Mechanical Vs. Hydraulic Disc Brakes: Pros, Cons & How To Choose

Published Categorized as Bicycles, Bike questions & beginner guides

Ideally, braking is intuitive and totally unsurprising. When obstacles loom, you shouldn’t have to think about whether or how your brakes will respond.

Riding experience and proper maintenance will always matter, but it’s equally important to choose the right type of brakes for your needs and priorities—regardless of what’s trendy in the industry or even among your riding buddies.

These days, disc brakes are practically a given. They’re not necessary for everybody—more on that toward the end—but our choices usually come down to mechanical versus hydraulic discs.

The latter are more common on higher-priced bikes, which gives you the (generally accurate) impression that they’re superior.

However, it’s not always that simple. Your budget, intended use, and even mechanical aptitude all factor into making a decision you’ll be happy with.

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Performance

Raw power

On average, hydraulic disc brakes are significantly more powerful than cable-actuated (mechanical) ones. My layman’s understanding is that a brake lever can increase fluid pressure exponentially, but cable tension only linearly. So, when squeezing hard in a steep or emergency situation.

(If any engineers out there can correct me or elaborate on this phenomenon, then please reach out!)

Modulation

Good mechanical and hydraulic disc brakes both have excellent modulation, meaning they respond subtly but precisely as you squeeze the lever. However, the weakness of low- and mid-range mechanical discs means you’re often squeezing so hard that modulation is a bit of an afterthought.

I’d tentatively say that high-end mechanical discs, when well adjusted, have slightly better modulation thanks to their relatively linear pressure. But that’s highly debatable, and will heavily depend on the exact brakes you’re comparing.

Tip: don’t judge until the pads “bed in”

Whichever style you choose, remember that performance will improve after they’ve bedded in. That’s nothing fancy: it’s just the term we use for the way disc brake pads break in. You’ll know this is happening when the brakes feel both more powerful and less grabby, and (potentially) any sounds or vibrations diminish.

This happens within several minutes of active braking, so perhaps a few hours of riding. If your bike is a previously test-ridden floor model, then its brakes are probably well on their way.

Side note: cable-actuated hydraulic discs

As of writing, there are a couple models that use a cable to actuate a hydraulic mechanism that’s located in/near the caliper. I won’t discuss these at length since they’re not very common—especially not on complete, stock bikes.

However, advocates would say they offer most of the power of hydraulic brakes plus most of the modulation and easy repair of mechanical ones. That said, they also require cable tension adjustment that purely hydraulic brakes eliminate.

Cost

Hydraulic disc brakes are more expensive. That’s partly because the brakes and levers themselves are more complex, and also because they’re also sold on altogether more expensive bicycles.

Mechanical can be cheaper

If you need the cheapest possible set of disc brakes, then you’ll probably need to go with mechanical for three reasons.

  1. Mechanical calipers are inexpensive. They’re as little as $30-$40 apiece for entry-level Promax, or around $80-$100 apiece for the excellent TRP Spyre. (Rotors are not mechanical- or hydraulic-specific, so we can ignore that cost for now.)
  2. Mechanical discs work with conventional brake levers, which may cost just $10-$20 apiece. They’re fairly universal, so any levers out of the bargain bin will work, as long as they have the correct (short vs. long) cable pull distance.
  3. Mechanical discs are usually quicker, simpler, and therefore cheaper to install. Even newer home mechanics can set them up and maintain them without special tools or supplies.

But the biggest question is whether cheap, easy installation is worth the hit in performance. Mechanical is the cheapest way to get into disc brakes, but performance at the entry level can be frustrating.

Cheap hydraulic are a better value

Entry-level hydraulic discs cost more than their entry-level mechanical counterparts, but also perform far better. You can expect more overall power and less adjustment and fine-tuning.

To be clear, the cost savings aren’t immense for mechanical discs on their own. You might expect to save $20-$50 per wheel. If you upgrade to mechanical discs that perform well, then you’ll have spent at least as much as an entry-level hydraulic set. More often than not, the latter will perform better.

But the bigger cost question is the bike they’re attached to. Stepping up to a hydraulic-equipment model comes with several other upgrades, which may add several hundred dollars to the price tag.

