Disk brakes - how much maintenance do they need?

[Andy in Germany]

We recommend to customers that if using disc brakes with DOT Mineral Hydraulic oil, they should get them bled at least once every two years, preferably once a year. This is because water will get into the system and the oil is hygroscopic, so the water will be absorbed into the oil changing the consistency. When the brakes are hot the water can evaporate creating bubbles. In the same way, air will get into the system and create bubbles, which will make the brakes less effective.

How often you need to change pads depends on how well they are fitted and how much you use the bike. We measure the pads and discs and compare this to the minimum wear given by the manufacturer.

As an aside, don't get a no-name brand of brakes because there's a risk the shop won't be able to bleed the brakes if they don't know what is used: some use hydraulic oil and some use mineral oil, and putting the wrong one in will damage the system.

I personally don't use them, but I ride a touring bike, not an MTB and I value ease of maintenance on the road. Also, I've found I can tune V-Brakes well enough that on my gentle riding it makes no difference anyway.

 

[chriswoody]

We recommend to customers that if using disc brakes with DOT Mineral oil

Just to point out that DOT 5.1 and Mineral oil are two totally different different things as you mention further down.

Broadly speaking SRAM uses DOT 5.1 and Shimano uses Mineral oil. Are there any differences and should you choose one over the other? Who knows to be honest. From a day to day useability perspective I really don't see any difference between the two.

As Andy rightly mentioned though, the DOT brakes will need bleeding much more frequently, his advice to do it yearly is a good one and in my experience I do sometimes stretch that out a tiny bit. I have aftermarket Hope brakes that are connected to SRAM Rival brake levers so they run DOT 5.1 fluid. They are fantastic powerful brakes and I've just returned from an 8 day bikepacking trip in the Alps where I covered nearly 10,000m of ascending and descending and they worked a charm in all weathers. Totally reliable and powerful breaking all the way.

 

[cyberknight]

I can only talk about cable discs as its the only sort i have tried , avoid single piston sort if you can as I found the braking very poor and the design tended to warp rotors in my case .When i upgraded to dual piston and shimano pads the braking was a vast improvement over the original set up and once i got it dialled in i reckon there is not much difference to a rim brake set up , im not saying they are as good but close enough with the bonus if consistent braking in the wet .
I still have a bike with QR rather than thru axles and do find if i need to take the wheel out then i will need to readjust the pad clearance particularly on the front .
As far as weight goes they are heavier as my carbon boardman team carbon when new was around 8.5 kg and the new ones with hydro discs ( 8.9 slr ) are listed as 9.6 kg.

 

[Drago]

I've twin piston cable and hydro bikes and I think the biggest difference is improved feel and refinement or the latter. The former ultimately seem to haul things up just as smartly.

 

[gcogger]

I can only talk about cable discs as its the only sort i have tried , avoid single piston sort if you can as I found the braking very poor and the design tended to warp rotors in my case .When i upgraded to dual piston and shimano pads the braking was a vast improvement over the original set up and once i got it dialled in i reckon there is not much difference to a rim brake set up , im not saying they are as good but close enough with the bonus if consistent braking in the wet .
I still have a bike with QR rather than thru axles and do find if i need to take the wheel out then i will need to readjust the pad clearance particularly on the front .
As far as weight goes they are heavier as my carbon boardman team carbon when new was around 8.5 kg and the new ones with hydro discs ( 8.9 slr ) are listed as 9.6 kg.

I used a bike with hydraulic discs and QR wheels for a year or two, and that's what my wife's current bike has. We've never had to re-adjust anything when taking wheels out/in, so maybe that's another down side of mechanical discs?

 

[T4tomo]

I used a bike with hydraulic discs and QR wheels for a year or two, and that's what my wife's current bike has. We've never had to re-adjust anything when taking wheels out/in, so maybe that's another down side of mechanical discs?

If you pinch up the QR whilst applying the brakes then it centres its self, cable or hydro.

 

[Andy in Germany]

Just to point out that DOT 5.1 and Mineral oil are two totally different different things as you mention further down.

