t have a tapered steering column with disc mounts, you might as well sell it on eBay for 10% of the price you paid for it.
Maybe it’s an upgrade. Just maybe. But the hassles outweigh the benefits, in my view. When they solve the wheel compatibility and ease of wheel changing issues, then I’ll reconsider my stance. Until then, I’m sticking with my views.
You can get this bike, with built in sensors, along with carbon disc rotors, for a mere $27,500.
I agree with you 100%.
Not sure if I’m going to be very happy when I show up for a Masters race, next year, and I see three guys, with deep pockets, show up at the line, with disc brakes……and it’s raining.
The only problems I’ve ever had in the rain, back in the day, was with rims that were “V” shaped, where the pads could not make a complete contact with the breaking surface. In the dry, they were OK, but in the wet, you had to have “manly hands”.
Another thing. With disc brakes, you won’t be able to file off your fork tabs.
All this was said when discs came onto MTBs as well. All I gotta say is I’d never ride cantilever again. Bring on better road braking.
Steve, regarding stopping capability, you’d be stunned at the number of club/ fondo riding adults who believe it is safer to only use their rear brake because they will flip over the bike if they use the front brake.
Willem-When disc came to MTB, you needed to use the same wheels the whole race. How would you address the wheel changing problem in races?
Bill, with discs, you’ll be threading thru-axles and there will be no “dropout” to speak of, tabs or no
KHS is one of our distributors. One of their folks came to our booth at Interbike with a novel brake safety accessory. it is a break-away link to release the brake cable pressure to prevent locking up the front brake. The two cable ends work with a spring loaded magnet, so they rejoin. I believe it is only for caliper brakes on roadbikes. It might work for V brakes too. I never even imagined such an “innovation” before. It is definitely not for hydraulic systems.
Once the through axle comes to road bikes, that will be the end of a fast wheel change in racing. Add the rotor brake and you could be stuck on the side of the road for a minute or two changing a back wheel. I have changed thousands of wheels in races as a team mechanic. This move to disk is going to hurt. 20 seconds you can make up by going up through the caravan and peloton. But a minute or two will be deadly. I firmly believe the manufacturers are churning the market to stimulate sales with a solution to a problem that does not exist.
You start out trying to tell us on how V brakes stop just fine. You state that when you pull your road brakes you stop! “Catherine when you pull your brakes do you stop..yes” – So there.. There you have it.. V brakes are just as good as disc? You might as well have even thrown in that lame argument “i can lock up my wheels just fine with V brakes”.
You immediately turn around and say this.
“And how about having a bunch of guys in the field with different braking capabilities. One guy pulls his brakes and stops in 15 meters, the next guy 20.”. That one statement has been the funniest argument i’ve heard against disc brakes. Right there you are saying “yes disc brakes work better than v brakes”. So much better that the rider on disc has an advantage or the ability to slow his bike down better than others. How do the anti disc brakers use this argument and not just step back and think about how dumb that is. “emmm.. they suck because they work better”.. nice
Swapping disc brakes wheels on the front is faster than I could do with V brakes (not all brake pads line up with the brake track with V brakes). The rear is slower, but that’s only because my bike has thru axles (which i am sure you will rant about that technology as not being needed either).
8watts? 8watts? Please, How about calculating all the little seconds here and there you gain by being able to brake later in a turn or having the confidence in any condition that your brakes are going to perform the same no matter what? I believe that holds a lot more value than 8watts.
The hassle comes from competition and everyone wanting to set standards. Now with shimano’s flat mount standard and it looks like 142 should settle in, things should get easier for you folk that are not always on the bleeding edge of marginal gains.
What about that fancy di2 you run? Doesn’t your bike “shift just fine with mech?”
Not an unexpected reaction from you. From the same Velonews article:
“Discs are simply better brakes; they stop better, under a wider range of conditions, than any rim brake.”
You can make your same arguments – hassle to fix, more parts, tougher to travel with – about electronic shifting; but last I heard, your road bikes aren’t mechanical any more. So why?
