Shimano Hydraulic brakes which bike shop to believe

soupsounds

I would be grateful for any advice on my disk break conundrum. Here is the sequence of events:

I have a relatively new road bike with shimano disk brakes. I mainly use for shortish commutes.

* Had Bike serviced at my local bike shop.
* This services includes new pads back and front
* After service one break in particualar squeales like a demented banchee
* Go back to bike shop and am told to bed it in - by breaking hard a few times whilst pedalling down a steep hill.
* Problem only cured for one day - continues to make one hell of a noise.
* Take it back to bike shop - they say they clean it up - But noise continues shortly after and if anything gets worse.
* Book it into Evans - They tell me that the breaks have been contaminated by Dot fluid - which because its not mineral fluid has ruined both breaks and everything, seals and all will have to be replaced. (Estimated bill £300)
* I take it back local bike shop and they tell me this can’t be the case because a) they didn’t bleed the breaks in the service and b) if Dot fluid had have been put it - they breaks would have failed completely - not just squeaked a lot.
* Even though they make a noise like hell freezing over they still seem to work.

My question: is the advice from the local Bike shop plusable. Or do I get a third opinion. The local bike shop have offered to do the work again for just the cost of materials and have explained that they are less likely to squeak if they replace the rotors at the same time.

mtbrider123

You can get a set of shimano XTR (top of the range) brakes for £300. Evans is trying to steal money from you. Even if dot fluid gets onto the brake pads, you can use sand paper to clean the pads and the rotor.

Thing to try: use sand paper on pads and rotors, put water onto the brake pads and rotors and then brake while descending.

lesfirth

My opinion is that what Evans are saying is unlikely to be correct. Your LBS should have no reason to do anything with the brake fluid. However if LBS saturday morning lad has messed up fitting pads and managed to lose fluid and contaminate the pads, it is remotely possible that Evans are closer to the truth.
It sounds like a bedding in problem to me.

step83

Take the pads out an give them a sand, wipe the discs down with isoprol alcohol this will remove any residue from them (post service its possible they got some grime on them)
Try again, if still no joy wheel off and pads out, Mineral oil is slightly sticky and shows up well under light so you'll be able to see if they have left any there.
Usually if you replace the pads you just open the lever end and space the pad back to avoid bubbles so I doubt they would have.

Lastly, road bike brakes are much more expensive as you have the shifter and brake all in one, unlike MTB ones, blessing and a curse at the same time!

Alejandrosdog

lesfirth wrote:

My opinion is that what Evans are saying is unlikely to be correct. Your LBS should have no reason to do anything with the brake fluid. However if LBS saturday morning lad has messed up fitting pads and managed to lose fluid and contaminate the pads, it is remotely possible that Evans are closer to the truth.
It sounds like a bedding in problem to me.

Even if that were the case, it shouldn't have DOT fluid in the system anyway. Either DOT or mineral oil on the pads will feck em up but it sounds like Evans must have tried to bleed the brakes and noticed a different colour than expected. hence the contaminated comment however, the brakes were working prior to changing the pads. no brake bleed has taken place so the fluid in the brakes would have been the same mineral oil that it always was. If it wasn't mineral oil in the first place then the seals would have shown it prior to the service.

So, I think its more likely that Evans noticed the difference in fluids but only because they were bleeding the brakes with the wrong stuff. Either that or its another case of bike shop ineptitude or deliberate bulls it.

lakesluddite

It is my (perhaps overly simplistic) understanding that Shimano use Mineral oil, Sram use Dot fluid, so I suspect given even I know this, then any decent LBS will definitely know which liquid to use. As has been said before, there didn't seem to be any reason to bleed or top up the fluid, and given there was no decrease in performance, then contamination of either the pads or rotor is the cause. It is very easy to contaminate either of these enough to give you that blood-curdling scream when braking - mine do it all the time. I have tried alcohol cleaner on the rotors, changing the pads, and while this works for a while, a few wet rides and it's back to the sound of a jumbo jet landing.

