dual vs single pivot brake

[Veloo]

Is there really benefit to having the single pivot brake on the back to prevent lockup?
I know the Campy groups tend to come with that combination. I've ridden Shimano forever with dual pivot and have locked up the rear but not catastrophically.

[thirdgenbird]

My single pivot rears can still lock up family easy. The braking modulation is great. I basically see it as lighter with no loss in braking power.

[sw3759]

if the aesthetics are any consideration i would say go with a dual pivot.it sure doesn't seem any more prone to lockup then the single pivot.the single pivot looks kind of cheap compared to the dual pivot

[EricEstlund]

Not sure if I understand your question, so bear with me here.

"Locking up" the rear usually means getting the rear wheel to stop and to begin to skid. If that's a problem for you, don't squeeze the lever so hard. Single pivot brakes with good pads should still be able to do this (not that you would want them to).

If you are having issues with the rear brake locking into engagement, then I would suggest you have other issues with your set up.

Most of your stopping power comes from the front with the rear providing some fine control. Split set ups are generally done to save weight, not specifically to decrease braking force.

[thirdgenbird]

if the aesthetics are any consideration i would say go with a dual pivot.it sure doesn't seem any more prone to lockup then the single pivot.the single pivot looks kind of cheap compared to the dual pivot

I actually like the look of the single pivot better. I do have the pre-skeleton calipers however. I think it has a clean and elegant shape.

[carpediemracing]

Is there really benefit to having the single pivot brake on the back to prevent lockup?
I know the Campy groups tend to come with that combination. I've ridden Shimano forever with dual pivot and have locked up the rear but not catastrophically.

At the limit there's a slight difference. Whether it's in my head or in real that's debatable of course. I used dual dual pivot brakes for many years, didn't really notice the difference when I went to the dual/single.

However eventually I got a set of dual/single for the second bike so it matches the rest of the bike. So much for my market-driven-free purity.

[sales guy]

I will say I like the look of the single pivot campy rear brakes better. BUT they do wear more than the duals. I have a bike for a friend I am working on right now. 10 yrs old and many tens of thousands of miles on it. The rear brake has some movement due to them being a single pivot. A ton of movement compared to my 2 yr old records on my personal bike. Versus the front with no movement in the pivot at all.

Now, this could all be coincidence and everything. But it does make sense given a single pivot has more pressure put on that single pivot than a two pivots.

But I do prefer the look of a single versus a dual. If Brew was selling the Brew Lite brakes, I would still have those on the bikes. Fantastic and light.

Oh, and you can get a dual/dual campy set. You just have to ask your shop to order them that way. Not common though.

[Mark McM]

Is there really benefit to having the single pivot brake on the back to prevent lockup?
I know the Campy groups tend to come with that combination. I've ridden Shimano forever with dual pivot and have locked up the rear but not catastrophically.

The rear wheel skids (i.e. the brake 'locks up') if you squeeze the lever too hard and you exceed the tire traction limit. Rear wheel skidding isn't so much an equipment failure, but more of a user error.

That being said, a single pivot rear brake can help in limiting the hazard of user error. Due to the forward weight shift during braking, the braking limit of the rear wheel is only about half that of the front wheel. So, if the front and rear brakes have the same mechanical advantage, and you squeeze both brake levers with the same hand force, you'll skid the rear tire before you reach maximum braking limit of the front wheel, so the total braking force before rear wheel skid is less than the maximum potential brake force.

Many people brake with nearly equal hand force on each lever (in fact, since most people are right handed, some people squeeze the rear brake lever harder). However, since single pivot brakes have a lower mechanical advantage (about 2/3rd that of a single pivot brake), if you squeeze both levers with the same hand force, a dual pivot front brake will produce a larger braking force than a single pivot rear brake. The end result is that with equal hand force, you can reach a higher total brake force before the rear wheel skids (because you'll be getting a larger contribution from the front brake).

[#campyuserftw]

Single pivot in rear = rear drum brakes on car

I roll with dual pivot, front and rear. Disk brakes in car versus drum brakes.

