kierin brake / fork failure
 

Anyone actually witnessed a broken fork due to kierin brake use? Or is it something that "could" happen because the fork wasn't meant to be braked? I use my kierin brake very supplementally, if at all.

u witnessed this? how?

No, I was told it could happen...Since I use my brake very lightly and sparingly I doubt my fork will fail, but I wanted to see if anyone has heard of such -

Where did you see it happen? Do you have pictures?!?!

Yes! There's a s1ck youtube video of a hipster bombing down a hill in sanfrancisco, and he applies his kierin brake and his fork explodes! Check it out! While you are doing that my original question might be answered!

whats a kierin brake?

i've never heard of this. do you have a link to the video?

never seen it happen, but ive heard that the round fork blades found on most njs trackbikes (and other legit track bikes) can not withstand braking forces..

my bianchi has oval blades at the top, where the brake is attached, but they round near the middle:
http://img.photobucket.com/albums/v2...bianchi007.jpg

http://img.photobucket.com/albums/v2...bianchi006.jpg
I was told by my lbs that my fork crown didn't have enough "meat" to drill for a front brake, then told it would fail when I showed them the kierin brake setup. I contend that the kierin brake can not fail if I don't use it, and it's there as an e-brake only.

Those brakes are used by keirin riders training on the road. Track cyclists never use backpressure because of the potential for knee strain, so I would assume that they're being used all the time in riding. If they caused forks to fail they probably wouldn't be able to sell them.

I've heard somewhere that the actual mounting bit supplements the fork and takes away the risk for braking. But that's just me being hopeful cause I need a brake too and don't want to bust out for a new fork..
I can't imagine that they would sell these things unless they were street legit.. Also, since you're gonna be using it as an e-brake (likehood of locking the front wheel) wouldn't you want to make extra sure that it won't **** up your fork too?

Let's see some answers, I've searched various threads regarding this topic without any real answers..

Wait. So what would cause the fork failure? That's the part I don't understand. Please elaborate.

I am guessing people suspect that when the pads are grabbing the wheel, this in turn pulls on the brake assembly, thus pulling on the fork as well.

I can see that... but it sounds a bit far-fetched for me...

where exactly do you think the force goes if not into the fork?

anyway, seems like all the tokyo bikes that I see with these have them mounted on the rear, maybe they know something we don't
and yes I'm well aware that most of the braking power comes from the front brake

Which becomes an issue with track forks because they aren't meant to withstand braking forces and are optimized for side to side stiffness.

I know the force goes into the fork. It just seemed weird to me since I would imagine the brace breaking before enough force was transferred to the fork. Tis all.

they have these things called engineers who might be able to calculate realistic forces during braking and test actual components out, etc. ... and then everyone would learn something ;)

are there any of these engineers on the board?

I would think the braking force would impact a kierin-brake equipped fork more than a normal drilled-bolt equipped fork because the fork crown plays a lesser role during braking. With a bolt embedded in the fork crown, more load is braced by it. The kierin brake has the fork tubes take the initial brunt of the load, which is multiplied by the distance from the brake braces to the fork crown along the fork tubes, like little lever arms.

I think your LBS guys might be mixing up a few different stories. I have never never ever heard of the bolt-on keirin front brake sets causing fork failure, but do share stories if any one has them! The famous fork failure was Vivalo--maybe they are confused? Those keirin front brake sets have been around for quite a while too (at least several decades in Japan).

Mugatu--- the ones mounted on the rear are easier to put on and cheaper. I think that's the main incentive to using those instead of the front.

My reason for getting the front was because I already had a rear brake - my legs. Plus I didn't want to route the cable/housing to the rear, the bike looks a little cleaner w/ the front brake imo.

I agree with those reasons, except maybe the last one. But yeah, I really don't think you have anything to worry about, especially since it doesn't sound as if you are doing heavy front braking as a habit.

Yes, and I can't be the only one. Bikes seem to attract a nerdy set. I however traded in my calculator for a pen and a camera.