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Hi All,

I have RS685's on my Canyon and the rear (left) brake feels a little spongey. I understand this means it potentially needs bleeding, however I know there are a couple hacks that can be done to help this.

(see about 7mins in) https://www.youtube.com/watch?v=gQ_oIAPuQR8&t=451s

I know I need several tools including the bleed kit (syringe and bucket etc) as well as the mineral oil - what is the black tool used for securing the bleed pipe to the calliper?

Next question, how the heck do I setup hydro disc brakes from the beginning?

I have a Whyte Wessex on it's way to me, but I already have a full 105 groupset from my current commuter/winter road bike. The only way I could afford to get a Wessex was by selling the R8020 shifters and brakes to my other (see: better) half. Anyway, I then managed to get some RS685's really cheap so need to take off the R8020 on the Wessex and replace it with the RS685 I have.

I simply have no idea what I am likely to face. I will use the cables (hydro outers) that come with the Wessex, but how do the hydro cables attach to the STI's and the callipers. Do I need any tools/parts other than the bleed kit and my usual toolkit?

I.e. is it as easy as emptying the hyfro fluid, removing the hydro cable from the calliper/sti and plugging in the new calliper and sti before filling again?

Replacing the fluid seems like a fairly easy job and there's plenty of youtube vids showing how to do it, but I cant find any good videos showing how to drain hydraulic fluid or any showing how to cut to size hydro cables and full setup the system.

Cheers!

11 comments

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sergius [471 posts] 2 months ago
1 like

Hands up first of all, I've got RS785's & RS685's on my bikes - but I've not yet had to bleed/mess about with either yet.  

 

On my old MTB, my attempt to bleed the hydraulics was a bit of a disaster when I did the typically male thing of refusing to RTFM and happened to lose a tiny washer which resulted in DOT4 fluid everywhere.

 

I enquired what my LBS would charge to swap over the bars on my best bike (to some carbon aero ones with integrated cable routings for Di2/Hydro brakes) - they quoted £40 labour to swap everything across, route the cables, bleed the brakes, wrap new bar tape etc.  

 

I've not done it yet as I've yet to find the ideal bar at a price I'm willing to pay - but I'm fairly tempted to get an expert to do a job I'm not particularly comfortable with this time.

Avatar
CasperCCC [56 posts] 2 months ago
2 likes

Wow. For once I can actually be useful on here. (Or try to be useful.)

I've just built up a bike using R685s. 

It wasn't as bad as it could have been. But if I'd had the right stuff from the start, I could have made it a lot easier.

The hose that came with the shifters/calipers for the front brake was about 10cm too short, so I needed to buy and fit a new hose, rather than just using the easy joint system that it came with. Back brake hose was too long, so I needed to shorten that.

So unless you want a last minute Wiggle order, double check you'll be OK for hose lengths. In fact, it seems that none of my local bike shops keep road hydraulic spares in stock, so anything I was missing needed an online order.

(Probably worth getting a few of the spare olive/connector sets in as well, just in case you mess up a cut. They're only £2, so it doesn't do any harm to get a couple of spares.)

The cable cutting guide (little plastic block that you can clamp on top of the hose) that comes with the hose is worth having. Not essential, but it made life a lot easier. Especially when it came to inserting the connector you need to shove in the end of the hose. 

That connector was a pain in the backside to insert. You need to hammer it in, and I struggled to get a good enough grip on the hose to let me do that. I ended up clamping the cable cutting guide to the end of the hose, and then gripping the hose with a pair of pliers right underneath that. 

You'll need an open-ended 8mm spanner to tighten the nut. 

A sharp craft knife was OK for cutting the hose itself.

Once I'd got all that sorted, it wasn't too bad. I used the bleed kit to drain the system. Then measured/cut/installed the hoses. Then used Shimano's tech documents + YouTube vids to work out how to re-fill/bleed the system.

