Rebelistic Posted October 30, 2006 Report Share Posted October 30, 2006 I did search but didn't find anything.I've been bleeding my hope mono and was wondering why it has an oil resevoir on the break lever?Should this resevoir be completely full of oil or should there be an air space in it?It seems silly to me, why not just have it like maguras with no resevoir?Cheers Quote Link to comment Share on other sites More sharing options...
N.Wood Posted October 30, 2006 Report Share Posted October 30, 2006 Because they're an open system, whereas Magura HS33's are a closed system.The diaphragm in the resovoir allows for heat expansion of the fluid. Quote Link to comment Share on other sites More sharing options...
Greetings Posted October 30, 2006 Report Share Posted October 30, 2006 (edited) Or in other words Bicycle disc brakes where at first used only on downhill rigs. As you can imagine, when you brake for a long period of time, the disc gets very hot, so do the pads. The heat is transferred into the system which warms up the fluid. This then makes the fluid expand, and without a resevoir it could lead to the brake locking itself up, which you wouldn't want to happen when riding over 30mph down a hill. With a resevoir, all the "additional" fluid, just flows into it, keeping the brake safe and this is what is refered to as an open system. It's not something you'd need in trials, actually I think a closed system is much better for this sport. But as there is no trials-specific brake (the Hope Trials uses the same lever which is mounted on every other Hope brake), they couldn't be bothered to make a closed system which would have very limited use. As for the resevoir itself, there should be no air between the membrane and where the fluid is, and no fluid above the membrane. There is normally a small hole in the resevoir cap which allows the air to be released from above the membrane when the fluid expands.Maguras don't have a resevoir because braking doesn't generate any heat = the fluid doesn't expand. Edited October 30, 2006 by Inur Quote Link to comment Share on other sites More sharing options...
Rebelistic Posted October 30, 2006 Author Report Share Posted October 30, 2006 Ah, thanks that makes sense.So on the upper side of the diaphram you may have air that is free to leave the system as the oil expands but you should not have any air under the diaphram.The small hole in the resevoir cap is probably the reason I thought mine was leaking as I just filled everything with oil.I assume there is some mechanism that removes the resevoir from the system while the lever is being pulled or the breaking would feel spongey like there was air in the system.Thanks again Quote Link to comment Share on other sites More sharing options...
N.Wood Posted October 30, 2006 Report Share Posted October 30, 2006 It's not something you'd need in trials, actually I think a closed system is much better for this sport. But as there is no trials-specific brake (the Hope Trials uses the same lever which is mounted on every other Hope brake), they couldn't be bothered to make a closed system which would have very limited use. Word, they used to make one (the C2, C denoting 'closed') with a dial on the lever to act as a TPA type device. To stop it locking up under heat you had to unscrew the dial slightly. Quote Link to comment Share on other sites More sharing options...
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