[jpw]

The rear wheel skids (i.e. the brake 'locks up') if you squeeze the lever too hard and you exceed the tire traction limit. Rear wheel skidding isn't so much an equipment failure, but more of a user error.

That being said, a single pivot rear brake can help in limiting the hazard of user error. Due to the forward weight shift during braking, the braking limit of the rear wheel is only about half that of the front wheel. So, if the front and rear brakes have the same mechanical advantage, and you squeeze both brake levers with the same hand force, you'll skid the rear tire before you reach maximum braking limit of the front wheel, so the total braking force before rear wheel skid is less than the maximum potential brake force.

Many people brake with nearly equal hand force on each lever (in fact, since most people are right handed, some people squeeze the rear brake lever harder). However, since single pivot brakes have a lower mechanical advantage (about 2/3rd that of a single pivot brake), if you squeeze both levers with the same hand force, a dual pivot front brake will produce a larger braking force than a single pivot rear brake. The end result is that with equal hand force, you can reach a higher total brake force before the rear wheel skids (because you'll be getting a larger contribution from the front brake).

a nice explanation.

[Mark McM]

Single pivot in rear = rear drum brakes on car

I roll with dual pivot, front and rear. Disk brakes in car versus drum brakes.

Poor analogy. Drum brakes of the same size actually require less pedal force than disc brakes, whereas as single pivot brakes require more hand force than dual pivot brakes, for the same braking force.

Disc brakes replaced drum brakes on cars for completely different reasons.

(By the way, disc brakes on cars almost exclusively require power assist, whereas drum brakes generally did not.)

[carpediemracing]

One additional thing about "single pivot movement". Single pivot brakes are meant to move freely around the pivot (aka the center bolt), with a spring returning the brake to a set point.

With dual pivot brakes they are not meant to pivot around the mounting bolt.

One minor inconvenience with single pivot brakes is that if you twist the brake to center it over the rim it doesn't stay put. The center bolt needs to be twisted and there's nothing outwardly available to twist that bolt. You need to grab the wrench flats behind the brake, usually requiring a thin open end wrench (cone wrench or a thinner open end wrench).

With a dual pivot you just twist the brake and it twists.

The nice thing about dual pivot brakes is that they have more movement for a given change in pressure. In other words it's easier to modulate.

Compare that to the "never-stop" Aero Gran Compes of years past, or to the new hydraulic rim brakes (which I haven't had a chance to try, but apparently they are much easier to modulate, especially at the limit).

With any rim brake you need a lot of force to stop hard. When braking very hard it's nice when it's easier to modulate the brake.

Someone tested different braking techniques using a steep hill to keep the required deceleration forces consistent. The surprising thing was that using the front brake alone resulted in the shortest stops, even compared to using both brakes. The test theorizes that focusing on one hand is easier than on two (and trying to modulate the rear so the tire doesn't lock). I would have thought that using both brakes would be best but that's not so, at least not on this steep hill. Using just the rear, btw, resulted in the test rider blowing through the stop sign at the bottom of the hill. Test used two riders, two bikes, to try and factor out individual skill.

[Ralph]

One additional thing about "single pivot movement". Single pivot brakes are meant to move freely around the pivot (aka the center bolt), with a spring returning the brake to a set point.

With dual pivot brakes they are not meant to pivot around the mounting bolt.

One minor inconvenience with single pivot brakes is that if you twist the brake to center it over the rim it doesn't stay put. The center bolt needs to be twisted and there's nothing outwardly available to twist that bolt. You need to grab the wrench flats behind the brake, usually requiring a thin open end wrench (cone wrench or a thinner open end wrench).

With a dual pivot you just twist the brake and it twists.

The nice thing about dual pivot brakes is that they have more movement for a given change in pressure. In other words it's easier to modulate.

Compare that to the "never-stop" Aero Gran Compes of years past, or to the new hydraulic rim brakes (which I haven't had a chance to try, but apparently they are much easier to modulate, especially at the limit).

With any rim brake you need a lot of force to stop hard. When braking very hard it's nice when it's easier to modulate the brake.