It was useful to have an extra pair of hands with the filling/bleeding. I recruited my 9-year-old's help. It wasn't anything technical - was just good to have someone who could hold the brake levers down at the right time, or hang onto the syringe thing that you use to add the oil.

Oh. And that syringe thing. It falls off the caliper *really* easily. Don't trust it. 

I was tempted to be lazy and not bother removing the pads. ("How hard can it be not to spill oil everywhere? I'll just be careful.")

I still think that if you know what you're doing, it probably would be pretty easy to do it without spilling oil everywhere. 

But I didn't know what I was doing, and I did spill oil everywhere. (Like I said, don't trust the syringe thing...) So I was very glad that for once in my life, I didn't take the lazy option, and that I did take the pads out.
 

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wellsprop [506 posts] 2 months ago
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CasperCCC wrote:

Wow. For once I can actually be useful on here. (Or try to be useful.)

THANKS  4

Sounds like I should find it fairly simple as I don't have to remove, replace or resize any cables. I just need to re-route and re-plumb them when I switch shifters.

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StraelGuy [1096 posts] 2 months ago
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I've also just fitted a full 685/805 setup and have a couple of tips. I was struggling to fill the front caliper by injecting oil into it the way you're supposed to. I just couldn't get any lever feel at all. I resorted to filling the little pot thing on top of the lever and attaching the empty syringe and tube to the caliper. I then drew the syringe out all the way creating a strong vacuum within it. I then cracked the bleed nut and the suction pulled a big plug of air out of the caliper and I suddenly had lever feel.

 

I used the brake block and took the pads out. I thought the whole process would be clean and simple but it only takes the hose to pop off a bleed nipple once (it happens) and you'll get oil everywhere. It's worth it in the end though, these are FANTASTIC brakes!

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CXR94Di2 [1859 posts] 2 months ago
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I've built up bikes with Shimano hydraulic s. It's very simple to do. My tips for a firm lever and very little travel. Bleed with the pads fitted(but wrapped in cling film) also use a small piece of paper on the surfaces of the pads, this is to create a small gap after final fit. Inject fluid from the bottom up but be patient as the mineral oil is thicker and bubbles are slow to travel. You can have the caliper positioned so that the hose is at the highest point to let air travel upward.

Once you've got all the bubbles out. Remove the cup, refit the cap on the brake lever. Last important step keep injecting fluid to make the pads squeeze tight against the rotor, lock of screw on caliper whilst holding pressure. Clean up, remove cling film and paper spacers, clean rotors with brake cleaner, reassemble and you should have a very firm lever with very little travel. Perfect brakes  1

Avatar
wellsprop [506 posts] 2 months ago
0 likes
CXR94Di2 wrote:

I've built up bikes with Shimano hydraulic s. It's very simple to do. My tips for a firm lever and very little travel. Bleed with the pads fitted(but wrapped in cling film) also use a small piece of paper on the surfaces of the pads, this is to create a small gap after final fit. Inject fluid from the bottom up but be patient as the mineral oil is thicker and bubbles are slow to travel. You can have the caliper positioned so that the hose is at the highest point to let air travel upward. Once you've got all the bubbles out. Remove the cup, refit the cap on the brake lever. Last important step keep injecting fluid to make the pads squeeze tight against the rotor, lock of screw on caliper whilst holding pressure. Clean up, remove cling film and paper spacers, clean rotors with brake cleaner, reassemble and you should have a very firm lever with very little travel. Perfect brakes  1

I would definitely like less travel in my RS685's and for them to be firmer. I've always had my brakes setup with little travel and firm brakes (just found that was the neatest way to setup my rim brakes and I've got used to the fine feeling and small movements). When my other half rode my bike, she nearly went over the bars because she's used to a lot of travel and give in the rubbish BB5's she has!