And your 8 watts statement is misleading, here is the full quote:
“Discs are the most detrimental in strong crosswinds, specifically right-side crosswinds. At -20˚ yaw, which is an uncommon but still feasible wind angle, the difference between the two Tarmacs is an astonishing 8 watts. Across more common wind angles, the gap between disc and rim-brake bikes is generally between 1 and 3 watts — not much, but not an insignificant amount either.”
Sorry to say Steve, but dinosaurs didn’t adapt and didn’t survive. This is good for the sport overall, having safer, better brakes. So why oppose it?
Discs grab better and feel better in the hand as well as never needing adjustment. They make the bike look cleaner at the frame too . It is also nice if a wheel comes out of true that you don’t have to loosen the brakes.
Calipers have enough power in all conditions except the rain.
If everyone is using discs in a race, then the added time is the same for all.
My opinion is they are not as necessary as for MTB, cross or tandems though.
I said years ago electronic shifting was an answer to a question nobody asked. Same for disc brakes. Unless you count the bike industry (“So, all our road bikes are becoming obsolete once again. If you don’t have a tapered steering column with disc mounts, you might as well sell it on eBay for 10% of the price you paid for it”) as somebody that is. Anyone who points this out is branded a Luddite, standing in the way of “evolution”. But what is the ultimate “evolution” of the bicycle? It’s called a MOTORCYCLE. One of the greatest attributes (for me) of the bicycle is its SIMPLICITY. I don’t think I’m the only one as the worldwide explosion of “bici di epoca” events such as l’Eroica illustrate. The bike industry decided awhile ago that simply making and selling things for a profit is not enough for them. They must have growth. Once everyone who’s interested has enough bikes, the marketing must then move to those who don’t care about bicycles. They get attracted by the same “point and shoot” techno crap used in consumer electronics. The result is recalls of millions of bicycles because the dolts can’t even use a simple quick-release skewer! Disc brake wheel swaps in racing will eventually force changes to bicycles with front ends much like the single-sided “Lefty” thing and a rear end to match. Flat tires will be swapped out F1 style though the transition will likely just mean entire bikes are switched out from atop the team or neutral car. Is the whole idea stupid? Certainly. Inevitable? Certainly.
kevink – First, I don’t agree with the Velonews quote about disc brakes stopping better that rim brakes in all conditions. 2nd, I never said the same about Di2. I’ve been quoted many times about the advantages of Di2. 3rd, my quote isn’t misleading. Maybe you don’t understand the “up to” before the 8 watts in my post?
The current generation of disc brakes aren’t good enough for road racing. Sorry, that is a fact. When they solve the wheel compatibility and ease of wheel changing issues, then I’ll reconsider my stance. Until then, I’m sticking with my views.
I seem to remember a big problem with rotors overheating on long descents. Has that been overcome?
I’m with Steve on this-simplicity has been swept away in favor of sales for manufacturers. Rather than “Who is the stronger rider?”, it has become “Who has the deepest pockets?” for amateurs and pros.
Braking is based on friction in two separate areas — 1)The wheel and the brake & 2) the tire and the ground.
Everybody seems to forget about the important tire vs ground part of braking. The reason disc brakes work so well with CX and MTB is that the tire to ground friction is greater with wide knobby tires.
There is a real point of diminishing return on the road tire vs the ground. I can lock my tires in hot dry conditions with my caliber brakes. I could probably lock them a bit easier with discs, but I don’t think I want to.
I’m sure there is a study to prove this out, but I don’t see a need for discs on the road. This smells like a money grab from the manufacturers trying to boost sales revenue without actually increasing market share.
When we used v brakes or cantilever brake for mtb racing I can remember my forearms becoming so tired in races that it would make me slower in technical sections. I raced road for 15 years and never once thought that. Not even in a crit with lots of braking. I’m with Steve on this one. When you can get a neutral wheel then I will maybe upgrade.
Ride a tandem much? A tandem is the only bike in my garage that runs disc brakes.
