Anyone know anything about disc brakes?

buy a new calliper

Sorry

Pull the red bit off, get some penetrating oil onto the threads, then you can get a spanner on the rounded torx bit, I think it's an 8mm, clean up if it's worked, throw away if it hasn't.

Good shout. Will try taking the red bit off and getting a spanner in there.

That did the trick, thank you! Saved me a few quid there.

No worries.

Just got round to replacing my pads on my R8020 hydro disks. One piston was stuck out way further than the other. I pulled the brake to show the pads and then cleaned them with alcohol. When I pushed them back in, there was a hiss from the hood. Did it again to clean some more and the same hiss.

Now the lever pulls right to the bar and barely engages the brake. I can't see any oil etc under the hood. Do I just need to bleed them, or top up the system? Running for about 9 months working fine until now.

After 9 months you may just bleed it, but if you can't be arsed just put the cup with some oil and stroke the brake a million times

Cross post from my CP thread, in case anyone wants to mount a juin tech R1 front brake on IS mount forks and use it with a 160mm rotor (A kona p2 fork in my case). I tried with various adapters and couldn't get it to work, either the caliper interfered with the IS tab or the caliper sat too far out on the rotor, only about half the pad would engage. Finally I gave up and went with a 180mm rotor instead. There are others who have failed and also arrived at the 180 mm rotor solution:

https://groups.google.com/forum/?_escape­d_fragment_=msg/650b/QhZA3dHfDYA/1ZMKaMU­5AQAJ

https://forums.mtbr.com/brake-time/mount­ing-juin-tech-r1-51-fork-997535.html

Caveat: have only worked with SRAM and have only done the following from the caliper end.

I need to internally route (through some new handlers) and shortern R7020 cables.
Can this be done easily at the lever end? It seems that Shimano uses an olive/barb at the lever end (different to SRAM) and caliper end.

The manual [https://si.shimano.com/pdfs/dm/DM-RADBR01-07-ENG.pdf] suggests you can shorten from the lever end (avoids having to deal with the internal routing on the frame) but they use a very elaborate and expensive tool, the TL-BH62.

Is the TL-BH62 necesary? It seems the same could be done with a dedicated cutter (already own) and a barb press, e.g. this for £16 https://www.wiggle.co.uk/lifeline-pro-hydraulic-hose-needle-driver/

cutter + vice with yellow plastic things (for holding hose) + small hammer (for barb) :

should be ok with dedicated effort:)

(put fitting + olive on hose before inserting the barb...)

You can shorten Shimano hoses at either end. The system is the same at both ends - barb/olive/compression nut. The advantage to doing it at the caliper end is that if you're careful you might get away without having to bleed the system at all, and if you do have to bleed it then it should be fairly straightforward as the lever (the hardest part in the system to get rid of air) should remain full of fluid.

You don't need the TL-BH62. I've just used the little yellow blocks that come with the retail kits held together with a small G-clamp and a small soft-faced mallet to drive the barb home. The Lifeline tool looks good FRM though - I could be tempted that that. The Park combined cutter and barb-inserter tool looked very tempting, until I saw the price.

Thanks and thanks @svenhöek, really useful, exactly what I needed to know.

Will probably get a bleed kit too, will want to service it eventually.

If you're shortening it at the lever end, you'll definitely need the bleed kit. You'll also need the adaptor to connect the fluid cup that fits onto the lever (Shimano part # Y0C698050 or equivalent) if one didn't come with your brake kit.

The lifeline tool looks interesting, I use this http://www.tektro.com/mobile/products.php?p=104

If you're shortening it at the lever end, you'll definitely need the bleed kit. You'll also need the adaptor to connect the fluid cup that fits onto the lever (Shimano part # Y0C698050 or equivalent) if one didn't come with your brake kit.

I disagree, shortening at the lever end is easy and often doesn't need bleeding, and at worse just needs a little burp with the cup, any air is right up at the top of the system so easy to get rid of that way.

And you can cut it with anything half decent, Stanley knife works well onto a hard surface, snips do the job but can be a little messy, yellow blocks with mole grips and twat the barb in with whatever, shimano doesn't need the olive on first but it's good practice as some brakes do.

shortening at the lever end is easy and often doesn't need bleeding

Yep.

I'm sure this has been asked before but i couldn't find any relevant threads via search.

Are there any options for (drop bar) shimano compatible singlespeed hydraulic brifters (thats a mouthful) out there?
I see theres the TRP hylex but ideally i wouldn't have to buy a brakeset, just the lever, if possible.

The only official shimano compatible levers are shimano´s own. And they don't make a single-speed dropbar lever.

edit: but then I find this https://www.amaincycling.com/shimano-grx-blrx600-dropbar-hydraulic-brake-lever-left-iblrx600l/p976207
https://www.bike24.com/p2323015.html

so the left side is possible...

or get some di2 levers and remove/ignore the paddle/buttons

one man on Cycling UK forums knows a LOT about paul klampers

https://forum.cyclinguk.org/viewtopic.php?f=5&t=136382

You'll find Brucey is the Tester of the CTC forum. Except he's slightly less cutting and writes much longer posts.

Gah, I am my own worst enemy sometimes .....

So I went to replace the front pads on my Shimano BR RS-505. One side of the pistons was very far out, so I cleaned it with alcohol and then tried to push it back in. It wouldn't go in easily, so I applied more pressure, until the whole thing went pop and started hissing out fluid.

So I'm sure I now need a new caliper thanks to me being heavy handed and impatient. What an idiot.

I've ordered a replacement caliper, and I already have a bleed kit + fluid for shimano. Are there any other parts that I need to be able to fit a new caliper and get it up and running that I've forgotten about?

If the caliper doesn't come with them, you'll need a new olive and barb to do the job properly.

Ah okay, I can't imagine it does. Will any barb and olive do, or are there specific ones for each type of shimano hose?

There are two types for Shimano hoses, one type for the older BH59 hose and a different set for the newer BH90 hose.