Someone tested different braking techniques using a steep hill to keep the required deceleration forces consistent. The surprising thing was that using the front brake alone resulted in the shortest stops, even compared to using both brakes. The test theorizes that focusing on one hand is easier than on two (and trying to modulate the rear so the tire doesn't lock). I would have thought that using both brakes would be best but that's not so, at least not on this steep hill. Using just the rear, btw, resulted in the test rider blowing through the stop sign at the bottom of the hill. Test used two riders, two bikes, to try and factor out individual skill.

Agree. To me the main difference is the rear single pivot is more sensitive to centering adjustment....getting the short cable housing length just right so it doesn't influence centering, and even then I usually have to use a thin wench on the flats and twist it offset a little, so brake centers when using. I'm picky about stuff like that.

On my bike with dual pivot campy rears, mostly just take my hands and center the brake while pulling the brake lever.

[Mark McM]

One additional thing about "single pivot movement". Single pivot brakes are meant to move freely around the pivot (aka the center bolt), with a spring returning the brake to a set point.

With dual pivot brakes they are not meant to pivot around the mounting bolt.

One minor inconvenience with single pivot brakes is that if you twist the brake to center it over the rim it doesn't stay put. The center bolt needs to be twisted and there's nothing outwardly available to twist that bolt. You need to grab the wrench flats behind the brake, usually requiring a thin open end wrench (cone wrench or a thinner open end wrench

With a dual pivot you just twist the brake and it twists.).

This is real purpose of the dual pivot design - the two arms are interlinked, so that they always move in unison. This allows the smaller pad clearances to be used - once adjusted, the arms always open in unison around their center point. The smaller required pad clearance in turn allows higher leverage ratios to be used, decreasing the hand force required. High leverage single pivot brakes could be built, but due to their less consistent retraction, there would be a higher likelihood of pad rub when open.


Someone tested different braking techniques using a steep hill to keep the required deceleration forces consistent. The surprising thing was that using the front brake alone resulted in the shortest stops, even compared to using both brakes. The test theorizes that focusing on one hand is easier than on two (and trying to modulate the rear so the tire doesn't lock). I would have thought that using both brakes would be best but that's not so, at least not on this steep hill. Using just the rear, btw, resulted in the test rider blowing through the stop sign at the bottom of the hill. Test used two riders, two bikes, to try and factor out individual skill.

There's a simpler reason than this. The limit of front wheel braking is the tip-over point - the point at which the forward weight shift causes the rear wheel to lift off the ground. Obviously, when there is no weight on the rear wheel, there is no rear traction, and the rear brake is useless. Trying to get some braking from the rear wheel requires maintaining some weight on the rear wheel, which by definition means braking below the maximum limit of the front brake alone.

[bfd]

Agree. To me the main difference is the rear single pivot is more sensitive to centering adjustment....getting the short cable housing length just right so it doesn't influence centering, and even then I usually have to use a thin wench on the flats and twist it offset a little, so brake centers when using. I'm picky about stuff like that.

On my bike with dual pivot campy rears, mostly just take my hands and center the brake while pulling the brake lever.

I don't know what the big deal is with "centering" a single pivot brake? I have both Campy Cobalto and DA single pivot brakes on my bikes and have no problems centering either of them.

There is a tool available to help, its called an offset brake tool and sold by Park. I have the older obw-1 with the 10mm and 13mm thin wrench. Park sells a newer version called the obw-4 that has 10, 11, 12 and 13mm:

http://www.cambriabike.com/shopexd.asp?ID=187961

Park also sells one with a 14mm and the other end fits into the tension spring:

http://www.cambriabike.com/shopexd.asp?ID=170514

Get the right tool for the job and its actually pretty easy! :) :eek::butt::banana: Good Luck!

[thirdgenbird]

I've got a few pairs of record differential brakes and one set of monoplanars and neither were difficult to center. I also don't recall them ever coming out of center. I've worked on troublesome cheaper brakes, but I've never had an issue with good campy brakes.

Edit: there was one time, but it forgot to tighten the brake pre ride...

[#campyuserftw]

Poor analogy. Drum brakes of the same size actually require less pedal force than disc brakes, whereas as single pivot brakes require more hand force than dual pivot brakes, for the same braking force.

