Freezing temperatures and Shimano hydraulic disc brakes

My bikes stored down in the shed, nice and dry but very cold at the moment (according the the BBC Weather website around -4). The odd thing is that the pistons in both calipers of my LX M585 brakes seemed a little proud (not enough to worry about but enough to give some rub and squeal throughout the ride) and the levers felt as it they had lost some throw (less movment), it was as if the hydraulic fluid had expanded. I remember a similar experience last winter but the brakes have been fine over the Summer with no new fluid.

I was under the impression that only water expanded when freezing and anyway hydraulic fluid is supposed to have a low freezing point (and -4, if that’s what it is, is hardly extreme). A quick Google suggests I’m not alone though and one suggestion was that water may have contaminated the fluid. However, the brakes work well with no spongeyness (whatever the temperature) and I can’t see how water could get into the system without oil leaking out. The rear brake has never been bled, the front was bled last year after I accidently popped out a piston and lost the fluid. Another suggestion was loss of flexibility in the seals due to cold, might this be the case?

Am I alone in this, and am I safe to ride? Stopping power seems fine (and with a little less lever travel I need to be care not to overdo it).

It works…ride it.

hehe.. I answered the same question yesterday..

Do you remember Richard Feynman pointing out what had gone wrong in the Challenger disaster, using a rubber o-ring and a glass of iced water? Well it’s that. But it won’t explode.

Bikes don’t belong in a shed, make room for it in the house. Build an extension if you have to. Problem solved.

I’ve found the other thread you were talking about and those were Shimano XT brakes. Examples of similar problems on the internet all also seemed to be Shimano brakes. Is this an issue with Shimano seals or does it affect all makes of disc brake?

Is there any potential for damange to the callipers/seals themselves if a bike is stored where it can get cold or used with the seals hardened?

It sounds like it’s fine to ride but does feel a bit disconcerting when you’re used to a certain ‘feel’ from the levers.

do the brakes feel better at the bottom of a descent?

I didn’t get too far today or do a descent(I wasn’t prepared for quite how bitter it was) but I suspect that that would have heated things up and warmed the seals. Like I said, it happened last winter with no adverse effects felt throughout the summer but I am a bit concerned about damage to the seals.

It’s not that the brakes don’t feel good, stopping power was find, it was just that the lever pull was noticiably less and they felt different to how they usually do; pretty much as Trent Steel describes in the thread Bike Whisperer refers to.

my rear deore completely locked onto the disc mid-night ride last winter 😡 still not quite worked out what happened, but those brakes dont seem to love the cold too much either

PJay – Member

I’ve found the other thread you were talking about and those were Shimano XT brakes. Examples of similar problems on the internet all also seemed to be Shimano brakes. Is this an issue with Shimano seals or does it affect all makes of disc brake?

I am suspecting that the different materials used for the seals as they are mineral oil not dot fluid might have some effect

Certainly I had no issues that I remember with a variety of hope brakes

Mine were fine today and it wasn’t exactly warm out there.

Yep, happens to mine too, wondered what that was all about.

Another reason (in my book anyway) for BB7s, but thats a whole other thread… 8)

Oh well, at least it’s not just mine although it doesn’t seem to affect everyone. I don’t really have any choice but to store the bike in a shed, so it’s going to get cold for prolonged periods, will this be alright or do I need to wrap my pride and joy up snuggly? Like I said, in was in the shed all last winter and temperatures were supposedly much lower then and the brakes have been fine since, I’m just concerned about any adverse effects on the seals, having to buy new brakes would be a pain but I can deal with it, but I’d imagine that a seal failing during a ride might be tricky.

Shimano brakes have had some problems in the cold during The last two years (fixed long ago on new ones). Something about bad seals, saw a lot of complaints on Finnish boards last winter.

i’m off out for a bit, in a bit.

my thermometer says it’s -5,

let’s see how my 3000 year old deore/lx hybrids get on…

My servowave XT’s do it.

“3000 year old deore/lx hybrids” – mine more like 5/6 years!

same here and working fine.

ditto – servowave XT here – hardly any free movement in the levers today! Not dragging though… (minus 9)

my deore did it last winter and the slx servowaces I’ve replaced them with aer doing it now. It never created a real problem and went away after the weather warmed up.

what he said. My old xt’s did it, as do my new servowave ones – they are fine next time once it has warmed up

hmm, no problems…

but my heritage deore/lx hybrids did go a bit ‘different’…

in-ter-esting.

My hunch would be that the contraction of the pipes etc. is having a greater effect that the contraction of the fluid in the pipes.

But would that vary between brands?

Well my main concern is whether anything will be damaged, mine worked fine over the Summer after hardening up last winter but I can’t imagine that regular freezing/thawing is going to do the seals any good.

I don’t think that the fluid should be contracting (doesn’t it have a freezing point in the -30 area?), it sounds like the seals as people have suggested. When I pumped the brakes a few times before setting off yesterday they felt like they do after you’ve pushed the pistons in to fit new pads and the pistons then adjust; the first pull felt normal but hardened up with each subsequent pull until there was virtually no travel (at which point the pistons didn’t seem to be retracting properly).

If there were ‘bad’ seals, can you get ‘good’ replacements, although it sounds like some newer brakes also struggle.

Never noticed this effect on my old Deore M555s, but went out in Jan when it was -1 and they did this (new style XT servo waves).
Have an M595 levers / M965 and M595 combo to try out this winter.

My XTs did exactly this when up Skiddaw on Saturday. It was ridiculously cold though.

Still felt wooden and screeching over next two days’ riding (a mere one or two degrees below zero rather than what felt like 10 or 20), but not as bad as the first day.

Hoping they will recover naturally.

as do my new servowave ones – they are fine next time once it has warmed up

Ah, just read that. Reassuring news thanks Iain!

Jusr resurrecting this one: My XTs have now developed leaking around the seals. I can’t complain too bitterly as they are about 4 years old.

However, I would suggest that riding in cold conditions could do the damage, they were fine until I took them out in the snow a few days ago.

Are we sure the seals can’t be replaced?

I’m starting another thread…