A mini-bleed whenever your brake levers start fading. (Mini-bleed; a master cylinder bleed only. I don’t remember where I heard this term.…but it works.)
Air accumulates within our brake systems (before , during or after a full bleed.)and eventually rises to the master cylinder making your brake(s) feel spongy, fading or ineffective. The vibration from riding will release more air bumbles into the hydraulic system therefore an additional “mini-bleed” may be required after a few rides. The trapped air will rise to the master cylinder.
Magura brake systems seem to require more mini-bleeds after the initial full-bleed but eventually they feel good and operate properly. I’ve installed a number of MT7’s on other bikes and this seems to be case on most.
I’ve only have experience with Shimano and Magura brake systems but they generally use the same braking systems. Heat dissipation is important to me as the rotors and callipers can be affected. Long descents can generate a lot of heat. Commuter bikes don’t seem to generate a lot of heat. But I did increase the rotor size (220mm front with 203mm rear) for a more balanced feel while braking hard. Anything larger than 203mm rotor size on the rear was not necessary for my body weight. A 220mm front rotor seemed to balance out the modulation feel, for me.
Anyways, a mini-bleed is fairly fast (3-5 minutes) with a funnel, adapter and small amount of mineral oil. Just pump the lever, rotate the master cylinder several times, watch for air bubbles (small and large) emerging in the funnel.
When no more bubbles appear, close the system and pump up the brakes. This method works for me and several others (Shimano or Magura).
Ps; I use the handle of a vibrating toothbrush if I don’t feel like tapping the hoses to free up some micro-bubbles.
