Anyone know anything about disc brakes?

Wondering if a new screw might help or fitting a helicoil in to the body so there is some thread taking up the slack.

Bloody seals on the Shimano rear calliper have gone again! I think this is the 3rd time on the particular bike - the only Shimano disc brake bike I have. Rear brake is super ineffective and squeaky, which is exactly what it's done previously when this has happened.

It is a decent age, so has ST-RS505 levers and the matching 505 callipers, which was 105 level at the time. I'd like to not have to replace my hoses at the same time I stick a new calliper on. As little fuss as possible is my MO.

Looking at the various compatibility charts, looks like me only options are the 505, 785, or 808 callipers. If I wanted to use anything more modern I'd need to change to the BH90 hose.

Could a disc brake guru just shout if I've got that wrong, and does anyone know if between any of those 3 options any of them is less likely to mess up and leak oil all over again?

Or is the more modern stuff just way better at not dropping the seals, and I really should consider upgrading to something like the 7070 calliper with the BH90 hose?

Just whack anything on there, it'll be reet.

Nah, the hoses are pretty much the same, you'll just need to get the correct barbs.

You can probably even just reused the barb and olive as it is and just plonk a new caliper on there.

Flat mount caliper?

Yes indeed, flat mount. Oh yeah you think current barb will be just fine? If so I'll take a look at the more modern compatible callipers from R7000 and R8000 series Shimano to see if they're more available.

Any view on whether the more modern ones are less likely to leak fluid past the seals after a while? First time this happened I thought bad luck, but this is the 3rd time in 6 years now. It's clearly just a poor design.

It's usually the ceramic pistons that go rather than the seals. Mostly pushing them back in at a wonky angle, but they're quite fragile and can just break. I'd guess the UR300 doesn't use them so you'll not need to worry about that, just be wary of the front caliper having it's adapter built in so front only for whatever the fork is set to rotorwise (probably 160) cheap AF though.

Yeah, I've just done some quick internet research and it sounds like the pistons on UR300 are resin rather than ceramic.

On this bike I actually have 160mm rotors on there front and back already despite it being road. I decided to increase from 140mm last year because I use it to drop my kid at nursery and on the way home we come down a very steep and twisty descent where I'm not gonna be bombing it down the same way I would it if were just me on the bike and I've got the extra weight of a hamax carress and a 2yr old on the back. I currently use the adapters front and rear to space out the existing calipers to 160mm.

I read that the UR300 are to be used with resin pads only. Is that correct? I'd thought that it was the disc that would dictate only being allowed to use resin, rather than the caliper, but I am clearly not incredibly knowledgeable on the subject.

Other considerations are that I'd need to change pads. Obviously a new caliper comes with the pads included. If I keep the current front caliper and only change the rear, then I'll have 1 type of pad on the rear and a different type on the front. That's okay, but I think in the long run I'd ideally also change the front to the same caliper. It's probably just a matter of time before that one goes.

Questions I have:

1. Front and rear callipers are not interchangeable, right? I think I've answered my own question looking at the images online - they look very different.
   
2. Are you sure my levers (RS505) are compatible with the UR300 calipers? Looking at Shimano's compatibility chart they aren't listed, but I think that's only because they are listed as different categories (road/gravel versus MTB/urban) and Shimano just isn't expecting people to want to mix and match.
   
3. Are my existing hoses and barbs definitely compatible? Shimano lists the SM-BH59-JK-SS separately for road and MTB for some reason, and says that UR300 are only compatible with MTB, but I can't tell why or how that would be different.
   
4. If I choose to re-use the existing hoses and barbs, what warning signs should I look for that it's not worked and I need to replace the barb? Presumably just leaking around where the hose connects to the caliper?
   
   

You are right that the UR300 is cheap as chips. I could get both front and rear from Ribble (including lever, hose, and pads) for £35 delivered, which is far cheaper than any of the other single calipers from the 105 or ultegra that I can find for sale online. Depending on answers to the above questions, I'll probably just order up both a front and rear.

Combination of bad design and bad luck.

Usually after a good clean it'll stop the leak.

I’ve just gone UR300 on my Sequoia flat bar conversion using the existing hoses. They screwed straight on without a problem. If I go back to drops I’ll just screw them on the RS505 levers. The discs that came with them have “resin only” stamped on them, but I’m sure you can use whatever you want with your road discs.

