New bottom bracket on an old frame?
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  1. #1
    rooky tour rider
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    New bottom bracket on an old frame?

    Hey people,

    as you can see, this is my first post.
    Just started cycling this year. About to pass my first 1000 km milestone and I'm loving it!

    My bike is a second-hand Cannondale Caad5 (r800 SI) frame, with a old model octalink bottom bracket.
    I'm looking to replace it and the crankset in the near future, but am confused as to what I could instal in its place since BB standards went through somewhat of a transformation since this baby came out.

    The numbers on the BB say: BC1.37 68, which are sizes rather than a modelnumber, but it's all I've got. Don't really feal like tearing the bike apart without heaving new parts.
    The crankset is a FC-7700, 175 mm set.

    I would like to replace it with something newer like a FC-6700 or FC-7900, depending on what I can find second-hand.
    BUT, these use the new type of BB's and I'm wondering if I can replace my bracket with a new model? If that's possible with this frame.

    Thanks in advance, hope to find some answers

  2. #2
    RoadBikeReview Member
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    You have a standard size English-threaded bottom-bracket shell. 1.37 is the diameter in inches of the threaded portion, and 68 mm is the width of the shell from face to face. The vast majority of bottom brackets out there will fit it. Just buy the appropriate bb for the crankset you choose.

    Is there a reason you want to replace the bb and crank? You didn't mention any issues with them. A newer model won't change performance unless your old ones are messed up in some way.
    "None of us knows for sure what's out there; that's why we keep looking. Keep your faith; travel hopefully. The universe will surprise you, constantly." The 13th Doctor.

  3. #3
    rooky tour rider
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    The old crank has a lot of tearing in the coating.
    It is nothing major that they will break anytime soon, but I'm looking for a replacement in let's say, a year or so.
    I know this could also be fixed with just a new chainring, but I'd rather have the whole thing replaced so it is good to go for another 5 years in its entirety



    I'm just waiting till I can find a second hand for a good price.

    Thanks for the info, I'm a lot more reassured in finding a bb
    I really thought for a second this frame was fixed for a certain type of bracket.

  4. #4
    RoadBikeReview Member
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    The Octalink BB was one of the best. When it comes to BB's newer is definitely not better. If there's nothing wrong with it I'd keep it as long as you can. The corrosion showing is cosmetic, and could be cleaned up.

    Being a CAAD 5 owner myself my first upgrade would be a set of 25mm tires, or even a 28mm on the rear. It fits, I've tried.
    We just don’t realize the most significant moments of our lives when they’re happening
    Back then I thought “well there'll be other days”
    I didn’t realize that was the only day
    https://www.youtube.com/watch?v=Y9yrupye7B0

    There's sometimes a buggy.
    How many drivers does a buggy have?
    One.
    So let's just say I'm drivin' this buggy...
    and if you fix your attitude you can ride along with me.
    http://www.youtube.com/watch?v=GekiIMh4ZkM

  5. #5
    RoadBikeReview Member
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    Based on your pictures, the rings don't really look all that worn at all. Also, those octalinks last forever so 5 years is very plausible depending on how it was all maintained.

  6. #6
    rooky tour rider
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    I just treated myself to a pair of Continental GP 4000s 23mm tires, so I dont think a new set will arrive for at least 1 season :P

    Why would I want to go bigger in tiresize? Isn't it very comprimising in speed?

  7. #7
    RoadBikeReview Member
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    Quote Originally Posted by Sanders View Post
    I just treated myself to a pair of Continental GP 4000s 23mm tires, so I dont think a new set will arrive for at least 1 season :P

    Why would I want to go bigger in tiresize? Isn't it very comprimising in speed?
    In future, come to this place before buying anything bike related. There's plenty of discussion and info about everything cycling, including the issue of tire size. And no, 25mm tires are probably faster in the real world than 23mm.
    We just don’t realize the most significant moments of our lives when they’re happening
    Back then I thought “well there'll be other days”
    I didn’t realize that was the only day
    https://www.youtube.com/watch?v=Y9yrupye7B0

    There's sometimes a buggy.
    How many drivers does a buggy have?
    One.
    So let's just say I'm drivin' this buggy...
    and if you fix your attitude you can ride along with me.
    http://www.youtube.com/watch?v=GekiIMh4ZkM

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