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ACS DOUBLER...DO THEY ACTUALLY WORK???  RSS Feed

#26 2015-10-01 10:11pm

IPD
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

http://www.technologystudent.com/gears1/pulley8.htm

Mechanically, you should have more clamping force, but with 2x the cable travel--unless I'm too drunk to think straight.


Those who dislike Israel are in favor of Jewish and Kurdish Genocide.  It's that simple.

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#27 2015-10-01 10:20pm

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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

CuriousTurtle wrote:

It'll double the force on the caliper for the same pull on the lever.

In a normal set-up, one half of the caliper is held steady whilst the other half is pulled against it with x amount of pressure. With the doubler, each half is pulled toward the other with x pressure.

Not exactly true, imho.  Both sides of a caliper can move--even if the cable doesn't move both equally.  Usually that means that one side may pull the pad into contact before the other moves the pad into contact.  But rest assured BOTH sides move, or else you wouldn't have pad contact on both sides.

And this is why U & V brakes are so much better.  The pivot point being closer to the pad than the arm gives the brake more clamping force.  Calipers have the pads further away from the pivot than the cable stop--which gives them less force.  No amount of pulley voodoo will fix that inherent limitation.


Those who dislike Israel are in favor of Jewish and Kurdish Genocide.  It's that simple.

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#28 2015-10-02 12:31am

Crashman
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

xtremevert wrote:

So has anyone used one of these ACS Doublers and do they actually work?  I bought 2 for my new build to use on my BOA's and was wondering if they are even worth the effort of setting up?  Got some feedback on this?

They work. They do double the clamping force in theory, in spite of what others might say. There's resistance in the cable (it has to bend around the pulley), the pully center, etc, but max force is exactly doubled while travel is exactly halved when you look at the actual math.

There are problems such as the cable not bending that nicely around so small a pulley, which means your brake travel will actually be less than half. If your rims are even slightly out of true, or your brake is slightly off center, it rubs.

These would probably be REALLY HANDY for running newer V-Brake levers with older caliper brakes big_smile


Wanted: Inexpensive lot of cheap 7/8" bars for grandkid's bikes. I will paint as needed.

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#29 2015-10-02 1:32am

socaldude
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Standard brakes for BMX (Non V-Brake Type) are Short Pull.  The Double adds leverage and cable pull.  If you were to pair a Doubler set-up with a Linear Pull or Long-Pull lever, you might eliminate a lot of the mushy feel.


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#30 2015-10-02 2:05am

Crashman
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

socaldude wrote:

Standard brakes for BMX (Non V-Brake Type) are Short Pull.  The Double adds leverage and cable pull.  If you were to pair a Doubler set-up with a Linear Pull or Long-Pull lever, you might eliminate a lot of the mushy feel.

Except that the loop of cable isn't "taut" around the pulley until it's pulled really hard, so the excess cable add mush smile


Wanted: Inexpensive lot of cheap 7/8" bars for grandkid's bikes. I will paint as needed.

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#31 2015-10-02 1:54pm

socaldude
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Yes, but the cable that comes with the Doubler is more flexible than a standard brake cable so it does wrap around better.  And a Long Pull lever should still make the brake feel a bit less mushy.


Duane@shootsbrah.com

Would love to find my old Dirt Bike.  It was stolen in Pompano Beach, Florida in about 1996.  It's a '92 with the block graphics on a Green frame.  Pitchforks, Slam bars, GT (DK-style) stem and GT/Profile cranks.  Superlace hubs.  Would really love to put this back in my collection.

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#32 2015-10-02 3:39pm

BRICKOS2
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

socaldude wrote:

Yes, but the cable that comes with the Doubler is more flexible than a standard brake cable so it does wrap around better.  And a Long Pull lever should still make the brake feel a bit less mushy.

The supplied cable I had was too short. Running an Odyssey slick cable instead. Not too fazed about the mush smile

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#33 2015-10-02 7:58pm

rcsnipe2000
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

https://farm9.staticflickr.com/8078/8381915870_e8b2e27218_o.jpg

used them on the front and rear of this elf 24. i loved em! they look trick, they stop on a dime, and i want some more! lol i did drill the fork too!

as for the mushy.....

most people dont (set the cable) to set the cable, ya get it all set up. (not dialed in, but make good contact) while the bike is upside down, step down on the brake lever for about 2 minits. what this does is, stretches and shaped the cable around the pully. you can even do this a couple times. once the cable is set, then dial in ya breaks, and no more spongy.

boas are awsome brakes, and love the doublers!

ohhh......also ran oddy slick cables, and kool stop brake pads

rc

Last edited by rcsnipe2000 (2015-10-02 8:00pm)


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#34 2015-10-02 8:36pm

BRICKOS2
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Nice DX... Running a rear BOA too smile

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#35 2015-10-02 8:59pm

BRICKOS2
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

https://c1.staticflickr.com/1/628/21912055151_e2b210c1d3_z.jpg

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#36 2015-10-03 3:58am

troynlori
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Obviously not a lot of engineers on the site in 2008....tongue

-1 moveable pulley = twice the force, 1/2 the movement for the arms.  Means you better bring 'em up closer, or pull the lever a lil more to make contact.  You need a straighter wheel for these.

