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Discussion Starter · #1 ·
I've got some avid BB7s put on my bike now. Can someone explain to me what is meant by the modulation adjustment? I am running speed dial levers and I do understand how those work. I can adjust the cable pivot point downward and increase the sponginess and the distance of travel when I pull the lever and the opposite is true when I adjust it upward. I'm just curious what modulation is all about? To me I either stop or I go lol

Give me some examples of different modulation settings and what you gain or don't gain from running your brakes this way and that will help me understand what it is about.
 

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Discussion Starter · #3 ·
See if this helps.

Yes I have experimented enough and felt all of those lever positions and currently have them set where I prefer. For some reason I was thinking modulation also had to do with how easy the brakes locked up. Stupid question but what is meant by lever feedback?

Also is it better to control the modulation with the inner and outer pad adjustment or with the speed dial lever knob? Does one way provide better modulation than the other?
 

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is it better to control the modulation with the inner and outer pad adjustment or with the speed dial lever knob? Does one way provide better modulation than the other?
It's been a while since I used BB7's, but as I recall, one pad moves, the other doesn't. If you set the non-moving pad as close as possible to the disc, it will take very little movement of the moving pad to push the disc into the non-moving pad. I would say that the result of that would be that it would tend to lock up sooner than if it is further from the pad, and therefore present less modulation. The opposite would result in more modulation.
Moving the distance on the movable pad would increase lever movement to engage the brakes.
Adjusting the pivot point on the levers will adjust how hard you have to squeeze to stop.
 

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Lever squishiness, power and modulation are three different things.

Modulation means how the brake force varies with applied lever force. Good modulation has a natural easy to control response so that you can finally control and get the amount you want. Some brakes have too much initial braking force which makes it hard to control the low breaking force needed in sketchy situations on loose surfaces without causing a wheel to skid or lock. This might be considered poor modulation.

Power is how much ultimate braking force there is for a given lever pressure. More powerful brakes require less lever force to achieve a desired level of braking. This can be good if it helps prevent hand fatigue. It can be bad if it's too easy to lock up a wheel.

Squishiness is how much a lever moves for a given applied lever force. Elasticity in the system, including air in the lever cylinder, hose or caliper, will cause the lever to move as you increase lever force. Too much elasticity, and the lever can reach the grip before sufficient braking force is achieved.
 

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Discussion Starter · #6 ·
Lever squishiness, power and modulation are three different things.

Modulation means how the brake force varies with applied lever force. Good modulation has a natural easy to control response so that you can finally control and get the amount you want. Some brakes have too much initial braking force which makes it hard to control the low breaking force needed in sketchy situations on loose surfaces without causing a wheel to skid or lock. This might be considered poor modulation.

Power is how much ultimate braking force there is for a given lever pressure. More powerful brakes require less lever force to achieve a desired level of braking. This can be good if it helps prevent hand fatigue. It can be bad if it's too easy to lock up a wheel.

Squishiness is how much a lever moves for a given applied lever force. Elasticity in the system, including air in the lever cylinder, hose or caliper, will cause the lever to move as you increase lever force. Too much elasticity, and the lever can reach the grip before sufficient braking force is achieved.
Thank you for breaking it down. No pun intended ;)
 

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Good modulation has a natural easy to control response so that you can finally control and get the amount you want.
I think this sums up Modulation quite well :thumbsup:

Squishiness is how much a lever moves for a given applied lever force. Elasticity in the system, including air in the lever cylinder, hose or caliper, will cause the lever to move as you increase lever force. Too much elasticity, and the lever can reach the grip before sufficient braking force is achieved.
Squishiness in my vocabulary however relates to poorly bled brakes, with inconsistent or "soft" lever feel due to air bubbles in the system.

However the lever movement or the part you mention "is how much a lever moves for a given applied lever force" is different thing and relates in my opinion more to "lever ratio" of a brake.
As an analogy, if you have long brake lever you need less force, but you need more "finger travel" to achieve same braking power, and with short lever you need less "finger travel" but more force to achieve same braking power. The same can be achieved by moving the pivot point of the main piston, or like in Shimano brakes with the Servo-wave -cam system.

Anyway, you can achieve good modulation with short or long "finger travel"...
 

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Squishiness in my vocabulary however relates to poorly bled brakes, with inconsistent or "soft" lever feel due to air bubbles in the system.
Since there are no air bubbles in a mechanical brake system this doesn't exactly apply. But you can still have a soft or squishy brake lever on mechanical brakes.

Regular brake housing is not compression-less. This leads to a spongy feel. You can pull harder but you are not slowing down any more. Very annoying.

Switching to compressionless brake housing will firm up the lever and give you much more power on a mechanical system. Big improvement. It's a bit more expensive but worth every penny.
 

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On the BB7s, as you dial the speed dial adjustment farther from the pivot point of the lever, the braking force decreases for the amount of finger force. This is not to the point of not being able to stop or skid. It also increases the amount of cable pulled - so it reduces the finger travel. Somewhere within the range of that adjustment, in concert with the angle of the caliper arm, and the pad gap, you can find your preference.

On bikes with BB7s, I have my Speed Dials at full leverage, which also means more lever throw - but I run the pads close to the rotor so the lever throw is not very far at all. Max braking power.

In this picture I'm not even squeezing the lever yet. The reach, lever throw, and bite point are all determined by ergonomics.
Finger Automotive tire Machine Tread Box


Other bike...
Bicycle accessory Bicycle part Bicycle tire Bicycle wheel rim Bicycle


Compressionless housing actually reduces the amount of modulation. Makes the system more responsive.

I actually tried putting a spring inline with the cable housing (note cheap cable housing). Getting the correct spring rate made modulation just like hydraulics. It does not even start to compress until the pads hit the rotor. It does add a smidge more cable pull.
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The braking force ramps up very linearly, AND with maximum braking force at full pull.

-F
 

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Compressionless housing actually reduces the amount of modulation. Makes the system more responsive.
Nah you're just not wasting hand strength compressing housing anymore. The brakes are more precise, if anything. A better solution would be to dial back the leverage ratio knob on the levers and open up the pads. You'd keep the precision feel, but wouldn't be overpowering them any more.

Used to work at a shop that sold marin flat-bar road bikes. They had some models where a spring mechanism like what you created was used to prevent the rider from grabbing the front brake too hard. I could bottom the lever out on the grip w/o hardly slowing, and my 100lb lead tech could do stoppies no problem. Those things were weird; seemed dangerous.

wow an iron horse mk3. Haven't seen one of those in ages; they used to be everywhere.
 

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Nah you're just not wasting hand strength compressing housing anymore. The brakes are more precise, if anything. A better solution would be to dial back the leverage ratio knob on the levers and open up the pads. You'd keep the precision feel, but wouldn't be overpowering them any more.

Used to work at a shop that sold marin flat-bar road bikes. They had some models where a spring mechanism like what you created was used to prevent the rider from grabbing the front brake too hard. I could bottom the lever out on the grip w/o hardly slowing, and my 100lb lead tech could do stoppies no problem. Those things were weird; seemed dangerous.

wow an iron horse mk3. Haven't seen one of those in ages; they used to be everywhere.
Yeah, I bought the IH new in '08. Rode it for maybe a year (going alarmingly fast - for me - with no body armor) and gave it to my wife. It's still a good bike - just not new.

My brake spring does not limit brake force. It just ramps it up after the pads contact the rotor. It has a really good feel, but it probably would need a different spring if the rider was much heavier or lighter.

-F
 
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