Hydro Brakes and cold Temps???

With winter showing its face this weekend, I was wondering if anyone has experienced the following with their Hydro's and How Cold is to Cold for a Hydro Brake system with mineral oil???


The Deore XT brakes. Several issues when riding in the cold (down to -12C degrees or so)
1) Levers tighten up. Seems the pads aren't returning properly (?).
2) Poor braking power. Particularly, front brake has very power. Possibly oil has leaked from the pistons onto the pad. Others have reported such problems.
3) Awful squeaking and squealing sounds. Especially bad when it's snowing. They can hear you from a kilometer away.

Some people have really bad oil leaks and local Shimano rep has replaced their calipers. This lousy performance is surely a result of a) seal failure or b) oil performance in the cold. Or a combination of both.

I've ran my shimano hydro's down into the 20 deg F range w/o issues except for the squealing presumably from the moisture btwn rotor and pad.

it sounds like you have a faulty piston or pistons based on the poor power and lever return. I'd be less inclined to think its from the cold than from a piston issue.

Just squeeky. My XT's were working great last winter.

Squeaking is normal... moisture cold etc....

The actual performance issues:

1-Generally weak braking power--could be they just need to be bled. They may have excess air in the lines that isn't an issue in warm temperatures, but the cold shrinks the air and causes even less compression when you pull the lever, resulting in poor braking performance.

2-The failure to return... not sure, but the brake bleed might fix this as well.

My advise, take in get the brakes bled (or try it yourself if you're adventurous). If that fixes both problems great! If not, get the mechanics opinion while you have it in.

I had the air in the line issue last year, but that is not a cold related issue. It was already there. I just noticed it when it was cold. The brake leaver was soft, but as soon as it warmed up it was stiff as hell because of the expanding air. Had the lines bled and the problem was solved.

Exactly what I mean.. the issue is not caused by the cold, just that the symptoms are intensified by the cold.

I'm betting the brake bleed will do the trick for ya!

This is just something I was reading about online (not a problem yet) and because this will be my first winter with Hydro's...I just wanted to know what my limitation are...

First, the freezing point for mineral oil is -30C and DOT fluid is even colder. There won't be any problem from that end.

Squeaking in the cold is normal. My avid's and my shimano's do it.

If you are having issues with the pistons there are a few things that can be going on.

There is really only a little rubber O-ring that seals the piston area. It is common to need to run the pistons out a bit, clean them, then re-lubricate them, and press them back in with something nonmetallic that won't damage the piston. Make sure you remove the pads and take the wheel out. Do not run the piston too far out because it will actually fall out and pour the oil out. Dirt will build up there and cause the piston to not move freely. Whether it is sticking in or not returning. This usually happens more in the colder parts of the year because that is when the weather turns bad. More mud and dirt means more problems. Plus people are less likely to take care of their bikes because it is cold and sitting on the couch is better in the winter.

Shimano makes a few lower brakes that are 2 piece caliper bodies and these were having sealing issues where the 2 pieces met, causing fluid to leak and contaminate pads and rotors. That was fixed a while back and I have not seen too many of them since. The XT is a one piece body and out of hundreds I have yet to see the seals fail on them. Not saying it doesn't happen, but the cold certainly is not what is causing it.

As for the lever, it is just like the caliper. Just rubber seals. These seals harden in the winter and give it a little bit of a tough feel. Nothing to be concerned with.

I do recommend a few things though. I would get my brakes and fork completely serviced before and after winter here. The season is long enough and the weather is bad enough that I would get the fluid changed out and seals cleaned and lubricated. Not just bled. When you take apart an old brake that has been used for a while the fluid is no longer clean. The shimano mineral oil is usually a red color but after a while dirt seeps past the seals and the oil will turn a nasty brown and have stuff floating in it. Get it all redone at the beginning and end of the better seasons.

I can help you bleed them if you need help Mark.

Thanks Slim. That is some good advice.

Good info Slim...THX!!!

I'm not have any problems, I just rode last Sunday and my SLX's are working better then ever. Now I know what to look for as this winter thing drags on for the next four to five months...

