Hydraulics vs Cables

compo

What are the advantages of hydraulic disk brakes over cable pul discs?

Is it advantageos to upgrade?

Torres

Hydro's tend to be more powerful, yet more expensive and more of a pain to set up. If done right they can be fit and forget, but if any problems arise they tend to be a bit more difficult to fix (depending on how mechanically competant you are.)

Cables are usualy cheaper, and any maintinance tendsto be easier. However they suffer the same pitfalls of any cable opperated system (ie cable stretch) and may need a bit more attention than hydros.

sniper68

IME cable offer no advantages over V-brakes,Hydros are far superior.

GHill

Cables have less modulation and also require more pad adjustment (hydraulics tend to self adjust as the pads wear).

Many cable brakes are only single actuation too, meaning that only one pad moves and pushes the rotor against the static pad.

Wacky Racer

I had mechanical disc brakes on my old Kona, and from a performance point of view they were excellent. But agree with previous posters, the cable does stretch over time and requires adjustment. I've been lucky with the hydraulic brakes on my Scale so far, they have been trouble free and great straight from the box, whereas one or two people I know have had some trouble getting them set up just right.

From Wikipedia -
Hydraulic vs mechanical
There are two main types of disc brake: mechanical (cable-actuated) and hydraulic. Mechanical disc brakes are almost always cheaper, but have less modulation, and may accumulate dirt in the cable lines since the cable is usually open to the outside.

Hydraulic disc brakes use fluid from a reservoir, pushed through a hose, to actuate the pistons in the disc calliper, that actuate the pads. They are better at excluding contaminants, but are difficult to repair on the trail, since they require fairly specialized tools. The brake lines occasionally require bleeding to remove air bubbles, whereas mechanical disc brakes rarely fail completely.

Also, the hydraulic fluid may boil on steep, continuous downhills. This is due to heat build up in the disc and pads and can cause the brake to lose its ability to transmit force ("brake fade") through incompressible fluids, since some of it has become a gas, which is compressible. To avoid this problem, 203 mm (8 inch) diameter disc rotors have become common on downhill bikes. Larger rotors require less calliper pressure for equal stopping power, dissipate heat more quickly, and have a larger amount of mass to absorb heat. Two types of brake fluid are used today: mineral oil and DOT fluid. Mineral oil is generally inert, while DOT is corrosive to frame paint but has a higher boiling point. Using the wrong fluid may cause the seals to swell or become corroded.

grumsta

Avid BB7s are really very good imo. Not far off the performance of decent hydro brakes, and no faff with bleeding etc

jay12

i went from vbrakes to hydros an they are better by several country miles.
but i'v had no experiance of cable disc brakes but i'v had no problems with the hydro brakes so far

Kiblams

I am pretty sure that hydro disks are better than cable disks, but I feel no need to move across to hydros for performance as an XC/trail rider.

That said, I wouldn't ever use any other mech disk brakes other than the Avid BB5/7s. They claim that they are the best mechanical disk brakes on the market and if you ever use one you will see why.

If you are fine maintaining hydro disk brakes, there is no reason not to use them IMO, I just like to keep things simple on my rig (hence my rigid forks )

bomberesque

I would not upgrade BB5/7s to hydros unless I was upgrading to higher end hydros.

I know though that most mechanical brakes specc'd on entry level bikes are not avid BBs (which aren't very cheap actually) and I've hard some fairly awful things about other mech discs (including Shimano) but I only have direct experience of BB5/7s

why not borrow a mates bike for an hour and see for yourself?

ratty2k

Wacky Racer wrote:

I had mechanical disc brakes on my old Kona, and from a performance point of view they were excellent. But agree with previous posters, the cable does stretch over time and requires adjustment. I've been lucky with the hydraulic brakes on my Scale so far, they have been trouble free and great straight from the box, whereas one or two people I know have had some trouble getting them set up just right.

From Wikipedia -
Hydraulic vs mechanical
There are two main types of disc brake: mechanical (cable-actuated) and hydraulic. Mechanical disc brakes are almost always cheaper, but have less modulation, and may accumulate dirt in the cable lines since the cable is usually open to the outside.

