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Disc brakes on road bikes, are they really needed?
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I am on the market for a new bike and as someone who rides a mountain bike a ton, I can't help but look at the models with disc brakes. I live in Florida, which is pancake flat, and never needed more braking power but the amazing modulation of disc brakes is hard to overlook. I do travel with my bike to various mountainous destinations quite often, but so far the only time I truly wished for disc brakes was Levi's Granfondo in NorCal. I realize that there's also an aero penalty of disc brakes but I can't imagine it being significant when sitting in a peloton.

I am mostly interested in hearing from people who actually have road bikes with disc brakes, rather than from keyboard jockeys dispensing opinions. What is your experience?


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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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I recently got a CAADX with disc brakes for commuting and getting into some CX fun this fall/winter. Secondary reason was to have a bike with disc brakes so I could still train if it was raining. Not that I haven't ridden my normal road/tri bikes in the rain before, but it's nice to have the disc brake option. In my area, we have lots of medium to steep hills that have very little vehicle traffic (residential areas with speed limits of 25 mph) but cyclists avoid them when it rains due to braking. The alternative is to ride the flatter roads in the rain where cars generally drive faster (35-50 mph), visibility is lower, and puddling comes into play.

I wouldn't mind disc brakes on a training road bike. Just like I don't mind using gatorskins, butyl tubes, or carrying a big saddle bag during training. But for racing...I probably would prefer standard rim brakes...just like I prefer faster tires, latex tubes, and hidden spare tubes/CO2 under my saddle.
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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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Just a keyboard jockey here. It I've descended some VERY steep stuff in the Alps and Dolomites with Zipp 303's and Swiss Stop pads in piss pour rainy conditions and never felt unsafe. For reference I live in the Houston area so I don't ride every day in mountain conditions but even with my limited exposure I felt fine.
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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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I got a Specialized Roubaix with Shimano disc brakes earlier this year. I was enticed by a good deal and by having broken my clavicle a couple of years ago on a long descent due to lousy brakes/pads. Generally, I really like my new bike, but not sure the disc brakes are even the stand-out feature for me. It's just a way more comfortable ride than my previous road bike and I love that I haven't even once dropped my chain since I've had it. Anyway, for the most part, I feel much more confident braking and cornering but with some important caveats... I learned soon after I got the bike, on a hilly century ride, that unless you regularly tighten the brake screws, you cannot come to a complete stop. In this incident, I had just enough braking power to slow down to a safe speed, but I missed a sharp turn and had unclip and plant my feet on the ground to fully stop my momentum. So, mixed reviews on the disc brakes, when the screws are tight, braking is great, but when they come loose, you are definitely less safe. Maybe I need to use some Loctite or something, because I have experienced loss of braking power twice now, mid-ride (fortunately without crashing). I am also told that disc brake pads are supposed to last longer than standard caliper brake pads, if that's worth's anything, but still too early for me to tell if that's true.
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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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I built a gravel bike frame with disc brakes (26" MTB wheel size) that sees a lot of road use. Just so you know I'm not just a keyboard jockey.

In dry road conditions, I've never needed anything more than the standard (and even single pivot) rim caliper brakes. Tire traction is the limiting factor, not brake force.

Once things get wet, though, it's discs all the way. Not just for the performance difference, but also because I'm not grinding away the rim every time I hit the stoppers. And no loads of black crap on my hands when I get a flat.

I see the pluses outweighing the minuses for discs, but I'm not road racing on them -- for that I'd go with calipers just for the weight advantage.

I'm in the process of building a second disc brake equipped frame that'll be using 700c/29'ers for 'cross/gravel and road use.

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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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Ironwimp wrote:
but I can't imagine it being significant when sitting in a peloton.

I am mostly interested in hearing from people who actually have road bikes with disc brakes, rather than from keyboard jockeys dispensing opinions. What is your experience?

I've actually been in a peleton, may I comment?



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Re: Disc brakes on road bikes, are they really needed? [jackmott] [ In reply to ]
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jackmott wrote:
I've actually been in a peleton, may I comment?

I thought you had carte blanche on this forum?


Velosurance - bicycle insurance
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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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If you live on flat / undulating terrain then no...
More weight, worse aero, but better braking... Which largely you won't gain from.

If you do CX / gravel riding or ride a lot of tames trails then a new generation CX bike with 2 sets of wheels is a great and huge versatile buy.... Can also be used with road tyres and relatively aero rim for a multitude of ride types including travel events with big ass mountains..