Maintenance

Hydraulic discs require less frequent but more complex maintenance than mechanical discs. That’s not a major problem for most of us, but it’s important to know what you’re signing up to live with.

Hydraulic discs are self-adjusting

Brake cables stretch over time, so mechanical disc brakes need occasional adjustment to keep the pads the right distance from the rotors. This isn’t difficult—in fact, calipers like the Avid BB7 make it downright easy—but it does require attention every few weeks or months.

But hydraulic brakes have self-adjusting pistons, meaning the pads simply “find” the right position. There’s no day-to-day adjustment, since there’s essentially nothing to adjust!

Pro tip: always keep a spacer between the brake pads when you remove the wheel. Otherwise, squeezing the lever will press the pads directly against each other, and they’ll self-adjust into a position that’s too tight to fit the rotor back in! It can be fixed, but it’s a big nuisance.

Mechanical discs are easier to service

Mechanical disc brakes rarely need anything more than new pads or new cables and housing. Pads take seconds to replace; cables and housing are more involved, but still feasible for any home mechanic. It’s easy to bring spares on a backcountry ride or self-supported tour, and even fix them on the spot if need be.

Hydraulic discs may be hands-off from day to day, but they’re harder to repair when something goes wrong. The main concern is a leak, which introduces air bubbles into the lines or fluid reservoir. This requires bleeding the brakes and replacing any failed parts.

The good news is it’s rare. It may not happen for years, if ever, and it’s a routine repair for any bike shop.

The bad news is it’s too tricky to do on the trailside or in a hurry. Again, that’s rarely necessary, but it’s worth considering if you won’t have access to a bike shop.

Storing hydraulic discs upside-up

Contrary to popular belief, it’s generally OK to store bikes with hydraulic disc brakes upside-down.

At least in theory…

When they’re in good condition, the entire brake system is sealed. Air cannot enter whether they’re right-side-up, upside-down, or anywhere in between.

But in reality, you may have minor leaks that admit a tiny bit of air. When kept upside-down, the bubbles will migrate down the lines and cause a mushy, changing feel when you get on your bike. If you notice that happening, then store the bike right-side-up until you can have the brakes inspected and (probably) bled.

This isn’t a concern for cable-actuated discs, since they don’t need to be airtight in the first place.

Which kind should you choose?

Steep off-road terrain, frequent mud, and heavy cargo all point toward hydraulic disc brakes over mechanical. However, there are no hard and fast rules. Rim brakes can still work terrifically, and may be more practical if you don’t deal with those conditions.

Mountain biking: hydraulic

Hydraulic disc brakes are the best choices for most mountain bikers. Their exceptional power and self-adjustment is a good match for steep terrain and muddy conditions you’ll frequently encounter. Even the best mechanical discs, in perfect adjustment, just can’t match their performance.

The one exception may be for certain bikepackers. Many do use hydraulic brakes without trouble, but the DIY ease of mechanical discs might be prudent for extended, backcountry travel.

Cyclocross & gravel: hydraulic (by a hair)

Hydraulic brakes are generally best for cyclocross and gravel riding. Their sheer power is arguably overkill, but I find it especially hard to get enough power from mechanical discs with road-style brake levers.

Good rim brakes are also fine if you ride in dry conditions, but you’ll be happier with disc brakes if mud and grid are par for the course.

Road, commuting & transportation: tie

For strictly paved riding, disc brakes aren’t necessary in the first place. A well-adjusted set of rim brakes usually works just fine. They’re simple, cheap, and more than adequate for most riders in most situations. Wider tires (~35 mm and up) require long-reach dual pivots, which can feel a bit weak or mushy, so I recommend V-brakes in that case.

However, [disc brakes are worth considering]() in some cases. They do prevent rim wear in a consistently wet climate, and are great at controlling the momentum of heavy cargo.

Hydraulic disc brakes are more than adequate, and decent mechanical discs have plenty of power for virtually any sort of riding on pavement. Beware that each manufacturer’s cheapest disc-equipped model (or two) will have bottom-of-the-barrel mechanical calipers that perform poorly. Consider buying a step up in the line, if at all possible.