Bicycle Mechanics - Broken Chainstay 3 Times Please Help

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intelcrash
10-31-05, 02:37 PM
hi i have 2003 Kona Kahuna frame with a few 2005 upgrades

i like to sometimes hop on my rear wheel but when i upgraded to disc brakes all the pressure goes to the left (rotor/caliper) side of the chainstay

i snapped the original chainstay with 6" rotors on and i snapped another 2005 replacement chainstay within 2 weeks with the same rotors, so i upgraded the rotors to 8" and it seemed to have lasted a little longer but the 3rd chainstay also snapped.

any ideas why this is happening ? or how to prevent it without stopping fun ?

i think it may also have something to do with rear suspension activating when it snaps..

any help is appreciated. and here are some photos of my bike
http://members.shaw.ca/phoenix4eleven/CHAINSTAY1.JPG
http://members.shaw.ca/phoenix4eleven/CHAINSTAY2.JPG
http://members.shaw.ca/phoenix4eleven/CHAINSTAY3.JPG
http://members.shaw.ca/phoenix4eleven/CHAINSTAY4.JPG

Thanks

Brian
10-31-05, 02:49 PM
Isn't this more of an XC bike? Sounds like you're putting loads on the stay that it was not designed for. What does Kona say about the problem? I'm sure they advice against the 8" rotor too.
intelcrash
10-31-05, 02:54 PM
they say don't do anything other than XC riding, but that's dumb.. i wanna do what i want when i want the brake side should have more support because the brakes are only on one side these days

Brian
10-31-05, 03:07 PM
Do some free-riding too, maybe a little DH action.
intelcrash
10-31-05, 03:09 PM
i do... crazy drops and everything :)
urban_assault
10-31-05, 03:22 PM
Buy another bike.
San Rensho
10-31-05, 03:23 PM
There is no way the brake is breaking the chain stay. The rear wheel will lock up well before it generates enough torque to break the chain stay. I would check the rear drop out spacing. If the stays are too far apart, then when you tighten the rear wheel, the stay is already stressed and hopping may be enough to snap the stay.

Another thing to try is go back to a caliper brake and if that solves the problem. It is so easy to lock up the rear even with a caliper, isn't a hydraulic disc a bit of overkill?
Brian
10-31-05, 03:24 PM
My sarcasm has been wasted.
urban_assault
10-31-05, 03:26 PM
if he didn't learn the first two times, what makes you think he would understand sarcasm?
Mentor58
10-31-05, 03:39 PM
I have the exact same problem when I do huge drops with my cervelo R2.5 Carbon. Cheap bikes, never let me have any fun.

Steve W.
Who has never tasted big air without a parachute, and doesn't intend to begin now.
Brian
10-31-05, 03:40 PM
Obviously, it's breaking because he's not jumping high enough.
intelcrash
10-31-05, 03:46 PM
lol yah i need the brakes for when i go to the mountains or my local ravine to do some drops ect.. anyway

i will get a coiler frame and hop on the rear for a few hours till it snaps haha i will prove kona wrong, that XC bike has nothing to do with the problem
urban_assault
10-31-05, 03:47 PM
Sometimes one must look to themself for the answers...
Brian
10-31-05, 03:52 PM
Could be a problem with one of the pivot points, but if an XC bike is being used for freeriding and DH, all bets are off. That frame was simply never intended for that kind of abuse.
intelcrash
10-31-05, 03:55 PM
why can't they just give me a stay with the one side all steel.. that would fix everything
Brian
10-31-05, 03:56 PM
Sometimes one must look to themselves for the answers...

I agree. It will take a broken collar bone for him to see the truth.
HillRider
10-31-05, 05:17 PM
I believe it was the Navy that said: "there is always the 3% that doesn't get the word."
Raiyn
11-01-05, 01:42 AM
why can't they just give me a stay with the one side all steel.. that would fix everything
Why can't you get a clue and stop using an XC bike for things it's NOT DESIGNED FOR?
Brian
11-01-05, 02:25 AM
Save your keystrokes, Raiyn. He doesn't get it.