So your answer is... As is often the case it depends...
Buy for what you ride.... Right toll for the job...

I did exactly this... I have 9 bikes tho...
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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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I have 700C sized aluminum disc brakes. They work awesome.
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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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Ironwimp wrote:
I am on the market for a new bike and as someone who rides a mountain bike a ton, I can't help but look at the models with disc brakes. I live in Florida, which is pancake flat, and never needed more braking power but the amazing modulation of disc brakes is hard to overlook. I do travel with my bike to various mountainous destinations quite often, but so far the only time I truly wished for disc brakes was Levi's Granfondo in NorCal. I realize that there's also an aero penalty of disc brakes but I can't imagine it being significant when sitting in a peloton.
I am mostly interested in hearing from people who actually have road bikes with disc brakes, rather than from keyboard jockeys dispensing opinions. What is your experience?

I've ridden with disc brakes and have only felt they were needed when riding dirt roads and trails on my bike.

I've been riding our F1 PR with the TRP RG957 calipers and while I haven't had the misfortune of getting stuck in the rain, I have ridden some -20% sections of trail and been able to navigate them safely.

I don't think I'd consider a disc brake road bike primarily for road use, just mixed surfaces; and certainly not if I lived in Florida.

-SD

https://www.kickstarter.com/...bike-for-the-new-era
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Re: Disc brakes on road bikes, are they really needed? [busynizzy] [ In reply to ]
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busynizzy wrote:
I got a Specialized Roubaix with Shimano disc brakes earlier this year. I was enticed by a good deal and by having broken my clavicle a couple of years ago on a long descent due to lousy brakes/pads.
lousy brakes or lousy braking technique? asking a sincere question as i live at the base of a 5.5-mile mountain pass / 8-10% grade. i've seen folks melt some rim/pad combinations, but it was more about technique than anything else.

busynizzy wrote:
I learned soon after I got the bike, on a hilly century ride, that unless you regularly tighten the brake screws, you cannot come to a complete stop.
what? some of us have been riding disc brakes for a long time (e.g., MTB use). i have no idea what you're talking about, but this is an issue to take up with your mechanic. i can assure you that it is NOT a reason to fault disc brakes.


busynizzy wrote:
I am also told that disc brake pads are supposed to last longer than standard caliper brake pads, if that's worth's anything, but still too early for me to tell if that's true.
it depends on the material (disc pads come in metallic pads or resin) and the conditions.

FWIW, as a road racer i'm firmly in the camp of "i hope disc brakes are not allowed any time soon in races." my reason is that when everyone is on carbon rims, there's a level playing field. i've been in a downpour during a race, and for 30 seconds people freak out until they remember that no one around you can stop on a dime. discs change this (a bit).

i ride disc brakes on my MTB and cross bikes. recently i've been switching between the cross and road bikes quite often. on the road, i've never wished for more power, but i have to admit that switching back and forth daily has highlighted a small but noticeable delay in how my rim brakes bite. (FWIW, i find zip rims + their platinum pads to have amazing braking in dry conditions, and i've noticed the "lag" with both carbon and aluminum brake tracks.)

i can easily lock up the wheels on my cross bike with 140mm rotors and 700x32-33c tires; i can imagine the limiter on a road bike would be the traction (lack of) or contact patch of a 700x23-25c tire.

i don't want the aero hit (on the road) either. for cross and MTB (for me / my terrain / my riding), disc beats rim braking.
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Re: Disc brakes on road bikes, are they really needed? [tetonrider] [ In reply to ]
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My crash two years ago was likely a combination of both worn pads and yes, probably some poor technique (it was an early season training ride, after all). All I know is that I was coasting along for a while at close to 30 mph down Bear Notch Road up in the NH White Mountains and just a slight involuntary pinky tap of the brake locked up the front wheel and sent me over the handlebars and into the hospital.

Anyway, after I encountered the loss of braking power with the new disc-brake equipped road bike on the century ride (this time coming down from Mt. Wachusett), I immediately took it into the shop. The mechanic simply tightened the screw as shown in the photo below and it was as good as new again. However, it loosened up again about a month or two later, and I found myself in a similar situation having to stop at a traffic light and not being able to do so, completely. Do you think something might be defective? I think I am now better at recognizing when they need tightening ahead of time, but still a little worried about them loosening up in the middle of a ride. All said, aside from this occasional issue, I still think the disc brakes are way better than calipers. I have definitely gotten over most of the fear of descending that I have had following my accident. I would attribute much of that to the new bike.

