Short Cut

I like the stopping power and all weather benefits of disc brakes, however I could stand to learn more about how hydraulic, mechanical and cable actuated compare and contrast. I'd appreciate any first hand knowledge or links to further explanations.

Thanks

lvick

here's a short answer based on my experiences with several types:

full hydraulic disc (e.g., Shimano BR-785) >> mechanical-hydraulic disc (TRP Hy/Rd) > mechanical disc (TRP Spyre) > V-brakes > cantis

the new Shimano hydro discs are pricy and heavy, but their power, smoothness, modulation and lack of fade make them worth every $ and gram
they're also very easy to set up and adjust

Andy_K 

Hydraulic brakes are top of the line. They don't lose force to things like cable compression so the force that you put into the brake levers is transferred directly to the calipers. They also self-adjust for pad wear, whereas with mechanical brakes you generally have to regularly turn a knob somewhere to move the pads closer to the rotor as they wear. Finally, most (but not all) mechanical disc brakes only move one pad, pushing the rotor into the other pad, while hydraulics move both pads together.

Options for full hydraulic braking with integrated shifters for drop bars are available from Shimano, SRAM and Gevenalle (though Gevenalle's are not what you typically think of when you think of integrated shifters).

"Cable actuated" is just another name for mechanical. Their primary advantages are that they are cheaper and that they work with brake levers designed for use with rim brakes (which is most brake levers for drop bar applications).

Another option is some sort of hybrid solution where a cable is used to pull an arm that operates on a hydraulic chamber. There are a couple of products available that put the hydraulic chamber near the handle bars. There is also the TRP HY/RD brake which puts the hydraulics at the caliper. I have the HY/RD's and they work great if you use them with full length compressionless brake cable housing. They aren't quite as good as full hydraulic, but they are much better than most mechanical disc brakes.

Among mechanical disc brakes, the TRP Spyre stands out in my mind. It is one of the exceptions to the statement I made above about mechanical discs moving only one brake pad. The Spyre moves both pads and by all accounts this makes a huge difference in how the brake performs.

Alias530

I've only ever ridden one type of mechanical discs, the TRP Spyres on my cross bike, and god they are awful compared to all the hydro disc mountain bike options I've ridden or higher end rim brake options (Ultegra, Dura Ace).

yochris 

Building up my first disc cross frame this summer so been asking myself a lot of these questions. Seems like the Spyre's are an improvement over BB7's for mechanical. Obviously neither will really compare to hydro. I have mechanical discs on my mtb so I could probably live with them.

Would be curious to hear any other experiences with the Hy/Rd. From what I've been reading, they are appealing option once you get them setup right.

Mr IGH

Call me a luddite but I just never found the need to move to hydros. My family runs BB7s and we get along just fine. We ride the front range so it's not as if we don't need good brakes. If you go to mtbr.com you'll see somewhere between 33%-50% of the members use BB7s because they work fine and have much lower cost. Upgrading to hydros on a road bike is big $$$ for marginal benefit and increased complexity.

mack_turtle

I have TRP Spyres actuated by SRAM Apex levers on my Double Cross and they have been fantastic. I have read some bad reviews of them but they work just fine for my application. no, they are not as powerful as the SLX hydros on my mountain bike, but I don't need that kind of punchy stopping power on my commute/road/gravel bike. I like the fact that I can lock them up when needed, which is rare, but they modulate my speed well when needed. I am usuing regular cable housing instead of "compressionless" housing, so maybe that would make a difference.

RocThrower

I have HyRds that came with a bike I purchased last fall. This is my first experience with disc brakes, and so far they have been great. I like that both pistons move and adjust for wear, so I haven't had to make any adjustments or changes to them. They just work. I haven't experienced any disc rub, they are powerful, and I've only had an occasional squeal, but that was when riding in snow/salt roads in the winter. This spring/summer they have been quiet, both in dry and wet conditions. My only "complaint" would be they look bulky compared to other hydraulic or mechanical setups.

Andy_K 

I don't think there's even any significant effort to get them set up right anymore. There were problems with the first generation, but they appear to have fixed that now. I had a set of the first generation Hy/Rds and they gave me a lot of trouble. Eventually TRP support sent me a set of the second gen calipers under warranty and in about 2000 miles since then the only thing I've had to do was change the pads. I would definitely recommend these brakes.

MudvilleStomper

With regards to spyres, is anyone having a problem with the caliper assembly hitting your spokes? What hubs/rims are you running?

Mr IGH

It's reviews like this that make me put up with BB7s. Once I learned the BB7 quirks they've worked very well for me. Clicking the pad adjusters isn't that hard.

