Wavy brakes.... WTF?

I was browsing the Cannondale website idly looking at the 2004
replacement for my hill bike, and saw something in the pictures which
made me think '...that can't possibly be right...' so I tracked it
down to the Magura website and... yes it is.

Now I could waste time at this point in a rant about deliberately
unbookmarkable websites, but I shan't. However, because of
deliberately unbookmarkable websites I can't direct you to a page
describing what I'm talking about, only to a picture of it:
URL: http://www.magura.com/english/bremsen/martasl_01.jpg

Yup. That's right. It's _like_ a disk brake, only the rotor isn't a
disk, it's a sort of weird sculptured shape.

*WTF*?!

What _on_ _earth_ is the point of a scalloped rotor? Can anyone see
any technical (as apart from marketing) benefit of this design?

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/
;; "If I were a Microsoft Public Relations person, I would probably
;; be sobbing on a desk right now" -- Rob Miller, editor, /.

Simon Brooke muttered:

Now I could waste time at this point in a rant about deliberately
unbookmarkable websites, but I shan't. However, because of
deliberately unbookmarkable websites I can't direct you to a page
describing what I'm talking about, only to a picture of it:
URL: http://www.magura.com/english/bremsen/martasl_01.jpg

http://www.magura.com/english/bremsen/martasl.htm

--
bob [at] bobarnott [dot] com http://www.bobarnott.com/
----------------------------------------------------------------------------
"Crash programs fail because they are based on theory that,
with nine women pregnant, you can get a baby in a month."
-- Wernher von Braun

On Thu, 11 Sep 2003 19:43:17 +0100, Huw Pritchard
wrote:

On Thu, 11 Sep 2003 18:35:01 +0000, Simon Brooke did issue forth:

Yup. That's right. It's _like_ a disk brake, only the rotor isn't a
disk, it's a sort of weird sculptured shape.

The Hope Mini also uses a wavy rotor. I seem to recall someone mentioning
something about it allowing better braking by allowing the pads to grab
the side of the disk a bit, but I could be imagining things.

Huw

It may also help with cooling down the rotor.

But more importantly, it looks much better.
And if you think that's ridiculous, Hope sell personalised rotors:
http://www.hopetech.com/products/rotor.htm
--
Craig Wallace
http://www.craigwallace.clara.co.uk/
NGPC - http://www.ngppower.fsnet.co.uk

On Thu, 11 Sep 2003 22:11:34 +0200, M-Gineering import & framebouw
wrote:

Craig Wallace wrote:

On Thu, 11 Sep 2003 19:43:17 +0100, Huw Pritchard
wrote:

On Thu, 11 Sep 2003 18:35:01 +0000, Simon Brooke did issue forth:

Yup. That's right. It's _like_ a disk brake, only the rotor isn't a
disk, it's a sort of weird sculptured shape.

The Hope Mini also uses a wavy rotor. I seem to recall someone mentioning
something about it allowing better braking by allowing the pads to grab
the side of the disk a bit, but I could be imagining things.

Huw

It may also help with cooling down the rotor.

But more importantly, it looks much better.

Best of all it gives lawyers something to write about, as it is a
patented design by Galfer. Magura has a licence, other exhibitors at the
Eurobike got nasty letters

Isn't marketing so effective.

Garryb

Bob wrote:

http://www.magura.com/english/bremsen/martasl.htm

Interesting bit at the bottom:

"Warning!
1. Disc brake calipers can generate a lot of heat during extreme riding
conditions. The resulting heat transfer from the caliper to the fork and/or
frame can have a negative influence on the mechanical characteristics of
both the fork and/or frame. 2. Insufficient heat transfer from the brake
caliper to the frame and the fork, caused by fork and/or frame components
having low heat transfer characteristics (e.g. carbon rear triangles) can
cause the brake caliper to overheat, with the possibility of a total failure
of the brake system. This can cause serious personal injury to yourself
and/or others. With respect to product liability we remind you that any
manufacturer (also bicycle mechanic or end consumer!) is responsible for the
correct function of the complete bicycle in this context. "

Not seen that before.

