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  1. #1
    Mouth-Breather / Huffer
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    Avid BB7 Disc Brakes - 203mm or 185mm?

    My stock Tektro disc brakes on my Peace 9r SUUUUCK. Big time. To be fair, I was warned about them on MTBR before my purchase.

    I know I can inquire over in the Brake Forum, but I'm a clyde and I want to hear specifically from other clydes: Do I go with 203mm or 185mm BB7s?

    No, I'm not going to be doing any major DH action on my rigid 9r. Nevertheless, I do go fast and I want to be able to stop quickly. I'm not interested in going the Juicy route. Mechanical BB7s only.

    Are there any disadvantages to going with 203mm both front and back relative to going with 185s? Warping, efficiency, bent rotors? What about a 203mm in the front and a 185mm in back?

    Also, I'm noticing that some retailers specify a difference between front and rear calipers while others do not. Has there been a change with 2009 units that make the calipers interchangeable between front and rear?

    TIA!
    Last edited by dog.gone; 04-27-2009 at 11:22 AM.

  2. #2
    Fat boy Mod Moderator
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    09 models now come with both front and rear IS adapters as I understand it...
    i

    i'm running 180mm (or 185 don't remember which) bb7's up front on my main 29er rig... tektro rotors (and slightly modified adapter) and am happy with it...

    while you're spending money... spend the extra $20 for some sd7 levers to get the most out of your new stoppers
    - Surly Disc trucker
    - '82 trek 560 roadie

  3. #3
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    Thanks Mark. Greenfish has the Avid Speed Dial levers for $16.50 for the pair and free shipping for orders over $59.. Since Universal Cycles is in my figurative backyard, I'll probably just price match (well... as close as UC gets to true price matching) and pick everything up from them. I think the total from UC after PMing will be roughly $117.

    On the topic of UC, I just went through their custom wheelset function to see what it would cost for a set of hand-built Kris Holm wheels (Deore hub in front, XT in back). Total came to $246.

  4. #4
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    Quote Originally Posted by donalson
    i'm running 180mm (or 185 don't remember which) bb7's up front on my main 29er rig... tektro rotors (and slightly modified adapter) and am happy with it...
    I like your thrifty (and effective) streak! Since most of the stopping power comes from the front, this might be a good way for me to go as well.

  5. #5
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    I'm 6'4" and 330 lbs and I just upgraded to the 203 MM BB7's on the front and back wheels. With my girth, this is the only way I can actually stop on a downhill section. My bike did have Hayes MX1 160mm's and they didn't stop for crap.

  6. #6
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    Thanks, Sasquatch; great feedback. Have you experienced any downside to using the larger discs?

  7. #7
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    I've heard that some frames may have clearance issues with large rotors in the back, so that's something to thing about. Also, most forks have a recommended maximum rotor size, due to the added force generated by a larger rotor I guess.

    If you're ok on both those fronts I can't really see any disadvantage to running the larger rotors, other than a small amount of additional rotating mass.

  8. #8
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    I have 203 BB7's on one bike (Giant Reign) and 185 BB7's on my hardtail. The 185's are fine for the riding I do on the hardtail. They are actually pretty damn good. I weigh 265lbs.

  9. #9
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    Thanks, bvibert & jeffj! I've looked through the documentation for my GT Peace 9r and can't find any information related to max rotor. I could have missed it, however; A.D.D. isn't conducive to patiently reading manuls, instructions, ingredient lists, etc.

    I'm really hankerin' for the 203mm rotors, but I think I'm going to start in a conservative manner and go the route donalson has chosen. I'll start with 185mm BB7 in the front and leave the rear with the stock set-up. Then I can decide if it makes sense for me to go with 203mm up front and migrate the 185s to the rear. All also be installing the Avid Speed Dial 7 levers.

    Does this make sense or am I delaying the inevitable?

