How do bicycle brake manufacturers balance their products' physical limitations?

Question

This question is valid for both mechanical and hydraulic brake systems.

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Premises:

• The human hand has a threshold value for what a comfortable level of squeezing force is, which will decrease with rider fatigue. (See Chris' excellent comment below.)
• The brake system is not externally powered.
• The usual laws of physics are being obeyed.

I am not understanding how some brakes can be unequivocally better than others.

Fundamentally, brakes can be modeled as a lever. A brake setup with large pad clearance is either going to be weak or have large lever throw. There's no free lunch; one always needs to balance power, lever force, lever freestroke, and pad clearance.

For example, the Shimano Saint and Zee downhill-oriented hydraulic brakes use a high leverage ratio in the levers to create more pad clamping force. The tradeoff for this is their long freestroke, i.e. how far one must pull the lever from its resting position until the brake engages. Conversely, most SRAM hydraulic brakes use a "normal" freestroke and a generous pad clearance, resulting in their characteristically mild power.

Of course, there are many design factors involved such as dual-pivot rim brakes, Shimano's "Servo-Wave" and SRAM's "Swinglink" variable-leverage designs, pivot bearing quality, two- versus four-piston hydraulic calipers, or even plain old manufacturing quality. These help overall, but since high-end brakes all incorporate these features, I don't see how any specific brand's implementation could clearly outshine the others'.

I suppose the inspiration for this was me wondering "How can $900 Trickstuff (or other premium manufacturer's) brakes be worth that price when they have to balance the exact same physical factors as $200 brakes from Shimano et al?" The high-end brakes are reportedly better than cheaper ones in every way, but I am not seeing how that is possible.

Answer 1

There is more to it than the 3 factors you describe beyond just the conversion of one force to another. A few others:

1. The deflection of the linkages in braking. A flimsy brake caliper will effectively increase the required lever throw and have a spongy feel, but a rock-solid caliper will either be heavier, or require more exotic materials.

2. Adjustability or ease of setup. Some brakes are miserable to get just right, others have well placed cable stops, tensioners, and other things that let a mechanical methodically dial them in. This especially separates the winners from the losers in canti brakes for anyone that wants them to be quiet.

3. Longevity - I think this one is pretty important too, even crappy tier brakes work pretty well when they're brand new, but can go to crap pretty rapidly, whereas better brakes last longer.

4. Overall Weight, and overall size. Think about trying to give great tire clearance while also keeping aspect #1 under control.

5. Trying to hit a particular price-point will change how all these factors are weighed. The cost includes not only the materials, but the manufacturing processes, and the engineering costs have to be amortized over each unit sold.

But unfortunately, engineering of anything is a balance of trade-offs, and the exact details of how those trade-offs are weighed against each other is truly the secret sauce, so, "it's a secret" is the only general answer you can get.

Answer 2

Talking to hydraulic disks, specifically MTB needs.

Raw power is about by pad and disc materials and fewer losses in the pipeline. The hydraulics virtually eliminate difference in losses, so more expensive disks come with grippier pads and rotors, of which the difference is small. Even the cheapest hydraulics provide more than enough raw power, on the first stop. More expensive brakes will provide the same power on each of many subsequent stops. Cheap brake can be prone to fade sooner.

However, braking on a MTB is not about a gorilla grabbing a lever and pulling as hard as he can. Its about finesse. A good set of brakes can be accurately controlled by a single finger with instant response (feathering). The feather benefits from non-linear response - early on in the lever movement the braking is subtle brake, later in the movement it become about raw power. Friction in the system (pistons, lever piviot etc) needs to be minimized. Expansion in hoses needs to be reduced to absolute minimums, and as always, weight needs to be controlled. For the likes of Dowhill use, the heat generated in the disks needs to be dissipated without overheating the caliper (more accurately, the fluid). Better brakes do all this better.

Then there are adjustments. The Shimano range from Deore SLX to XT are essentially the same brakes with more adjustments added as you go up the range. Gorilla grabbing lever does not care about the finer adjustments, many MTBers can get quite particular about exactly where the lever is and how far it moves before pad engagement.