Just wait until there is a through axle on some road bikes and conventional on others. That will mean at least 3 different wheel configurations for neutral or even team support.
I hate this so much. First off, they are ugly..IMHO. I prefer the traditional look of rim brakes on a road bike. Regardless of how great they are, I haven’t had any issue stopping my road bike with its current set up. MTB totally different (happy for the disc technology there). Also, I feel like the industry is forcing us down certain paths. Cross was a bit like this. It is getting harder to find canti bikes for cx. The through axle stuff is also a problem. New wheels, new freehubs (11spd), new axles, new bikes..new bikes again. It is hard and expensive to keep up. Why do we need 100 variables. Surely this is expensive for the manufacturer as well.
Even worse when you buy your own stuff. A hassle? I’d take twice the hassle of “switching” if it was handed to me.
Am I missing something or is this going to lead to more crashes in crits because part of a field is riding disc brake equipped bakes and part is riding cantilever brakes?
And does anyone wonder what a rotor running into a downed rider might do?
I’m frankly worried that this is going to cause far more safety problems, let alone financial, for the average amateur.
One point I didn’t see being addressed is the continual development and force-feeding of new standards is only affordable by the wealthy. Continually being forced to buy new equipment is not affordable for many of us. Throw out a $400 fork (or a frame that cost thousands) because it doesn’t have disk brake mounts and we need a new wheel set and all the new wheels coming out are through axle with disk brake hubs? The introduction of all of these new standards is just selling the same apple with a slightly different polish. It’s called planned obsolescence. Shimano aggressively practiced this for years before the entire bike industry conspired to force new standards on us, making past standards (and parts availability) obsolete. They create new products and phase out the old, to guarantee a continued income stream for the corporations. No matter if whatever they’re forcing on the cycling public is better or not. There is a certain market that will always buy the newest, latest and greatest thing, and then there are the rest of us who are forced to buy it because we have no other choice. Even with disc brakes already on mountain bike frames at 135 spacing, they made the rear spacing wider to 142 anyway. Some can argue forever that 1×11 is better than 2×10 but it’s six of one and half dozen of another for most of us.
It’s about money, and greed, and the downfall of quality and efficiency. I’d guess other yesteryear trends would re-appear, if the profits made sense…steel comes to mind, but actually welding is so…so…just sooooo labor intensive when you can pour a gallon of slop into a mold and presto – Jello-Bike!
Peter, what if those “dangerous” disc rotors also had sharp teeth carved into them? Sounds lethal, eh? Oh wait, there are already 2 of those on your road bike already; they are called chainrings. Bring on disc brakes. I run them and I love them. I would love them even more if they lost just a little weight and we’re a little more aero, but you know that will come.
I think that a lot of the readers of this site are coming from a point of view that the manufacturers dont really care about. What percentage of people who buy mid to high end road bikes race them? 5%? Most people are out riding and just want to be able to stop faster and more reliably. They are not concerned one bit about switching wheels mid ride or the time difference between removing a through axle vs. QR. I will say that visually the road canti’s look better though.
Rotors heating up? I went down Pikes Peak 150 or so switch backs and 20 some mile descent without issue. No rotor or pad wear.
Anyone able to confirm this?
Death by a thousand cuts. As most have noticed, wheel changes are already slower at the pro level due to the enforcement of “no filing lawyer tabs”. Me thinks there will come a consensus of year to year standards in the pro peleton (axle type, rotor shiming, hub width) before the big teams sign on. This will simplify neutral support. The argument that wheel swaps require caliper alignment is naive. I have several disc wheels that have the rotos spaced exactly the same. Took more setup but wheel swaps are easy. Add in a 15mm similar to Manitou’s Quick release and it is actually faster than using a quick release.
Like it or hate it, owever, it is coming to a race near you …. modulation is the key, not brute power. Any fool can lock up a brake … the ability to brake hard, late and with good modulation is what makes disc’s king on bicycles. The comparisons to F1 and the like are not valid here.