The Smut Pedaller: TRP Spyre disc brake: Long term review

Andy_K 

I used to think clicking the pad adjusters wasn't that hard, but I rode my bike in the rain enough that the inside knob became so hard to turn that I had to use a Torx wrench. Plus, I could never get the road version of the BB7 setup so that it would brake properly without at least a little bit of rub.

I don't miss BB7's at all. Even when I was having to open up my Hy/Rd's every 500 miles or so to top off the hydraulic fluid or try a new gasket or whatever other idea TRP support had I wasn't tempted to switch back.

The MTB version of the BB7, on the other hand, is great.

mack_turtle

the clearance between my Spyres and the spokes coming out of my SRAM hubs is close. I could see how that could be a problem with some hubs.

Mr IGH

I undestand your issues. I'm a good mechanic and take care of my bike so both versions of BB7s work well for me. I have 7 BB7 disc bikes including all the family so I couldn't allow anything less than that.

veganbikes

You filthy, unwashed, scruffy nosed Luddite ; )

The BB7s are a good brake and I am hoping my TRP Spyres are also going to be good (they did some recalling a little while back and things are supposed to be back on track) and the nice thing with mechanicals is you can easily repair them in the field providing you have a new cable. They are easy to set up and maintain with little work and offer better braking than rim brakes for sure. Plus you can run cross levers in addition to brifters or drop bar brake levers which isn't possible on hydro.
That all being said hydraulic discs are quite nice, they do offer nice modulation and good power and a nice lever pull. Plus the hydro stuff usually is two or four pistons where as BB7s and many other mechanicals (minus Spyres and Rever, I believe) are only one piston (only one pad moves which can lead to uneven brake wear). However bleeding a brake isn't always easy and cannot really be done in the field properly and they do cost more generally.

If you want a sort of inbetween the TRP Hy/Rd are a good option as they combine mechanical actuation with a hydro brake at the caliper. You will still need to bleed the brakes but if you had a cable snafu in the field you can replace that and not be completely brakeless.

For me as a touring cyclist and a lazy bum I would probably stick with mechanical. Though the rides I have done on hydro have all been nice.

Garfield Cat

Here's a quote for Magura (2011) so its dated. Magura has a new lineup:

[I have had Magura Martas SLs and BB7s...just recently. I have run Marta, BB7s, and Elixir CRs interchangably over the last year. I'm only on the BB7s as the IS mount Martas would not fit my new bike (so I sold them), and my elixirs are on my downhill bike. I was running Martas at 160mm F+R, and run BB7s 200mm F, 185 R (Avid Ultimate levers, jagwire ripstops).

I truly loved my Maguras Marta SLs. I really thought, for 160mm, they were extremely powerful, felt great, and were extremely light. They were extremely easy to bleed as well...easier than any other braking system I've bled....avid and hayes.

The BB7s have great adjustment for lever pull ratios (assuming you're using speed dial style levers), but still don't have as nice of a level feel as the Martas (or even avid elixirs), even with the top of the line levers and cables. With the 200mm, they are extremely powerful though...very powerful. I went with 200mm as those are what I had lying around. I am planning on going down to a 185mm to see if it calms them down a bit. A slight pull can easily lock up my front wheel in dirt. It's cool when playing around, but scary when actually riding. I've messed with adjustments constantly, but still can't get the lever feel I'd like. I'm hoping a 185 will help.

I still think a Marta would be way more powerful, while also feeling better and having better control if I were to compare with the same rotor size. I have also found that BB7's require more maintenance than hydraulic brakes (assuming you know how to bleed your brakes). BB7's are not sealed nearly as well as hydraulic brakes (for obvious reasons). Dirt will get in there, and you will need to tear them apart, clean, and regrease every once in a while.

The maguras are also way lighter. I think a decent set of hydraulics will win over BB7s almost any day. So Martas are my call...especially if at the same price. ....And Magura Martas are definitely not cheap brakes. They are probably closing them out since Magura just released a whole new line up of brakes. This is not because the Martas were bad brakes though. I think people just began to stop buying them as they haven't changed in such a long time (because they worked as they were)...marketing hype.

Hope this helps. -Nick]

Andy_K 

Actually, although the Hy/Rd's have fittings for bleeding, they really shouldn't ever need to do it. The system is closed and since you don't need to open it up for installation and cable changes, you'd only need to bleed it if it was wrong to begin with (which some of the early ones were).

Alias530

Fluid still goes bad... I bleed my MTB brakes once a year and it comes out all black and nasty and lever feel improves afterwards. I have a feeling that heat, lots of compression cycles, and microscopic amounts of air/moisture that were originally there break it down over time.

fietsbob

cable discs require You to be the pad wear adjuster..

hydraulics auto adjust, and will do so when you wish it wont, like with the wheel out.

