Cycling UK Forum

Lets start with the facts -

I'm a fairly decent mechanic and have done most of the servicing on my bike. I may not always know the name of the thingy-majig but I can probably fix it with confidence.

I am the happy (sort of) owner of a pair of Avid Disc Brakes. Juicy Fives to be precise. Despite being happy with them I can't maintain these buggers myself!!

So with the weekend coming up I thought I might take the opportunity to give the bike a thorough service. The poor thing has been left to sit in the garden all winter under a bike wrap!
Before I abandoned and neglected it to the winter weather I had a problem with the disc on the front. It was like squeezing a sponge. Worse then that it was like squeezing a sponge and not getting any water out of it!! So I figure, since I can't make matters much worse I shall endeavour to learn!

And that is where I turn to you. Am I foolhardy soul on the potholed glass strewn road to ruin or do you reckon I can pull this off?

No, no, that's not what I wanted to ask! I wanted to ask for advice on the best way to achieve results and to achieve braking perfection once more!!

Basically how to guide!

Sounds like they need bleeding.

First have a good look at all the joints and along the hose to check for leaks. Give the lever a couple of good squeezes and recheck.

If there are no leaks then start bleeding. I don't know your particular model but the process is basically:

Top up the reservoir on the lever assembly.
Attach a bleed hose and jar (to catch the old fluid) to the bleed nipple on the caliper.
Loosen the nipple enough to allow fluid to pass through when you squeeze the lever.
"Nip up" the nipple at the end of the squeeze, then release the lever, open the nipple, squeeze the lever again, close the nipple..........
Carry on until you are satisfied that all air is out of the system. Don't forget to keep topping up the reservoir!!
Tighten the nipple fully.

I am sure there will be instructions specific to your model somewhere on the web - try Avid's website or Youtube.

Thanks for that. The Avid site promotes the use of a bit of kit that costs almost £30..

Can what you said be done with what I already carry in a regular cyclist toolbox?


ETA: Though, if anyone has a bleed kit in N.London that they wouldn't mind loaning out I would be most grateful.

My bleed kit consists of about 30-40cm of rubber hose (it's a snug fit over the bleed nipple) and a jam jar.

Car accessory shops usually sell a bleed hose with a one way valve in the end. This eliminates the need to close the bleed nipple at the end of each squeeze of the lever. It's not foolproof as sometimes air can get in around the thread of the loosened nipple.

The avid bleed procedure is slightly different as there is no reservoir to top up. The official method is http://www.youtube.com/watch?v=IoaPUw5DliA and requires 2 syringes and a few other specific bits and peices. I think I got a kit for my avids from ebay for £12

The Avid kit is worth buying for a few reasons:

1. It comes with some oil. This alone is worth about £5.

2. It comes with the required bleed blocks, these replace the pads when bleeding the brakes to avoid contaminating the pads.

3. The syringes have clamps to block the hose which is a vital part of the bleed procedure.

4. The syringe hoses have the required threaded ends which seal perfectly into the bleed holes in the calliper and lever.

Sure, you can probably make your own kit out of bits and bobs, but the end result won't be as good, will probably end up being a lot messier and do you really want iffy brake performance?

The biggest improvement I made to my Avid brakes was ditching the factory hoses and fitting Goodridge hoses.

robc02 wrote:My bleed kit consists of about 30-40cm of rubber hose (it's a snug fit over the bleed nipple) and a jam jar.

Avid brakes don't have nipples. they have a small grub screw which you remove and screw a hose into.

I use one of these bleed kits http://www.reddogracing.co.uk/itemdetails.php?partno=32 costs about half the price of the Avid one. If you go to the download section you can read the instructions which are included with the kit, it's pretty straight forward.
The only problem I had the first time I did mine was pulling too hard on the plunger and pulling the syringe out of the hose, wasn't too much of a disaster I just had to start the whole procedure again.

Is why I love Vee-Brakes, I hated bleeding brakes on my motorbikes and can't see the need for that complexity on a pushbike, the simplicity of a bike is one of it's strengths. Saying that, I do like the feel and power of the cable disc front on my Airnimal.

It's probably not much help to you but...

We used to have a Juicy 7 on the back of the tandem, which lives in a very damp garage. I found regularly that after a month or so the brakes would be rubbing again - the Avids absorbed water when stood about in the damp. This, I understand, is a factor of the Dot 5.1 (?) fluid that many hydraulic brakes use, and presumably slightly porous hoses!

Bleeding every month seems an unacceptable maintenance demand to me. So the long-term solution if you store in a damp environment is to change your disc brakes. Either Magura (and Shimano?) hydraulics which use mineral oil that doesn't absorb water, or cable-operated discs, which (most people agree) means Avid BB7.

Or possibly different hoses will cut the speed of absorption - I don't know about this.

robc02 wrote:Car accessory shops usually sell a bleed hose with a one way valve in the end.

not nearly as much use as a friend - or even well trained wife

mill4six wrote:can't see the need for that complexity on a pushbike . . I do like the feel and power of the cable disc

silly isn't it. i've not tried fluid brakes on a bike, but given that my cable disc would send me over or skid the front wheel if fully applied, i don't fell the need

mill4six wrote:Is why I love Vee-Brakes, I hated bleeding brakes on my motorbikes and can't see the need for that complexity on a pushbike, the simplicity of a bike is one of it's strengths. Saying that, I do like the feel and power of the cable disc front on my Airnimal.

Cable disc brakes are more fiddly, bulky and have more to go wrong than hydraulic disc brakes. Cable stretch, cable adjustment, cable snap and pad adjustment (both sides), bearings to wear out. Hydraulics only have one or two problems, leaks and pistol seizure.

Hydraulics need no adjustment at all. You only need to bleed them once usually, if the factory hasn't done it correctly.

The hydraulic action is like the perfect cable and the lever feel is really good, rock solid feeling and no rattly levers. Not to mention more modulation.

It takes longer to fit cable disc brakes since they are supplied with no cables, you have to cut and fit the outers, insert the cables, connect them up and so on. Disc brakes are supplied connected with hoses, you fit them to the bike and that's it.

gilesjuk wrote:

mill4six wrote:Is why I love Vee-Brakes, I hated bleeding brakes on my motorbikes and can't see the need for that complexity on a pushbike, the simplicity of a bike is one of it's strengths. Saying that, I do like the feel and power of the cable disc front on my Airnimal.

Hydraulics need no adjustment at all. You only need to bleed them once usually, if the factory hasn't done it correctly.

The hydraulic action is like the perfect cable and the lever feel is really good, rock solid feeling and no rattly levers. Not to mention more modulation.

It takes longer to fit cable disc brakes since they are supplied with no cables, you have to cut and fit the outers, insert the cables, connect them up and so on. Disc brakes are supplied connected with hoses, you fit them to the bike and that's it.

Not strictly true, most hydraulics come with the hoses too long, I cut mine down and bled them when I fitted them, the rest I agree with, more power, better modulation, better feel, smooth levers, just better.

The Hope hydraulic discs on my Heckler mountain bike are 10 years old. In that time I've only bled them once and replaced worn out pads a few times. Other than that I haven't touched them and they work just fine. Maybe it's because it's a closed hydraulic system though. Certainly my v-brakes are much greater maintenance and hassle.

I got the Avids when I was snow biking down ski slopes. The problem with the rim brakes is that half the time they were buried in the snow and most of the time were iced over. So I bought the discs to solve that..