Never need adjustment????? Hmmm, you haven’t ridden many disc equipped road and cross bikes (granted my mtb brakes rarely need adjustment … no more than my road brakes anyway)
Steve … interesting post today as well as the comments it generated. I am offering my thoughts as someone that doesn’t race anymore but still enjoys riding.
My thoughts center around three main points which are: 1) cycling manufacturers are all concerned about profit first … not right or wrong, just a fact; 2) the cycling market is not necessarily racer focused … not right or wrong, just a fact and, 3) while disc brakes definitely add stopping power at certain price points, they create some other issues.
First, to help manufacturers maximize their profits, they want to provide the safest product at the cheapest cost. This was brought to light recently as I was visiting with my great nephew who was proudly showing off his new bike that his parents had bought him. This was not a “big box store” bike but one from a reputable company, although admittedly at their lower price range. Interesting thing was that it was identical to one they had bought for him two years ago except for the fact that it was much larger (grew like a beanpole) and it had disc brakes, cheap disc brakes, but nonetheless disc brakes. The stopping power of these was amazing compared to his old bike. which even had new pads. Would a set of Dura Ace calipers on his old bike helped … you betcha. Would they have cost almost as much as the bike … pretty close. So manufacturers today can slap on disc brakes, even if they are a bit more expensive, and produce a bike with more stopping power in their lower and mid cost ranges, which if you look a sales figures, is where the majority of bikes sell.
Second, as Tripod Ron already pointed out, the majority of bicyclists are not racers. So going back to the paragraph above, manufacturers are going to produce bicycles first for the masses. Although, as I looked around a LBS recently, almost every mid to high end bike that featured disc brakes also had the same model with calipers. True, we don’t know how long this will be this way but for the time being, they are offering up choices to both markets.
Third, the issues highlighted by the advent of disc brakes on road bikes have been described, or in some cases hypothesized, by many posters already. To be clear, I have disc brakes on my road, cross and tandem, although the tandem is rear only, and I love them. Of course, as I stated earlier on, I don’t race anymore so quick wheel changes are not a necessity in my riding. I do know, from seat time experience that even low end disc brakes will stop better than low to mid range calipers. What persons need to remember though is that disc brakes apply torque/strain at a different point on the front fork. It is much lower down … in fact, almost at the axle point rather than up at the crown … biggest reason we have canti’s on the front of our tandem rather than a disc. If you ever have seen a front fork fold on a front, disc braked tandem because of that stress you would understand … not ours thank heavens! And, you add to that that the forces are being applied to one side of the wheel, rather than both, you fully understand the need of a beefed up forks and possibly through axles to handle the added stress. So while the discs bring about the stopping power I want and need (short of equipping my bikes with the top of the line brakes), they also bring about other issues that I need to remind myself of.
So Steve, while could agree with you on a “racer’s” view of discs on road bikes, I can’t necessarily agree with those same views carried over for who never raced, or don’t anymore.
Makes for real quick wheel changes.
Bikes have always been this way, back in the day it was ‘ French, English or Italian thread please’ and what fun would it be if in your home bike shop you didn’t have boxes and boxes and more boxes of part to spew out onto the floor to find that perfect piece to take to the grinder for the perfect fit.
If you all raced track you wouldn’t have to worry about disc brakes, Di2, through axles, or differing over locknut spacing.
🙂
Do they heat up? Of course they do. Do the pads and rotors wear? Of course they do … more pads than rotors but the rotors have to some. I ride discs on all my bikes so am speaking from experience. Can also tell you that they can get quite warm after long descents. All that said, I can tell you they don’t heat up my rims at all on those long descents so I never worry about increasing air pressures on any tires, especially those of a tandem. l have found the replacement costs for pads is usually cheaper than quality rim pads and they last longer.
Steve,
GCN has done a comparison of rim vs. disc brakes. Not too scientific, but shows the differences.
I’m fine with my rim brake-equipped road bike, and I don’t care if people ride/race disc road bikes, because no one is forcing me to “upgrade” the bike that I currently own and am really happy with. Why should I care if others want to “upgrade”? It’s not my money.