Avatar
ajvb65 [14 posts] 2 months ago
1 like

Interesting as last Sunday I "attempted" to move my SRAM Rival hydraulic groupset onto a CX frame for winter commuting duty. All went OK until I injected the DOT fluid into the caliper reservoir bleed port at which point most of it ended up on the floor & I gave up. I will have another attempt before resorting to taking it to a shop.

 

 

Avatar
wellsprop [506 posts] 2 months ago
0 likes
ajvb65 wrote:

Interesting as last Sunday I "attempted" to move my SRAM Rival hydraulic groupset onto a CX frame for winter commuting duty. All went OK until I injected the DOT fluid into the caliper reservoir bleed port at which point most of it ended up on the floor & I gave up. I will have another attempt before resorting to taking it to a shop.

Glad it's not just me!

Just waiting for my Wessex now.

Avatar
DaveE128 [955 posts] 2 months ago
1 like
CXR94Di2 wrote:

I've built up bikes with Shimano hydraulic s. It's very simple to do. My tips for a firm lever and very little travel. Bleed with the pads fitted(but wrapped in cling film) also use a small piece of paper on the surfaces of the pads, this is to create a small gap after final fit. Inject fluid from the bottom up but be patient as the mineral oil is thicker and bubbles are slow to travel. You can have the caliper positioned so that the hose is at the highest point to let air travel upward. Once you've got all the bubbles out. Remove the cup, refit the cap on the brake lever. Last important step keep injecting fluid to make the pads squeeze tight against the rotor, lock of screw on caliper whilst holding pressure. Clean up, remove cling film and paper spacers, clean rotors with brake cleaner, reassemble and you should have a very firm lever with very little travel. Perfect brakes  1

The bleed block should be put in in place of the pads. Personally I wouldn't trust clingfilm to keep oil off the pads - it is very good at penetrating small gaps, you don't need much at all to ruin pads and I've never managed to avoid oil running down over the caliper when removing the bleed hose. Use disc brake cleaner to remove all spilled oil before replacing pads. In addition, if you overfill the brakes (which is what you're doing if you use something narrower than the bleed blocks) then you may find it very difficult or impossible to replace brake pads in future, especially if there is any wear on the ones you are using during the bleed.

I believe it isn't necessary to empty the caliper when changing brake levers or shortening hoses (plenty of videos about easy hose shortening on youtube). If you can keep the hose pointing upwards, then the oil will just sit in it (keep the bleed nipple closed on the caliper) until you put it into the new lever. I'm not familiar with the procedure for filling an empty brake lever, but I imagine it works by pushing the fluid from the caliper up to fill it. Keeping the fluid in the caliper and hose means you'll need less, and you'll probably need less bubbles. Of course, if your fluid needs changing anyway, you'll still want to pump it right through.

Agree with comments above about making sure you have the spare inserts for hose shortening.

Have fun!

Avatar
CXR94Di2 [1859 posts] 2 months ago
1 like
DaveE128 wrote:
CXR94Di2 wrote:

I've built up bikes with Shimano hydraulic s. It's very simple to do. My tips for a firm lever and very little travel. Bleed with the pads fitted(but wrapped in cling film) also use a small piece of paper on the surfaces of the pads, this is to create a small gap after final fit. Inject fluid from the bottom up but be patient as the mineral oil is thicker and bubbles are slow to travel. You can have the caliper positioned so that the hose is at the highest point to let air travel upward. Once you've got all the bubbles out. Remove the cup, refit the cap on the brake lever. Last important step keep injecting fluid to make the pads squeeze tight against the rotor, lock of screw on caliper whilst holding pressure. Clean up, remove cling film and paper spacers, clean rotors with brake cleaner, reassemble and you should have a very firm lever with very little travel. Perfect brakes  1

The bleed block should be put in in place of the pads. Personally I wouldn't trust clingfilm to keep oil off the pads - it is very good at penetrating small gaps, you don't need much at all to ruin pads and I've never managed to avoid oil running down over the caliper when removing the bleed hose. Use disc brake cleaner to remove all spilled oil before replacing pads. In addition, if you overfill the brakes (which is what you're doing if you use something narrower than the bleed blocks) then you may find it very difficult or impossible to replace brake pads in future, especially if there is any wear on the ones you are using during the bleed.

