rear rotor 8in vs 6in?- Mtbr.com
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  1. #1
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    rear rotor 8in vs 6in?

    is there any reason for an 8in rear rotor? i understand and enjoy an 8in rotor in the front since you get more stopping power and better heat dissipation but does an 8in rear rotor do anything besides add more weight and make a bigger target for rocks to bend it?
    I currently have 8in rotors front and rear on both my freeride full suspension and hardtail.
    Has anyone rode their bike 8in front 8in rear and 8in front 6in rear and noticed any difference?

  2. #2
    moaaar shimz
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    6 rear doesn't lock up as often as a 8, but locking up a 8 is fun when you skid in turns (without damaging the trail).

  3. #3
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    There was actually a thread about this in recent weeks on the brake forum, with opinions from both sides. Got heated, if I remember right.

  4. #4
    ride hard take risks
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    6in rear 8in front.
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  5. #5
    Shortcutting Hikabiker
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    Quote Originally Posted by tacubaya
    (without damaging the trail).
    LOL, nice disclaimer, made me laugh.

  6. #6
    clyde in training
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    8 in. is pointless for the rear

  7. #7
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    Quote Originally Posted by 08nwsula
    8 in. is pointless for the rear
    Completely disagree. For your type of riding they are. Also, if one picks brakes that modulate well, little is lost in moving up in rotor size.

  8. #8
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    Quote Originally Posted by 08nwsula
    8 in. is pointless for the rear
    actually if you are heavier, you can really feel the difference
    the trick is ENJOYING YOUR LIFE EACH DAY, don't waste them away wishing for better days

  9. #9
    ride hard take risks
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    Quote Originally Posted by Jerk_Chicken
    Completely disagree. For your type of riding they are. Also, if one picks brakes that modulate well, little is lost in moving up in rotor size.
    Like you said there is a post on this that got carried away.








    6in Rotor on the back
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  10. #10
    Hard as nails
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    I guess it is fair to say that an 8in rotor is not necessary for most applications, but there is a home for them in certain instanses
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  11. #11
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    What about strictly Dh racing would a 8 or 6 be better in the rear provided your on a bike with a floating system. Does the size of the rotor affect brake jack at all?

  12. #12
    ride hard take risks
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    Quote Originally Posted by Jettj45
    What about strictly Dh racing would a 8 or 6 be better in the rear provided your on a bike with a floating system. Does the size of the rotor affect brake jack at all?
    It's all up to the nut holding the handlebar.
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  13. #13
    jones'in
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    Depends on your riding style, brakes and weight. I ride really hard AM, light FR and I weight 200 lbs. I run 8" front and rear. The bike came w' a 6" rotor in the rear....it was one of the first things that I changed out.

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  14. #14
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    ... and if we just ...

    well.. i like a big ones in the rear

    wow.. ok but really i run a 9" up front and an 8" out back.
    doesn't really feel more powerful then my previous 8/8 and 8/6 setups.
    but then again i'm 160 with gear, and can only notice a difference when on uber high speed sections. in the tight stuff I can't tell a difference.
    personal preference I guess.
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  15. #15
    keystone addict
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    Quote Originally Posted by chooofoojoo
    well.. i like a big ones in the rear

    wow.. ok but really i run a 9" up front and an 8" out back.
    doesn't really feel more powerful then my previous 8/8 and 8/6 setups.
    but then again i'm 160 with gear, and can only notice a difference when on uber high speed sections. in the tight stuff I can't tell a difference.
    personal preference I guess.

    wow.... confirming my suspicions.....

    and dont i remember you telling me those were too powerful?


    I like 8 and 8 for dh, and 6/6 for everything else
    I kinda wish my brakes actually worked, but I guess that just makes me faster, right?

  16. #16
    Happy Preston Owner
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    According to MBA magazine, an 8 inch rotor in back is useless, because a 6 inch rotor an lock up the rear wheel, and once that happens, more brake power isn't going to do you any good. I love my 8" rotor in front though!
    Quote Originally Posted by Hardtails Are Better
    Remember, the proper number of bikes for anyone to have is n+1, where n is the number of bikes you currently own.