Craig
October 12, 2015 at 1:31 pm
Never need adjustment????? Hmmm, you haven’t ridden many disc equipped road and cross bikes (granted my mtb brakes rarely need adjustment … no more than my road brakes anyway)
I meant Hydraulic disks. Cable actuated brakes DO need regular adjustment.
Guys – We’re just going to be 3D printing our bikes soon anyway.
http://www.slowtwitch.com/Products/With_a_Culprit_Legend_at_IM_Kona_5419.html
Swapping disc brakes wheels on the front is faster than I could do with V brakes
Are you sure?
Bike 1: traditional dropout + qr + rim brake
Bike 2: thru-axle + qr + disk brake.
You are telling me you can thread the thru-axle faster? I don’t believe it.
But what is the ultimate “evolution” of the bicycle? It’s called a MOTORCYCLE.
The vast, vast, vast majority of consumers like to buy and use stuff that makes a bicycle look like a motorcycle. Build something for purpose that doesn’t look like a motorcycle and you are almost guaranteed to be putting yourself out of business.
I’ve given up and will get some very good gear for very cheap in another year or two from people with much more money than common sense.
It’s more than just braking differential between two different types of brake.
We all have been in packs that slow down rapidly for whatever reason. Now there will be more powerful braking that is guaranteed to cause mid-field crashes.
A solution for a problem that doesn’t exist. Please leave your disc brake road home on race day.
I don’t get all the fuss. I ride a 16 year old Seven, full Campi, nice wheels and I’m happy. The World Tour Pros will figure out what works for them and adjust the support vehicles over time to work or not. Thats Pro Racing! If your an amateur then ride what you can afford and like. The legs will do the talking at that level. If your touring then it really doesn’t matter anyway. I think its important to have fun and make sure you have an OK bike but don’t get sucked in to the idea that you have to have the best to love riding. If your racing train and train and train and watch what you eat and buy a used 16 LB bike and you’ll be fine and win. If your rich and want the best go for it but you wont go that much faster than a fit rider in a light older bike.
Funny how resistant people are to change, and even more interesting that racing is lagging so far behind consumers. We have the same braking system for a 100lb rider on the flats as we do for a 250lb rider in the mountains. For 40+ years (more?) there has been basically minimal innovation in road brakes and one could argue that carbon rims have made being able to consistently and predictability stop in all weather conditions worse. This would never be acceptable for cars. With disck brakes at least you can vary the rotor size and someone in Kansas might be able to get away with a 120/140mm rotor were as some with a few extra lbs can get more braking power with 180/200mm rotors. This is not possible, even with cantelivers on rim brakes. Besides, pro teams are adding weights to their bikes, why not attempt to improve modulation which might reduce crashes?
I’ve been on road hydro disc brakes for 2 years and won’t go back especially after touring in Corsica with 12’k days and 1500m tight descents that make Colorado seem boring. Could a skilled rider make it down with rim brakes, sure. What sane person would want too? That would be the guy with his Motorola RAzor cell phone who doesn’t understand why you would txt or use data when you can telephone.
“the tire to ground friction is greater with wide knobby tires”
Really?
IF you have wide *slick* tires on pavement, then yes, they will have a greater coefficient of friction than skinny tires, but knobby tires on dirt absolutely, unequivocally do not have more friction (i.e. grip). That’s not me, that’s science…
“I can lock my tires in hot dry conditions with my caliber brakes. I could probably lock them a bit easier with discs”
You apparently do not understand what “modulation” is.
No worries, it’ll just become standard for everyone to have a spare “pit” bike just like in cyclocross, making wheel changes a thing of the past. This also means the cost of entry will be TWO overpriced bikes – another boon for the manufacturers.
This also means dedicated team follow cars for Cat 4s and masters.
God I hope I’m wrong.
I think Tripod Ron is correct wrt the component makers.
As for racing I think the pros are going to make the switch to disk brakes due to sponsor pressure and we are going to see only complete bike swaps in the future. I’m not sure how that will work out in practice though unless the UCI let two or three bike-carrying cars per team follow the race.
