Home

I know, the subject name doesn't make sense, right!?

I bought a hybrid bike in the summer which has hydraulic disks (Shimano BR-M355) and as soon as it gets wet, they are almost completely useless.  Like dangerously ineffective useless.  In the dry they are fantastic.

The bike has been back to the shop twice and they have fully cleaned out the system and replaced the pads (apparently), all for free, of course, but the problem persists.

Has anyone ever come across this before or have any suggestions?  I guess I'll be taking it back in again but don't have total faith in their ability to fix it so I wouldn't mind being armed with a few suggestions (I'm new to disc breaks and so far, obviously, underwhelmed!).

Cheers

15 comments

Avatar
BrokenBootneck [208 posts] 4 months ago
0 likes

they need to bed in, get them on a steep hill, get up to speed and yank em on about 30-40 times!

Avatar
CXR94Di2 [1586 posts] 4 months ago
1 like

I have never experienced any fade with 4 bikes with disc brakes. Points I have learned with them. Certain pads aren't as good as others. Mainly organics are good in the dry but squeal like mad in the wet. The braking performance is still excellent. Sintered pads need a little more heat to work well but are better in the wet regarding noise. Again they work very will.
Bedding in is a few hard stops but not long dragging as this might glaze the pad surface, do short hard stops then ride to cool brakes down.
My question to you would be, is the brake lever a little spongy or has lots of travel before braking becomes affective? Disc brakes are easy to keep in good order. Clean the rotor with brake clean and clean rag after washing bike. Best practice is to remove pads before washing bike so no soapy liquid contaminates the material. Other than that I have only had to bleed one bike because of spongy lever.

Avatar
Swiss [55 posts] 4 months ago
0 likes

Similar experience mine need prompting in the wet especially when it's cold and drizzle. Sometimes they are noisy as well. Have tried heavy braking and disc cleaner.
Now I just feather brakes now and then to clear discs when it's wet.

Avatar
The _Kaner [1075 posts] 4 months ago
0 likes

Metal/sintered or resin pads?

The metal pad type may be a better bet in the rain for outright stopping power, as long as they are bedded in properly.

Resin offer a slightly better modulation (and less noise/less longevity).

Also what type disk rotors are being used?

I find that the more solid type rotors (with less cut outs) are less effective in wet as they don't allow the excess water to be expelled as quickly. Other users may have different experiences.

It's a "swings and roundabouts" scenario...finding the right balance for you is a probably going to be a bit of trial and error.

Avatar
abusivemonk [18 posts] 4 months ago
0 likes

I've moved onto Kevlar pads from Gorilla brakes. Been near silent in all conditions. Haven't got the initial bite of organics, but the heat up quickly, with great profession as you pull the lever harder.

Avatar
SingleSpeed [314 posts] 4 months ago
1 like

The Br-M355 as a budget brake will have I believe the Resin Pads and a Resin Only Rotor from memory.

 

A couple of things, firstly the brake is about the cheapest hydraulic Shimano make so it's not up there in performance anyway. There is no need to "clean out the system" if you bought the bike in summer, they may have bled them but you wouldn't get good braking in the dry either if they needed bleeding.

Contamination of the pads through use of cleaning products or lubrication may be the cuase but you'd expect the pads to howl if this was the case.

How do you apply your brakes? Mostly it's down to user error if you slowly apply the brakes and gradually apply pressure this is wrong and can lead to what is called fade, this is where the oil heats up and the brakes lose pressure. You should brake in short blasts... you know like last minute, knee on the ground cornering like a boss.

Another consideration you're not some massive heffer are you? We had some 18stoner who kept saying his bike was crap so we stuck some 200/180 rotors on and told him to lay off the pies.

as another bloke said also its advisable much like in a car to every so often dry off the rotors by applying the brake in the wet

 

Avatar
lxtwin [4 posts] 4 months ago
0 likes
SingleSpeed wrote:

Another consideration you're not some massive heffer are you? We had some 18stoner who kept saying his bike was crap so we stuck some 200/180 rotors on and told him to lay off the pies.
 

At 6"2 and 250lb mine stop instantly, so I guess I am a 400mile a month heffer too. But like most of the components the XTs and Ultegra brakes are great.

Avatar
nadsta [172 posts] 4 months ago
0 likes

There is no good reason or lack of technique that would make a properly set up hydraulic brake work in the dry but not in the wet. It is either a manufacturing issue or pad/disc related. Take your bike to another workshop and pay them to sort it. It shouldn't cost much. 

Avatar
beezus fufoon [673 posts] 4 months ago
0 likes

sounds like you got some oily stuff on the discs and the water lifts it into a film - I wouldn;t be too precious about cleaning them - I've had a single pair of hopes on different mountain bikes for 15 years and never had to bleed them, just wash the occasional grit out with water and leave them to themselves - they need to get a patina on them

I've only changed the pads once in that time

Avatar
newtonk [43 posts] 4 months ago
0 likes

Thanks for everyone's replies here.  I did try to bed the brakes in when they were new but as the problem only surfaced in the wet I may or may not have done this successfully!

I'm not 'some massive heffer' either, so that's out cheeky, but I'll take the F1-style braking tip and implement immediately, with gusto!

They were squealing like crazy before the last trip to the workshop but this seems to have subsided, however no performance improvement has occured.

I am tempted to take it to another shop for fettling but at the same time loathed to part with actual money when the place I bought it from should really fix for free (imo).

In terms of contamination on the discs or pads, I've always wondered how exactly you ride on roads without oil getting kicked up onto your brakes!! 

Avatar
beezus fufoon [673 posts] 4 months ago
0 likes

well - if you do want to clean them - use only isopropyl - anything else will leave a residue

Avatar
huntswheelers [91 posts] 4 months ago
0 likes

Ditto the above.... I have all sorts in the workshop with disc brake issues.... cable and hydraulic.... 9/10 is contaminated pads....but then here in the low lands of East Anglia....we do have a few hills... disc brakes are not used hard enough to prevent glazing ... with all the crap on the roads( brake and other particulates from vehicles) and discs low down the are quick to collect such matter.... 

I say to all disc users this way.... use them hard... 

Avatar
newtonk [43 posts] 4 months ago
0 likes

I pretty much only use it on the flat as well so what you're saying certainly applies huntswheelers, cheers. I think I'll bust out the isopropyl, give them a decent clean, find a 'hill' and have another go at breaking in and see how we go from there. Cheers all.

Avatar
SingleSpeed [314 posts] 4 months ago
1 like

If they have been contaminated or glazed it's worth popping the pads out laying a sheet of of 400 Grade Wet and dry on a very flat surface and rubbing the pad in a circular motion to take of the surface layer, you can then re bed them in.

You can get back most pads by using this method

Avatar
DrG82 [132 posts] 4 months ago
2 likes

Being Shimano they will be mineral oil filled, which is not hygroscopic unlike dot fluid, so they are unlikely to need bleading unless they have been very poorly bled initially, which is quite a rare situation as they are all done in factory. The easy way to check is simply be lever feel, ie. is it firm?

Shimano pads are probably IMO the achiles heel of their brakes, they are hippy hugging envioment friendly organic things that just don't do as good a job as the fluffy animal poisoning evil sintered pads.

Try looking at superstar components for pads, theey are super cheap and work well.

As stated above, keep any lube or WD40 type products away from them and occasionally give them a really good yank when heading down hill fast to take off any glaze andbuild a bit of heat in them.

Sintered pads are also less succeptible to contamination than organic/fibre pads.