nickc – Member
“Shimano 525 here, not touched in 5 years. Still work just fine. “
Mineral oil though, right? Avid use DOT, they act differently over time.
If anyone’s not convinced, here’s some numbers, based on the DOT4 standards. The minimum “dry” or fresh boiling point for DOT4 is 230 .C. It’s possible to boil it in a mountain bike brake but pretty uncommon. But the wet boiling point is only 155 degrees. The initial performance will be almost unchanged- there’s some minor differences but it’ll still stop you hard. But once you run up the temperatures, that’s when it all goes wrong. And boiling brakes can mean it all goes wrong in a pretty painful manner.
Now after a few years, the fluid might well not be so wet that it drops that far, but it will have dropped. Which is why so many people ride around in the UK perfectly happy and think their brakes are awesome, then they go to France or Fort William and spend the whole time moaning about fade.