Disc brakes replaced drum brakes on cars for completely different reasons.

(By the way, disc brakes on cars almost exclusively require power assist, whereas drum brakes generally did not.)

Appropriate comparison from my perspective. Pedal height, foot pressure or input from power brake boosters? Which calipers look better? Ease of centering? Uneven pad wear? For me it's about results.

My opinion is based on results, and performance; brakes simply exist to slow and stop me and my bike, and in some situations, allow my machine to come to an abrupt, important halt. I choose not the lightest, nor the best looking calipers, but for me, the brakes, with superior leverage, and a system which is the most effective.

I will not be riding around on cycling disc brakes, it's not needed on my road bike. However, having owned several cars with rear drum brakes, several bikes with single-pivot calipers front and rear, at 188 lbs, I enjoy both the stopping power and feel of dual-pivot, front and back. Just as I'd prefer the upgrade of installing disc brakes on the front of a 1964 Thunderbird (they came out standard up front in 1965):

http://www.tbirdranch.com/discbrk.html

Drum brakes were good. Better than a hand lever on a horse carriage. Disc brakes up front became the new standard, as the lion's share of stopping power in a car is in the front wheels. Four-wheel disc became the standard in the early 70's. We still see rear drums on modern cars, though with today's front disc technology, rear drums could be sufficient and rear drums do save cost for the manufacturer (aka greater profit). That said, four wheel disc is the upgrade for both feel, lack of brake fade, and sheer stopping power, especially in wet weather and during long descents.

On the bike, the dual pivot in the rear offers me the feeling of getting the rear wheel to brake more, as much as possible, as fast as possible, when I truly need it. There are zero cars today manufactured with drum brakes up front, and while cycling still offers single or dual pivot, I'll take dual, front and rear. To each their own. I enjoy my Campy dual pivots, with fresh pads, properly adjusted, clean braking surfaces and focusing on the opposite of braking...going! :)

[thwart]

Front dual pivot, rear single pivot.

I'll take a bike that remains under control in panic braking over a bike that stops a bit shorter in theory but tends to lock up the rear in that situation.

Why second guess Campy's great engineering by using a dual at the rear?

[carpediemracing]

There's a simpler reason than this. The limit of front wheel braking is the tip-over point - the point at which the forward weight shift causes the rear wheel to lift off the ground. Obviously, when there is no weight on the rear wheel, there is no rear traction, and the rear brake is useless. Trying to get some braking from the rear wheel requires maintaining some weight on the rear wheel, which by definition means braking below the maximum limit of the front brake alone.

What's interesting is that the front brake only resulted in stops much quicker than using both brakes, even though the front brake would have the same amount of stopping power (and therefore should have been able to stop the bike in the same distance whether using one brake lever or both).

The testers didn't expect this result. Neither did I. I figured that if you use both brakes and you "know how to brake" then using just the front brake wouldn't be very different. A good bike handler would be able to do a "stoppie" (lifting the rear wheel) whether using just the front brake or while using both brake levers.

One of my things that I liked to do when my driveway was a slight downhill was I'd roll into the driveway at speed and try to stop the tire as close to the door as possible. I'd get it pretty close (1/4-1/2") by rolling up to it, braking hard when I thought it was time, and then fine tune the actual stopping point by locking the front brake and doing a "stoppie" to absorb the rest of of the kinetic energy. Sometimes the stoppie was barely measurable. On aggressive days it might have been 6-8 inches up.

Obviously at the very end of the stop, when the rear wheel was in the air, using the rear brake would have been superfluous. Yet apparently if I used mental energy to use the back brake I'd have stopped less quickly than if I only used the front brake.

I moved from that house in 2007 and for the life of me I can't remember how I brake, using just the front or using both brakes. Now I'll have to go try it somewhere.

[carpediemracing]

I don't know what the big deal is with "centering" a single pivot brake? I have both Campy Cobalto and DA single pivot brakes on my bikes and have no problems centering either of them.

It's not difficult to center, given the right tool. However I don't carry such a tool when I ride. I used to not carry such a tool in my gear bag, when I went to a race or something (in the old days I carried a cone wrench, now I actually have a few different open end wrenches).