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Re: Disc brakes on road bikes, are they really needed? [Ironwimp] [ In reply to ]
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My commuter bike is a 'cross bike with disc brakes, and I have to say that they're the best in wet conditions.

I can lock those babies up in a downpour or right after having rolled through puddles.


Can you rent a road bike with the disc brakes and see how you like it before you buy?


http://aclockworkmango.com
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Re: Disc brakes on road bikes, are they really needed? [LuvMyCrappyBike] [ In reply to ]
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Need more room for fat tires or ride in rainy or trail like conditions? Then discs are a darn good way to go.

If your area is not too extreme pavement and rain is not a big factor for you I'd say not worth it,
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Re: Disc brakes on road bikes, are they really needed? [busynizzy] [ In reply to ]
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busynizzy wrote:
...The mechanic simply tightened the screw as shown in the photo below and it was as good as new again. However, it loosened up again about a month or two later, and I found myself in a similar situation having to stop at a traffic light and not being able to do so, completely. Do you think something might be defective?

No, but you have to realize there is a substantial difference in performance, reliability, and maintenance between hydraulic brakes and cable operated brakes. This goes for rim brakes (such as the Magura's, both new and old) as well as disc brakes, but it's probably more pronounced with disc brakes. Most hydraulic systems automatically compensate for brake pad wear by having a bit of extra fluid reserve in the master cylinder at the lever; you can brake until the pads are down to the metal without ever having to adjust anything. Some hydraulic systems (such as my old Hope XC system) is a little more finicky and it has an adjustment knob on the lever whereby you can adjust the pad slack on the fly, but most master cylinders bleed any backpressure when you fully release the lever and they 'just work'.

Cable operated disc brakes can't automatically adjust for pad wear, and so you have to take care of that on a regular basis (as you found out).

Note that there are a few cable operated disc brakes that actually have an integrated hydraulic system at the caliper itself, giving you the best(?) of both worlds - the old AMP systems did that, and there is a current road brake setup that was featured on Cyclingnews this past summer, but I forget the name.

Hydraulic braking systems might seem daunting but they've been on mountainbikes for almost two decades now, and the equipment from the major vendors (Magura, Hayes, Hope, Shimano) is generally rock solid, provided it is installed properly.

Less is more.
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Re: Disc brakes on road bikes, are they really needed? [Big Endian] [ In reply to ]
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.
i have bikes with and without disc brakes.
the disc brakes are heavier.
issues i experience with conventional side pull road brakes
is when using carbon rims. the brakes squeal and pulse and make noises on descents
noises i don't usually experience when i use my aluminum wheels .
this noise occurs even though i use the cork brake pads
.
disc brakes work really good even in a really wet or rainy condition.
.
here is one of my bikes with disc brakes
Last edited by: Swanbird: Dec 9, 14 20:32
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Re: Disc brakes on road bikes, are they really needed? [Swanbird] [ In reply to ]
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Isn't the aero penalty of the discs offsetting anything you gain from the deep carbon wheels?

Edit: just saw the other thread... maybe not so much...

Swanbird wrote:
.
i have bikes with and without disc brakes.
the disc brakes are heavier.
issues i experience with conventional side pull road brakes
is when using carbon rims. the brakes squeal and pulse and make noises on descents
noises i don't usually experience when i use my aluminum wheels .
this noise occurs even with though i use cork brake pads
.
disc brakes work really good even in a really wet or rainy condition.
.
here is one of my bikes with disc brakes
Last edited by: NordicSkier: Dec 9, 14 20:31
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Re: Disc brakes on road bikes, are they really needed? [NordicSkier] [ In reply to ]
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.
he was only asking about need for disc brakes ?
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Re: Disc brakes on road bikes, are they really needed? [NordicSkier] [ In reply to ]
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NordicSkier wrote:


Isn't the aero penalty of the discs offsetting anything you gain from the deep carbon wheels?

