20 inch brakes wtf?? *pic*
so i was arguing with my friend about how only 12 inch rotors are currently avaliable and he shows me this pic...i think its quite pointless as no body needs that kind of stopping power.
http://photo.pinkbike.com/photo/709/pbpic709253.jpg |
And not to mention it's on the rear wheel.
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Hahah I was actually going to start a thread on this. I dont get it.
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that looks rediculas.
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uhm, on a trials bike like that, don't you want massive rear holding power? same idea as Magura hydro rim brakes, right?
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That looks like the ultimate trials brake.
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Bend a wheel, bend a rotor...... :rolleyes:
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butt ugly
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i don't really understand what the difference between that and just a regular magura rim brake would be. for trials riding, i don't see an advantage to having disc brakes.
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I wonder if it does have great stopping power? But it looks stupid IMO.
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Originally Posted by xenochimera
so i was arguing with my friend about how only 12 inch rotors are currently avaliable
caboose |
Originally Posted by OneTinSloth
i don't really understand what the difference between that and just a regular magura rim brake would be. for trials riding, i don't see an advantage to having disc brakes.
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That is bloody stupid. For a trials bike you wat either on or off, ok big brake yay. The only advantage a trials bike could gain from a disc brake is that the braking surface is not effected by the shape of the rim. The rim actually flexes quite alot no matter how strong the wheel. Now this has lost the advantage.
Also this set up is going to be heavy compared to hydraulic V brakes (arguably the best thing for trials, lots of power and lighter than discs) another problem with discs in trials is the forces sent through the caliper has been known to rip the brake mounts off a frame. Finally, the main reason 8 inch rotors have better stopping capability over 6 inch is not the distance from the axel (that helps a bit but is not the main reason). The main reason is a larger surface to dissipate heat! The rotor can cool down better, the brakes don't over heat and voila..... better braking performance. Now on a trials bike there is no draggin of the brakes, therefore little there is little heat created so no need for large surface. |
The larger diamater creates better leverage, thus better braking?
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Ancient picture of an old show bike.
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Originally Posted by Flak
The larger diamater creates better leverage, thus better braking?
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Originally Posted by MattBeaty
The longer the lever arm, the greater the stopping power from the same amount of frictional force.
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Originally Posted by mx_599
...the greater the stopping power due to an increased amount of frictional force.
The frictional force would not change, kinetic friction is defined as the coefficient of kinetic friction x the normal force. The coefficient of friction is derived from the properties of the materials (not changing, regardless of the size and shape of the brakes and pads) The normal force is simply the squeezing power of the brakes,, also doesn't change when the rotors size changes. The only difference is the lever warm, which is why the braking power increases. Also the increased mass would prevent overheating the brakes, but the main difference would be the increased lever arm. |
Originally Posted by MattBeaty
Exactly, let me put it into a different perspective. The friction between the pad and the rotor is always parallel with the rotor. You could say that the friction between the pad and the rotor was like a hand pushing on the end of a wrench trying to turn it. Now imagine you had a really stubborn bolt (covered deeply enough in another thread:)) would you want a long wrench or a short wrench. Of course you would want a long wrench. The same thing applies for brakes. The longer the lever arm, the greater the stopping power from the same amount of frictional force.
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Originally Posted by MattBeaty
Exactly, let me put it into a different perspective. The friction between the pad and the rotor is always parallel with the rotor. You could say that the friction between the pad and the rotor was like a hand pushing on the end of a wrench trying to turn it. Now imagine you had a really stubborn bolt (covered deeply enough in another thread:)) would you want a long wrench or a short wrench. Of course you would want a long wrench. The same thing applies for brakes. The longer the lever arm, the greater the stopping power from the same amount of frictional force.
yes, its called torque. For a given force (the friction of the brake) the stopping power increases as the length of the moment arm (radius of rotor) increases. If there is also more friction due to surface area, that is just another added bonus. pretty soon they might even put the brakes on the rim... crazy! |
Originally Posted by MattBeaty
The only difference is the lever warm, which is why the braking power increases. Also the increased mass would prevent overheating the brakes, but the main difference would be the increased lever arm.
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Originally Posted by MattBeaty
The frictional force would not change, kinetic friction is defined as the coefficient of kinetic friction x the normal force. The coefficient of friction is derived from the properties of the materials (not changing, regardless of the size and shape of the brakes and pads) The normal force is simply the squeezing power of the brakes,, also doesn't change when the rotors size changes. The only difference is the lever warm, which is why the braking power increases. Also the increased mass would prevent overheating the brakes, but the main difference would be the increased lever arm.
dude, are you like an engineer or something? wow you must be REALLY smart as for the brakes... i wouldnt have 20" disc(s) i hardly use my 6" rotors to the max |
A similar setup has been used on the front wheel of Buell motorcycles for the past few years.
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pretty soon they might even put the brakes on the rim... crazy! |
Originally Posted by FF 6800
holy crap
dude, are you like an engineer or something? wow you must be REALLY smart as for the brakes... i wouldnt have 20" disc(s) i hardly use my 6" rotors to the max |
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