  17. #17
    J'aime le Dunkeld
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    Quote Originally Posted by glacierangel
    According to MBA magazine, an 8 inch rotor in back is useless, because a 6 inch rotor an lock up the rear wheel, and once that happens, more brake power isn't going to do you any good. I love my 8" rotor in front though!
    MBA say a lot of things... I have one bike on 8/6 and one 8/8, both will be 8/8 as soon as i get round to it. On long downhills you will really appreciate how much less pressure is needed with the 8" rotor. Both my steeds are really heavy though, so I cant comment on the weight difference. Maybe not for weight weenie types

  18. #18
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    One place where the rear 8" saves my ass is on this sketchy descent from the summit point at Blue Mountain. Lots of babyheads and when you come down off some rocks, you're risking an endo because of the next ones. You need a really strong rear brake here to control the speed at this steep descent because front braking would put you over and into the rocks.

    The greater braking power also helps me to get into trackstand, or near trackstands fast at switchbacks. I have a sub 68 degree headangle and ride lots of singletrack, so I need more time in some places to make tough, technical switchbacks. The only way to do it is a slow speed turn or trackstand. The instant braking allows this.
    Last edited by Jerk_Chicken; 07-16-2007 at 12:52 PM.

  19. #19
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    What about pad wear? Running a 6 in disc in the rear means that you need more pressure to get the same stopping power as you would if you had a 8". If your are exerting more pressure (without locking up the brakes) your pads are getting worn faster. I run a 8" in front and 6" in back but I just thought I would bring up the point. For all out downhill I would say 8 and 8 because you can modulate your power better and you wont over heat your brake.

  20. #20
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    6" rear rotors can overheat on long, steep decents causing brake fade (loud squeal and bike vibration withreduction in brake power). This just happened to me this weekend in Snowmass. I lost my rear brake about 3/4 of the way down and I wan't able to lock it up when I wanted to. The dust didn't help the situation either. I'll be getting 8" for the rear soon. Not as big an issue if you don't race...

  21. #21
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    Split the difference....I am perfectly happy with my 7"

  22. #22
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    Same here. I run a 183 for almost all occasions and since I changed my brake layout with a Mono M4, I dropped to a 183 and have been fine.

  23. #23
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    Quote Originally Posted by rudeboybl
    6" rear rotors can overheat on long, steep decents causing brake fade (loud squeal and bike vibration withreduction in brake power). This just happened to me this weekend in Snowmass. I lost my rear brake about 3/4 of the way down and I wan't able to lock it up when I wanted to. The dust didn't help the situation either. I'll be getting 8" for the rear soon. Not as big an issue if you don't race...

    Exactly. The same happens on 8" rotors too. But you'll burn up pads quicker on fast descents w/6-7" rotors, been there and done that. Bigger rotors give you more power to modulate and allow you to ride faster and use the brake for less time, each time you use it, i.e. you aren't using the brake as long because it's more powerful and can be applied later than a brake that isn't as powerful and requires you to begin it's application much sooner to be as effective. Also takes less effort to use bigger rotors.
    All that said, 8" rotors aren't necessary for all types of riding and terrain, but it is nice to have when you get in an unforeseen situation where a lesser rotor might cause you to get injured. A helmet is only working when your head takes a shot from something, but you don't get on your bike w/o it.
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  24. #24
    I wear two thongs
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    Both!





    Keep in mind this is coming from a 230lb rider who needs all the stopping power I can find and Im on mech discs.
    I notice with the 8 all around my rear braking hand is less tired at the end of a day, I get less modulation controll but it is easy to attain more power with less work.

    With the 6 in the rear it takes more hand force to obtain maximum braking power but I do notice a ton more modulation that I have before the brake locks up on me.
    Hiking is just walking where its okay to pee... Sometimes old people go hiking by accident. -Demetri Martin-

  25. #25
    mtbr member
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    Quote Originally Posted by string
    Split the difference....I am perfectly happy with my 7"
    EXACTLY! If you're less than 200 lbs that's the way to go IMHO; more rock clearance and a good rotor design (I swear by Galfers) can more than make up for the one inch difference.

    Have FUN!

    G

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