I know 180mm rotors have more leverage than 160mm, but how can that make a difference on a bike?
Bike Forum
Why are 180mm rotors more powerful than 160mm?
-
Posted 10 months ago #
-
It's to do with the fact they have more leverage!
For a given brake, force at calliper is constant, therefore the further from the hub you apply that force, the more effective the brake. They also disipate heat better as there's a larger mass/surface area. The trade off is less modulation and more weight.
Posted 10 months ago # -
I think you have answered your own question
Posted 10 months ago # -
Someone failed their Physics exam
Posted 10 months ago # -
Dumbass
Posted 10 months ago # -
For the same reason that it is easier to undo a nut with a 200mm long spanner than a 50mm long spanner.
Posted 10 months ago # -
I'm sure the extra surface area for heat dissipation plays a small role.
Posted 10 months ago # -
The rotors are not 'more powerful'
Power comes from the caliper.
Larger rotors have more 'leverage' if you like, and turn the same pressure at the caliper into more braking force at the rim** I think!
Posted 10 months ago # -
Or to explain the same thing in a different way, force x distance = work done. You apply a fixed force to the brake. If the rotor is bigger then it's travelling further in a fixed time so you're converting more energy to heat so you slow faster for the same brake pressure.
Posted 10 months ago # -
"I know 180mm rotors have more leverage than 160mm, but how can that make a difference on a bike?"
Um... Why would it not make a difference on a bike? Do bikes occupy some parallel universe where normal physics doesn't apply?
Anyway, words 3-9 of your question constitute the answer.
Posted 10 months ago # -
Dumbass
Talk about saying how it is! lol
Posted 10 months ago # -
it does have more leverage, but there is less friction on the disk, as 2 surfaces travelling over each other have more friction when the speed differential is less.
larger rotors heat up less though
Posted 10 months ago # -
Why are 180mm rotors more powerful than 160mm?
Well.... the rotors are not more powerful.
Neither is the calliper.
So to answer your question they arn't.
Posted 10 months ago # -
So if you were clever enough to invent a system that used the rim as the braking surface then you'd have a brilliant brake.
Posted 10 months ago # -
Yeah, until it either wore out, got covered in crap, etc
Posted 10 months ago # -
but there is less friction on the disk, as 2 surfaces travelling over each other have more friction when the speed differential is less
Not true - friction interface is an incredibly complicated subject and simple statements like this are mis-leading
Posted 10 months ago # -
invent a system that used the rim as the braking surface
Now dont quote me on this but wasn't this 'invention' used before discs on bikes. I'm sure i used these things called 'v-brakes' and also some 'magura's' and before all of that i used 'cantilevers' but i'm quite positive that my disc brakes worked better than all of them
Posted 10 months ago # -
There is no extra leverage from the disc size nor is there any extra leverage from the calliper. These will always remain the same whatever size disc you run.
Picture this two bikes side by side. One with a 180mm disc, the other with 165mm. If both bikes started braking at the same time the reality is the larger disc would offer more surface area to the pad over the same distance covered under braking. Simple!
Posted 10 months ago # -
I'm sure i used these things called 'v-brakes' and also some 'magura's' and before all of that i used 'cantilevers'
No you couldn't have done - you wouldn't have stopped by now.
Posted 10 months ago # -
Birch1983 you are a dumbass too
Posted 10 months ago # -
Birch - FAIL!
Posted 10 months ago # -
Picture this two bikes side by side. One with a 180mm disc, the other with 165mm. If both bikes started braking at the same time the reality is the larger disc would offer more surface area to the pad over the same distance covered under braking. Simple!
Wrong
Have a think about it.
Posted 10 months ago # -
it's called mechanical advantage
Birch, harry tonight’s reading:
Posted 10 months ago # -
So if you were clever enough to invent a system that used the rim as the braking surface then you'd have a brilliant brake.
Yeah, until it either wore out, got covered in crap, etc
The best solution to this issue is to combine the two. You have a secondary rim near the actual rim, which you use as a braking surface. Erik Buell does this and calls it perimeter braking.
Posted 10 months ago # -
You have a think about your comment. Same speed initially and same total stopping distance. The larger disc will expose more surface area! Study physics.
Posted 10 months ago # -
can't believe some of the nonsense in here!! worse than the logo thread!
Posted 10 months ago # -
Or simply read this..
http://www.bikeradar.com/gear/article/buyers-guide-to-disc-brakes-45/
And pay particular attention to this....
Power varies with each calliper and its pad surface/leverage, but the biggest difference is in disc (or rotor in the US) size. The bigger the disc, the more leverage your brake has on the wheel and the faster it can stop it. Each 20mm increase in size roughly equates to a 20 percent increase in power.
NOW GO STUDY PHYSICS DUMBASS!
Posted 10 months ago # -
What we really need is a disk rotor the same size as the wheel.
Posted 10 months ago # -
You have a think about your comment. Same speed initially and same total stopping distance. The larger disc will expose more surface area! Study physics.
hi dylan
Posted 10 months ago # -
flow - Member
Dumbasslol.
+1Posted 10 months ago # -
So all you guys are saying that you use brakes?
Posted 10 months ago # -
Yep, and Harry333, Birch1983, Peterpoddy and Clubber are thick as shite
Posted 10 months ago # -
Birch - do the pads grow in size? Does their surface area increase? LOL
Posted 10 months ago # -
Okee day, basic stuff, between a 180 and 160 braking system look at what stays constant and what changes.
Constants
Force (the calliper applies the same amount of force regardless of rotor size)
Friction Surface (brake pads and the area the contact area doesn't change)Variables
Distance of the contact points (pads to disc) to the axle (moment of force)
(We are going to ignore thermal properties)And then if you get some cheese and add that to the rotor you can fill your head with it.
Posted 10 months ago # -
So if you were clever enough to invent a system that used the rim as the braking surface then you'd have a brilliant brake
and if it were hydraulic it would be even better!
oh, they did that already - Magura HS33s
Posted 10 months ago #
Reply »
You must log in to post.
