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How To Swap Hydraulic Disc Brake Hoses On A Road Bike | Maintenance Monday

How To Swap Hydraulic Disc Brake Hoses On A Road Bike | Maintenance Monday

– Coming up, we are going to show you how to swap over your
front and rear brakes on Shimano hydraulic disc brakes. So for example, you might
have bought a second hand bike or a new one that’s just come with the brakes the wrong way
around for you personally. Now I’ve got some good
news, and that is if you’ve got these junctions on the
outer cables just here, then it’s actually an
easier and a quicker job than on standard rim brake cabled bikes. If you don’t have these
and the cable simply runs all the way from the brake lever
down to the calliper itself, it is a much lengthier
and more in depth job and something for another video. Right, let’s go through the tools that you’re going to need for the job. It might be that you don’t
need too many at all. You’re going to need a
couple of open ended spanners or wrenches, in this particular bike it’s two eight millimetre
sizes that you’re going to need and that might differ slightly
for your own personal bike you’re gonna have to see
in a few moments time. I’m also going to need to be able to take the front wheel
out and I’m going to need a six millimetre Allen key for that, and also a travel spacer like
this for the disc brake pads. If things don’t go to
plan, and I’ll explain that a little bit later in the video, there could be some more
tools that you need. Firstly, a very small
flat headed screwdriver, a two and a half millimetre Allen key, a bleeding block, a plastic
block which looks like this, some disc brake hydraulic mineral oil, a hydraulic funnel which
you put in the top, possibly a magnet, some rag and some alcohol based cleaning fluid, I’m having
to borrow some from GMBN. And finally, an old piece
of rag, a bit like this. Before we get on with the job proper, I’m going to remove the front wheel which is what I need my six
millimetre allen key for. That’s just in case any of the hydraulic brake fluid drips out, we don’t want to get it onto the disc rotor itself. So remove that, put it to one side. Now during the process,
you don’t want to be pulling on the brake levers at all. If you think that might
accidentally happen, something like this travel
spacer would be a good idea is to slip up inside the calliper. That will mean if you do accidentally pull on the brake levers, it won’t push the pistons out which is something that requires another job
to get them back out again. Then drape an old rag over,
this is to stop any drips going onto the calliper itself. You gotta drape it over, or
as I’m doing, tying it on. Next up, we are going to
slide the rubber covers to reveal the fixing underneath. Do it on both of the front
and the rear brakes like so. Then, get your two spanners, as I said, on this particular bike it’s two eight millimetre open ended spanners. And then, we’re going to undo very slightly one of the hoses. And that’s it, just a quarter of a turn. As you see, there’s a bit
of a jolt when I did that. And what happens if you
remove it completely, and you do that on the other
side with another jolt, that can lead to losing some
of the internal mineral oil. So do the same on the other side. Once you’ve given them
both an initial loosen, you can undo one of them the whole way and pull the cable out of
one and then the other. You can leave them dangling. And a very important reminder now, do not pull your brake
levers on at this point. Then, it’s simply a matter
of swapping the lines over. So we now want the front brake to be operated by the left lever. Do the same for the rear. Then it’s just a reversal of the process. Make sure you don’t
cross thread this screw as it goes back in, just do
them by hand to start with. Once you’ve got them tight before you put those rubber covers back over, just give it all a quick
clean with some rag and that alcohol based cleaner, ’cause there has been very
small amounts of fluid got out, not enough to affect the
braking or the system. Just make sure it’s all clean, then slide these rubber covers back on. Once you’ve done that,
the job is probably done if you’ve been pretty careful
about this and not lost much fluid, so take the rag
off from around the calliper, take the travel spacer
out if you’ve used one, replace the front wheel, and time to see if they feel alright. And the answer is, front
brake is now on the left and working very smoothly,
rear brake not so smooth. I’d love to say that I
did that deliberately for the purposes of the
next part of this video, but I didn’t, I’ve just got it wrong. Nevertheless, we’ll go
through the next steps, which should hopefully solve this problem. So for the next step, you want to reveal what is under the rubber
hoods here at the top. Now these will differ ever so slightly, but for this particular Shimano model we’re going to need our very small, fine, flat headed screwdriver
to remove this cover. So I’m gonna take it out with this magnet, I don’t want to lose that,
so just put it very carefully to one side, I’m gonna leave
it on the magnet there. Then, with that screw out, you
can remove this plastic cover which will reveal this two
and a half millimetre screw that we want to take out
in a few moment’s time. Before we get around to that though, we want to take out the rear wheel ’cause that is the brake with the problem. Now at this point, we are going to take the brake pads themselves out. That’s when you’re gonna need your flat head screwdriver again. But firstly, you need to
take this very small pin out. Then, use your flat headed screwdriver to undo this screw down here. And then removing that will mean that you can remove the pads themselves. You push them down, hold
them at the other end. They they are, put them
carefully to one side. Now is the point at which you want to insert your bleed block. Now, you could get a specific Shimano one, we couldn’t find ours so we’re
using this as a replacement. Basically the idea is that
it’s a piece of plastic that prevents the pistons from coming out when you pull on the
brake lever at the front. So we can now undo this bolt
with our two and a half mil Allen key, again it’s a
small one so just be careful. And then, you can get
your bleeding funnel. Screw that in replacement
of the screw itself. Now it should be firm, but don’t go overboard, this is only plastic. Then, take the mineral oil,
and just put a small amount in the top, don’t need too much. Then, remove the plug. Now, to encourage the bubbles
in the system in the air to come up, you can give a
few pulls of the brake lever. Oh, I got some bubbles
there, look already. If that doesn’t work,
give the cables some taps, that will encourage the air up as well. Now this is an internally cabled bike which means we can’t of
course access and tap it all, but we can start down
near the rear calliper and do the stuff up here as well. And another good idea,
we’re putting the bike on a stand for demonstration purposes, but of course the air
tends to travel upwards, so raising the front of the
bike so that the reservoir is close to the highest
point is also a good idea. Wow, we’ve made quite
a few bubbles actually. So hopefully that will resolve our issues. Once you’re happy that you got all the air out of the system, replace the plunger in the
top, unscrew the funnel, and because we haven’t
actually used that fluid in the system, it’s perfectly fine to just tip it back into its container. I’m just gonna give that
a quick wipe with a rag. Right, then, get your two
and a half millimetre bolt and the appropriate allen key, and replace the bolt, making sure that you haven’t lost that rubber o-ring. Then, you can replace the plastic cover which goes over the top and
take that very small screw which is attached to my magnet, put that back in and then
screw that up tight too. (light instrumental music) That feels a lot better. If you’ve had the same
problem on both sides, of course you just repeat all those steps but for the front wheel
instead of the rear, and then you should be all sorted. And as I said, if you’ve done things or if I’ve done things much
more carefully to begin with, I probably wouldn’t have needed
to do all those last steps. Well, I hope that’s helped
you, if you’ve had this problem where you need to swap
the brake levers over. If you’ve enjoyed this
video, give it a thumbs up. If you haven’t subscribed to GCN, there are loads of maintenance videos and loads of other videos too, you can do so by clicking on the globe. Now, we’ve got a few maintenance mistakes which you shouldn’t make and you can find them by clicking just down here, or if you’d like to know
how to bleed disc brakes on road bikes, you can click down here.

