UKC

I've got a Genesis Croix de Fer, which has TRP HyRd mechanically-operated hydraulic disc brakes (that's a bloody mouthful). Anyway, after about 2000 miles they gradually deteriorated to the point where they're not really gripping very much at the back (if I pull the brake, I can spin the wheel with my other hand). So far I've looked for advice online and subsequently replaced the pads and cleaned down the disc itself with isopropyl alcohol. I've also adjusted the cable so that there's less play, but I'm just not getting anywhere.
The next step is to just take to my bike shop, but to be honest I'd really prefer to solve/understand the problem first. Any ideas?

In reply to FrankBooth:

Has this happened to both brakes?

In reply to FrankBooth:

Not come across these hybrid cable activated hydraulics myself, but could it be cable stretch? Sounds like you've tried everything else obvious.

In reply to FrankBooth:

The hydraulic fluid is probably full of gunk. I have no experience of these brakes and although mineral oil is much better than Dot oil for moisture absorption I'd have a go bleeding them. Until recently I was always under the impression that mineral oil brakes, like shimano, were pretty much service free items when compared to dot filled brakes. This was until I saw the crud that came out of a friends brakes.

In reply to FrankBooth:
I would clean the disks with a degreaser and check the cable the housing can make a big difference if compressing.

In reply to FrankBooth:

Sounds like the brake fluid is contaminated

try bleeding

In reply to FrankBooth:

have you looked here http://www.trpbrakes.com/category.php?productid=1198&catid=206

In reply to Greasy Prusiks:

it's mainly the back but the front is quite sloppy, too

In reply to FrankBooth:

Ditch them and get some BB7s? They just work.

In reply to Mountain Llama:

thank ML - that's really interesting, the Lock Knob on mine isn't threading (as per the advise/warning), suggesting problem with the actuator arm preventing the piston from returning fully. A job for the LBS I think.

Thanks, guys

In reply to DaveHK:


I'd consider this too, I don't really understand what the benefit is of having them. On a full hydraulic system you get the benefit of removing the cable but when you have the cable anyhow why bother with the extra weight and faff of hydraulic bits.

In reply to gethin_allen:

I've got BB5s on my CX and they are the poorest thing about the bike. Having commuted on a hybrid with full hydraulics before swapping having poorer brakes was the most noticeable downside to the swap. Anyway, I've been seriously considering swapping to the HY/RD semi hydraulics. They have had generally glowing reviews - most saying considerably better than BB7s or Spyres.

Frank - if you haven't bled them, that's the obvious thing. Don't know how easy/hard that it though with that model. It was pretty straightforward on an old shimano set and a total pain on some old Avids!

In reply to FrankBooth:
With that many miles and the symptoms you describe I would suggest a full fluid change. Easy enough to do , just don't contaminate your new pads with fluid/oil! over time the fluids absorb moisture and become compressable. I change mine on my mtbs every3-6 months you can tell if this is the problem by the cloudiness of the fluid you remove

In reply to FrankBooth:

As a fellow CdF owner I'm watching this thread with interest. Do let us know how you get on.

In reply to FrankBooth:
there is only one solution ditch them and get your self some shinmano disc brakes the most reliable brakes out there ran some on a hard tail for nine years and had them service once in nine years ,now currently use them on my full suss and hybrid amazing brakes especially so on the full suss with a 203 front rotor amazing stopping power.

In reply to neil0968:
I wouldn't ditch as they are good brakes lots better then all the other cable operated brakes, as it the rear I still would ensure both the disks and pads are grease free.
And change the hydraulic fluid as it needs to changed each year

In reply to FrankBooth:

Here you go, answer to all your problems:

http://tinyurl.com/htxw2kh

Wally

In reply to FrankBooth:

Have you tried 'bedding in' the brakes. Find a safe spot. Build up speed, then drag the brake a bit then brake harder to come to a stop (as its the rear, keep weight back to reduce skidding). Repeat this several times. The idea is to get the rotor and pad to heat up, and so they say, to transfer some of the pad material onto the rotor. The first few times you do this you won't notice much but you should gradually notice an increase in bite and braking effectiveness. Don't touch the brakes and rotors after this, until they've cooled

This may not be the cause of your problem, but is a common issue with people keeping brakes lightly applied on long descents in the belief that it will slow them down, but this glazes the surface of pad and rotor giving brake fade - pulling harder has no effect. Can be avoided by pulsing the brakes. (a friend's daughter had this problem on her MTB - a few blasts up and down the road with repeated hard braking resolved it).