New rotors?



konasunset

New Member
Oct 13, 2009
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I am considering an upgrade for my mechanical disc brakes as the Promax models that came stock on my K2 Zed are acting kinda strange. I have tried replacing the pads but I think they gave me the wrong ones at the bike shop and they have not been good. I am considering some Avid BB7's. Are these the best I can get in that price range? And do I need to replace the rotors? Or are they pretty standard and compatible with other systems?
 
What do you mean by "acting kinda strange"? Were they acting NOT strange at some time in the past? If so then consider reparing before replacing. Changing between different types of cable disc brakes won't provide huge differences in performance.

The most common complaint with disc brakes is dirt or contamination. The mechanisms are tighter than those of V-brakes and if they are not kept clean they will degrade with time. Contamination of the pads or discs (with certain types of cleaners, hydrocarbons, oils or brake fluid) ruins the surface, reduces performance and increases the propensity to squeal.

I once saw one guy who completely destroyed his near new brakes by chosing to clean his whole bike with petrol or kero or WD40 (something like that). He initially denied it even though I could smell it all over the macine and still see the residue of it on the discs. We cleaned up the discs but the pads are almost impossible to clean up as they are porous and soak up the contaminants.

Rotors are standardised on diameter (either 160 or 185mm in this case). An increase in diameter will yield extra stopping power but each size requires a correspondingly sized brake mounting.
I wouldn't use Avid rotors. They're really flimsy and never come straight out of the box. Unless they are dirty (in which case you can clean them) or warped, you can stick with the rotors you have.

If your heart is set on "upgrading" consider shimano cable discs or hydraulics rather than Avids. They are cheaper, far easier to set up, their rotors are more robust and they are no less powerful.
 
tafi said:
What do you mean by "acting kinda strange"? Were they acting NOT strange at some time in the past? If so then consider reparing before replacing. Changing between different types of cable disc brakes won't provide huge differences in performance.

The most common complaint with disc brakes is dirt or contamination. The mechanisms are tighter than those of V-brakes and if they are not kept clean they will degrade with time. Contamination of the pads or discs (with certain types of cleaners, hydrocarbons, oils or brake fluid) ruins the surface, reduces performance and increases the propensity to squeal.

I once saw one guy who completely destroyed his near new brakes by chosing to clean his whole bike with petrol or kero or WD40 (something like that). He initially denied it even though I could smell it all over the macine and still see the residue of it on the discs. We cleaned up the discs but the pads are almost impossible to clean up as they are porous and soak up the contaminants.

Rotors are standardised on diameter (either 160 or 185mm in this case). An increase in diameter will yield extra stopping power but each size requires a correspondingly sized brake mounting.
I wouldn't use Avid rotors. They're really flimsy and never come straight out of the box. Unless they are dirty (in which case you can clean them) or warped, you can stick with the rotors you have.

If your heart is set on "upgrading" consider shimano cable discs or hydraulics rather than Avids. They are cheaper, far easier to set up, their rotors are more robust and they are no less powerful.

Thanks... :) Makes sense. I will keep that in mind. Maybe I just need some new pads and to clean the rotors with alcohol. Or is there something better to clean them with? I am pretty new to the disc brakes scene. I have ridden mostly with caliper brakes for a long time. So thanks for the info.. :) I will check out the Shimanos...
 
If the discs are dirty then alcohol alone probably won't dissolve grease. So wash them first with a simple detergent and water and then rinse well with water. Alcohol is optional. The pads often need soaking, but I have no idea what you could soak them which would clean them well without adding any further contamination.

Someone told me that an overnight soak in Coca-Cola does the trick but I'm not sure what you do about the sticky sugary mess left behind after this "cleaning". It got me to thinking that perhaps it is the carbonation and bubbling which may help to loosen dirt from the pores in the pads. Or perhaps it is a combination of this and the acid content. I'm far from an expert on that. Experimentation required.

I can't guarantee that this will fix your issues (you haven't really said what they are), but it is the least expensive step and so is the logical first port of call.
 
From all the reviews I have read the avid BB7s are some of the best BB7s that you can buy, and better then some low end hydros. Actually just ordered some from performance because they got such good reviews.
 
Sure, once set up they're probably fine. But I would rather set up some shimanos in ten minutes and then go riding than mess around aligning avid calipers and straightening avid rotors for sometimes an hour or more.

Your mileage might vary (I have gotten lucky before too) but in general the bikes we get new with avids fitted are a real pain to build.
 
Ill have to take your word for now and find out how hard they are to set up when mine get here in a few days. I have heard that the roundagon style avid rotors can get warped fairly easily, but apparently the g2s are much better.