Hydraulic help - I've lost my brakes!

[Chris71]

Finally got my road bike out after a very long hibernation and there's zero pressure on the rear brake. It's a Kona Dew with hydraulic discs. I'm assuming there was a leak somewhere and the fluid has all vanished, although I haven't had time to check yet. It's been stood for a very long time - the best part of four years - and there are no outward signs of dripping fluid or anything like that.

Can anyone recommend how to go about diagnosing/fixing the problem? Just moved to a new area with loads of quiet lanes that I'm desperate to explore. Currently bouncing around on my full susser feeling very unfit.

[NorthDave]

They probably just needing bleeding. Go on youtube and search for the make and model. Park Tools have some great videos. Shouldn't be a big job.

[Watchman]

You'll need to spend a few quid on parts to bleed them yourself. If you've no mechanical interest, I'd just take it to a bike shop and pay them to do it.

I have all the kit and I've bled 30+ now - just amateur bike repairs from friends and colleagues. Some of them can be bds to bleed - some versions of Shimanos are the worst.

Different types will need mineral or synth fluid - although I've only so far encountered mineral.

Some require you to introduce the fluid into the reservoir at the lever end, so you have to raise the caliper end above it. Easier to remove the caliper unless you have a bike stand. Then it's a case of fill, apply lever pressure, open bleed nipple and close before end of lever travel. Repeat until no more bubbles.

Oh, you will need some way of catching expelled fluid too.

Others require you to introduce the fluid into the caliper. Don't assume the same technique will work on all - it doesn't.

[Chris71]

Sounds like a job for the bike shop. It's weird - the lever has no resistance at all, as if the fluid has just gone. The other brake is fine.

[5tuartw]

I'd zip tie the offending lever to the bars overnight and flick the hose frequently, there is probably just an air bubble somewhere.

Bleeding brakes isn't too hard and is worth learning to do.