Big Front Disc on a Gravel Bike?
#26
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#27
Non omnino gravis
#28
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I understand the dilemma and see that harder pads are advised which can be a solution however it might not be the answer on cars
harder pads may be better in endurance and repeated deceleration but, it will lose immediate cold bit.
if you want more deceleration when cold bigger mechanical advantage is better (on sprint car, larger disc with road pads give the immediate bit needed for the 2 min race)
if it’s endurance, loads of fast decelrations, you need endurance and sintered pads which does not work well cold (squeal too), these need to be warmed up with tyres hence seeing cars zigzaging and braking hard on set up lap.
point being, harder pads or bigger pads is not the simple answer; the type of ride is also needed.
in my case, i want quick decelarations but I don t do many down hills so I would think 180 with organic pad would be better and more versatile when commuting.
harder pads may be better in endurance and repeated deceleration but, it will lose immediate cold bit.
if you want more deceleration when cold bigger mechanical advantage is better (on sprint car, larger disc with road pads give the immediate bit needed for the 2 min race)
if it’s endurance, loads of fast decelrations, you need endurance and sintered pads which does not work well cold (squeal too), these need to be warmed up with tyres hence seeing cars zigzaging and braking hard on set up lap.
point being, harder pads or bigger pads is not the simple answer; the type of ride is also needed.
in my case, i want quick decelarations but I don t do many down hills so I would think 180 with organic pad would be better and more versatile when commuting.
#29
Senior Member
I'm putting a 180 on the front of my daughter's bike. She has tiny hands and has trouble getting a good squeeze on the brakes even with her 105 levers adjusted close. Her and the bike together weigh about 130 lbs/59 kg. This is, of course, not a usual case...
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Part of effective front braking on the variable traction available in gravel is modulation. A bigger rotor will give you more braking power but LESS modulation on the front not more.
#31
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the video is OK and it talking about trail braking and clearly show that if you brake in the apex, you oversteer and fall (on a wet race track, you spin and end in a wall...). Rear will help to control the skid.
But, if you are not in a curve and need to break your speed quickly, you need to stamp on the brake and release slowly to avoid locking the wheel. It's all a balancing act between oversteer and understeer in order to maximise grip.
#32
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Assuming we are talking hydraulic brakes, the only reason to go with a larger rotor is for better cooling, which is only an issue on really long descents and/or repeated hard braking. If you are overheating a160mm rotor (which is obvious because your brakes start to noticeably fade), going to a 180mm rotor would help, but otherwise you're just adding unnecessary weight.
A 160mm (or even 140mm) rotor provides more than enough power to overcome the available traction, so "stopping power" isn't increased by going with larger rotors. You can lock up the rear wheel or go over the handlebars with any of these. The only difference is that with larger rotors you can do it 10-15 times in a row, or drag your brakes down a long descent, and experience less degradation in brake performance. Any difference in feel/modulation/effort is going to be minimal at best between 160/180. A larger rotor has a slight leverage advantage, but a much bigger difference would be felt by simply using different pads.
The same is true for cars. Track-day cars benefit from large/cross-drilled rotors and steel brake lines because they withstand heat buildup better, which reduces brake fade. On a race track-cars are subjected to repeated hard braking efforts and heat buildup causes brake fade. A car with standard rotors will stop in the exact same distance as one with large cross-drilled rotors on the first few stops. The difference isn't noticeable until the standard system starts to overheat, which will only start to happen after a few laps.
A 160mm (or even 140mm) rotor provides more than enough power to overcome the available traction, so "stopping power" isn't increased by going with larger rotors. You can lock up the rear wheel or go over the handlebars with any of these. The only difference is that with larger rotors you can do it 10-15 times in a row, or drag your brakes down a long descent, and experience less degradation in brake performance. Any difference in feel/modulation/effort is going to be minimal at best between 160/180. A larger rotor has a slight leverage advantage, but a much bigger difference would be felt by simply using different pads.
The same is true for cars. Track-day cars benefit from large/cross-drilled rotors and steel brake lines because they withstand heat buildup better, which reduces brake fade. On a race track-cars are subjected to repeated hard braking efforts and heat buildup causes brake fade. A car with standard rotors will stop in the exact same distance as one with large cross-drilled rotors on the first few stops. The difference isn't noticeable until the standard system starts to overheat, which will only start to happen after a few laps.
#33
Junior Member
I use 160/140 on drop bar bike. I agree that front should be larger than rear, based in part on extensive motorcycle experience. Enduro bike is 203/180, XC is 180/160.
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