(my Magura Rim brakes truly are a closed System, once the air is out , i just replaced the brake pads as they wore)



hydro discs have a pad to slave cylinder heat transfer , causing fluid expansion, needing the tank in the master cylinder-Lever..

DirtRoadRunner

Hydraulic brake fluid DOES collect water - I recently flushed the brakes on one of our cars and the ~10 year old fluid was greenish-black instead of yellowish clear - and this is on a totally closed system.

Having water in the brake fluid means that the water will boil if it gets hot enough (e.g. a long mountain descent where a rider is not breaking in a safe/smart manner). Boiling the water introduces bubbles gas into the system, and gas is compressible (whereas a liquid - brake fluid - is not). This means you can completely loose braking power from hydraulic brakes IF you get the caliper/rotor hot enough AND there is water in the brake fluid, because your braking force will just compress that little bubble of gas, rather than push the pads onto the rotor.

This is why most automotive manufactures recommend flushing the brake system every few years - get out the moisture and avoid boiling fluid and loss of brakes under very hot conditions. I would imagine the bike component manufactures specify a yearly bleeding for the same reason.

Hydraulic brakes are great for automotive and motorcycle applications where the amount of braking force required to lock up a tire on a "normal" surface is high, and you have a big, fat steel rotor and huge cast iron caliper that can absorb a ton of heat before getting really hot. I personally do not see the minor braking advantages to be worth the extra complexity for a road-going bicycle, where very little braking force is required to lock up a tire and you have tiny little rotors and calipers that can easily get very hot. Any well-adjusted set of caliper, cantilever, or mechanical disc brakes should be able to easily lock up a tire so braking force is not the controlling factor in stopping the bicycle - instead it is the friction of the tire against the riding surface.

Andy_K 

I stand corrected on the Hy/Rd bleed issue, though it is still something you aren't likely to have to worry about out on the trail/road. I haven't had a problem with my fluid degrading in 2000+ miles with the new calipers though I admit that I have no idea what it looks like now -- I can only say it is performing well. With the first gen calipers, it was nice and pink every time I opened them up (every 500 miles or so).


This is an interesting argument to apply to road bikes. You'd have a hard time selling mountain bikers on the sufficiency of mechanical discs versus hydraulic and in the vast majority of situations a mountain bike requires much, much less force to lock of a tire than a road bike does. That is to say, you have significantly better traction with a road bike. The tiny rotor issue has been shown to be a problem for people who drag their brakes down a mountain, but on the road there is rarely a reason to do that.

The "I can lock the wheel" argument is one of my pet peeves. Who wants to lock the wheel? Disc brakes aren't about being able to lock the wheel. Disc brakes are about being able to give the lever a gentle squeeze and get a solid, predictable response from the brakes.

DirtRoadRunner

My argument is in regard to road-going bikes, rather than mountain bikes (I'm not a mountain biker). Locking up a wheel is of course never a good thing on a road or gravel bike, and decent modulation allows the rider to precisely control the brake force right on the edge of lockup, maintaining static friction between the tire and riding surface (rather than sliding friction, which is much lower).

Do hydraulic brakes, on a road bike, provide slightly better modulation? Probably. I haven't ridden any so I can't tell you from experience. However, adding hydraulics to the bicycle - especially full hydraulic brakes - increases the complexity of the braking system and adds a totally new failure mode (boiling of old brake fluid on a long descent). This can of course be avoided by flushing the brake system often and using smart braking on a long descents. However, if it DOES occur, the results can be catastrophic and result in serious injury or death - if you are using you brakes enough to overheat them, you must really need them. Having no brakes could be much worse than locking up a wheel.

I also believe the heat generated on a road/gravel bike braking system to be much higher than slowing a mountain bike down - simply because you can go MUCH faster on a road/gravel bike than a MTB. Slowing down from 40 mph creates a lot more heat than slowing down from 10 mph.

mack_turtle

hydro brakes with DOT fluid needs to be bled much more often than mineral oil systems, which is why I put Shimano hydros on my mountain bike an not Avid. DOT fluid absorbs water, mineral oil does not. so you do not need to worry about the boiling point of the fluid in Shimano brakes getting dangerously low after 3% water.

also, Spyres\ Spykes do not require that you adjust the pads to make up for pad wear like most other mechanical disc brakes do. you might need to occasionally give a barrel adjuster a little twist, but that's it because both pads are actuated with TRP mechanicals. other than that, they are set-and-forget if you are not a hack.

Mr IGH

I've blued 210mm rotors on my mtb, never gonna happen on a road bike even with wimpy 160mm rotors.

Andy_K 

Here's a report of a guy bluing his rotors on a cross bike doing a gravel ride:

Road Bike Disc Brakes Are Coming, But Will They Work?

Consensus seems to be that it could have easily been avoided if he knew during the ride what he learned afterward.