PYGA1 Posted May 30, 2011 Posted May 30, 2011 Hi all, A mate of mine suggested that I increase my rotor size from the current 160mm to a 180mm on the front in order to increase my braking power. Is this the case ? I definitely could use some increased stopping power on my mountain bike, I had a few close calls on Joberg2C and on 3 Towers last year on a few of the descents.
patches Posted May 30, 2011 Posted May 30, 2011 (edited) yup! larger rotors mean your braking force is applied further away from the pivot point (ie your hub) which means the moment (torque) is greater even though your brakes themselves are the same. I run a 180 font, 160 rear on my 4X bike, and 203mm front and back on my DH bike (where breaking power is essential) Edited May 30, 2011 by patches
Capricorn Posted May 30, 2011 Posted May 30, 2011 Patches hit all the buttons there. GT1: what brakes do you have, and do you brake drag?
GTRacing Posted May 30, 2011 Posted May 30, 2011 203mm Avid rotor with hope 3 brakes. Bring me to a standstill on a drop off.
patches Posted May 30, 2011 Posted May 30, 2011 Do the frames brake mount point dictate rotor size? to a degree. A frame and fork will often have a "maximum rotor size", but in order to mount your caliper to work with that size, an adapter is needed
MartinO Posted May 30, 2011 Posted May 30, 2011 (edited) You get adaptors for each brake size... I am a large guy 120kg+ and 185mm avids are more than enough in the front and 160mm rear. Need to balance off weight versus stopping power.. also you can have too much stopping power and end up being catapulted over the bars if you are not careful... horses for courses. Edited May 30, 2011 by MartinO
Moolz Posted May 30, 2011 Posted May 30, 2011 Best upgrade for me was changing my 160mm to a 180mm front rotor...Took me a few goes to get used to...a noticeable difference though! Next thing is to see if changing to sintered pads up front makes really makes that big of a difference...Bought a set of EBC gold stuff seeing that the EU reviews were pretty good... Will let u know if there is a noticeable difference...
Dubber88 Posted May 30, 2011 Posted May 30, 2011 (edited) Smaller rotors causes your wheel to lockout faster with bigger rotors giving a more evenly braking affect. I had 185 cleen sweep G2's back and front on my Spark 50, switched back to 160 at the back, best downgrade I have ever done with regards to XC. 185mm at the back heats up quite quick and bends easier with more problems than solutions and is mostly used on trail bikes. I'm running Juicy 3.5's with heavy duty alligator hoses. Edited May 30, 2011 by Dubber88
Capricorn Posted May 31, 2011 Posted May 31, 2011 dubber: lolwut? smaller rotors cause faster wheel lockups? That's interesting cos the thread's about bigger rotors creating more stopping force.185mm heats up quite quick? compared to...?bends easier? More problems? Sounds like you bash your rotor alot. Did u also swop to single speed rear end due to bashing your rear mech?
splat Posted May 31, 2011 Posted May 31, 2011 Another benefit: A larger rotor cools quicker Your braking power is also only as good as the grip of your tyres though.No good putting dustbin lids onto semi slick racing tyres...
AndreZA Posted May 31, 2011 Posted May 31, 2011 Just remember that you can have a disc the size of the moon, if you do not have traction, you will not stop.
Slowbee Posted May 31, 2011 Posted May 31, 2011 yup! larger rotors mean your braking force is applied further away from the pivot point (ie your hub) which means the moment (torque) is greater even though your brakes themselves are the same. I run a 180 font, 160 rear on my 4X bike, and 203mm front and back on my DH bike (where breaking power is essential) so why does my road bike take so long to stop, as I usually wonder about this before hitting the tree/signpost/curb/car/other rider in front of me. *ya ya breaking, brake force and all that nonsense.
Skott5 Posted May 31, 2011 Posted May 31, 2011 A lot depends on your brakes themselves. I run 160mm Rotors front and back with Formula R1's and have way more stopping power than I did with Hope mini's and 180mm rotors.
Puncher Posted May 31, 2011 Posted May 31, 2011 Torque = force x radius Assuming the force applied remains the same, the only variable will be an increase in the rotor radius, thus and increase in the torque. Not forgeting that larger rotor has more capacity for heat absorbtion.
AndreZA Posted May 31, 2011 Posted May 31, 2011 so why does my road bike take so long to stop, as I usually wonder about this before hitting the tree/signpost/curb/car/other rider in front of me. k@k pads and/or braking surface.
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