Plan to bleed hydraulic bike brakes about once a year with DOT fluid and about every two years with mineral oil, the schedule SRAM publishes for its own brakes. Bleed sooner, whatever the date, if the lever feels spongy, the bite point keeps moving, or the lever still pulls toward the bar after you have ruled out worn pads.
That is the short answer to how often to bleed brakes. Makers do not all agree, though, and one of them says no schedule is needed. Below are the figures each one publishes, where we could find them, and how to tell a brake that needs a bleed from one that needs pads. For why fluid ages, boiling points and the bleed procedure, see our hydraulic brake fluid guide.
How Often Should You Bleed Disc Brakes? Intervals by Brake and Fluid
| Brake or fluid | Published interval | Source |
|---|---|---|
| SRAM, DOT fluid | "Once per year or as needed" | SRAM service interval sheet |
| SRAM, mineral oil | "Once every two years or as needed" | SRAM service interval sheet |
| Hope Tech 4, DOT fluid | "You shouldn't need to bleed your brake more than once a year" | Hope Tech 4 bleed instructions |
| Magura, Royal Blood mineral oil | No regular bleed: Magura says Royal Blood does not age, so bleed only when a symptom calls for it or after a hose change | Magura MT manual, 2017 |
| Trickstuff, Bionol fluid | Service the brakes every two years | Trickstuff service page |
| Shimano, mineral oil | No Shimano document we could open. In a 2016 interview, Shimano's Nick Murdick said annually for most recreational mountain bikers (see below) | Cyclocross Magazine |
| TRP, mineral oil | No TRP document found. TRP's Bryce Olsen said once a year in the same 2016 article | Cyclocross Magazine |
| Formula | No Formula figure found. BikeRadar's workshop guide says at least once a year | BikeRadar |
| Hayes, Tektro | No published interval found | Check your brake's manual |
One year is the most common figure, and BikeRadar's general advice matches it: once a year, or when the lever feels spongy. The two-year figures come from brakes that do not use DOT fluid, though Murdick's annual figure shows that mineral oil does not always mean two years. No maker we checked gives a distance figure, so a bleed is a calendar job first.
Shimano's documents blocked our checks, so we can't quote its manuals here. If you have the manual for your model, it comes first.
Mineral Oil vs. DOT: Why the Numbers Differ
DOT fluid draws water from the air. BikeRadar says it is "said to generally let in two to three per cent of its volume in water a year", and water lowers its boiling point. Mineral oil does not absorb water the same way. So for mineral oil, Murdick said, dirt getting in is what sets the interval, and he put DOT at about every two years because its boiling point drops over time. That two-year DOT remark is longer than SRAM's and Hope's yearly figures, which is one more reason to follow the maker of your own brake.
