Now, I’ve done some searching, but can’t find everything I want to know (I generally suck at searching things online anyway so feel free to direct me to past threads I may have missed).
I’ve just been bought a Magura HS33 brake for my KH24 muni, and have fitted and given it a trial run. It works great, and I’m really happy with it, but the cable is far too long, and I need to go about making it shorter.
Now, from my searching, I have found that:
• I need a replacement olive to fit to the end of the cut cable to re-attach it, so have ordered a couple of these.
• I can do this carefully and not lose any oil, which will save having to bleed the system afterwards.
• I can disassemble the cable from either end in order to cut it to new length.
• If all goes wrong and I end up losing oil out of the cable I need to use Magura oil, mineral oil for mtb shock absorbers, sewing machine oil, or water, but some people say never to use water.
So… my questions are…
• Any tips on not losing any oil from the cable after I start taking bits apart?
• Which end would be best to detach? Master or slave end?
• If I lose oil would water be so bad to use instead? I don’t live anywhere cold, and my uni is kept indoors anyway when not in use.
• Any other general tips for Magura hs33 brakes on a muni?
You need a bleed kit ($24), it can be a real hassle to shorten a line, are you absolutely sure you “need” it shorter? If you’re not a good bike mechanic, you may want to take it over to you LBS.
No, you can’t use water! I wouldn’t use anything but Magura oil, but it’s your brake. How much is it to replace? It sounds you need to take it to a bike shop. Water, nice.
Not sure about this, as I can’t imagine you could do this without getting just a bit of air in the system. I can’t say for sure though, as I’ve never done this. A little bit of air isn’t going to be the end of the world though, as unicyclists only use Maguras for slowing the wheel down, not outright stopping on a dime as trials riders do.
When I changed the lines in my Maguras, I opted for water rather than oil, and this works fine for me. By the look of things you already know the pros and potential cons of water so I won’t go in to that again.
Did you buy them new or off of ebay? If they are second hand, then how do you know they have Magura Blood in them rather than any other kind of oil, or water?
STM
Edit: Oh, I forgot to mention. Why not just wrap the pipe around the seat post a bit more. If you bought a ‘front’ brake, it’ll need this, but a ‘back’ brake will be best off shortened a fair bit.
This is what I found before, some people thinking water is bad and will completely ruin the seals, but then there are a few that swear that water, and sometimes distilled water (less dissolved oxygen to compress) works perfectly fine.
It’s brand new, bought for me from unicycle.uk.com, and as it is, the cable loops round twice and hits my leg. I have my seat quite low as I’m not very tall, and the cable is quite stiff so wrapping it round more than once isn’t possible.
Where I live now, I only have one LBS I can easily get to, but he doesn’t seem to stock anything to do with magura. Being out in the countryside is lovely and all till I need something
i have mine twizzled round several times. The key to doing it is not to do it when fitting the brake. Rather put the brake on untwisted then put the seat on the unicycle, and just turn the whole seat round a few times while it is on the unicycle. Then it’s pretty easy to twist it.
The bonus of having twisted lines is that it is easy to take your seatpost off when you need to. It doesn’t seem to make any difference to braking.
I managed to find a measuring tape, and the length of the cable is approx. 130 cm (51"). From looking at muni pics with maguras in the gallery, I can see where people have wrapped the cable round the seat post, but I can’t see mine wrapping less than 5 - 6 times at this length. Ideally I’d like it to be a length where I wrap it round once.
Have I been sent a rear HS33? Can’t see it being a front with a length of 130 cm to be honest.
@joemarshall
I will give your idea a go tomorrow morning anyway. The worst that’ll happen is the whole seat + post getting spring loaded by the coiled cable and flying across the room
Mine has the braided cable and wraps around the post 3 times, I’d guess. I’m fairly tall, though (6’2") so have a lot of seatpost. I agree with JoeMarshall–just attach it to your seat, then spin the seat. That’s how I do it.
I had a shorter line, once, but it was a pain to get the seatpost in and out without removing the brake lever.
Oh, and I successfully shortened a rear brake hose without losing oil some time ago, with standard hose (not braided). The advantage of the braided steel is that the hardware is easier to work with–no olives needed. I shortened from the lever side, and just kept the hose above the level of the calipers. No problem. There may be a little air in the line, but my son can lock up his wheel at need anyway.
