J
Jobst Brandt
Guest
Risto Varanka writes:
>> It depends on how fast you are going. If you are holding the brakes hard enough to only go 1 or 2
>> kph, they won't get very hot because there is lots of time to dissipate heat, and if you are
>> going 30+ not using the brakes they obviously won't get hot. The max heat generation is somewhere
>> between these two extremes.
> I thought we were talking the extreme where you have to do constant and significant braking just
> to keep from going faster than the 30 km/h.
> If you go faster, you lose altitude at a greater rate, ie. you convert potential energy to kinetic
> at a greater rate. To me this would appear to mean that you need to apply the brakes more, in
> order to control the resulting acceleration.
To hold the bicycle at constant speed below 30km/h requires practically the same brake force
regardless of speed, wind being an insignificant brake on such steep gradients at least up to that
speed. The greatest problem is air cooling and heating rate. At less than 15km/h, convection cooling
becomes miserable and it is for this reason that the cautious rider is most likely to blow a tire if
it is going to happen at all.
With straight sections between curves, letting the bicycle roll free between curves produces far
lower temperatures than continuous braking at a slow speed.
http://tinyurl.com/pd86
Jobst Brandt [email protected]
>> It depends on how fast you are going. If you are holding the brakes hard enough to only go 1 or 2
>> kph, they won't get very hot because there is lots of time to dissipate heat, and if you are
>> going 30+ not using the brakes they obviously won't get hot. The max heat generation is somewhere
>> between these two extremes.
> I thought we were talking the extreme where you have to do constant and significant braking just
> to keep from going faster than the 30 km/h.
> If you go faster, you lose altitude at a greater rate, ie. you convert potential energy to kinetic
> at a greater rate. To me this would appear to mean that you need to apply the brakes more, in
> order to control the resulting acceleration.
To hold the bicycle at constant speed below 30km/h requires practically the same brake force
regardless of speed, wind being an insignificant brake on such steep gradients at least up to that
speed. The greatest problem is air cooling and heating rate. At less than 15km/h, convection cooling
becomes miserable and it is for this reason that the cautious rider is most likely to blow a tire if
it is going to happen at all.
With straight sections between curves, letting the bicycle roll free between curves produces far
lower temperatures than continuous braking at a slow speed.
http://tinyurl.com/pd86
Jobst Brandt [email protected]