Stopping power

pittpony

I have a brake question i'm struggling to find the answer to. I'm not happy with the stopping power of my Juicy 3's and can't change the rotor size because my frame will only take a 160mm. If i upgrade to Juicy 5's / 7's etc am i likely to notice much difference? How about any other manufacturers brakes with a 160mm rotor? I mostly just ride XC and trails but I hate hitting those really steep downhill sections with the feeling of being unable to stop!!

papasmurf.

don't like any of the juicy brakes..so i'd recommend formula oro k18 best brakes in the price range..cheap at merlin at mo..

http://www.merlincycles.co.uk/?fn=produ ... egoryId=71

Splasher

Something's not right. With a 160mm rotor on the back, you should be able to lock the back wheel with one finger or at worst two.

Have your brakes always been this poor? Do you spray your bike with WD40 after you wash it? Do you lube your chain with a spray lubricant? Do you know what pads you have?

Answer the above and we can probably help you transform your brakes without buying a new set.

pittpony

The brakes have been poor since i got the bike in August. To my knowledge the rotors have not been contaminated with any lubricants etc. I've also throughly cleaned them numerous times with white spirit, IPA and muc-off disk cleaner. I've tried 3 sets of pads in the rear caliper (2 different compounds) so i'm happy the pads aren't the problem. I've also lost count of the number of times i've re-aligned the caliper. Its the rear brake that is the problem - the front one is more than capable of putting me over my handlebars :oops: I checked out the disk brake FAQ section and tried everything there.

I re-bled the brakes a few weeks ago which does seem to have helped but they still aren't as crisp as I'd like. As its my first 'serious' mountain bike i don't know if I'm expecting too much from them? On the rough tarmac road outside my house its quite hard to get the bike to skid using just the rear brake (not so bad if i use the front too). Is this normal, as i used to skid all over the place with my old V brakes?! I realise I don't want to be skidding about while i'm riding trails but i'm just using it as an indication of how well the brakes are working.

Thanks for your help

supersonic

White spirit.. that is most likely your problem. Its very oily, and shopuld not be anywhere a disc. Meths is better. Once it gets on the pads, thats the end of them.

pittpony

Thanks Supersonic

:roll: To think i checked with my LBS and they said white spirit would be fine :roll:

Looks like its time to give the rotor another good clean and try yet another new set of pads then!! What compound would you recommend for wet, muddy (English!) conditions?

dav1

A tip my LBS gave me was to flame the pads or bake them in the oven to decontaminate them. You may have to bed them in a bit afterwards but its worth a go.

and what do you mean by crisp? Are you referring to the spongy feeling in the lever? The spongy feel is normal for avids, for us fans of avids we like the control over the power it offers over levers that are more on/off. If you get the brake back up to full power though the feeling will change, there is a fair distance you can pull the lever but you should only need to use real hand-fulls of it for the most ridiculas of speeds you would hope to achieve on your rig. for my 5s I'm only ever using a small amount of the lever travel after initial engagement before i need to be careful to avoid locking my wheels up and skidding/catapulting myself.

Splasher

Surgical spirit is the best as it is pure alcohol. Procedure to follow is something like this:

1. Take the old pads out and throw them away

2. Degrease the rotor and caliper carefully.

3. Wash your hands and install brand new pads.

4. Bed them in with a few fast runs and hard back brake applications.

5. Post to let us know how you got on.

pittpony

Dav1 wrote:

A tip my LBS gave me was to flame the pads or bake them in the oven to de-contaminate them. You may have to bed them in a bit afterwards but its worth a go.

Might give it a try - can't hurt!!

I've heard of baking them in the oven, but could you just hold them over a candle? The oven tends to be reserved for food use

dav1

yeah i have done it over a lighter flame before with my old hayes brakes. Found the oven to be more effective (but my partner would muder me if she knew about that ). Be sure to give em a good heating though, i think i was too lazy with the lighter and should have spent a bit longer.