Hydraulic disc brakes use fluid from a reservoir, pushed through a hose, to actuate the pistons in the disc calliper, that actuate the pads. They are better at excluding contaminants, but are difficult to repair on the trail, since they require fairly specialized tools. The brake lines occasionally require bleeding to remove air bubbles, whereas mechanical disc brakes rarely fail completely.

Also, the hydraulic fluid may boil on steep, continuous downhills. This is due to heat build up in the disc and pads and can cause the brake to lose its ability to transmit force ("brake fade") through incompressible fluids, since some of it has become a gas, which is compressible. To avoid this problem, 203 mm (8 inch) diameter disc rotors have become common on downhill bikes. Larger rotors require less calliper pressure for equal stopping power, dissipate heat more quickly, and have a larger amount of mass to absorb heat. Two types of brake fluid are used today: mineral oil and DOT fluid. Mineral oil is generally inert, while DOT is corrosive to frame paint but has a higher boiling point. Using the wrong fluid may cause the seals to swell or become corroded.

Yer all very well, but if they are set up correctly they are easier to look after than cable setups. Fluid change, not hard to do if needed. I've NEVER had to repair a brake on the trail bar changing a set of pads. Boiling yes, but under extreme prolonged braking only. The DH boys have no issues with them. As for corrosive fluid, well yes, if you leave it where it shouldn't be, be water washes it away quite nicely if any spillages occur.

biff55

was considering the same issue myself , whether to change my cable discs to hydro's
now not so sure.....
clearly they are more powerful with better "feel" as has been stated from other posts but..
every week there are posts in the tech section of this forum with folk having one problem or another with hydros ; siezed calipers , fault lever seals , oil leaks ,
contaminated pads , ingress of air into system , different bleed kits , the list is endless.
hardly see any posts for problematic cable discs.
want to bike abroad next year , maybe national parks of the USA , and i dont want the faff and aggro of dealing with hydro repairs in the middle of nowhere.
from what i've read above the only downside folk have mentioned is cable stretch -
hardly an issue to adjust cable tension is it ?
its not gonna break a ride like complete fade of hydros from boiled oil.
think i'll just get bigger discs and keep the mech system for now.

Sarnian

It could be worth reading the reviews on CRC for Avid B5/B7 there are some good points.

biff55

and just to prove my point , had quick look on tech section and the first post was some
poor sod with avid hydro bleed problems.
:?

ratty2k

Only time I've had to bleed brakes is when upgrading to braided hoses (not really necessary to do so) and a lot of the people who have problems just dont know what hey are doing on something that is VERY simple. Some blow the pistons out when bleeding, because they either dont know what they are doing, or dont listen when give advice.
As I say, I have NEVER had to repair a brake out on a ride, and neither has anyone I ride with. Dont change to hydros if you dont want, but they do not need faffing with constantly- neither does a very similar system on cars or motorbikes...
Dont let the numpties scare you off 'em.

jay12

them people usuallyt hink they can repair it but if i had a problem with minei wouldsendthem off to theLBSasi haven't got the money to replace them if i screw up rapiring them and anyway my bike is in it's last times so thats why i'm getting anew one in february

biff55

ratty2k wrote:

Only time I've had to bleed brakes is when upgrading to braided hoses (not really necessary to do so) and a lot of the people who have problems just dont know what hey are doing on something that is VERY simple. Some blow the pistons out when bleeding, because they either dont know what they are doing, or dont listen when give advice.
As I say, I have NEVER had to repair a brake out on a ride, and neither has anyone I ride with. Dont change to hydros if you dont want, but they do not need faffing with constantly- neither does a very similar system on cars or motorbikes...
Dont let the numpties scare you off 'em.

yet our forum is filled with folk having hydro brake probs of one kind or another ?
you must be one of the forntunate few to be problem free
i doubt theres much improvement between correctly set-up and maintained cable discs
and entry level basic hydros.

Wacky Racer

Dont let the numpties scare you off 'em.

Not sure where you are coming from! I haven't read a single post above which suggests Hydraulic brakes are no good, many posts above offer a balanced view, with positives and potential shortcomings of both. Personally I have had good experience of both, therefore wouldn't condemn either. But there is often a misconception that someone will see a vast difference between mechanicals and Hydraulics, whereas in reality, top end mechanicals versus bottom end hydraulics are probably not far apart. But if you have the money to buy premium then you will see and feel many advantages.