-Add a pulley and you'll increase the force again, but cut the arm travel again.  Keep adding pulleys and you'll keep increasing the clamping force, but keep cutting the arm travel = increasing the distance required for the brake lever.

-Slack in cable, someone said otherwise you must have tension in the cable at all times - that's how all brakes work!

-Both arms always move in any brake, and the force on each arm is always = to the other.... ("equal and opposite reaction")...

-Cable tension is not more with this, actually less unless you are using more than twice the braking force for some kind of emergency.  Anyhow it's related to the lever and the rider more than anything.

-I just restated everything the 2015 people said.

-V brakes make much better use of leverage concepts than does this device that I don't recall.


Hutch Fun Facts: All main line Hutch's with digits only S/N (no letters or baseballs) on the rear drop outs were US made and had their dropouts stamped between late '83 and '86.  Obviously the frame manufacture would occur slightly after that, even if they just threw 'em in a bucket randomly.  There is an obvious date code in that the first 2 digits seem to be the month and the 3rd digit is pretty obviously the last digit of the year running from '83-'86.

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#37 2015-10-03 4:47am

Crashman
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

troynlori wrote:

Obviously not a lot of engineers on the site in 2008....tongue

-1 moveable pulley = twice the force, 1/2 the movement for the arms.  Means you better bring 'em up closer, or pull the lever a lil more to make contact.  You need a straighter wheel for these.

-Add a pulley and you'll increase the force again, but cut the arm travel again.  Keep adding pulleys and you'll keep increasing the clamping force, but keep cutting the arm travel = increasing the distance required for the brake lever.

-Slack in cable, someone said otherwise you must have tension in the cable at all times - that's how all brakes work!

Well yeh, except that the return spring isn't strong enough to pull all of the loop slack out of the cable, and the little bit that remains keeps your brakes from releasing half way (they never release all the way with this device attached :p ).


Wanted: Inexpensive lot of cheap 7/8" bars for grandkid's bikes. I will paint as needed.

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#38 2015-10-03 5:12am

troynlori
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Gotcha.  Maybe a bigger loop would help.  Anyhow brakes are made to keep the cable in tension even in "idle".


Hutch Fun Facts: All main line Hutch's with digits only S/N (no letters or baseballs) on the rear drop outs were US made and had their dropouts stamped between late '83 and '86.  Obviously the frame manufacture would occur slightly after that, even if they just threw 'em in a bucket randomly.  There is an obvious date code in that the first 2 digits seem to be the month and the 3rd digit is pretty obviously the last digit of the year running from '83-'86.

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#39 2015-10-03 6:35am

IPD
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Thx, troy.  I knew I wasn't smoking crack.


Those who dislike Israel are in favor of Jewish and Kurdish Genocide.  It's that simple.

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#40 2015-10-03 2:04pm

adamdawson
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

no. no they dont work.  gimmick.

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#41 2015-10-03 2:32pm

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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

cool info


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#42 2018-10-31 11:37pm

benmad
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

They do work, no gimmick.
Installed on 48volt electric 1988 GT pit bike.
When applied lightly they throw me over bars. A lot of weight with battery packs. Worn out three front tyres and brake cable still going strong.
Used same brake on same bike without  ACS doubler. Very different.
Get sick of people commenting on things they've never tried. Especially BMXers that only finger tighten there bikes and don't ride them
Going to try one with ACS BOA on my just built Hawk with Odyssey Xtro forks.
Built to ride not carry to shows..

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#43 2018-11-01 8:50am

El Gecko
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

I kinda want to try these with sidepulls and V brake levers just to see what it's like.  Theoretically you should have the same travel as a short lever without a doubler, but you would get better clamping force on the rim with the same amount of force on the lever.

Otherwise, just putting a doubler on a sidepull with short pull lever is probably just like running V brakes with a short pull lever.  Sure, they lock up at the lightest touch, but like everyone else said, the rims gotta be super straight and you can only have a hair of clearance if you want half a chance of the brakes even grabbing before the lever hits the grip.


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#44 2018-11-01 8:53am

Crashman
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

El Gecko wrote:

I kinda want to try these with sidepulls and V brake levers just to see what it's like.  Theoretically you should have the same travel as a short lever without a doubler, but you would get better clamping force on the rim with the same amount of force on the lever.

Otherwise, just putting a doubler on a sidepull with short pull lever is probably just like running V brakes with a short pull lever.  Sure, they lock up at the lightest touch, but like everyone else said, the rims gotta be super straight and you can only have a hair of clearance if you want half a chance of the brakes even grabbing before the lever hits the grip.

You got it backwards, it's caliper-ratio levers with v-brakes that have a similar effect to using a doubler (half the open distance, twice the force).