Broadly speaking SRAM uses DOT 5.1 and Shimano uses Mineral oil. Are there any differences and should you choose one over the other? Who knows to be honest. From a day to day useability perspective I really don't see any difference between the two.

You are quite correct, sloppy writing on my part. Mineral oil and Hydraulic oils are of course different.

DOT 5 is a silicon based oil. Dot 1-4 and 5.1 are all organic based, although that's as far as my understanding goes. As far as I know Magura uses Mineral oil in their HS 11 and HS 33 systems (both rim brakes)

My personal theory why Sram uses one DOT oil and Shimano uses another is that they are conspiring to make life complicated for poor, hardworking bike mechanics.

 

[Ming the Merciless]

Regarding pad wear. What you’ll find is that the lever travel and feel will remain consistent whilst the pads are within their wear limits. Once you start getting more lever travel or they feel different make sure to check pad wear as a first step.

 

[si_c]

You are quite correct, sloppy writing on my part. Mineral oil and Hydraulic oils are of course different.

DOT 5 is a silicon based oil. Dot 1-4 and 5.1 are all organic based, although that's as far as my understanding goes. As far as I know Magura uses Mineral oil in their HS 11 and HS 33 systems (both rim brakes)

My personal theory why Sram uses one DOT oil and Shimano uses another is that they are conspiring to make life complicated for poor, hardworking bike mechanics.

SRAM have started moving to mineral oil from DOT fluid now. Their entire MTB lineup now uses it and I would expect their road brakes to change in due course.

 

[cyberknight]

If you pinch up the QR whilst applying the brakes then it centres its self, cable or hydro.

Even when doing this I still found the need to twiddle, I do run the pads as close as I can though

 

[Tigerbiten]

Just bled the Tektro Auriga Twins on the front of my bent trike.
Changed the 4th set of new pads in and then decided the brakes where still a bit soft.
It must be over 10 years since they where last bled, but that was done by someone else while I looked on.
So got a cheap kit off the internet and looked up how to do it on you-tube.
The hardest part was loosening a bleed nipple on one of the callipers.
Apart from that it was easy.
It surprising how much better the brakes are now ...

 

[Mazz]

An earlier reply got me thinking - if I need to take the wheel off to repair a puncture, for example - is it easy enough to realign the disc/brake pads when refitting the wheel? I'm assuming QR levers come as standard on disc brake wheels, maybe I'm wrong.

 

[Psamathe]

An earlier reply got me thinking - if I need to take the wheel off to repair a puncture, for example - is it easy enough to realign the disc/brake pads when refitting the wheel?

With my mechanical disks removing and replacing the wheel is not an issue, no realignment needed, just put the wheel back in job done.

Ian

 

[Richard A Thackeray]

Hmm
My rear brake (Tiagra 10-speed/RS7800 caliper? has started (can't really say it's stopped/stopping) to give excessive lever travel
I'd taken the pads out a few days ago, to give them a quick sandpapering, as they were squealing slightly

Inadvertantly, I caught the lever, pushing the pistons out
I pressed them back in, using a tool (kiddies fork, with a very solid plastic handle)
All seemed fine, pads back in
Then on riding to work; maximum lever travel/minumum retardation (would lock at full travel on a loose surface)

I've never bled them, as there's never been an issue in that respect
There's no visible leakage/drips, so I don't think I've damaged a piston seal
I am going to put a new pair of pads in, over the weekend, when I get them

(as an aside; I used to have a Pace Research RC100, with the Magura set-up)

 

[Webbo2]

An earlier reply got me thinking - if I need to take the wheel off to repair a puncture, for example - is it easy enough to realign the disc/brake pads when refitting the wheel? I'm assuming QR levers come as standard on disc brake wheels, maybe I'm wrong.

Lots of disc braked bikes come with a through axle these days. They have a removable lever which looks like a quick release but you just screw the axle out. In the 9 months I’ve had my bike I‘ve removed he back wheel once. So just unscrew the axle, take the wheel out, do your fettling or whatever, the slot the wheel back while putting the disc in to calliper. Screw axle back in, job done.