65 comments on “How To Swap Hydraulic Disc Brake Hoses On A Road Bike | Maintenance Monday

  1. I mean, I love these videos, but I know that I have no intention of ever doing this job. Still watching though.
    Looking at Dan in that apron makes me crave a latte and chocolate twist.

  2. Excellent demonstration and presentation. Very clearly explained and seems like a pretty straightforward job…not that I will be doing it but it's interesting to watch and I like knowing (vaguely, anyway) what I'm talking about when at the LBS. Thanks as always, Dan 👍🏻

  3. Dontcha need to replace the brass olive before reinserting the hoses? A fresh olive will give a proper seal. Reusing the old (crushed) olive may result in leaks, no?

  4. Isn't the step where you remove rear wheel redundant? Does it matter if your brake pads grab onto the wheel versus pistons grabbing the plastic bit? It's the same.

  5. Could GCN do a maintenance video on what to lubricate/ grease other than the drive train, e.g. Axels, brake calipers, pedals, etc. You may have done this before but I could not find?
    Also, what is the best way to prevent rust on the various nuts and bolts, etc


  6. Alcoholic Cleaning Fluid. My Aunty used to use that in the shower, the Lush.
    I do miss her, she was never the same since going top the meetings.

  7. Well, this video made the hair stand up. It might be from motorbiking but if I do any maintenance on the braking lines I always do a full bleed on the system to make sure there's no air bubbles in it. Even on a bicycle it would make the brakes spongy.

  8. I know the hydraulic fluid in the Airbus A320 becomes hot but can bike brake hydraulic fluid heat up during heavy use?

  9. If it isn't there, it can't break, it doesen't weight, it doesen't cost anything.
    Disc brakes on road bikes are exactly the opposite!!

  10. So, who are the lucky GCN presenters at the Eurobike this week? I live close to Friedrichshafen 🙂 Hope to meet one of you guys! Let me know if you need tips for the region.

  11. I'm sorry to say this guys but you do give some wrong information in this video. If you open an hydraulic circuit you should ALWAYS bleed the system. To bleed the systeem you need to pump the air thru the system. The way you bleed youre brakes is incorrect, however it can work somethimes, but this is not how it should be taught to people who have never worked on hydr. brakes. I should also point out to the viewer how you can tell something is wrong (example: no pressure build ip in the first squize of the brake, pressure comes up after several squizes,…).
    I'm not here to comment on all that is wrong, this comment is only because brakes are a safety measure and as licensed car mecanic and workshop supervisor, I feel obliged to step in.

  12. 1:31 I was not aware that they made special cleaning fluid for alchoholics. I usually just hose them down in the cell if they smell too bad.

  13. Great video! …but i still don't understand why anyone thinks hydraulics on a bicycle are a good idea. I can't imagine doing this on the road if needed!

  14. Cables? Why are you calling the hoses cables?
    Remind me to order 3 more liters of Shimano fluid for the shop….. this video may have started a rash of roadies in need of a proper brake service.
    Thanks for the business boys!

  15. For what purpose were the rear pads removed? Could you not have used the red spacer instead? No fluid was going near the rear and instead you've made it more likely to contaminate the pads.

  16. oh lord! I needed this so badly last year…

    you guys have already done the bleeding video? cause I need that now.

  17. at 3:19 dont you need to replave the "olive" cooper ring from the brake line with a new one? will ti work with the old one?

  18. have you the part number or model of the junctions?, i'm interested to buy a pair of junctions to install on my disc brake hoses, but i can't found them

  19. shimano rep told me that these quick connects are one time use only, and are not meant to be used after disconnected. someone please explain.

  20. This is the stupidest video I've ever seen… how many bikes has anyone seen with brake hoses that have the inline couplers on their brake hose? If you want to show anything useful, than replace the entire hose through the frame.

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