It might be good to actually name the LBS - there's likely to be someone on here who knows it and could give you their opinion of them (ie 'yeah, I know them, they know what they are doing' or 'wouldn't trust them to fit an inner tube')

Alejandrosdog

LakesLuddite wrote:

It is my (perhaps overly simplistic) understanding that Shimano use Mineral oil, Sram use Dot fluid, so I suspect given even I know this, then any decent LBS will definitely know which liquid to use. As has been said before, there didn't seem to be any reason to bleed or top up the fluid, and given there was no decrease in performance, then contamination of either the pads or rotor is the cause. It is very easy to contaminate either of these enough to give you that blood-curdling scream when braking - mine do it all the time. I have tried alcohol cleaner on the rotors, changing the pads, and while this works for a while, a few wet rides and it's back to the sound of a jumbo jet landing.

It might be good to actually name the LBS - there's likely to be someone on here who knows it and could give you their opinion of them (ie 'yeah, I know them, they know what they are doing' or 'wouldn't trust them to fit an inner tube')

Your understanding is correct, so for Evans to assert that DOT fluid has been use precipitating the change of the system (not just pads and rotor) then they are either talking complete bo blocks, or there really has been a mix up. since the lbs hasn't done a fluid change, the only way that it has now happened is because some numb nuts has introduced it. Since you haven't, and the lbs hasn't then that only leaves Evans or the brake fairy.

You didn't leave your callipers under the pillow did you?

Alejandrosdog

also if the rotor is contaminated you can clean it. if the pads are badly contaminated then its usually more effective to replace than to start messing about. providing your financial situation permits of course. if not then sanding with successive clean bits of sand paper has worked for me in the dim and distant past.

apreading

Did you have the bike from new? You say its relatively new but not if it had a previous owner?

If you arent the first owner then it is possible the previous owner replaced the fluid at some time and didnt use the branded Shimano mineral oil which is red but some other mineral oil which is just as good but a different colour.

Then its possible that Evans noticed the oil was not the right colour for shimano and assumed it was DOT.

I doubt very much if the LBS would have replaced the fluid as they would have charged you extra for doing so. So the odds of them not only doing that work free but then also putting the wrong fluid in are remote - unless they made a complete hash of things, confused your bike with someone elses, did work to it they shouldnt have and then tried to cover it up. I dont imagine that to be very likely.

More likely, they contaminated the pads and its often then hard to sort them without replacing them.

Can you swap the pads from front to rear? If you do then does the brake which squeals also swap from front to rear (or vice versa)?

kajjal

Sounds like the pads are contaminated with oil or something similar. The only real solution is remove the wheel and throw the current pads away. Then clean thoroughly the rotor and calliper with disk brake cleaner. A simple way to tell if it is clean is to clean using white kitchen roll and when it stays white you know whatever you are cleaning is completely clean. Unfortunately the pads will absorb oil and it is not worth wasting time on them. Once clean fit new pads and after a few hard goes on the brakes you are in business.

The contamination could come from anywhere so make sure you chain is not too over oiled or covered in gunk which can flick onto the rotor and cause the same problem again. The same is true of your cassette and don't forget to check the rear of the cassette which can build up all kinds of nasties. If it is the front wheel then just cleaning will be fine. I have a disk brake road bike and mountain bikes which very rarely have this problem but it can happen.

Alejandrosdog

I think you should burn the wheel and the first born child of everyone in your street.

cycleclinic

There are two cause for noise. Contamination is one but that is normally accompanied by rubbish braking. With contamination the above advise is sounds but IPA is better than brake cleaner for cleaning rotors. Sanding the rotors can also help.

If the braking is fine then it can caused by caliper set up. Post mount brakes suffered from this if they were not secure or there were too many spacer I.e budged. It more difficult with flat mount. Also the caliper mounts should be faced as this can be another cause of noise.