Here's and article I found with some good insight:

Your significant other’s caught you fondling and caressing your bike ... again? Surfed the web dry of mountain bike content? Eyes tired of staring at digital spinning discs? It might be time to get a two-wheeled fix—something besides doing circles in the basement lab. Just because it’s winter doesn’t mean you can’t ride. You won’t be bombing down double-black diamond trails; however, the addition of snow to your favorite cross-country trails boosts their difficulty, and you’ll hone technical skills while enhancing endurance and strength.

The bike:

You don’t need a dedicated snow bicycle to ride in the winter. A simple, classic hardtail works awesomely, and the larger the tire the better (Read: 29er). But don’t let that fact keep the squish indoors: your dually is plenty tough and will perform admirably when tuned correctly. Just remember: winter conditions are harsh on components, including pivot bearings and shocks. Shocks smooth bumps—including ones in the form of snow banks, ice chunks, and Narwhal carcasses left by satisfied polar bears. If your bike’s equipped with suspension, some quick adjustments will enable big performance rewards. If you don’t have any squish, you’re either in the know and already ice hard, or ... you’re one of these pedal pushers.

Suspension setup:

Keep in mind that, if your bike lives inside where it’s nice and warm, you’re going to want to tune the suspension after its acclimated to the outside, ambient temperature. Air shock pressure changes as a result of temperature fluctuation. Colder temps equal less air pressure, so you’ll need to increase pressure to your air shocks—or you’ll be bottoming out your suspension, and the bike’s geometry will be off. Near freezing and freezing temps cause oil’s viscosity to increase, which results in rebound that’s too slow. A shock with slow rebound ‘packs up’—meaning it never returns to full extension. This leaves the bike less lively and with poor geometry. Increase rebound by opening up the oil passageway; this allows thicker oil to flow freer for faster rebound. In some extreme cases (if you live in a constantly cold climate), changing your suspension oil to a lighter weight will be beneficial.

Tires:

Knobby, widely spaced, large volume, and low durometer tires work well in snow, and that’s probably what’s already on your bike or hanging around. You’ll want to set tire pressure about 7.75 psi lower than what you normally run—this’ll provide enhanced traction. For the best traction, dedicated snow tires exist, complete with ultra-low durometers—and black-ice-thwarting studs.

Brakes:

The best brakes for winter cycling are disc. They’re mounted as far away from the snow as possible to avoid buildup, and have a self-cleaning surface. Even though disc brakes are leaps and bounds better then rim brakes, make sure you do periodic brake checks as you ride, they can still pack with ice and snow. If a disc brake starts to drag while riding, the pads may have snow or ice packed behind them. This won’t allow the pads to retract into the caliper, causing drag. If this is the case, pull the pads out, chip the ice away, put them back in and keep riding—or, retreat home to some hot, hard cider.

If your bike’s not equipped with disc brakes, rim-based stoppers will work for a short time. However, they quickly pack with snow and eventually, undoubtedly will fail. Do yourself a long overdue favor and make the upgrade to disc brakes.

Pedals:

Like brakes, clipless pedals have moving parts that can pack with ice and fail to allow entry or exit. If you’re going to use clip-in pedals, coat them with a water-displacing oil to prevent ice buildup, or better yet, ride with platform pedals. Winter riding can require extensive use of tripodding (think crotch on the top tube, feet on the ground—while sliding for your life) and platform pedals let you plant your feet quicker.

Clothing:

Sure, flannel-lined canvas pants provide warmth for the outdoors, but keep in mind you have a hungry drivetrain (read: pants ripped or caught in the chainring), these pants have irritating seams where the cheeks meet the saddle, and you’ll be working up a sweat while riding—which will leave you cold and damp when it’s time to rest. Dedicated cold-weather cycling clothing exits from the feet to the legs, torso, arms, hands, and noggin. Expect these garments to provide easy temperature regulation, freedom of movement, and moisture management.

Now go ahead and hit up the trails, or better yet poach a ski groomer run. Keep in mind that riding in snow increases wear on your bike. You may be traversing on grimy roads or transporting your bike by car and exposing it to corrosive elements ... be prepared to scrub it afterward. If venturing outside is just too daunting, options like indoor trainers, indoor parks, and vacations in warm climates exist.

http://www.hucknroll.com/mountainbike/newsletter/a1091/Bust-the-Crust-Winter-Mountain-Biking.html?cmp_id=EM_SAL12079a2&mv_pc=r105&rmid=HnR_11_ForkDeal&rrid=77816160