With current neutral support a rider has decent odds of getting a wheel and regaining the group. If neutral support is providing disks with thru axles how is that going to work? I can’t imagine having neutral support rolling up as I’m fiddling with my axle and when I finally complete the change trying to catch back on–unless I’m Nibali.
I’ve been alarmed at the number and severity of crashes in pro road races lately. I can’t help but hope this might result in more safety, which in the final analysis is job one.
Tito
Gotcha. Makes sense if you are riding Shimano’s for sure. My son’s Sram brakes on the other hand … need adjustment a bunch. My XT’s … never touch em.
Craig
Just another thing –
http://velonews.competitor.com/2015/10/news/cyclocross/boost-in-cross-or-foot-in-mouth_387633
Steve, by moving the braking surface to the rotor, it seems that it would open up a significant potential weight savings at the rim, akin to tubular and clincher weight savings, since the rim does not need to be engineered for braking surface. I’d think that that potentially could overcome the wattage penalty for the rotor exposed in the wind, (as well as potentially moving towards smaller rotors). I have about 3k miles now on my CX disc brake bike, personally, I think they are amazing. But, you’re right, wheel changes are a major hassle, especially with TA since you have to line up the QR on the thread as well as keep the wheel straight and the weight of the bike suspended. There are certainly a handful of other reasons that adoption at the pro tour level is questionable. This might inspire me to do a full write up on the experience. No one is forcing anyone, but at least riders can have the option.
This is just craziness. Do disc brakes “perform” better? I’m sure they do. But ask yourself, did you ever REALLY have a problem with stopping before? How big was this problem? I don’t think I can recall a specific situation of riders complaining to each other about needing better braking solutions. Sure, in rainy conditions, the rider must adapt his or her behavior to the realities of the situation. Gotta clear that water off the rim with an initial touch of the brakes. Big deal.
People don’t realize the totality of what they’re trading-away here. The net: Simplicity for complexity. You’re already starting to hand over the control of your shift to an electronic device. Now you want to make the bike infinitely more complicated to maintain. And of course, more expensive.
But all of this is just pedantic. This move is not being driven by either racer OR consumer demand. This is being driven by manufacturers who want to create more obsolescence in the old, and get people replacing their equipment more often. They sponsor the WT teams, and they want to see their new equipment on WT bikes, and they need the UCI to say OK. And of course, they have given in to their bread and butter.
And I’m just left to wonder what new “innovation” will come next. They’ve already exhausted the “carbon” revolution. They’ve created machine-based gearing. They’ve done this. Now what?
The uptick in crashes has to do with two basic things:
1) People who train mostly alone (and only encounter groups when they’re racing). Bike handling skills have gone WAY down in recent years. Just ask anyone who used to race back in the day AND still races today. Skills have clearly eroded.
2) Directeurs who order their entire squads to ride at the front (x however many teams)
I was on caliper braked road bikes for years and didn’t know I “needed” disc brakes until I bought a cyclo-cross bike which came standard with cable operated disc brakes as standard. I soon found that as soon as there was any sign of rain, I’d be taking the CX out rather put up with the vagaries of caliper brakes in the wet; wishing and hoping the bike would stop in time.
I’ve since found that hydraulic disc brakes, at least the Shimano ones, are on another level again, well above cable operated discs in terms of braking power and control. Not to mention the self-adjusting capability of hydraulics, which makes maintenance so much simpler compared to calipers or cable operated discs.
Some recent comments from Sir Chris Hoy:-
(who is admittedly trying to talk up his new range of bikes)
I had Di2 it on a team bike and I must admit I did like it. ….. Di2 is cool. A bit like disc brakes, until you’ve tried it it’s easy to slag it off – then you try it and it’s like…
I never thought I’d be here advocating road bike disc brakes – but I love them.
I’m not a big fan of technology for technology’s sake – but I honestly think this is where it’s going to go.
I recommend people try riding a bike that’s been built from scratch to be a disc brake road bike – not just a standard road bike that’s had disc brakes stuck on – try it, and go back to your calipers and see how you feel.
