Disc brake question for the engineers out there...

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Disc brake question for the engineers out there...
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flag TheDoctoRR
Posted: Apr 4, 2014 at 8:04 Quote
Ive been looking for the answer to this question for a while to no avail. If you look at the splines on a brake rotor they are generally forward facing which to the non-engineer seems counter intuitive. Is there a engineering based reason for this or is it simply a design choice?


Unsecure image, only https images allowed: http://upload.wikimedia.org/wikipedia/commons/2/21/BrakeDiskVR.JPG
flag MaxAlary
Posted: Apr 4, 2014 at 16:15 Quote
From what I've read, It's mainly because of weight and ductile vs tensile strenght reasons. Failure due to shearing aren't that much of an issue in mountain biking since materials are much more resilient to the forces involved in a mtb brake. Stainless steels used in disc brakes are more ductile( compressive force) than tensile (stretching force) hence the forward facing arms that will be compressed when force is applied to braking surface. In the best of worlds, a symmetrical X pattern mirrored all around the inner area of the disc with each branch of the X towards adjacent bolt holes would be ideal ( imagine a snowflake). Probably that brake manufacturers went for the tiller blade desing for weight savings.

by the way I got this info in a masters degree thesis about mountain bike disc brake desing from a guy named Kenneth
Domond so all the credits goes to him.
flag TheDoctoRR
Posted: Apr 5, 2014 at 11:57 Quote
MaxAlary wrote:
by the way I got this info in a masters degree thesis about mountain bike disc brake desing from a guy named Kenneth
Domond so all the credits goes to him.

Do you have a copy of this paper by chance?
flag TheDoctoRR
Posted: Apr 5, 2014 at 11:58 Quote
What happened here?

cobba wrote:
photo
flag Dani87
Posted: Apr 6, 2014 at 10:51 Quote
Disk was on the wrong way round. The spiral pattern faces direction of travel so when the brake working the disk flexes outward. Increases braking force.
flag MaxAlary
Posted: Apr 6, 2014 at 15:59 Quote
TheDoctoRR wrote:
MaxAlary wrote:
by the way I got this info in a masters degree thesis about mountain bike disc brake desing from a guy named Kenneth
Domond so all the credits goes to him.

Do you have a copy of this paper by chance?

Actually I found it pretty easily on the first page of a google search I made so give it a shot I lost the link but it should be
pretty easy to find if you search with the name and subject.
flag TheDoctoRR
Posted: Apr 10, 2014 at 14:07 Quote
Its a lot of math-speak but it does address some interesting issues..
flag TheDoctoRR
Posted: Apr 10, 2014 at 14:18 Quote
It is interesting that it the paper does point out that the 'tiller' style rotor common to bicycles is inherently inferior to the 'truss' stye rotor common in motorcycles (and Hope brake rotors) and yet its still dominant in the marketplace...
flag TheDoctoRR
Posted: Apr 10, 2014 at 14:21 Quote
Dani87 wrote:
when the brake working the disk flexes outward.

Im not sure I follow what you mean by the disc flexing outward? outward from the center of the rotor?
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