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  1. #1
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    Will these brakes break my fork??

    First off, I don't know whether to post this on the brake or susp. forum, the brake forum won the coin toss.
    I live on the top of a very steep hill, the road to my house is near vertical, I'm also a clyd. (6'6", 240 lbs + 28 lbs of bike). I was running Avid Juicy 5 brakes with 160 mm rotors both front and rear. They worked good, but not great, they lacked power, and they would overheat, by the time I made it down to the bottom of the hill.
    Last summer, Pricepoint had a sale on Alligator Wind Cutter rotors, so the first thing I did, was to go to the Rock Shox web site, and check the max rotor size spec. for my Dart 3 fork. I was amazed to find 203mm listed, so I ordered a 203mm front rotor, a 180mm rear rotor, and the caliper mounting adapters, and WOW they work great.
    Last night I went to the Rock Shox site again and I noticed the spec. had been changed to 160 mm
    Was the 203 mm spec. a typo?... Have they changed the forks, in a way that they will no longer withstand the stress caused by the larger brake rotors?... Will my fork snap like a wishbone, if I continue to use the larger rotors?... Should I mount my 160 mm rotors back on, and just live with the weak brakes?... Should I just continue to ride and say the hell with it?
    I honestly think it would be hard to go back to the 160 mm rotors after having a 203 mm rotor on for so long. I can't afford a new fork, and I can't afford to move either.
    Last edited by Diamondhead; 11-07-2008 at 05:51 PM.
    "It's a Sledgehamer" "Dang! You got shocks, pegs...lucky! " Napoleon Dynamite & Pedro Sanchez

  2. #2
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    call a RS tech, talk to them directly. Thats what I did. CHEERS.
    Oldest daughter doesn't ride, she fights MMA.

  3. #3
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    Quote Originally Posted by skip canfield
    call a RS tech, talk to them directly. Thats what I did. CHEERS.

    Hey skip, thanx for the quick reply
    Did you have the same issue, and what did the fine folks at Rock Shox say to you?
    "It's a Sledgehamer" "Dang! You got shocks, pegs...lucky! " Napoleon Dynamite & Pedro Sanchez

  4. #4
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    I would still call the RS peeps, but it is possible that they changed model years on you and the new ones aren't near as beefy, that is my guess as to what happened. And your fork probably won't snap due to extra braking forces, but premature wear on the bushings is something to keep an eye on.
    Save the Earth, Ride a Cyclist

  5. #5
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    I would be most concerned with the dropouts not being able to handle the extra forces and breaking before the premature bushing wear.

    Contact RS on Monday.

  6. #6
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    Probably has to do with the lawsuit that's coming back up that is responsible for the lawyer-tabs. main thing is that if you haul on a big rotor like that with a QR fork, there's a decent chance that you will rip the wheel out of the dropouts and crash. And YES, this DOES happen, even if rarely. I definitely second talking to RS directly though, they are awesome. Number is on the site.

  7. #7
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    I would just ride it, what kind of statement is that, limitation on rotor size, the dont know what caliper you are using, could be tektro or beefy 6 pots or so. I would just use what u got, if something snaps I guess you will notice pretty quick, and even so you can make some "trial runs" before just to make sure they are safe, things start behaving crazy then you know you cant push em harder. IMO of course.

  8. #8
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    it's physics. The caliper distance is more important than the braking force. And I wouldn't "just ride it" if it were mine. That's just lazy. If there is a problem, fix it. That aforementioned lawsuit involved a guy losing his qr while riding and he's now paraplegic.

  9. #9
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    Exactly what happened, and what equipment was involved?

  10. #10
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    RS psylo..............

    Quote Originally Posted by Diamondhead
    Hey skip, thanx for the quick reply
    Did you have the same issue, and what did the fine folks at Rock Shox say to you?
    I had an 01 RS Psylo that I wanted to run a 203mm rotor on, called RS and they recommended no bigger than the 7" rotor (185mm). Needless to say I put the 203mm on there anyway, cause thats all I had, and never experienced any problems. Just make sure your QR skewer is always tight. I checked mine before every ride.
    Oldest daughter doesn't ride, she fights MMA.

  11. #11
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    Ok, I will contact the fine folks at Rock Shox. personaly I think the 203 mm specification was a misprint, that was later corrected by the courteous staff at Rock Shox (hopeing no one would notice). even though the Dart series forks where the first in the Rock Shox line up to use the 74 mm post mount, which is alot stronger then the 51 mm IS mount.
    If it was a misprint, I will be so pissed off , because now I would now have to buy another fork, I'm not going back to the 160 mm rotors!
    Thanks for all your input.
    "It's a Sledgehamer" "Dang! You got shocks, pegs...lucky! " Napoleon Dynamite & Pedro Sanchez

  12. #12
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    Yeah, I second wanting to know about the lawsuit and the guy that got injured.

  13. #13
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    You might cause fatigue to the lowers, or damage the bushings but from what I understand of the QR+discs issue, the larger the rotor, the less likely the ejection problem is to occur. This is something to do with changing the angle of the force applied to the dropout when braking. Don't take my word for it though, there is loads of info out there on this.

    Info regarding the case in the UK currently running:
    http://spoomplim.blogspot.com/

  14. #14
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    Diamonhead:
    Did you ever get a response from RS and are you having any issues?

  15. #15
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    Quote Originally Posted by Baine
    Diamonhead:
    Did you ever get a response from RS and are you having any issues?
    yes I contacted RS via email shortly after posting my concern, they simply replied the max rotor dia. for the Dart 3 is 160mm, with no mention of the typo on their web site.
    However I continuied to ride with the 203mm rotor up front, and I've found the Dart 3 fork to have the same structural integrity of a wet noodle, under hard braking, especially in tight technical down hill single track sections. Grab a handfull of of front brake, and veer staight off the trail into a tree!
    So I went out and found a smoke'n deal on RS Recon Soloair fork (3 times stronger and a pound lighter), and installled the Dart 3 on my wife's commuter bike, were they work just fine.

    Cheers
    "It's a Sledgehamer" "Dang! You got shocks, pegs...lucky! " Napoleon Dynamite & Pedro Sanchez

  16. #16
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    Thanks for the update. I will stick with the Elixirs/160 until I can afford a new fork. I just
    upgraded my Dart 3 to the heavy spring and it's riding good enough for now.

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