Doesn't matter what is offsetting what. If you gain 10 watts from the wheels and lose 10 watts from the disc brakes you are better off having both and a net 0 than having just the disc brakes and having a net loss of 10 watts.
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Re: Disc brakes on road bikes, are they really needed? [JTolandTRI] [ In reply to ]
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My 0,02 $

Unless I would live in a hilly environment (i.e. The Alps or similar) where you do a lot of ascending / descending with high speeds and tight corners, changing weather-conditions, I would not opt for disc-brakes on my road / tri-equipment. If you have multiple bikes (road + tri) and probably a spouse also similarly equipped, it's eazsier to stick with just rim-brakes. You can use different wheelsets for each situation that you both use. It is what I have done with my partner and it allows us to mix-and-match wheels as we see fit for the race. Going disc-brake will remove that option (unless you don't have it in the first place), or you have enough cash and storage to buy multiple identical wheelsets, or you sell everything and also buy new bikes and wheelsets for all the other "needs" and your spouse.

Disc-brakes are superior in their braking performance in every single way that matters (brake-feel, stopping power, fading resistance, durability,...)
They are worse in terms of weight and you could probably say aero. The area-impact (I would assume) would not come as much from the brake-disc itself (it's going to be 140mm disc in the back and 160 in the front at max) and the frontal-profile is very minimal.

The only thing that could/would impact the aero is the brake-calipers and their position on the fork. The fork (as we know) is one of the key-factors for determining air-flow over the rest of the bike and hence putting a nice chunky block on the backside of it will have it's impact on what's downstream of it. Then again, the calipers are positioned at just-above axle-height, which means at the same height as your feet are pedalling, so I would assume that impact again will be minimal. The rear-calipers can be hidden nicely inside the rear-right triangle and behind the foot when it's pedalling so a very aero-noisy aera anyway, again little aero-impact

The other impact would come from the need to strengthen the frame which brings a weight-penalty, especially in the fork. This is the reason many CX top-performers are sticking with cantilever brakes when it is dry or when there's a lot of running to do (they carry the bike and they do feel the additional 3-400gr). For us roadie's and tri-guys, I don't think it has such a large impact, especially in a flat area. (read Cervélo's "Ask the enginer" section, aero vs weight).

In my situation:
Living at the coast (ie flat), a road-bike, a tri-bike, a spouse with same bike-set, I would not opt for disc-brakes. It just doesn't make sense from "needs" perspective and from operational/financial perspective (replace 3 more bikes and 5 more wheelsets.... )

However, if I where just replacing my only road-bike and only have 1 existing wheelset and no spouse that rides bikes, I would probably go for disc-brakes.

Steven
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Re: Disc brakes on road bikes, are they really needed? [Swanbird] [ In reply to ]
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I just think the disc brakes look cool.

Still hoping someone like cervelo will come out with them on a TT frame

.

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Re: Disc brakes on road bikes, are they really needed? [h2ofun] [ In reply to ]
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It seems that Cervélo are reasonably committed to hydraulic rim brakes with their Magura tie-up.

On the subject of Magura I had their HS33 hydraulic rim brakes on a commuter bike here in Germany, and they are absolutely bloody awesome.

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Re: Disc brakes on road bikes, are they really needed? [Barchettaman] [ In reply to ]
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Barchettaman wrote:
It seems that Cervélo are reasonably committed to hydraulic rim brakes with their Magura tie-up.

On the subject of Magura I had their HS33 hydraulic rim brakes on a commuter bike here in Germany, and they are absolutely bloody awesome.

Yep, that is what I am assuming I will get.

.

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Re: Disc brakes on road bikes, are they really needed? [shamerli] [ In reply to ]
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shamerli wrote:
The area-impact (I would assume) would not come as much from the brake-disc itself (it's going to be 140mm disc in the back and 160 in the front at max) and the frontal-profile is very minimal.

Bad assumption. The majority of the drag IS from the disc itself, along with the necessary hub structures to mount the disc and the additional spokes required (for an equivalent strength wheel) to handle the braking loads. Sure, that's not necessarily a large hit at zero yaw, but that disc quickly comes into play once any yaw angle is experienced.

One thing the Specialized test didn't include is power-to-rotate, which will be slightly higher just due to the additional spokes alone.

http://bikeblather.blogspot.com/
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Re: Disc brakes on road bikes, are they really needed? [Barchettaman] [ In reply to ]
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Barchettaman wrote:
It seems that Cervélo are reasonably committed to hydraulic rim brakes with their Magura tie-up.

On the subject of Magura I had their HS33 hydraulic rim brakes on a commuter bike here in Germany, and they are absolutely bloody awesome.

That commuter has the largest hydraulically actuated disc brake you can fit in the bike! ;-)

http://bikeblather.blogspot.com/
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