  10. #10
    Fat boy Mod Moderator
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    i got the bike setup with 160 (or 165 whatever it is) up front and the V in the back (refered to as running mullet)... the guy I got the bike from had done this because the karate monkey is a bit of a PITA to remove the rear wheel thanks to those track ends... have to loosen the rear caliper... lot easier to pull the V apart... the rear could use a dab more power.. but much more and i'd skid everywhere... a new set of pads should be good... only time it's not great is when it's wet out... and thats mostly the noise that annoys me (grinding sound akk)

    and yup... the kris hold wheelset should be fairly inexpensive...

    also speedgoat has the KH rims on sale right now... 36$ as i recall...

    will be a heavy wheelset... but outside of the worries of that hub and occasional maintenance you won't have to worry about em
    - Surly Disc trucker
    - '82 trek 560 roadie

  11. #11
    Fat boy Mod Moderator
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    prob delaying the inevatble... but worth a try...
    - Surly Disc trucker
    - '82 trek 560 roadie

  12. #12
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    Out of curiosity, are the BB7 calipers rotor-size specific, or is the only difference the adapter? In other words, if I get the 185mm BB7 rotor kit, could I simply buy a larger rotor and different adapter at a later date rather than a whole 203mm kit?

  13. #13
    Fat boy Mod Moderator
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    adapter specific... to upgrade size you swap adapters and the rotor and you are good to go... but in the end you'd spend a good bit more money going that route then just buying the whatever sized one up front
    - Surly Disc trucker
    - '82 trek 560 roadie

  14. #14
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    Understood. I went ahead and pulled the trigger on the 185mm front, a pair of Speed Dials and a new WTB Power V (to replace my Laser V that took a beating during a clipless/wheelie/brain fart moment).

    I price matched my Universal Cycles purchase to Grreenfish (well, as close as UC goes with their funky "price matching" policy) and I'll pick up the goods at their warehouse on Monday or Tuesday. Should be fun...

    Now I start a quest to find a replacement seatpost clamp for my funky-sized 26.8mm seatpost. Salsa doesn't seem to make a Lip Lock in 26.8mm nor does Hope, Thomson, etc. *THEN* I'll replace the seatpost I bent during the previously mentioned "brain fart" with a Thomson Elite setback in 26.8/330mm flavor.

  15. #15
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    Sounds like I'm a little late, but here is my 2 cents. They are quite a bit heavier than the 160's I had on there (doesn't matter when you weight 330 lbs ). They are pretty stout, it seems like I would have a harder time bending these than the 160's just because they are a lot thicker. The 200 MM on the back did just barely fit. It is probably 1/8" from the inside of my frame, but I haven't seen any rubbing. Overall the BB7's are awesome mechanical brakes and depending on your weight, you probably don't need the 200's.
    In reference to the max sized rotor for the fork, I have a Tora 318 air fork that allows up to 200 mm rotors. I also think this limitation is due to the strength of the fork and the higher torque of a larger rotor.

  16. #16
    Fat boy Mod Moderator
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    sure you are looking at the right sized post clamp? example... my karate monkey has a 27.2 post... but uses a 30mm clamp... clamp size is based on the OD of the tube
    - Surly Disc trucker
    - '82 trek 560 roadie

  17. #17
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    Quote Originally Posted by Sasquatch1413
    Sounds like I'm a little late, but here is my 2 cents.
    It's NEVER too late! All the feedback just adds to the ever-expanding knowledge base that is MTBR.

    They are quite a bit heavier than the 160's I had on there (doesn't matter when you weight 330 lbs ). They are pretty stout, it seems like I would have a harder time bending these than the 160's just because they are a lot thicker. The 200 MM on the back did just barely fit. It is probably 1/8" from the inside of my frame, but I haven't seen any rubbing. Overall the BB7's are awesome mechanical brakes and depending on your weight, you probably don't need the 200's.
    I'm 300# and could use all the braking power possible!

    In reference to the max sized rotor for the fork, I have a Tora 318 air fork that allows up to 200 mm rotors. I also think this limitation is due to the strength of the fork and the higher torque of a larger rotor.
    Once I put the new rotor(s) on, I'll report back here regarding any potential or actual clearance issues on the Peace 9r frame.

    Thanks!

