Cannondale Crosser Cable AVID Disc brakes - poor stoppers

[simon]

Hi There - looks like I found you all and glad of it - I had gone over to BikeRadar but the regulars had all disappeared - was missing you all -

Anyway - the avid cable disc brakes on my nice cannondal crosser are rubbish - they used to be OK but over time have lost their strength - I changed the pads to no avail and even emery papered the discs. Someone mentioned the cables but they seem OK - movement is all transferred to the caliper?

My only though is I have got oil or polish on the discs and its affecting their performance?

Please help - otherwise I will just have to sell the bike!

 

[Monty Dog]

The Avid BB discs in my experience are reliable and dependable, so surprised to hear about your woes. Obviosly, check to make sure you haven't contaminated the pads - chain lube/WD40 could render them useless - try abrading them lightly with some emery paper over a flat surface to remove the glaze. Wipe the disc clean with solvent. Maybe worth taking them off and giving them a bit of a clean to remove any gunk inside the caliper - check the inside and outside adjuster knobs turn freely, and then repositioning and readjusting them using the installation instructions (download from website).

 

[Steve Austin]

i know you say the movement at the lever is being transferred to the caliper, is it being transferred to the pistons inside the caliper?
ie are the pads moving when you squeeze the lever?

 

[simon]

Steve - calipers aren't seized and are working correctly - pads are moving - just not very powerful

Monty - what solvent do you recommend please? I use carwash/wax to clean my bikes and then bikemagic spray to get a shine on the paintwork - wondering if this has contaminated discs?

 

[Peyote]

Avid BBs are supposed to be the best Mechnical Disc brakes you can get, haven't ever seen or heard a bad review about them.

RE: disc cleaning solvent, I use methylated spirits. Some will recommend isoproyl alcohol (you should be able to get it at the Chemists) alternatively there are bicycle disc brake specific sprays on the market. All should be able to remove any residual grease/wax on the disc rotors surface.

 

[simon]

Peyote

Aha - thanks for this tip - I have just found some disc cleaner at Evans - am going to get some on the way home and give it a go
http://www.evanscycles.com/product.jsp?style=13970

 

[Monty Dog]

I use white spirit to clean the discs.

 

[simon]

SUCCESS! - I bought some mucoff disc cleaner which had only a minor effect (if any) but what did make a difference was when I adjusted the red knobs such that both pads were just off the disc - which has improved things a fair bit - I was using these to adjust the brake lever travel but hadn't realised that the mechanical advantage of the caliper lever is greatest when at 90 degrees to the cable - ie when there is no gap - I then used the cable barrel adjusters to allow some play at the brake lever - obvious when you know ...

 

[Peyote]

I'm glad you got it sorted Simon!

Monty Dog - I used to use White Spirit to clean my brakes, but then I got told off by a more experienced Grease Monkey! Apparently it leaves an oily redisue behind which can affect the braking efficiency. I never really noticed it myself but thought you should know just in case.

As it is I prefer the smell of Meths, so stick with that these days!