The improvements as you go up the price range is subtle - Most riders will notice the difference between $30 and $1000 brakes. Aside having more adjustments, I suspect few will notice meaningful difference between $100 and $200 brakes.

Then you add the marketing....

Answer 3

We can approach your question from another angle: What are the tangible improvements in modern braking systems over older designs?

Given the main job of a brake is to turn momentum into friction/heat and dissipate it, the concept is quite straightforward.

Modern systems eliminate more losses between the lever and caliper. Hydraulic is the most obvious example but even cable operated brakes benefit from slick, lined, low friction cables in rigid casing. Certain high performace rim brakes use ball bearing races instead of bushes at the pivot points to eliminate as much of these losses as possible. Other examples, such as cable pull ratio, partly explain why v-brakes are so powerful. Even though the lever feel is similar, the brake uses about twice as much cable travel with half the force running through it, so that even corners and pinch points have lower friction as the cable requires less tension.

Other improvements are down to manufacturing accuracy and consistency: rim brakes can operate closer to the rim on road bikes where the rim is machined flat and the rim is a stiff box section that doesn't distort under load. This is part of the reason modern road brake designs have become more powerful. Material choice can also have an effect: Mavic produce a rim called Exalith with a textured/ribbed ceramic coated surface and very hard pads that last a very long time and give more power than a standard rim due to the extra edges involved.

Disc brakes benefit from tighter tolerances and better materials at a higher price point: more advanced rotors dissipate heat better and warp less than basic cheap ones. The more heat that can be dissipated means more heat can be generated at the pad/rotor interface by using higher friction materials (eg metallic). Magura state that their 4-piston calipers provide more braking power because the two sets of edges provide more braking power. Their 4-piston calipers are not much more expensive than their equivalent 2-piston calipers so I do not think they are lying about this to get you to spend more money -- it is a result of research. But not everyone wants that extra braking effect.
Of course, using a bigger rotor also can give an improved brake effect, provided the rotor can heat up enough to give optimum braking effect for the pad compound used.
Disc brakes can use very tight tolerences between rotor and pad, maximising the leverage available to the hand. This is why good disc brakes are so much more effective than rim brakes -- the rim always needs some space for rim run out, no rim ever runs 100% true through a ride, due to the forces involved.

That's about as much as I can think of now.

Answer 4

I have fiddled around a lot with linear pull brakes, including modifying other types of brake to behave like them, mixing and matching components and I've been using several quality levels of components from very-low to mid range.

I have found that some designs use some material "limitations" or characteristics in clever ways to yield a better use experience. For example, all linear pull brake arms flex to some extent, some designs use this flex in a way that they sort of wedge-in the pads into the rim when it drags against the pads, giving you a type of "brake boost". This is not obvious to spot, but if the brake system is correctly installed and tuned, you can clearly feel the difference.

In other example, I've had levers at look fairly common at first, but upon use, I noticed they had optimized the adjuster bolt angle for the lever's middle of travel position, which yield less total cable friction at engagement region.

So, even if the basic physics are fairly well understood, there may still be several improvements to be made.

Some products are engineered, others are proper implementation of previous designs, and others are simply copies (look-a-likes). That changes the selling price a lot. A company that does engineering will charge for that. A company that only manufactures a known design, is able to sell a similar product for way less.

Another consideration is that, this "engineering" may not be what one, as a buyer, may expect. Some products are designed or optimized for "ease of manufacturing", or other cost-lowering measures. For example, design "good enough" brake arms than can be manufactured out of cheap aluminium.

All of that, regardless of what marketing says or hides about it. Marketing uses a lot of clever tricks not many of us are fully aware of. Some reviews one sees online may actually be undisclosed advertisement. Some products develop brand name and reputation, and thus "everybody" regard them as indisputably better, while they may actually be "a little more than OK".

So, why or how something is worth the price? Because people are willing to pay that price. They are convinced and will try to convince other that what they bough is actually better, but there may be a generic copy or another implementation that actually performs as good, if not better, but without the hype.

Consider that patents and other legal protection may prevent such copies from existing commercially/legally, creating exclusivity, another element that drives price up.