Are our brakes axial or radial pump?

[Olyrider]

just curious. Was reading an old review of the R-nine-T, and the subject came up.

No idea how to determine it on our bikes.

 

[kmoney_imp]

Axial. Radial brakes look like this:



and the MC like this:

The idea is that none of the forces involved have to deviate from their natural direction, thereby significantly reducing deflection and increasing feel. That's the grade-school answer, there is tons of good articles out there on this.

 

[AzBob_imp]

Axial. Radial brakes look like this:



and the MC like this:

The idea is that none of the forces involved have to deviate from their natural direction, thereby significantly reducing deflection and increasing feel. That's the grade-school answer, there is tons of good articles out there on this.

I thought I'd quickly explain what makes this a radial mount caliper as opposed to an axial mount. Just look at the bolts that hold the caliper to the fork. The bolts are in the same plane as the vehicle motion (e.g. they're parallel to the wheel). An axial mount caliper's bolts are 90 degrees to the wheel, as on our CB's, and you see the head of the bolt as you look at the bike from the side. Armed with this information, you can easily identify any caliper you see.

 

[Chapomis_imp]

That's interesting. The terms certainly make sense, learn something new every day I have always considered hydraulics to be more of a solid action, not making any difference how many bends were made, unlike exhaust or say dust collection where every bend is restricting.

 

[the Ferret]

I don't see how that caliper mounting is much different than our caliper mounting. Both from behind at a slight angle. What am I missing?

 

[kmoney_imp]

I don't see how that caliper mounting is much different than our caliper mounting. Both from behind at a slight angle. What am I missing?

The bolts attaching the radial caliper are parallel to the direction of the rotation of the wheel (they bolt down through the very top and bottom of the caliper with the bolts pointing straight toward the fork tube), whereas as on ours they are at 90 degrees to the direction of rotation (the bolts face toward the tire).

When you hit the brakes hard the callipers grip the calipers and are immediately pushed upward (opposite rotation). At the same time they deflect a few thousanths of an inch to the left and right. Radial mounting significantly reduces this, giving you much better feel and preedictable/consistent braking.

They don't serve a huge purpose on street bikes, unless you really are a track rat. They were one of those products born from racing that probably served as more of a marketing tool to shore up companies' "from the racetrack to the road" street credit (like carbon ceramic brakes on sports cars). Now everything with sporting pretentions has them, as anything less is falsely perceived as sub-par.

 

[Pterodactyl_imp]

That's interesting Kmoney. Amazing the things you learn on this forum. Your explanation is clear and well illustrated and your opinion on the effectiveness of the two systems interesting.

Cheers

 

[Olyrider]

Thanks, guys, for the explanation.

The article that spurred my interest was an online review of the R-nine-T in MCN (the european version).

They lamented that BMW had "cheaped out" by putting axial-pump brakes on their bike. The bike was roasted for its lack of feel and length of pull. The article said that radial-pump brakes would haved cured the problem.

Surprising to me, they wrote that there are after-market solutions...suggesting that radial-pump brakes can be bought (model specific!) for bikes. Didn't know that.[/i]

 

[kmoney_imp]

Thanks, guys, for the explanation.

The article that spurred my interest was an online review of the R-nine-T in MCN (the european version).

They lamented that BMW had "cheaped out" by putting axial-pump brakes on their bike. The bike was roasted for its lack of feel and length of pull. The article said that radial-pump brakes would haved cured the problem.

Surprising to me, they wrote that there are after-market solutions...suggesting that radial-pump brakes can be bought (model specific!) for bikes. Didn't know that.[/i]

Yeah, they are referring the master cylinder then, as the r-nine-t has had radial mount calipers since the beginning. A radial master would be an easy swap, the only thing you would have to make sure of is that you choose the right piston size.

Lots of sportbike guys seem to go to upgrade to the Brembo RCS series masters -- even if their bikes come stock with a radial master.

 

[the Ferret]

Ahh so it's the direction the mounting BOLTS are facing. Ok got it. Thanks.