Anyone know anything about disc brakes?

why would SRAM build their brakes with dot 4? Christ that stuff is horrible!

They use 5.1 same as Hope and others do, but can use/mix with 4, for it's better heat dealing with properties compared to mineral oil, but it is horrible.

Yeah I've never found heat an issue. Ok once I boiled my shimano but that was on a horrible descent and I dragged the brakes all the way down.

I wouldn't mind the dot if they were easy to bleed.

Yeah, mineral is fine, and better in other ways, I dislike DOT too.

I’m guessing there’s patents involved with mineral oil that prevents manufacturers other than Shimano and Magura from using it.

And Tektro, it's just oil, can't see what could be patented but that doesn't mean someone hasn't.

Agreed!

Ok well I bought the proper bleed kit and followed their weird procedure and it bled rock solid first time, so fair enough, sorry sram.
But still, dot is ugly.

Waiting for Seth's Bike Hacks' Johnson Baby Oil long term test. It's just mineral oil (ymmv).

Gah, my brakes had been lacking power recently. I finally got round to buying a bleed kit, and this morning set about bleeding both brakes. It took me ages as it was my first time, and I had to take the rear caliper off the frame.

The old brake fluid came out looking very discolored, so I was hopeful a good replace of the fluid and then bleed would have helped.

Alas, they still feel terrible.

I'll try changing to brand new rotors and pads tomorrow ....

discoloured brake fluid means the seals are gone. sorry but you will have to get new calipers

I’m having to swap out a calliper tonight - will I have to replace both the connector and the olive. Or can I do just the connector?

Probably do a bleed afterwards.

usually have to do olive as well.. but can sometimes get away without

BH59 or 90?

discoloured brake fluid means the seals are gone.

Hmmm it can mean there's a problem but even without an issue, year or two old brake fluid will come out slightly blackened.

Bh59 - on the carbonda... :)

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Hmm, so is there another way to know my seals are gone and I need a new caliper? Or is it just a case of replacing everything else in the system and if that doesn't help, replacing the calipers?

Re my travails upthread, I failed to get the pistons to retract, succumbed to LBS as I needed the bike pre-Swinley visit. Turns out they were fucked so had to run round various shops to get a new set of brakes in time. Thankfully Evans had some in stock and on sale and Balfes boshed them on.
Had a great time with the third child. And was able to stop, so - expensive, but worth it.

Pffft which brakes are they? Are they still in warranty?

Suddenly failing pads accompanied with squeaky noises is a sign of leaking piston seals.

BR-RS505, about 26 months old so out of warranty. I'll try brand new pads and rotors tomorrow, as there's nothing to lose even if that's not the issue (I can just stick the old pads and rotors back on there).

If the seal is leaking, I should be able to see that visually, right? I just don't want to buy and replace calipers if that's not definitely the problem.

If the seal is leaking, I should be able to see that visually, right?

You could take the pads out, push the pistons in, put the bleed block in, pump the brake up rock hard then strap the lever down tight then leave it over night. See what you come back to. The bleed block won't soak it up like a pad might.

Thanks, I'll give that a go in the flat. I'll just make sure I leave plenty of rags down so no oil gets on the floor.

In case I do need to replace the caliper, it's an easy job, right? The olive in the hydraulic hose means the oil won't just leak out all over the place and I can just move the brake hose over to the new caliper?

I thought I had a leaky calliper but it was just a contaminated pad. Heated it on the hob and now it runs great. Hasn't got recontamination since touch wood

Been reading this thread with interest...

My partner has the choice between buying an Arkose Women's D1 with Spyre Mechanical brakes or a D2 with RS405 hydraulics.

Complicating factor is a sale means the two bikes are essentially the same price, so my inclination therefore is to go for the more expensive bike in the sale.

But...how much of a faff are the RS405s? Partner is not keen/interested in doing her own mechanics and will be heading off touring this summer with other people with no hydraulic brake experience. Am worried there will be a problem at some point on the tour and it'll be more complicated to fix than the Sypres, which can effectively be adjusted with a single allen key.

Are hydraulics and beginners a bad idea?

Are hydraulics and beginners a bad idea?

Not necessarily, but keeping it simple and using Spyres is a good idea.