I believe it isn't necessary to empty the caliper when changing brake levers or shortening hoses (plenty of videos about easy hose shortening on youtube). If you can keep the hose pointing upwards, then the oil will just sit in it (keep the bleed nipple closed on the caliper) until you put it into the new lever. I'm not familiar with the procedure for filling an empty brake lever, but I imagine it works by pushing the fluid from the caliper up to fill it. Keeping the fluid in the caliper and hose means you'll need less, and you'll probably need less bubbles. Of course, if your fluid needs changing anyway, you'll still want to pump it right through.

Agree with comments above about making sure you have the spare inserts for hose shortening.

Have fun!

 

Ive used the shimano spacer, which is actually too wide and leaves too much of a gap after refitting pads, resulting in far too much lever travel, to the point the lever hits the bar before becoming firm.  I made a smaller spacer(0.5mm narrower) which worked very well except the gap was very minimal, this also didnt work for another set of pads which were slightly thicker.  Wrapping in cling film will be fine with a paper spacer.  There is minimal spillage if you take your time and with care.   

Avatar
wellsprop [506 posts] 2 months ago
0 likes
CXR94Di2 wrote:
DaveE128 wrote:
CXR94Di2 wrote:

I've built up bikes with Shimano hydraulic s. It's very simple to do. My tips for a firm lever and very little travel. Bleed with the pads fitted(but wrapped in cling film) also use a small piece of paper on the surfaces of the pads, this is to create a small gap after final fit. Inject fluid from the bottom up but be patient as the mineral oil is thicker and bubbles are slow to travel. You can have the caliper positioned so that the hose is at the highest point to let air travel upward. Once you've got all the bubbles out. Remove the cup, refit the cap on the brake lever. Last important step keep injecting fluid to make the pads squeeze tight against the rotor, lock of screw on caliper whilst holding pressure. Clean up, remove cling film and paper spacers, clean rotors with brake cleaner, reassemble and you should have a very firm lever with very little travel. Perfect brakes  1

The bleed block should be put in in place of the pads. Personally I wouldn't trust clingfilm to keep oil off the pads - it is very good at penetrating small gaps, you don't need much at all to ruin pads and I've never managed to avoid oil running down over the caliper when removing the bleed hose. Use disc brake cleaner to remove all spilled oil before replacing pads. In addition, if you overfill the brakes (which is what you're doing if you use something narrower than the bleed blocks) then you may find it very difficult or impossible to replace brake pads in future, especially if there is any wear on the ones you are using during the bleed.

I believe it isn't necessary to empty the caliper when changing brake levers or shortening hoses (plenty of videos about easy hose shortening on youtube). If you can keep the hose pointing upwards, then the oil will just sit in it (keep the bleed nipple closed on the caliper) until you put it into the new lever. I'm not familiar with the procedure for filling an empty brake lever, but I imagine it works by pushing the fluid from the caliper up to fill it. Keeping the fluid in the caliper and hose means you'll need less, and you'll probably need less bubbles. Of course, if your fluid needs changing anyway, you'll still want to pump it right through.

Agree with comments above about making sure you have the spare inserts for hose shortening.

Have fun!

 

Ive used the shimano spacer, which is actually too wide and leaves too much of a gap after refitting pads, resulting in far too much lever travel, to the point the lever hits the bar before becoming firm.  I made a smaller spacer(0.5mm narrower) which worked very well except the gap was very minimal, this also didnt work for another set of pads which were slightly thicker.  Wrapping in cling film will be fine with a paper spacer.  There is minimal spillage if you take your time and with care.   

I think I'm going to file down my Shimano spacer by 0.3-0.5mm and give it a go.