BTW edited my post since you replied so read up.

pittpony

Splasher wrote:

Surgical spirit is the best as it is pure alcohol.

I have access to *ahem* free solvents from work so have used neat isopropyl alcohol. Would ethanol be better? I'm assuming IPA would work just fine.

I'll let you know how i get on anyway!

dav1

most manufacturers recommend isopropyl alcohol as far as I know.

pittpony

Dav1 wrote:

and what do you mean by crisp? Are you referring to the spongy feeling in the lever? The spongy feel is normal for avids, for us fans of avids we like the control over the power it offers over levers that are more on/off. If you get the brake back up to full power though the feeling will change, there is a fair distance you can pull the lever but you should only need to use real hand-fulls of it for the most ridiculas of speeds you would hope to achieve on your rig. for my 5s I'm only ever using a small amount of the lever travel after initial engagement before i need to be careful to avoid locking my wheels up and skidding/catapulting myself.

Cheers Dav

By crisp i'm referring to the responsiveness i would expect from a properly working brake - i.e. the ability to lock up if i wanted to. I've heard about the sponginess of Avid brakes and how it is an advantage, but i think mine are just too spongy.

Splasher

pittpony wrote:

Splasher wrote:

Surgical spirit is the best as it is pure alcohol.

I have access to *ahem* free solvents from work so have used neat isopropyl alcohol. Would ethanol be better? I'm assuming IPA would work just fine.

I'll let you know how i get on anyway!

IPA is fine, any solvent that flashes off clean - Trike or Genclean if you have any

The Spiderman

I once got my pads contaminated by me touching the rotor with oily fiingers.I whipped the pads out,lightly sanded the pads with some fine wet and dry,degreased the rotors and normal service was resumed.

pittpony

Splasher wrote:

Surgical spirit is the best as it is pure alcohol. Procedure to follow is something like this:

1. Take the old pads out and throw them away

2. Degrease the rotor and caliper carefully.

3. Wash your hands and install brand new pads.

4. Bed them in with a few fast runs and hard back brake applications.

5. Post to let us know how you got on.

Thanks for all the help guys. Just had a chance to work on the bike and used the following procedure:

1. Wait for gf to go out

2. Bake pads in oven. Gas mark 8, 60 minutes until lightly blackened

3. Thoroughly clean all acessible parts of the caliper

4. Cool and refit pads

I just need to wait for them to bed in now but riding up and down the street they were a millin times better Only problem is the 'Avid mating call' has returned with a vengeance Ah well i'd rather they worked and were noisy than were quiet and not working!! I'm taking the bike out tomorrow night so maybe they'll bed in and quieten down...

I noticed my pads had worn a lot further than I'd expected. At what point would you recommend i replace them? Is there a recommended minimun thickness or do you wait until they wear right down / stop working so well?

dav1

ROFL "avid mating call".

Mine make that noise for the first few stops after cleaning with disk brake cleaner or when the rotors have picked up a lot of crap from the trail, nothing to worry about once everything is bedded in again.

The mating call is nothing to worry about, avid do make beautiful babies

pittpony

Lol they were still pretty noisy on the trails tonight but i've never known them stop so well It gave me so much more confidence to pick up a bit of speed!

They're usually quiet in the dry but very noisy in the wet. Have ordered some EBC pads to see if they'll quieten the setup down - guess it might be a case of trial and error! Lots of people say its just a characteristic of disc brakes but they're never so bad on other people's bikes :roll:

Splasher

I have Oros on one and Mono Minis on the other, and unless they are contaminated, they squeal wet but are silent in the dry. And even in the wet they only squeal until they get some heat and dry out.

One thing I've come across recently was taking my bike to Chicksands on a mates car. He has a towbar mounted rack and a diesel car and the oil residues from the exhaust meant the brakes squealed all day.

Matteeboy

To be honest, my Juicy 5s have been a total pain in the neck (constant juddering, excessive squeaking, rubbing, etc, and have been back to the LBS twice but are FINALLY working very well.
After five months of it, I was close to giving up but they are now excellent.

