newbie hydraulic disc brake Qs
 

Hello,

I have two bikes equipped with Shimano hydraulic disc brakes and am interesting in learning to service them at home. One is a newish road bike equipped with the latest Ultegra BR-8170, the other is a more long-standing MTB equipped with XT BR-M8100. Although these two are certainly in the higher-use category, I have 6 total bikes so I won't be needing to do this so often. So, I'm mostly interested in low to middle tier solutions for 2).

Would it be possible to help with the following questions?

1) Oil -
I assume I can use any old mineral oil (marketed for disc brakes), but that Shimano is preferred. Can anyone recommend an alternate product that is more cost effective for the above brakes, or is Shimano the way to go?

2) Bleed kit -
Can anyone recommend a bleed kit that will work fine with current gen. Ultegra 12 speed group, and previous gen XT 11 speed brakes? The Park Tool kit looks appealing. but I don't think it makes sense for me to fork out 150 bucks for something that will get used somewhat seldomly.

3) New Lines -
Can I use the same brake fluid lines for both groups, or do I need to purchase them separately? A quick google search reveals BH59 and BH90 and some compatibility charts I could look up. Just wondering if there is any universal third party hoses, hacks or other "pro tips" before I purchase whatever the "box recommendation" is.

I don't have questions regarding pads or how to replace them.

Thanks!
-David

Just get the Shimano oil, or if you'd prefer, the Finish Line stuff. While other oils are likely to work, the total cost is pretty low and it's worth it not to play experiments with your braking system.

Get https://www.amazon.com/Workshop-TL-B...57431091&psc=1 . The Park kit is crap. The fitting on the syringe on the Shimano kit works better on Shimano brakes than anything I've tried. Or you can just get a single bleed funnel, the m5>m7 adapter, and use any syringe with some surgical tubing and it'll work entirely fine. Anything that fills the space between the pistons securely works as a bleed block.

awesome, thanks for the suggestion. For those hoses - do you think that I should swap them, or re-use the same ones? They look to be about 40-50 bucks a piece, so I'd like to re-use unless there is a compelling reason not to.

EDIT: The bike in question has about 2,500 miles of mostly fair weather riding. Not much hard braking either or long descents.

I bought the Shimano Professional Disc Brake Bleed Kit (#SHIU1HU) but have not had to use it yet, because I have read reviews that say that the Park version makes bleeding difficult.

I had a fitting on the DOT kit fail and spray fluidin my eye. Good thing for the eye wash station!

Damn. Thankfully Shimano only uses mineral oil so I can leave the DOT fluid for my cars.

https://www.amazon.com/Revmega-Bleed...A2IECG3TZSUX31
I just use that. It is cheap and seems to be quality to me certainly good enough for something you use once every 2 or 3 years. Shimano's looks cheap to me.

I purchased one of those Fit-All-Brakes bleed kit. It works, but it is not as reliable as the shimano kit.

But ​​​​TMonk needs something that would work for both Shimano MTB and road, whereas this kit specifically excludes the latter.

Based on watching a quick youtube video, I think the main are where they would differ is the attachment of the cup into the lever? If so, is there like a cheap plastic adapter I can get to make most kits universal? Also, does anyone specifically know what the attachment type/threading is into a BR-8170 lever?

ok so after looking this up, the initial installation with hoses looks way more difficult than a simple bleed job. I have internally routed bars and want to swap them out so the hoses need to get pulled. The joys of new technology and all that.

Question - do you think it may be worth it to just ask the shop to install the new bars and re-do the brakes? A bleed job looks pretty easy to do on my own. On a related note - once the new lines are installed, if done correctly, is it a "set it and forget it" situation? Like how often do the actual lines need to get re-done, versus a simple bleed job?

Not necessarily? If the hoses are sufficiently long, you can also consider disconnecting the hoses from the STI levers to get them out of the old handlebar, cutting off the old olives, and reinserting the hoses into the STI levers with new olives. Of course you will have to bleed the brakes afterward.

I hope so too! Otherwise I would have bought the bleed kit for nothing.

I think the hoses are forever unless they somehow get damaged. Especially if you spread your mileage among 6 bikes.

Thanks for the advice SoSmellyAir. I like your idea of trying to disconnect the hoses at the caliper and leave them installed in the lever. I should only have to cut off a cm or so and re-do new barb and olives. There seems to be enough slack for that. I think I will give that a go, thanks.

I bought a bike new that came with Shimano R8000 series hydraulic brakes back in 2020. I've yet to have to do anything to the brakes or for any other part in general other than tubes and tires. I bought some new pads for it thinking that surely those would go soon, but so far it looks like I'm going to go a few thousand more than the just under 6000 miles that is on it before changing pads. And no issues at all from spongy brake levers.

So don't be all antsy to do something. If it's working well enough, leave them alone. At most I sometimes clean the grunge out from around the piston seals when I remove the pads to check their thickness.

My main quandary is that I need to swap bars and the brake lines are internally routed. So, there is some minimum effort involved in that. But I think I will try SoSmellyAir's suggestion. Glad to hear it's low maintenance after I get it re-installed.

I didn't read down to that post where you disclosed that. So yeah you have to do something. Fall back on the installation procedures in the DM's that can be found here http://si.shimano.com/#/ if you have issues after trying the other suggested methods.

You misunderstood me above; I had actually suggested disconnecting the hose from the STI lever, not from the brake caliper. From my research (rather than from actual experience) the bleeding process involves first orienting the bike such that (i) the brake caliper is at the lowest point and (ii) the STI lever is at the highest point along the brake hose, so that gravity pulls the mineral oil down, while any trapped air rises. Thus, to the extent you open up the system by disconnecting any component, doing so at the higher point would be preferable. But like I said, this is all just theoretical (but logical to me).

I will be swapping from the EA70 AX handlebar (too much flair) to a new CF road handlebar, of which I have several different ones. I am still debating whether to route the brake hoses and shift cables through the handlebar.

You can drain/bleed the lines by just opening the port in the lever. You don't need to disconnect the hose. At least that's what I've learned from a couple youtube vds. I realize that your message doesn't imply that you aren't aware of that, just that it might be preferable to do it there, if I have to break it anyway to get it through the bars.

I do like the idea of disconnecting at the lever, since I wouldn't have to re-route the lines through the frame and work. I think the only thing balancing that, is the relative complexity of breaking/installing the line at the lever vs the caliper, which IDK yet.

SoSmellyAir I found this vid on how to re-do the hose at the lever. I had watched it a few days ago and felt pretty bewildered; no it is starting to seem less foreign. I just need a new insert and barb. Thanks for the suggestion.

I had watched the same video too. I am debating whether to buy the official Shimano brake hose insert insertion tool or just have my LBS do it.