Looking at buying some Magura Louise BATs but I’ve read several reports of both XT 775 and Magura brakes not liking cold weather. Both use mineral oil.

Quite a few reports on mtbr about it and a letter in one of the mags this month. Seems either the oil expands or the seals stiffen up and the brakes don’t work too well when temps drop to freezing.

Has anyone on here experienced this?

Never suffered this on XT M760 and Saint M800 brakes that I’ve used in the past.

I have Magura Martas’ been out in freezing conditions many times, no problems. I can’t see how the oil would expand, although it might thicken at really extreme temperatures.

How timely!

My Marta’s have stopped working well, since I took them out in the snow last week and today 🙁

They have been newly bled after last week and were working perfectly (no leaks etc) yesterday but now I am pulling the levers to the bars…

My deores on the commuter have not been affected whatsoever. I will concede my commute sn’t the most gruelling test of brakes.

Cold things generally shrink.

oxym0r0n – Are you sure you bled them thoroughly? They can be a bit of a pain to bleed, unless you have the new style master cylinder with the bleed port. Did you push and pull the fluid through the system, with the caliper oriented so the hose is vertical?

Are you sure you bled them thoroughly? They can be a bit of a pain to bleed, unless you have the new style master cylinder with the bleed port. Did you push and pull the fluid through the system, with the caliper oriented so the hose is vertical?

Yes. Followed the Magura workshop instructions to the letter and they were working like new yesterday on the Quantocks. Took the bike out at Cwm Carn today and slowly lost the front brake then the rear. I am not a happy bunny 🙁

I’ve found that in cold/damp conditions, there can be a bit of a “lag” when first using the brakes. This is resolved once they’ve been used a couple of time. You’ll notice this on any disk-braked vehicle (well – I’ve noticed it on cars. motorbikes and bicycles). I don’t think this is anything to do with the type of brake fluid though – my BB7-braked tourer exhibits the same phenomenon.

Not had a problem with my Marta BAT but my freehub froze when we stoped for a wee nip!

ok – sounds like it’s not been too much of a problem then 🙂

All winter I’ve had problems with my shimano (Lx and SLX) pistons seizing up. Not sure if it’s the cold or the mud to be honest, but either way it’s a PITA. The brakes still work, but usually one piston won’t retract meaning it grinds on the disc.

My Louise have been trouble free through long rides in freezing conditions, so cold Ice formed on the frame etc.