A newbie needs help

Discussion in 'Bicycle Mechanics and Repairs' started by zigma, 7 Aug 2012.

  1. zigma

    zigma New Member

    Hi Everyone

    My name is Simon and I really need help and advice. This area will most likely become the biggest thread here, So here goes with the Newbie questions.

    1.I have been looking at chainsets and bottom brackets, Are they inter-changeable because I cannot figure out the difference.

    Thanks in advance everyone.
  2. rusty bearing

    rusty bearing Über Member

    Are we talking road bike or MTB here? What are you planning on swapping from and to so we can give a more definitive answer rather than generalisation?

    Hi back by the way:smile:
  3. OP

    zigma New Member

    Hi Rusty

    I believe the bike is a touring frame, it was originally made by orbit cycles. Been looking for a hands on project and get away from my computer. At least I can learn a lot by doing this also.
  4. rusty bearing

    rusty bearing Über Member

    I'm assuming that you probably have a square taper BB in place, so called because if you take the cranks off it's, well, square and tapered. It will be either a 68mm or 73mm shell if you measure it.The next measurement you need concerns the overall length of the rotating bit so you might end up with say 68 x 118 and that is what you would replace with. The second measurement (118) is important to maintain correct chainline. If you're luck when you've removed the old one it will have the size written on the barrel . There is english thread and italian thread but in this case it will be english so ignore that.
    If you change to a modern chainset with outboard cups the instructions will ask you to fit spacers for 68mm or omit them for 73mm.... simples.
    chainsets are reasonably interchangeable in that you are most likely to swap like for like and on your tourer this is probably a triple? If you wanted to put on a double or compact you might run into problems with the front mech and possibly shifter but I wouldn't worry about that for now.
    A bit of light reading for you.
    fortunately Alf has made just the bit you need free to download.
  5. and now you're tied to the computer trying to sort out your project. Don't you love irony? :tongue:
  6. OP

    zigma New Member

    Thanks for the advice!
    Yes my current bottom bracket is square taper, would it matter if i changed it for one that is not square? providing it is the same dimensions....

    Yes smokey I do see the irony! :smile:
  7. sidevalve

    sidevalve Über Member

    You can change it for anything you want if you have the engineering skills and equipment to do it. However unless you're just doing it for the sake of it, then why ? A large variety of straight replacements are available along with cranks,chainrings to mix n match to your taste. By all means do as you wish but if you want a bicycle as opposed to an engineering project keep it simple. It often works out better.
  8. accountantpete

    accountantpete Legendary Member

    You might consider updating to an external bearing based chainset.

    Shimano - Hollowtech II or Camapagnolo Ultra Torque etc.

  9. rusty bearing

    rusty bearing Über Member

    No you can change it to any other variety as long as you change to the matching chainset as well. Best way to go is probably the outboard cup route that accountantpete mentions in the previous reply. Reasonably priced, quick and easy to work on and widely available.
  10. RecordAceFromNew

    RecordAceFromNew Swinging Member

    West London
    Since it sounds like your bike can be oldish you might want to know that you might have to get your bb shell faced if you were to adopt an external BB and for it to last.

    For online diy texts you could do worse by looking up Park's extensive guides.
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