Wanted: Inexpensive lot of cheap 7/8" bars for grandkid's bikes. I will paint as needed.

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#45 2018-11-01 8:57am

El Gecko
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Crashman wrote:

El Gecko wrote:

I kinda want to try these with sidepulls and V brake levers just to see what it's like.  Theoretically you should have the same travel as a short lever without a doubler, but you would get better clamping force on the rim with the same amount of force on the lever.

Otherwise, just putting a doubler on a sidepull with short pull lever is probably just like running V brakes with a short pull lever.  Sure, they lock up at the lightest touch, but like everyone else said, the rims gotta be super straight and you can only have a hair of clearance if you want half a chance of the brakes even grabbing before the lever hits the grip.

You got it backwards, it's caliper-ratio levers with v-brakes that have a similar effect to using a doubler (half the open distance, twice the force).

Uhh... you just said the exact same thing I did with different words.


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#46 2018-11-01 9:23am

Crashman
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

El Gecko wrote:

Crashman wrote:

El Gecko wrote:

I kinda want to try these with sidepulls and V brake levers just to see what it's like.  Theoretically you should have the same travel as a short lever without a doubler, but you would get better clamping force on the rim with the same amount of force on the lever.

Otherwise, just putting a doubler on a sidepull with short pull lever is probably just like running V brakes with a short pull lever.  Sure, they lock up at the lightest touch, but like everyone else said, the rims gotta be super straight and you can only have a hair of clearance if you want half a chance of the brakes even grabbing before the lever hits the grip.

You got it backwards, it's caliper-ratio levers with v-brakes that have a similar effect to using a doubler (half the open distance, twice the force).

Uhh... you just said the exact same thing I did with different words.

No, I said the opposite thing: You said "sidepulls and V-brake levers....better clamping force on the rim with the same amount of force on the lever".
I said "V-brakes with sidepull levers...better clamping force on the rim with the same amount of force on the lever".

The problem is that I ignored the SECOND thing you said wink

Last edited by Crashman (2018-11-01 9:24am)


Wanted: Inexpensive lot of cheap 7/8" bars for grandkid's bikes. I will paint as needed.

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#47 2018-11-01 9:47am

El Gecko
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

Crashman wrote:

El Gecko wrote:

Crashman wrote:

You got it backwards, it's caliper-ratio levers with v-brakes that have a similar effect to using a doubler (half the open distance, twice the force).

Uhh... you just said the exact same thing I did with different words.

No, I said the opposite thing: You said "sidepulls and V-brake levers....better clamping force on the rim with the same amount of force on the lever".
I said "V-brakes with sidepull levers...better clamping force on the rim with the same amount of force on the lever".

The problem is that I ignored the SECOND thing you said wink

I see.  But back to my original point.  Here is how I understand it:

- If you use short pull levers with a sidepull brake and NO doubler, you have normal pull and normal lever force and normal pad force on the rim.

- If you use short pull levers with a sidepull brake WITH a doubler, you have longer to pull on the lever for less movement on the brake pads.  But you have more braking force at the pads and less force needed at the lever.  The rim must be super straight because the un-pulled pads have to be so close to the rim.   If the brake arms are too far out, the lever will bottom out on the grip before the pads engage.

- If you use short pull levers with a V-brake, it's the same as a short pull lever with a sidepull and doubler.  Longer pull on the lever for shorter movement on the pads, but more braking force at the pads and a lighter touch on the lever.  Again, rims must be really straight since there is less pad movement available.

- If you use long pull levers with a V-brake, you get normal pull and normal lever force, and normal pad force on the rim.

Soooo..... I want to use long pull levers with a sidepull WITH a doubler, which should theoretically give me normal lever and pad movement, but with increased braking power at the pads due to the inclusion of the pulley.  Whether that's actually how it works or not, I don't know.  That's why I want to try.  Worst case is that the long pull lever negates the benefits of the doubler, and you just end up with normal feeling brakes.

Last edited by El Gecko (2018-11-01 9:53am)


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#48 2018-11-01 1:06pm

squirrelsmith
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

they work fuckiing great i have them on all my bikes with small bolt boas


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#49 2018-11-01 3:55pm

kalel92198
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

I am going to have to check this out because I am still having a hard time dialing in my brakes on my master. I have the boas as well with a rotor and the acs levers and I can’t get my brakes to work good at all. I think I am going to ditch the linear slic cable and go with the non linear slic cable to see if it makes a difference. Hopefully if no change then I will try with this pulley setup.


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#50 2018-11-01 4:28pm

Draw
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Re: ACS DOUBLER...DO THEY ACTUALLY WORK???

CuriousTurtle wrote:

It'll double the clamping force on the caliper for the same pull on the lever.

^ this

https://www.explainthatstuff.com/pulleys.html
i never knew so many of you dont know how a pulley works lol

this thread is pure gold.

Last edited by Draw (2018-11-01 4:29pm)


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