Does anyone else think the contamination thing is a bit daft? They are mountain bikes after all? Touch a rotor and it ruins them - how stupid is that?!

My old V braked Stumpy could have anything thrown at it and would still brake fine (although with a lot less power).

pittpony

Matteeboy wrote:

To be honest, my Juicy 5s have been a total pain in the neck (constant juddering, excessive squeaking, rubbing, etc, and have been back to the LBS twice but are FINALLY working very well.
After five months of it, I was close to giving up but they are now excellent.

Does anyone else think the contamination thing is a bit daft? They are mountain bikes after all? Touch a rotor and it ruins them - how stupid is that?!

My old V braked Stumpy could have anything thrown at it and would still brake fine (although with a lot less power).

So what was it that finally cured the squealing? I think the actual brakes on my bike are pretty good and just needed setting up properly. I'd just love to get them running a little more quietly...

Steve_b77

Gencleane, I remember when that stuff was still legal.

My Grandad and Dad used to use it to clean off welds before bombing (non-destructive testing) them.

We used to have a half oil drum sized container in the shed for a few years 'till it all ran out and then no more could be found summit to do with carcenogenic /potential death type properties :shock:

http://www.genchemcorp.com/pdf/msds/GenClean%20CMP-300%20%20-%20%202-03.pdf

fireheed

Try some petrol to clean the rotors, it's what i use.
Get a blowtorch to the pads for 5 mins then scuff them with some wet and dry or sandpaper.
Should all be fine after that.

Anonymous

for the sakes of all the dicking around, surely the 13 quid a new set of pads cost is worth it.

i havent used disc brake cleaner on any of the brakes ive used and they all work fine, noisy when wet but stil just as powerful and nothing a hose doesnt sort out after a ride.

edit: as for replacement recomendations, i would say ebc gold sintered pads as they are supremely powerful and last for ages and ages and ages and...........

pittpony

sheepsteeth wrote:

for the sakes of all the dicking around, surely the 13 quid a new set of pads cost is worth it.

i havent used disc brake cleaner on any of the brakes ive used and they all work fine, noisy when wet but stil just as powerful and nothing a hose doesnt sort out after a ride.

I see your point, but was worth an hour in the oven to see if it would work. I've got a bit of a bugbear about the horrendous noise the brakes make as i spent a lot of money on the bike so wasn't expecting these kind of problems. You live and learn eh?

Anonymous

tis afair one, someone mentioned formula oros earlier, i use them on the willow and they are awesome, but make the loudest noise ever (still work good tho) i doubt i will ever get used to it.

Bikedevil

Dav1 wrote:

A tip my LBS gave me was to flame the pads or bake them in the oven to decontaminate them. You may have to bed them in a bit afterwards but its worth a go.

Sounds like job for one of my numerous Trangia reservoirs!! My oven's tosh.

Will Snow

fireheed wrote:

Try some petrol to clean the rotors, it's what i use.
Get a blowtorch to the pads for 5 mins then scuff them with some wet and dry or sandpaper.
Should all be fine after that.

petrol + blowtorch. :shock: am i the only one who sees someone with no eyebrows after???

pittpony

Will Snow wrote:

petrol + blowtorch. :shock: am i the only one who sees someone with no eyebrows after???

Lol - what's the worst that can happen?!?! :twisted: :shock:

Splasher

pittpony wrote:

Will Snow wrote:

petrol + blowtorch. :shock: am i the only one who sees someone with no eyebrows after???

Lol - what's the worst that can happen?!?! :twisted: :shock:

Joking aside, if you clean your rotors with petrol, the worst that can happen is that you've just contaminated your rotors with petrol. Petrol contains additives to lubricate your engine which are designed not to flash off or burn (otherwise they'd be no good).

ride_whenever

Not to mention that petrol goes through the skin and isn't the most pleasant thing in the world.