I’ve just tried putting it all back on and twirling the seat around the wrap the cable up, but that hasn’t worked. As the cable is quite stiff, after 5 revolutions it starts to tangle itself up, and it feels like I’m going to end up pulling something out that shouldn’t be pulled out
What I’m going to do is wait for the replacement olive to arrive (hopefully tomorrow), measure out the cable so it’s long enough to wrap round once or maybe twice around the seat post, shorten it and see how that goes. I hardly ever take my seat out, but I’m thinking of replacing my seat post at some point in the future, and I don’t want to get stuck if I decide to take my seat out on a regular basis once I start riding regularly again.
From what some people have said, I suppose losing a tiny bit of oil isn’t going to be the end of the world, as I’m not going to want trials bike stopping on a sixpence performance, I just want to slow the wheel down a bit on steep descents. Then at some point I can buy the bleeding kit and sort it all out then. I won’t be using water at all, I think in the long run I’ll want to stick with what was originally meant to be used. I don’t want to regret anything if what some people say is true, and water can ruin the brakes. The water’s a bit funny round here anyway At some point I may switch to braided cable, but at the moment, I can’t afford to spend much more on my uni.
Thanks all for your replies, but feel free to continue with hints and tips for using/maintaining uni brakes.
Success! This morning the olives arrived for me to attach to my cable, so I got everything ready and shortened it. No oil was lost, and no oil from the cut off cable went onto the carpet, so I see it as a double win
Just got to adjust the position of the lever under the seat so it’s comfortable to operate.
Ummm, water is H2O, the “O” stands for oxygen. I have been using disc brakes on bikes for years. Here are some of the problems with using water:
Lack of proper lubrication.
When heated, water breaks down, expands, contracts.
Water and oil don’t mix, there’s no way to get all of the oil out in order to change over to water.
Water causes oxidation, so your brake internals will corrode.
Don’t use water, worse case scenario use a similar approved fluid.
The reason your brakes work and you “think” you didn’t lose any fluid is because brakes will work with air in the lines, but sooner or later you’ll start feeling a spongy brake lever, then you’ll lose pressure, then you’ll need a bleed kit.
Unis are different than bicycles, we don’t use the brakes more than a small fraction as much, so they are less likely to have problems in the short run. But hey, all I can do is answer your question. How you interpret the science and assess the risk is all your. Water, nice
You can in theory undo / cut magura tubing without losing any magura blood - it’s the same principle as the thing you do as a kid with a straw full of water, and your finger on the end. Lots of people seem to do okay with it in practice.
The great thing about maguras is they don’t need bleeding unless you actually break the hose. They don’t need the bleeding as maintenance that bike disc brakes do.
Yeah, I realised about the whole oxygen in water thing being wrong after I posted it. I found the quote on another website while searching for info and I should have thought about it more. It’s the impurities that are removed in distilled water.
Lack of lubrication and corrosion of the insides are the main reasons why I’ve decided not to put water in at all, and I doubt I ever will. I like the fact that with the proper oil, I should be able to leave them on there and not have to do much maintenance at all.
Why is there no chance of me not getting any air in the line, and I just think I didn’t? I’ve followed 3 sets of similar instructions to do this, one was someone’s message from these forums a few years ago, one was from Kris Holm advising someone on how to shorten cable, and the third was the Magura manual that came with the brake. They have all said that it can be done without losing any oil, hence removing the need to bleed afterwards.
It’s not difficult to shorten a magura brake hose without losing fluid. Magura fluid is very thick compared with normal car-type brake fluid and doesn’t run out if you cut one end of the pipe carefully. Capillary action holds it in place nicely.
I did it when I fitted HS66s to my tandem years ago - I actually bought a bleed kit because I didn’t believe it would be possible not to lose some fluid, but didn’t need it. Five years later the brakes are still firm as ever. And believe me, brakes on a tandem get USED.
I’d be a bit warey about using water though, for the corrosion reasons you mentioned, although loads of trials riders seem to do it without apparent problems. Perhaps they never keep kit long enough for it to be a problem.
