Originally Posted by
Camilo
These are my first bikes with hydraulic brakes so other than being able to install them successfully, I have no experience with maintenance other than adjusting the calipers and knowing how to replace pads. My wife and I got them 3 years ago (spring 2021) and I built them up with Sram AXS Force 2x with the standard Force hydraulic discs (DOT fluid). So, 3 seasons of use. We have other bikes we ride quite a bit, so I imagine they might have 2,000 miles each, not a lot.
My simple question is: Is there any reason to do routine brake bleeding and/or fluid replacement on DOT brakes if the levers are still firm and the brakes work well? I know that if they get squishy, it's time, but how about routinely in the absence of any issues?
Thanks.
They're SRAM brakes. At some moment the issues will came from nowhere and you'll be bleeding them at least twice for each couple of pads you use. After more miles/time, you can expect having to do a master cylinder overhaul and maybe calipers too. I have had too many SRAM brakes (and still have a road brake with Rival HRD) and they all deserve to burn in hell.
That being said: yes, there's a reason to replace fluid regularly even if they work well. DOT fluid is hygroscopic. That means that it absorbs moisture. If the water content on the fluid is too high, it can boil when you brake and you definitely don't want that. That's the same reason why brake fluid is regularly replaced on cars.
In mineral oil brakes, liquid also has to be replaced because, despite the liquid not being hygroscopic, moisture still can get inside and, water being heavier than oil, it tends to pool at the lowest point of the system (the caliper), posing the same boiling risk.
This being said, I used a Shimano SLX for 7 years without bleeding. I could only wish my SRAM brakes lasted half of that without an issue popping up from nowhere... they're 6 years old and I've lost count of the times I have bled them. I think I'm bleeding them at least a couple of times a year.