Hydraulic Brake - lever spongy... can I do anything without bleeding?

[chugsy]

Hi guys,

since my latest acquisition on the Cyclescheme my Giant Escape R1 hybrid has stood neglected in the shed for a while now - I'm thinking of rolling it out again for winter duties but have discovered that the front brake - or the lever that is, has gone a bit spongy. I can still brake but it pulls back to the bar - pumping it stiffens the lever but it gradually softens again. Short of bleeding the system with new fluid can I force the air bubble out (assuming bubbles are the problem) any other way? This is my first bike with hydraulic brakes so I'm a novice when it comes to bleeding - instructions look straightforward enough but I'd like a stopgap solution whilst I look into brake fluids.

Brakes are Giant MPH Root

http://www2.giant-bicycles.com/en-gb/bikes/lifestyle/2137/31765/?collections_id=3


Cheers in advance,

Chugs

 

[smokeysmoo]

Needs bleeding. A simple enough job with some basic DIY bike skills, or shouldn't cost much for your LBS to do it for you.

 

[chugsy]

Hmmm... I'm thinking for the cost of a bleed kit I could just replace the front brake with a cheap mechanical setup (CRC selling a Clark caliper and rotor for 18 quid). I already have spare cables and levers from previous projects. I've read somewhere that tapping the caliper with a mallet can move bubbles up to the resevoir where I could pump them out with the lever... anyone tried this?

 

[actonblue]

Bleed it. Seems wrong to change the system because you can not service it. Read the manual and you will surprise yourself.
Check out the bleed kits from here My link

 

[vernon]

Hmmm... I'm thinking for the cost of a bleed kit I could just replace the front brake with a cheap mechanical setup (CRC selling a Clark caliper and rotor for 18 quid). I already have spare cables and levers from previous projects. I've read somewhere that tapping the caliper with a mallet can move bubbles up to the resevoir where I could pump them out with the lever... anyone tried this?

You might strike it lucky and align the air bubble with the entry hole in the cylinder but for the amount of time spent tapping and trying and manipulating the position of the bike you might as well do it properly and then you'll be set up for any future bleeding activities. It really isn't a chore.

You'll spend just asmuch time swapping parts over as you would bleeding the brakes.

 

[smokeysmoo]

If you are used to hydraulic brakes I certainly wouldn't change to mechanical, they're crap in comparison.

 

[Bobtoo]

Do you need a bleed kit to bleed bike brakes? I've never used one for car or motorcycle brakes.

 

[steve52]

set the bike up so the top of the resivour is level (i put my frount wheel on a chair) tie the leaver into the on position and go to sleep then when u get up tap the hose, then have a good breakfast the ait should all have bubbled up the the resivour Ps (i know its spelt wrong but dont care) its best to top it up to prevent it happening again.

 

[rusty bearing]

Some can, some are more complicated requiring three hands at least.

Chugsy...Just consulted the manual, the brakes take DOT 4 or 5.1, either will do.You can mix them quite safely. If you do bleed them yourself just make sure and clean off with some meths afterwards.

 

[chugsy]

Thanks for all the input guys... Rusty - the manual that came with the bike states mineral oil only. shame as i have some dot 4 left over from bleeding my car brakes years ago. Ill look into mineral oil and a syringe as i canibalised the one that came with the bike into a makeshift grease gun when i rebuilt a hub a while ago.
in the meantime the bike is in the stand as per Steve's suggestion... do i remove the resevoir plug whilst it is standing Steve?
Excuse the grammar/unctuation... typing from a kindle atm

 

[2Loose]

Thanks for all the input guys... Rusty - the manual that came with the bike states mineral oil only. shame as i have some dot 4 left over from bleeding my car brakes years ago. Ill look into mineral oil and a syringe as i canibalised the one that came with the bike into a makeshift grease gun when i rebuilt a hub a while ago.
in the meantime the bike is in the stand as per Steve's suggestion... do i remove the resevoir plug whilst it is standing Steve?
Excuse the grammar/unctuation... typing from a kindle atm

You may as well, it wont do any harm to remove it while the bike is tilted upwards. It may even help the egress of air. Give the hose a few taps starting from the bottom, all the way up to the top whenever you walk past it to help.

 

[actonblue]

You have to use the fluid that is stated for the system. DOT fluid will corrode all the seals in your mineral oil system.
And it is not a good idea to use old DOT fluid as it absorbs water and does work too well after a while. Best not skimp on things when it comes to brakes.

 

[Moodyman]

Needs bleeding. A simple enough job with some basic DIY bike skills, or shouldn't cost much for your LBS to do it for you.

I rang a few shops when I first needed to do mine. They all quoted £20 per brake - £40 for the set.

The reason given was that it was a faff and needed two people to do it properly.

So I watched a few online videos and read the Shimano Tech Doc.

They were right, it takes two people to do it properly, and it's a bit of a faff - I ruined (contaminated) some new brake pads. But the second time and third times have been a doddle. I get one of the kids to help and cover the caliper/discs so they don't get contaminated again.

I paid £26 for the bleed kit - Small bottle mineral oil, 1 litre bottle mineral oil and small tube to carry away waste. I reckon I can keep bleeding until 2030.

 

[chugsy]

You have to use the fluid that is stated for the system. DOT fluid will corrode all the seals in your mineral oil system.
And it is not a good idea to use old DOT fluid as it absorbs water and does work too well after a while. Best not skimp on things when it comes to brakes.

I didn't say I was going to use it! Skimping is in my nature though so have found out that Halfords are selling Bikehut brand mineral for a fiver - need 20cc syringes too (ebay). The rest I have (will sub out the short bleed hoses for some leftover aquarium airline to avoid dripping over the pads)





All in should be less than a tenner but I might check the lbs as their rates are pretty cheap for "small" jobs - it's only the front brake remember.




Cheers all,

 

[chugsy]

After leaving the bike to stand for the weekend with the master cylinder horizontal I went to insert the bleed screw back in only to round it off! I guess some brake fluid got between torx head and the screw lubing it and causing it to slip.... seeing as I can't find replacement Giant bleed screws anywhere and other brands don't look exactly the same I've gone back to plan A (good job I didn't order the oil and syringes already - normally I rush ahead). Old Tektro IO calipers seem to go for far too much on Ebay - why I don't know - then I saw this in the early hours of the morning and saw it as a sign:

http://www.chainreactioncycles.com/Models.aspx?ModelID=56306

Should suit my commuting requirements nicely. This is a rear model and I need a front - I figure I'll cadge the mounting hardware from the Giant caliper. Anyone see a flaw in this plan?

Cheers,

Chugs