Magura Hydraulic Rim Brakes (MHRB)

RCOH

RCOH

Eats Squid
I have just installed MHRB on the back of my 125, I do not know if they are HS33 or HS11 model (cave dweller, l'il help?). They are aligned properly & hitting the rim in the correct spot but I cannot get any bite/power at all. They won't even lock up.

Are there any tricks to getting them to bite with trials-like power? Do I have to get new pads, clean/tar/grind rim? Should I rebleed then?

BTW they are on normal V-Brake bosses not the 4-post trials set up. For this reason i don't think they are HS33's.

I did a search & only came up with this topic:
http://www.farkin.net/forums/viewtopic.php?t=8198&highlight=magura+rim

Thanks in advance, Rod :)
 
RCOH said:
I have just installed MHRB on the back of my 125, I do not know if they are HS33 or HS11 model (cave dweller, l'il help?). They are aligned properly & hitting the rim in the correct spot but I cannot get any bite/power at all. They won't even lock up.

Are there any tricks to getting them to bite with trials-like power? Do I have to get new pads, clean/tar/grind rim? Should I rebleed then?

BTW they are on normal V-Brake bosses not the 4-post trials set up. For this reason i don't think they are HS33's.

I did a search & only came up with this topic:
http://www.farkin.net/forums/viewtopic.php?t=8198&highlight=magura+rim

Thanks in advance, Rod :)
Click to expand...
The HS33's don't need to have the 4 post set up so it could well be the 33's still. it's very unusual that they wont bite! ow close are they set away from the rim? should only be a mm or so. my guess is a rebleed but its only a guess. i'd try your LBS.
 
Not sure of the model, they are a few years old, pre hs11 or hs33 i think. Might be the raceline models, but im not sure

Could be the pads. Try cleaning and roughing them up a bit. Trials riders use plasma pads, those are just normal pads. If you want trials power you will probably need the plasma pads but don't expect to get much modulation :)

Also try cleaning your rim, could be dirty. I would try the pads and rims first. They have been sitting in a box for a few years along with other dirty and greasy bike parts.

-Matt
 
The difference is the lever. My Hs33 has a dial on the end that adjusts the resevoir size (like hope C2s).

Mine also aren't that powerful, but from what i can see they come with hard compound pads as stock, and all the trials riders were using plazmatics or milk pads from memory.
 
clean your pads and rim with metho, let it dry, then wind the TPA (little red dial) all the way out so its really loose, then align the pads as close as possible to the rim without rubbing, now try your brakes, if they arent grabbing move the tpa a bit till it feels better.
ultimatley they will still suck so either get some plaz pads www.btaustralia.tk has them at a fantastic price, then get a heavy grind on your rim, you know have on/off trials brakes! :D
 
monkeymagic said:
clean your pads and rim with metho, let it dry, then wind the TPA (little red dial) all the way out so its really loose, then align the pads as close as possible to the rim without rubbing, now try your brakes, if they arent grabbing move the tpa a bit till it feels better.
ultimatley they will still suck so either get some plaz pads www.btaustralia.tk has them at a fantastic price, then get a heavy grind on your rim, you know have on/off trials brakes! :D
Click to expand...

I don't have the TPA.

But I will get some plazmatic pads. Cheers
 
Personally I'd steer clear of the Plazmatics as they have an issue with sloppy fit in the housing and "can" cause a housing breakage due to knocking back and forward. More likely to be a concern with trials riding but even so the "milk" pads have always seemed to have more stop in them anyway.

Unless the lever is spongy to the feel and before you bother with a rebleed, take the pads out and sand them. Put sandpaper (fine), rough-side UP on a perfectly flat surface and gently take a fine layer off the brake surface by moving the pads over the sandpaper. Try to keep as flat as possible.

The best surface for maggies and milk pads is a rim grind, but you wont get much modulation. Just leave the rims but make sure they are clean.

Rim hydros are very good but VERY hard to get set up right. I've seen many shops stuff the setup totally because even when they "look" right they may not be set up for optimum braking power. Ensure pads are set absolutely square and "flat" to the braking surface on the rim and as close as possible. Also have a good look for flex around the brakes when applying hard. Those adapters for post mounts may be flexing, or the stays themselves, or one pad could be hitting the rim before the 2nd one and pushing the wheel across just enough to ruing the pad alignment.
 
Cheers Grip & everyone else, I will keep all information in mind. Friday is the day for fixing my brakes!!!
 
Also keep in mind, that the bite that trials have usually comes at the sacrifice of modulation. So try and go for soft pads, but not overly sticky pads.
 
I've had 2 sets of HS-33s before. Set-up well, they're pretty good brakes.

Havn't noticed anyone mention about the boosters. Are you using one?
The earlier stock ones aren't up to it i feel and are way heavier than the aftermarket ones.

http://www.execulink.com/~dtierney/wmc/Magura/geninfo.htm#Boosters

I used a CNC'd aluminum booster and that helped abit.

Yeah, as the rest have said, clean the rims/pads free of oily stuff and bleed the brakes. You shouldn't have to grind/tar the rims to feel the brakes working well. I wouldn't recommend you use trial pads either unless u're really riding trials. I had a plazmatic pad shoot out ahead of me on a run. The braking pad separated from the mounting block. :D

Good luck~
 
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