I rarely have my bike inside the car now when I go to a race since there's a (new to us) kid and his stuff inside the car. I use the roof rack. However in the old days, like 2 years ago, I'd jam everything in the back of the car. This resulted in the brakes sometimes getting knocked off center. The front was easy to fix, especially in the heat of the moment like if I got to a race venue 20 minutes before my race started. The single pivot, not so much.

For newer riders used to only dual pivot, the single pivot "non-centeringness" would come as a surprise. For us oldies, those that worked in shops, etc, it's just another brake adjustment.

To sort of point out what I did, even though I prefer the convenience of the dual pivot brake, I actually went out and bought (used - from a user here I think) a pair of skeleton brakes, single pivot rear, dual front, to put on my bike when I built it back up.

[Chance]

Single pivot in rear = rear drum brakes on car

I roll with dual pivot, front and rear. Disk brakes in car versus drum brakes.

Appropriate comparison from my perspective.
....cut.....

Mark is right, your analogy is poor. In the context of what is being discussed in this thread, comparing auto drum brakes versus disc brakes to bike single-pivot versus dual-pivot brakes makes no sense at all. If anything, in the context of this thread, it’s backwards.

Drum brakes typically had higher mechanical advantage compared to disc which is similar to dual pivots over single. What’s clear is that you seem to think Mark is making a case for drum brakes being superior to discs; which of course is not the case at all. He’s simply stating it’s a bad analogy; not that drums are better.

Another major difference between auto drum and disc brakes is that drum brakes often had some level of self-actuation. That essentially increased their braking mechanical advantage even more so.

[Chance]

What's interesting is that the front brake only resulted in stops much quicker than using both brakes, even though the front brake would have the same amount of stopping power (and therefore should have been able to stop the bike in the same distance whether using one brake lever or both).

The testers didn't expect this result. Neither did I. I figured that if you use both brakes and you "know how to brake" then using just the front brake wouldn't be very different. A good bike handler would be able to do a "stoppie" (lifting the rear wheel) whether using just the front brake or while using both brake levers.
......cut.........

Agree that at the limit it shouldn't matter if you apply the rear brake or not (assuming single bike on dry pavement and normal tires) but you are correct that the human factor plays a role. If the rider initially applied both, he/she would have to soon completely ease off on the rear in order to max the front. And that's unlikely to happen unless it's practiced on a regular basis.

Trying to brake until rear tire lifts off seems too dangerous on a longer stop. The rider would have to be lifting and releasing constantly to stay in control. Not sure too many people -- even proffessionals -- can do that for extended periods.

A great suggestion from Sheldon Brown is for the rider to apply just a little brake at the rear in order to use the rear tire as an indicator of impending lock-up at the front. With just a little rear brake applied if the rear tire starts to skid it's a sign that the rider is about to go over the bars. Time to limit additional front braking.

[thirdgenbird]

To take the automotive analogy further, the single pivot rear is similar to having smaller diameter rotors and pistons out back. Too much rear bias is not a fun experience. Well, it can be depending on your personality and road conditions.

[carpediemracing]

Agree that at the limit it shouldn't matter if you apply the rear brake or not (assuming single bike on dry pavement and normal tires) but you are correct that the human factor plays a role. If the rider initially applied both, he/she would have to soon completely ease off on the rear in order to max the front. And that's unlikely to happen unless it's practiced on a regular basis.

Trying to brake until rear tire lifts off seems too dangerous on a longer stop. The rider would have to be lifting and releasing constantly to stay in control. Not sure too many people -- even proffessionals -- can do that for extended periods.

A great suggestion from Sheldon Brown is for the rider to apply just a little brake at the rear in order to use the rear tire as an indicator of impending lock-up at the front. With just a little rear brake applied if the rear tire starts to skid it's a sign that the rider is about to go over the bars. Time to limit additional front braking.

This is what I thought also.

The experienced riders that did the test found that using only the front brake allowed them to stop significantly quicker than using both brakes. Obviously the front brake does most of the braking, especially on the steep downhill they used as their "braking area". Obviously the riders are the same (and experienced).

