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Are radial brakes really better than non-radial?

Do radial brakes have better stopping power by design than non-radial brakes?

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Kornholio

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Apr 29, 2008
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According to this, they are not. Yet, I keep reading in the magazines that they are. Is it simply a structural design improvement or is there actually a noticeable benefit to radial-mount brakes? :dunno


Your thoughts? And why.

Around 2003, motorbikes started to hit the showrooms with a new feature - radial brakes. The magazines and testers will all tell you that radial brakes make the bike stop quicker. Not true - they have nothing to do with stopping power and everything to do with the design of the front forks of the bike. More and more bikes are coming out with upside-down forks. ie. instead of the fat canister part of the fork being at the bottom of the assembly, it's at the top. This means that the fork pistons are now the part of the suspension with the wheel attached to them. It also means that it's impossible to put a stiffening fork brace down there now because the brace would need to move with the wheel, and the length of the fork pistons precludes that.
The difference between regular caliper mounting and radial caliper mounting

The stiffness of the front end is now entirely dependent on the size of the front axle. Bigger axle = stiffer front end. A side-effect of this design was that traditionally-mounted brake calipers could cause a lot of vibration in the steering because of flex between the wheel (with the brake disc bolted to it), and the fork leg (with the caliper). The slight tolerance allowed by floating brake rotors couldn't compensate for the amount of flexing in the forks. To reduce the brake-induced fork vibration, the brake calipers were moved around the rotors slightly so that they fell into the front-rear alignment of the wheel axle. There's less lateral flex at that point, which means less or no vibration. The caliper mounts were changed too. Traditional calipers bolt on to the forks with bolts going through them at 90° to the face of the brake rotor. With radial calipers, the bolts are aligned parallel to the brake rotor - effectively also in the front-rear alignment of the wheel. This design is a trickle-down technology from superbike racing where a radial caliper mount allows the racing teams to use different diameters of brake rotor by simply adding spacers between the caliper and the mounting bracket.
The image here shows the difference between traditional and radially mounted brake calipers.


Read more: http://www.carbibles.com/brake_bible.html#ixzz0z3wLfTBG
Click to expand...
 
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Ok, but just because the high-end bikes have them doesn't necessarily mean that they have more power. I'm simply trying to understand why a radial mounted brake is inherently more strong in terms of stopping power than a non-radial-mounted brake. I think it's just a design feature that has become common place. I'm just seeing what the deal is with them.
 
Dude, car bibles is good information, but it's neither complete, nor 100% accurate. Don't take it as gospel.
 
Yes, the reason is the direction of the forces. When the brakes are applied the friction between the pads and rotors makes the pads/calipers want to move forward with the rotation of the wheel. When the calipers are axial mounted the bolts are mounted perpendicular to the wheel, there is mechanical play between the mounting bolts and holes which is where braking energy is lost. In a radial mount the bolt is mounted in parallel with the direction of the forces. So when the brakes are applied there is no slop.

That is the best I can describe while quickly typing. Take a look at a set of each after reading my description and you will see what I mean.
 
The whole design increases stability which increases braking force. The design is also more aerodynamic. I'm biased because my brakes are unreal.
 
radial brakes are not better at all. remove the radial brakes from your bike and install some from a ninja 650r instead. since they are from a ninja, they not only stop quicker, they also throw ninja stars at cars that cut you off.
 
number_6 said:
This thread has a lot of :Popcorn potential. The quote in the first post is :wtf

Not to spoil the fun but, "because racers do it" is probably a perfectly reasonable explanation. Its safe to assume someone at Brembo did back to back testing. But that isn't very fun.

I always assumed it was done to improve feel. A non radial caliper is sort of cantilevered off its mounting bolts and should be more free to bend than an radial caliper. Any bending could possibly make for some non-linear response and confusing feedback to the rider. I don't think improved braking power is the reason for radial. But I'm just guessing.
Click to expand...

I don't think that there is more power, but the feel is where it's at. Look at the new radial calipers now - monobloc is nothing to do with more power, but rather because the caliper is one machined piece, so no movement between the pieces may give you .1 percent micron better feel.
 
Radial calipers vs. axial calipers have always been about which gave better feel, consistency, and pad wear, in my opinion.
 
stan23 said:
I don't think that there is more power, but the feel is where it's at. Look at the new radial calipers now - monobloc is nothing to do with more power, but rather because the caliper is one machined piece, so no movement between the pieces may give you .1 percent micron better feel.
Click to expand...

Mono-block callipers have noticeably less flex than 2 piece callipers.
 
yes, rigidity, adaptability. Will you feel the difference cruising down the street? Not really
 
Yes, because I paid more for them. And they allow the calipers to be set closer to the ground instead of closer to the forks. This lowers the center of mass during hard braking and cornering. ;)
 
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Typo "lowers", my reason is not flawed... just insignificant. :p
 
No one has been lacking power in brakes for decades. Locking the front wheel...no problem.

Effort, feel, impact on other components. I believe they're stiffer just by looking at the mounts.
 
Burning1 said:
Dude, car bibles is good information, but it's neither complete, nor 100% accurate. Don't take it as gospel.
Click to expand...

Oh I'm not. It was just something I found with a quick Google search.


That's why I'm asking you guys now! :laughing
 
STIdevildog said:
The whole design increases stability which increases braking force. The design is also more aerodynamic. I'm biased because my brakes are unreal.
Click to expand...

Actual braking force is a function of the rotor and pad materials, surface areas, swept diameters, hydraulic pressures, etc. Where and how the caliper is mounted has little to do with braking force as long as the mounting scheme is capable of handling the forces.

However, how and where the caliper is mounted does have an effect on how braking forces are transmitted into the suspension and the rest of the bike. And also how the braking "feels" to the rider. Of course, at the highest levels of racing, these factors are very important. At the level of street riding, they usually aren't and differences are very difficult to notice.
 
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