There’s more to braking than what type of brakes you have. Super Week, 1980, Milwaukee Lakefront course, Saturday morning, it was raining. Most everyone had ridden the Milk Race the previous week, so that was two straight weeks of racing. A lot of criteriums with a lot of braking. Most everyone had the same brake pads since the beginning of the season. I replaced the brake pads on my Campy short-reach side-pulls just before the trip to Wisconsin.
First lap, coming down the hill along the lake, everyone is full tilt. There is a right-hander to go up the bluff. More than half the field goes straight through the barricades because they can’t slow down. I have no problem making the corner with three-week old brake pads compared to three-month old brake pads.
Do disc brakes solve the pad wear problem ?
“How about calculating all the little seconds here and there you gain by being able to brake later in a turn or having the confidence in any condition that your brakes are going to perform the same no matter what?”
Ok, I’ll bite. Let’s first find a break even point for time trialing.
Imagine a flat, two corner course requiring huge braking. Let’s use stopping distances of 30 and 20 meters. (33% improvement is pretty extreme BTW, even including modulation advantages) Let’s assume approach speed of 40 kph. How much time would we save per corner? We don’t have to stop completely, so let’s assume we enter at 20kph, which means that our braking must start 15 meters before the corner with calipers, and 10 with discs. So what is the difference? with standard brakes you take 2 seconds to travel the last 15 meters to the corner, while with disks it’s 1.83. so 0.34 seconds saved per lap. Every second counts right?
Now let’s compare to 8 watts in time savings. Using the following calculator (http://bikecalculator.com/veloUS.html) (with a 160 lb time trialist on a 21 lb bike using tubulars in the aerobars) comparing 300 watts to 292 results in a 34 second savings over 40k. If we decide that 8 watts is too much we can cut the power down to 2 watts lost, and get 8.4 seconds.
So what is the break even point for our time trialist? Well, it would take 100 laps of a 0.4 km circuit before the braking savings equal 34 seconds. That’s ~180 meters from one corner to the next. If a crit was held on such a course most would boycott. Can you imagine holding a time trial on it? Me neither. Any less cornering and discs would hurt you. Even if cutting the power loss to 2 watts, you would still have fifty 180 degree corners in a 40k TT. If you find such a TT course anywhere I’d be shocked.
So what are some other situations where extreme braking helps?
Descending for one. In a group, most braking is done in excess of cornering requirements to avoid the wheel in front of you. So it won’t matter unless you’re leading the descent or are solo. If you’re in that position and still have a shot to win then congratulations, you’re a climbing badass. But given the dynamics, that’s basically a purple unicorn in amateur bike racing. How many races are won on descents? I can only think of two significant descents on our local cat 3 race calendar out of 15 road races. And remember that aero losses go crazy high at descending speeds. By doubling your speed, you increase drag by 8 times, so you get 16-64 watts lost at 80 kph. Of course in the rain on carbon there actually would be a significant advantage, but how often does that actually happen?
Crits are another possibility. But I raced ~10 crits last year, and only one course had a single corner that required heavy braking for a solo rider. Many corners required me to scrub speed in the pack, but that was to avoid the wheel in front of me. Many corners were also terrifying at speed, but braking at all would have been slower than no brakes with perfect cornering technique. The race requiring hard braking ended in a field sprint BTW. And remember that if you’re off the front, the time trialling physics apply again. The only legitimate advantage would come if a hard corner was the last before the sprint. If a disc rider led the group in, he could gain 0.34 seconds before starting his sprint, which would be pretty significant. Remember though that he would have to expend energy moving up on the back straight as well.
So yeah, maybe they’re “better” for braking performance but the aero loss, increased cost, wheel change time and maintenance hassle are real, non trivial issues that are guaranteed to have an effect in the next year of my racing. Based on the above analysis, it may take several years before disc brakes even have an opportunity to change a race for or against me. If you race against me, PLEASE take the guaranteed disadvantages in exchange for a tiny chance to get a benefit.