Tony

--
"If you tell the truth you don't have to remember anything."
Mark Twain

is it not also something to do with providing a better mud / water clearance
from the rotor when braking? I know my comparatively boring round discs get
easily clogged up in muddy conditions and start making horrible noises.

Rupert



"Huw Pritchard" wrote in message
news
On Thu, 11 Sep 2003 18:35:01 +0000, Simon Brooke did issue forth:

Yup. That's right. It's _like_ a disk brake, only the rotor isn't a
disk, it's a sort of weird sculptured shape.

The Hope Mini also uses a wavy rotor. I seem to recall someone mentioning
something about it allowing better braking by allowing the pads to grab
the side of the disk a bit, but I could be imagining things.

Huw

Yup. That's right. It's _like_ a disk brake, only the rotor isn't a
disk, it's a sort of weird sculptured shape.

*WTF*?!

What _on_ _earth_ is the point of a scalloped rotor? Can anyone see
any technical (as apart from marketing) benefit of this design?


Given that it's a brake designed for XC racing, less metal = less weight,
also the wavey shape of the rotor makes it far more efficient at shedding
mud and water.
You don't have to believe it but it does work.

Phil

"Tony Raven" writes:

Bob wrote:

http://www.magura.com/english/bremsen/martasl.htm

Interesting bit at the bottom:

"Warning!
1. Disc brake calipers can generate a lot of heat during extreme riding
conditions. The resulting heat transfer from the caliper to the fork and/or
frame can have a negative influence on the mechanical characteristics of
both the fork and/or frame. 2. Insufficient heat transfer from the brake
caliper to the frame and the fork, caused by fork and/or frame components
having low heat transfer characteristics (e.g. carbon rear triangles) can
cause the brake caliper to overheat, with the possibility of a total failure
of the brake system. This can cause serious personal injury to yourself
and/or others. With respect to product liability we remind you that any
manufacturer (also bicycle mechanic or end consumer!) is responsible for the
correct function of the complete bicycle in this context. "

Yup, I noticed that.

Presumably they've had a failure. It makes me think about what happens
when you transfer that much heat into an oil-damped front fork leg (and
particularly into just one leg of a pair of forks), as well.

Surely the answer would be to add more finning to the caliper, as on an
air-cooled engine or a computer heatsink, to increase the area over
which the heat can transfer to the air... and I would have thought
that was a more important innovation than wavey edges, and could be
made to look just as k00l in marketing terms.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

[ This .sig subject to change without notice ]

"Philthy" wrote in message
...

Yup. That's right. It's _like_ a disk brake, only the rotor isn't a
disk, it's a sort of weird sculptured shape.

*WTF*?!

What _on_ _earth_ is the point of a scalloped rotor? Can anyone see
any technical (as apart from marketing) benefit of this design?


Given that it's a brake designed for XC racing, less metal = less weight,
also the wavey shape of the rotor makes it far more efficient at shedding
mud and water.
You don't have to believe it but it does work.

Phil

All the latest MX and enduro m/c's have them now. They are also finding
their way onto top spec road bikes as well. I guess it could just be a
fashion thing but KTM, etc claim less likelihood of deformation, reduced
heat build up and better contamination clearance. There's also some
nonsense about reducing risk of pads binding to the disk.

I still haven't seen a comprehensive technical assessment.

It sort of makes sense when you are chucking 100kilos of KTM around at
100mph but on a push bike?

They do look good and if they work better then who are we to argue?


Matt

Craig Wallace wrote:

And if you think that's ridiculous, Hope sell personalised rotors:
http://www.hopetech.com/products/rotor.htm

Word! My Speedmachine's discs have the word "Speedmachine" write large
thereupon. In my defence, I didn't ask for this - it was something Darth
Stuart did off his own bat.

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
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