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  1. #1
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    Is NRS brake jack worse with V brakes

    Just trying to work out the physics but is there more leverage working aginst the suspension action with V brakes than a disk?

    Would I notice any improvment by going to a disk brake

    Also why wouldnt it work to mount the caliper under the chain stay? Wouldnet this isolate the braking forces from the suspension

    I know it couldnt be that simple or Giant would have already done it

    Thanks
    Pete

  2. #2
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    When I had my Giant Boulder SE with XT brakes, often times the brake pads would overheat (the rim gets really hot) and lose part of its grip when I'm trying to slow down on a decent. So I would tend to pump my brakes in intervals or alternate between the front and rear when going down hill. After I bought my NRS with Avid disc brakes, I didnt have that problem anymore but i tend to pump my brakes anyways just in case.

  3. #3
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    I personally don't have a problem with "brake jack" on my NRS. I have no clue why you would wnat to go to Vs from discs? My frame doesn't have bosses anyway.

  4. #4
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    I was talking about going from vees to disks

    Quote Originally Posted by BikeSATORI
    I personally don't have a problem with "brake jack" on my NRS. I have no clue why you would wnat to go to Vs from discs? My frame doesn't have bosses anyway.
    I find my suspension feels like it locks out under brakes which I know is a trait of the NRS
    When I look at my vees I can see that the braking forces are actually acting against the suspension

    I was wondering if the disc brake has the same leverage as the vees due to it being at the other end of the seatstay

    Just wondering if there would be any additional benifit that will justify my spending money on discs

  5. #5
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    Yeah, now that I think about it, the susp. does top out or lock out when I am braking downhill, I didn't think that is what you meant by "brake jack." It really doesn't bother me anyway because I bought the NRS wanting it to ride like a hardtail in most situations. I really like to ride wheelies and manual everywhere possible, so I like the stiffer rear end, although I like to ride a plush bike everynow and then, I just don't expect it out of my NRS.
    If your looking for a reason to switch to discs, just go for a good ride on a demo or freinds bike. You won't ever want to go back to Vs. You can switch over, including a wheelset, for around $300 bucks now, maybe cheaper if you find a deal or shop ebay.

  6. #6
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    Quote Originally Posted by BikeSATORI
    I really like to ride wheelies and manual everywhere possible, so I like the stiffer rear end, although I like to ride a plush bike everynow and then, I just don't expect it out of my NRS.
    Funny, that's the same reason I bought an NRS.

  7. #7
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    Yeah, I'm a converted BMX dirt jumper and street rider (which I still do). BTW, I have a WeThePeople Thrillseeker decked out for sale cheap.
    Right now I am trying to build up a Freeride rig because there is a pretty big scene here on Lake Superior, and my NRS can't handle most of it w/steep headtube. - but I'm poor and the parts aren't getting any cheaper.

  8. #8
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    It MAY (and I repeat MAY since mine has disks and I don't know anyone who's ridden both) make it worse with V's. The jacking is caused by making the seatstay turn about the lower pivot at the chainstay which causes the top joint at the rocker to go down. That forces the shock to top out. Since V's act much further out at the rim they would have a longer lever arm about the chainstay pivot. That'd cause more torque and thus more force at the rocker pivot which equals more tendancy to top out the shock.
    That's my theory anyway! It's a moot point if you don't have bosses though...
    Big hoopy.
    Turner Sultan / On One Inbred

  9. #9
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    All 4-bars have "brake jack"

    Quote Originally Posted by RePete
    Just trying to work out the physics but is there more leverage working aginst the suspension action with V brakes than a disk?

    Would I notice any improvment by going to a disk brake

    Also why wouldnt it work to mount the caliper under the chain stay? Wouldnet this isolate the braking forces from the suspension

    I know it couldnt be that simple or Giant would have already done it

    Thanks
    Pete
    All 4-bar suspension bikes have the "brake jack" that you describe. I'm not a physicist or an engineer, but I've read a number of technical descriptions about the subject on MTBR. The idea is that the resistance against the rotational force of the rear wheel counteracts against the rear suspension and causes it to top out. I don't think it would matter where the braking force was applied to the wheel (rim vs. disc or even where on the rim).

    To make matters worse, when braking downhill you are usually out of your seat, thus removing all of the weight from the rear end. On an NRS this won't make much of a difference since the suspension is "no sag". But on a standard 4-bar bike, this further causes the rear suspension to top out and lock up.

    Thx...Doug

  10. #10
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    If you're that concerned about "brake jack" you can get a bolt on floating caliper setup like those on full on DH rigs, I forget what the name of the company was though.

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