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Riding in the mountains (self.motorcycles)

submitted 5 months ago by InternetCitizen2 to c/motorcycles

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I am someone who lives in a very flat area, not a single hill. Suppose I was taking a road trip and had to go up and down some mountains, what tips should I consider to be safe? How do I avoid ruining my clutch or my breaks?

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[–] [email protected] 2 points 5 months ago (1 children)

Which is what I said - they have a longer cooling time between braking cycles.

A longer braking cycle also occurs over a longer distance and time, meaning more time for gravity to continue contributing energy to the equation. A faster deceleration between the same two speeds is less energy dissipation overall (say 70 to 60 over 5 seconds VS 30 seconds). There's 5 seconds of additional acceleration due to gravity VS 30 seconds more.

But the biggest thing is you get a long cooling cycle instead of steadily heating the pads and rotors to simply "hold" against gravity. The rotors simply don't have the mass the absorb and dissipate that steady, continual heat input.

[–] RubberElectrons 2 points 5 months ago

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.