Just a shiny male toy…

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Joined 1 year ago
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Cake day: July 1st, 2023

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  • Thanks for your response, friend. Last point is what I disagree with, for any bike manufactured past the late 70s. I’m clarifying that although sharp braking will lead to a seemingly cooler system, it actually isn’t a constraint because of how effective modern brake design is, and in fact invites danger through loss of control.

    To the other points, brakes dissipate KE only, any sane designer will make brakes able to handle the heat load of a 140kg (300lb) rider on a 25% grade in ambient temps of 40c (104f) holding velocity steady at 50kph (30mph), all reasonable assumptions as I wouldn’t really want to ride at the edges of those specific envelopes. We’re not a truck hauling 36000kg (80000lbs), whose driver may accidentally approach the boundaries of their brake system a lot more easily.

    Dot3 brake fluid is common, it’s at a 205c (400°f) boiling point and (this is key) we’ve got airflow interacting with the brake assembly over a longer period of time, while accruing less input thermal energy vs the sharp stop per moment of time.

    If we sum the energy going in over the entire time vs energy going out (via air flow, fluid flow etc), the boiling point of the dot3 isn’t approached for any moto brake system designed past the late 70s, unless you’re slowly decreasing speed from a very, very high initial velocity, inputting thermal energy faster than the system can discard it.

    We again reach the conclusion that within reasonable limits, holding speed steady using brakes alone won’t lead to brake fade on a bike manufactured past the 80s, no matter how long the descent.


  • Good comment, though I need to disagree re: quick braking based on physics principles; moto brakes are designed to handle heat load in most common environments, whether from fast hard braking or long moderate applications.

    Energy cannot be created or destroyed, right? Brakes turn kinetic energy into heat, and that’s a function of clamping force.

    You’re applying less clamping to your brakes over a long period, and rejecting that energy as heat. You’re in fact generating very close to the same net heat with a sharp, fast change in velocity, as between the two options what you’re really affecting is your kinetic energy.

    The difference between the two options is subtle actually, quick steps allow cooling air to access the center of the brake pad between applications, long stop actions don’t. But pads and fluid are now designed to conduct heat well enough to transfer the heat away faster than it can be generated, even if cooling now only affects 5 sides instead of six. That’s the primary and crucial reason why brake fade is no longer common.

    Fast breaking adds potential loss of control into the mix, so it shouldn’t be necessary or recommended.









  • RubberElectrons@lemmy.world
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    2 months ago

    All good points here. If you take a look at your clutch cable, you’ll notice it’s a bunch of long thin steel strands, twisted together. This keeps the wire both flexible and strong.

    However, if even a single cable stand has broken somewhere in the middle of the cable, that strand is scratching at the inside of the cable, causing resistance.

    Just as bad, there’s now slightly less strength to the remaining part of the cable that’s still connected. Another strand pops. Then another. This progresses over a couple of days. Suddenly, mid ride on the highway, there’s a gentle crunching feeling in the clutch, and the clutch can no longer disengage. You’re no longer able to disengage engine from wheels.

    Should this ever happen to you, by the way, you can still shift very carefully using only the pedal, but you must accelerate your engine then let go of the throttle before quickly stepping up or down a gear. That quick throttle action sorta disconnects the engine from transmission for a brief instant due to backlash in the transmission gears.

    I digress. Replace your cable with OEM, lube before install and don’t worry about replacing it for another 4 or 5 years, so long as you relube every year.