Turning disc braked bikes upside down
11-10-20, 10:23 AM
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Turning disc braked bikes upside down
So I just got back from a long weekend of riding and for a bunch of reasons, my Factor was kept upside down for about 30-40 min in the evening. After that, I pretty much lost all braking. The levers would travel all the way back without any appreciable braking resistance. I had to pump the brake levers a few times to get some braking power, which would give me some braking force for a short while (about the equivalent of poorly set-up canti brakes) and then nada.
My question - is this normal when a disc-braked bike is turned upside down? I was under the impression that a few pumps of the brakes should bring the braking force/modulation back to normal, but that didnt happen here at all. Or is this because the brakes were not bled properly? Mainly I ask because I plan to travel a fair bit with this bike and if the bike being upside down or sideways is going to screw up the braking, that is going to be a big problem.
TIA.
My question - is this normal when a disc-braked bike is turned upside down? I was under the impression that a few pumps of the brakes should bring the braking force/modulation back to normal, but that didnt happen here at all. Or is this because the brakes were not bled properly? Mainly I ask because I plan to travel a fair bit with this bike and if the bike being upside down or sideways is going to screw up the braking, that is going to be a big problem.
TIA.
11-10-20, 10:42 AM
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Air is supposed to gather in the reservoir in the hoods, and it can migrate past the cylinder and in to the lines when inverted, but this sounds excessive and it makes me think that it wasn't bled well.
I have experienced a total lack of braking power after transportation (~1400 mile road trip, albeit laying on its side, not inverted), but it came back within 30 sec of vigorous lever flicks. Go to ~2:30 of this video for an idea of what I'm talking about (you do this without opening the system, but seeing the bubble in the bleed cup in this video provides a nice visual) - https://www.youtube.com/watch?v=NxxWQ4lFHio
Note that for the rear brake line, there's often a low point at the BB, and that can act as a trap if bubbles are behind it. If some lever flicking doesn't seem to be helping much, I'd stand the bike up on the rear wheel, eliminating the trap at the BB, and give it some more flicks.
I have experienced a total lack of braking power after transportation (~1400 mile road trip, albeit laying on its side, not inverted), but it came back within 30 sec of vigorous lever flicks. Go to ~2:30 of this video for an idea of what I'm talking about (you do this without opening the system, but seeing the bubble in the bleed cup in this video provides a nice visual) - https://www.youtube.com/watch?v=NxxWQ4lFHio
Note that for the rear brake line, there's often a low point at the BB, and that can act as a trap if bubbles are behind it. If some lever flicking doesn't seem to be helping much, I'd stand the bike up on the rear wheel, eliminating the trap at the BB, and give it some more flicks.
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11-10-20, 11:47 AM
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Yeah, that's what I figured too - that typically, a few lever squeezes gets the brakes up to where they need to be. In this case, both my front and rear brake are mush - so i am guessing that it wasnt bled properly. Gonna get them bled again tomorrow and will make sure the bike passes the upside-down test this time!
The good news is, i was able to do a mountain ride with a lot of descents and switchbacks despite the brakes being mush - just had to make sure i keep the speed under control on the downhills (which isnt fun, but better than not being able to ride!).
Thanks for the info!
The good news is, i was able to do a mountain ride with a lot of descents and switchbacks despite the brakes being mush - just had to make sure i keep the speed under control on the downhills (which isnt fun, but better than not being able to ride!).
Thanks for the info!