What was interesting is that experienced riders using their own bikes could stop much better using only the front brake.

They stopped better using just the front brake versus using both brakes.

For me this was counter to what I was brought up believing. I believed that using the rear brake as the canary in the coal mine was the best practice.

I Googled the test stuff because it explains things more than I can explain in a thread post.
http://janheine.wordpress.com/2013/08/23/how-to-brake-on-a-bicycle/

Image from the post/test:
http://janheine.files.wordpress.com/2013/04/lift_rear.jpg?w=640&h=551

[Chance]

To take the automotive analogy further, the single pivot rear is similar to having smaller diameter rotors and pistons out back. Too much rear bias is not a fun experience. Well, it can be depending on your personality and road conditions.

A better analogy in my opinion.:beer:

[Chance]

....cut.....

Image from the post/test:
http://janheine.files.wordpress.com/2013/04/lift_rear.jpg?w=640&h=551

Confirms we need bike ABS ;)

[dana_e]

Dual rear

More braking better

Modulate your mojo

[#campyuserftw]

Dual rear

More braking better

Modulate your mojo

"Dual-pivot side-pull caliper brakes are used on most modern racing bicycles. One arm pivots at the centre, like a side-pull; and the other pivots at the side, like a centre-pull. The cable housing attaches like that of a side-pull brake.

The centering of side-pull brakes was improved with the mass-market adoption of dual-pivot side-pulls (an old design re-discovered by Shimano in the early 1990s). These brakes offer a higher mechanical advantage, and result in better braking. Dual-pivot brakes are slightly heavier than conventional side-pull calipers and cannot accurately track an out-of-true rim, or a wheel that flexes from side to side in the frame during hard climbing. It is common to see professional racers climbing mountains with the quick-release undone on the rear brake, to eliminate drag from this source."

~Wiki

For humans in cars, brakes are on autopilot, once you hit the pedal; with traction control and proportioning valves, the pressure front/rear is taken care of for the driver. Me? I, like many, prefer the braking power, whether this is perceived in feel for some, or fact for others, of having dual pivots front and rear.

Tubulars vs clinchers. Campy vs. Shimano. Dual vs Single pivot.

[oldpotatoe]

Front dual pivot, rear single pivot.

I'll take a bike that remains under control in panic braking over a bike that stops a bit shorter in theory but tends to lock up the rear in that situation.

Why second guess Campy's great engineering by using a dual at the rear?

Cuz they make them that way? Option of DP or SP rears?

I prefer DP rears cuz it's easier to center on the road. Cannot center SP rear Campagnolo unless you have a 15mm open end/cone wrench with ya.

[thwart]

I prefer DP rears cuz it's easier to center on the road. Cannot center SP rear Campagnolo unless you have a 15mm open end/cone wrench with ya.I hear you.

But several bikes set up DP/SP, and yet to be an issue.

But... then again, I seldom have to transport my bikes. Most of my rides originate from home... I'm very fortunate that way.

[Liharvy]

I've used both and prefer DP front and rear. Ease of setup is a plus but familiarity with the braking characteristics make it very rare for me to lock up the rear.

[cmbicycles]

I prefer DP rears cuz it's easier to center on the road. Cannot center SP rear Campagnolo unless you have a 15mm open end/cone wrench with ya.

You can loosen the mounting bolt and recenter the brake that way if absolutely needed, it just takes some patience and a 5mm allen wrench, which many more carry with them. If you run 11s Campy you may need to plan ahead for a torx wrench instead.
I don't see why centering the brake out on a ride is such a big deal. I have never needed to center one of my brakes on a ride yet, either DP or SP... been 20 yrs, but maybe I have been unusually lucky in that regard. Might be different in a race situation, but if you crash then you are pretty much out of contention anyway, at least for most.

[thirdgenbird]

The only time I had the need to center was when I didn't get the bolt tight enough to begin with. I couldn't get it quite centered with an Allen wrench so I just opened the quick release and rode that way. I had no rub and the brake still worked.

I've never had to center one that was properly installed...