Dodgy disc brakes

[gareth h]

Guys any advice, I bought a Cannondale Rush almost a year ago, Avid Juicy brakes were c**p from the start, thought they might bed in but they haven't improved, is there anything obvious that I should check before I treck back to the shop I bought it from?
Ta

[chrisga]

When you say crap, how do you mean. There are a few different ways hydraulic disc brakes can feel crap. My other half has juicy 3's and they work brilliantly. I have juicy ultimate 7's and again they work well so the brakes arent bad.

Does the lever come back to the bars before enough pressure is applied to stop you? If so they need bleeding. Bleeding juicy's is quite a laborious process so if you arent sure what to do and dont have the bleed kit then probably best to get the shop to do it for you. If the lever is solid but when you pull on it not a lot happens then there could be a problem with the pads. When you get the disc brakes you need to bed the pads in by putting them through a few heat cycles before they work properly. This involves as it sounds, gettingthem hot, so doing a series of stops, then letting them cool between. This does something to the glazing of the pad material I believe. The other thing is the pad material could be contaminated with something like wd40 ot gt85. If you get this on it then the pad can be ruined, and might need changing.

If its none of these things then you could try putting bigger rotors on. Depending how big and heavy you are and what size rotors your bike came equipped with it may be worth it. If you weigh 18 stone and your bike came with 165 rotors then think about going bigger. In fact i'd recommend going for the biggest you can anyway. The weight gain is negligible but is worht the increase in stopping power.

Hope that helps.

Edited by chrisga on Sunday 6th September 11:31

[gbbird]

My avid Juicy 3s work fine, so would suggest you try bleeding them as previously posted.

However, I have an almost opposite problem with my Magura Louise brakes, insomuch that they are too responsive. Just the slightest pull on the lever and the wheels will lock and send the rider over the bars if they are not careful - there is hardly any graduation - either the brakes are not doing anything, or the wheel locks. Is there a way to reduce the sensitivity, so that there is more lever movement with different degrees of braking modulation?

Edited by gbbird on Sunday 6th September 12:57

[chris_sw]

gbbird said:

However, I have an almost opposite problem with my Magura Louise brakes, insomuch that they are too responsive. Just the slightest pull on the lever and the wheels will lock and send the rider over the bars if they are not careful - there is hardly any graduation - either the brakes are not doing anything, or the wheel locks. Is there a way to reduce the sensitivity, so that there is more lever movement with different degrees of braking modulation?

What size rotors are you using? Big rotors can make it make it feel like that, as there's too much power. 203mm rotors with a light rider are an overkill.

[gareth h]

Thanks for the replies.
It's not air which I know about having spent 3 hours this morning bleeding the brakes on my Aprilia RSV.
I went through the heat cycle thing.
The rear wheel wont lock up and the front slows me, well very slowly.
From whats been said I think it probably points to pads.

[chrisga]

Cool hope you get it sorted.

[lewis_sharman]

gbbird said:

. . . either the brakes are not doing anything, or the wheel locks. Is there a way to reduce the sensitivity, so that there is more lever movement with different degrees of braking modulation?

Edited by gbbird on Sunday 6th September 12:57

WD40?












(don't do this!)

Edited by lewis_sharman on Sunday 6th September 23:55

[gbbird]

chris_sw said:

gbbird said:

However, I have an almost opposite problem with my Magura Louise brakes, insomuch that they are too responsive. Just the slightest pull on the lever and the wheels will lock and send the rider over the bars if they are not careful - there is hardly any graduation - either the brakes are not doing anything, or the wheel locks. Is there a way to reduce the sensitivity, so that there is more lever movement with different degrees of braking modulation?

What size rotors are you using? Big rotors can make it make it feel like that, as there's too much power. 203mm rotors with a light rider are an overkill.

I am using 185mm rotors front and rear (i think). They are definitely not 203s, but i will double check tonight.

[Floor Tom]

gbbird said:

I am using 185mm rotors front and rear (i think). They are definitely not 203s, but i will double check tonight.

Just incase you arn't aware, stick a 203mm rotor on most XC or All Mountain forks and you might have problems with warranty if the lowers crack/snap. I'm pretty shure rockshox (for instance) are only covered up to a 185mm on Pikes and anything smaller.