  18. #18
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    Quote Originally Posted by donalson
    sure you are looking at the right sized post clamp? example... my karate monkey has a 27.2 post... but uses a 30mm clamp... clamp size is based on the OD of the tube
    Oh. It looks like I might have to investigate a bit further then. That could have been a real bummer if you hadn't mentioned that key little fact. Thanks yet *again* for your insight!

  19. #19
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    How many miles are on your ride? It took about 20-25 to get my tektro's broken in. They worked great, but the rear sounds like shiat. I went with the fx-9's on the front and I am just now getting them broken in. I ordered the 185 mm rotor with the fronts, but stuck with the stock 6 in. Tektro rotor when it came time to install. No complaints about staying with the six.

  20. #20
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    I'm running 185 BB7's front and rear and love it. I did rough up the pads and rotors with sandpaper to help "bed" the pads... or you could just slap a little mud on the rotors.

    265lbs now, 298lbs when I bought the BB7's

  21. #21
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    Quote Originally Posted by bornhere
    How many miles are on your ride? It took about 20-25 to get my tektro's broken in. They worked great, but the rear sounds like shiat.
    I don't have a bike computer yet, but I would estimate about 45-50 miles on the bike/brakes.

    I went with the fx-9's on the front and I am just now getting them broken in. I ordered the 185 mm rotor with the fronts, but stuck with the stock 6 in. Tektro rotor when it came time to install. No complaints about staying with the six.
    I'll give the rear Tektros another chance while I test the new BB7 on the front. If I don't have to invest in new rear brakes, I can use the $$$ to replace my %$^# bent stock seatpost.

    I'm running 185 BB7's front and rear and love it. I did rough up the pads and rotors with sandpaper to help "bed" the pads... or you could just slap a little mud on the rotors.
    I might break out the sandpaper myself...

    265lbs now, 298lbs when I bought the BB7's
    Congratulations! I'd like to get back to a fightin' weight of about 250#

  22. #22
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    Quote Originally Posted by dog.gone
    Understood. I went ahead and pulled the trigger on the 185mm front, a pair of Speed Dials and a new WTB Power V (to replace my Laser V that took a beating during a clipless/wheelie/brain fart moment).

    I price matched my Universal Cycles purchase to Grreenfish (well, as close as UC goes with their funky "price matching" policy) and I'll pick up the goods at their warehouse on Monday or Tuesday. Should be fun...

    Now I start a quest to find a replacement seatpost clamp for my funky-sized 26.8mm seatpost. Salsa doesn't seem to make a Lip Lock in 26.8mm nor does Hope, Thomson, etc. *THEN* I'll replace the seatpost I bent during the previously mentioned "brain fart" with a Thomson Elite setback in 26.8/330mm flavor.
    I have a Thomson Elite 26.8 seatpost in like new condition that I'm willing to sell; however, it is not setback. I also might be willing to take the Tektro Disc brakes off your hands. Perhaps a deal could be arrranged. Send me a PM if interested.

  23. #23
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    Hey foxtrot,

    After donalson mentioned that I would need a seatpost collar that had a bigger diameter than my seatpost (doh!), I also took a closer look at the seatpost itself. It turns out that not only do I need a setback, but I need it in the 410mm length.

    As for the Tektros, once I get the BB7s installed and seated, I'll probably be willing to part with the stock brakes. I'll send you a PM when all the dust as cleared.

    Thanks!

  24. #24
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    Quote Originally Posted by dog.gone
    Hey foxtrot,

    After donalson mentioned that I would need a seatpost collar that had a bigger diameter than my seatpost (doh!), I also took a closer look at the seatpost itself. It turns out that not only do I need a setback, but I need it in the 410mm length.

    As for the Tektros, once I get the BB7s installed and seated, I'll probably be willing to part with the stock brakes. I'll send you a PM when all the dust as cleared.

    Thanks!
    Cool...just let me know.

  25. #25
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    good thoughts on the break set up... I like your thinking..
    I had hyd. juicy 7's on my evo with the big rotors... was nice, but I personally bent two rotors on size alone... they got in the way for some reason.
    My current ride has the same brakes but I have the smaller rotors... contemplating going with a larger up front, but for now its working very well...

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