Interesting, thank you!

I'll be interested to hear how you go with this over the next couple of months.

I've decided to just order a pair of the UR300 as it almost feels too cheap to miss for a functioning set of disc brakes! After scouring ebay I've also found an RS505 rear caliper listed as used but working, which they accepted an offer of £15 for, so the way I see it I've now got several options for the price of a new 105 rear caliper.

Big thanks to @coventry_eagle and @snottyotter for sharing your thoughts and experiences. I really appreciate it!

That’s why I went down the cheap brake route. There was no way on earth I was paying for a pair of new rs505 calipers for what is now just a grocery getter. So far 200miles in, they seem fine you can still lock up the rear and do impressive stoppies.
Oh I’m using some old cheapy Tektro discs as well.

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Resin only is the rotors that kinda fall apart of used with sintered pads.

Thankfully they were only an extra £1 for the pair!

I've been using these guys following a recommendation from the Peak Torque youtube channel. They've been really great, and incredible value at £5 each: https://www.amazon.co.uk/gp/product/B08Z3MXHDS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

Look like avid clean sweep G3.

Have you found anything better than the standard retaining pins for the pads? I'm used to the sort that screws in and then has a retaining pin, which feels nice and secure to me.

I've fitted the brakes now, but I'm not looking forward to needing to replace the pads ...

I’m looking forward to not having to spend hours looking for that little clip thing that I always drop when I change the pads on other brakes ;) a split pin will be fine.

Fuck me, hydros are a shitting nightmare.

My SLX front brake has been leaking (I think) from between the caliper halves.

I’ve been using a set of Guides that I have but when I was out on the bike there other day the front was rubbing and I couldn’t get it not to so that spotted me on to getting the SLXs sorted.

I bought a rear Deore 4 pot from Merlin which arrived as the lever and the caliper/hose separate so I hooked the caliper and hose up to my SLX lever today, got a good bleed on it, had to do other stuff so left it sitting in the garage with the bleed block in, went back out just before dinner to put the pads back in and install it and gave it a little squeeze to check it still felt nice and a bit of the piston pinged off and a jet of oil squirted out the hole!

Have contacted Merlin to but I’m thinking that they might be shitty about it since I bought a rear brake and cut the hose down to front brake length and the Deore lever is sitting there untouched with its little bung in etc because I was hooked it up to my SLX lever.

Silver lining: I took the Guide front brake off off in anticipation of putting the SLXs back on and then obviously had to refit the Guide and someone along the line it stopped rubbing!

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You can get a new ceramic pretty easily if Merlin get shitty?

I’m looking at swapping the drop bars out on Liz’s Giant TCX. I have a flat bar shifter, but it is Rival 1X with flat mounts. What levers will work with the calipers? Or should I just buy a whole new brake set? I really want to keep this as cheap as possible, it is for testing purposes really.

Yeah I figured that might be a possibility.

Just ironic as swapping in the new caliper was meant to be an easier option than fixing my SLX one.

You'll also need new hose kit too.

Might as well get a complete set and save you the hassle of swapping.

Cheers, I’ll get on the Ribble for another ur300 set :)

I'm setting up SRAM hydraulic disc for the first time (Force 1), and it's a little annoying. I bought the shifters 2nd hand and somehow overlooked the fact they use a banjo at the shifters rather than olive. Am I right in thinking that I...

a) Cannot in any way re-attach a banjo as they are factory crimped?
b) Need to buy a stupid SRAM cable kit with beveled banjo for about £40/lever?

This isn't the budget build I was aiming for!

Yeah, I've just been through this. Yes you need the SRAM hose kit, the banjo is crimped on, you can't reuse it.
If they have hoses attached, you could do what I did and buy some TRP hose connectors and fit them inline somewhere along the hose and then add however much length of new hose on the other end. You will need several new olive and barb fittings for this but it's cheaper than SRAM hose.
Otherwise jagwire apparently do a compatible hose but I haven't tried it.

https://www.tradeinn.com/bikeinn/en/jagwire-sram-red-force-post-mount-brake-hose-kit-2-meters/138155329/p

https://www.bikeparts.co.uk/products/trp-sparehose-coupler-5-0-mm-tl1-3