old bike new cranks

Discussion in 'Cycling Equipment' started by robsy, Aug 19, 2009.

  1. robsy

    robsy New Member

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    I have a 15 yr old Dawes road bike and need a new crankset, the thread in one of the cranks is all but ruined and my pedal dropped off. I just know its probably not a simple option of buying a new one and getting it fitted but am not sure. Are there issues with the bottom bracket?
    Any advice is appreciated
    Cheers
     
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  2. jhuskey

    jhuskey Moderator

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    If the bottom bracket is 15 years old I would look at replacing it also.It probably has issues at that age.
     
  3. robsy

    robsy New Member

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    how can i tell which bottom bracket to get?
    Sorry if the question is a bit dumb
     
  4. Peter@vecchios

    [email protected] New Member

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    The bottom bracket is matched to the crank. If you BB feels smooth, doesn't look pitted, it 'may' be OK. Which crank do you have on the bicycle?

    If both done, it is simple to install a modern one onto the frame.
     
  5. robsy

    robsy New Member

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    they are 500EX shimano, bio pace.
    is there a way to measure the BB?
     
  6. robsy

    robsy New Member

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    I probably have to take it out and look i guess?

     
  7. alfeng

    alfeng Well-Known Member

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    The frame's BB shell is probably 68mm wide ...

    The threading is more than likely ENGLISH ...

    You should therefore buy a BB with ENGLISH THREADED cups (left hand thread on the fixed, drive side, right hand thread on the adustable, non-drive side.)

    My only recommendation is that you DO NOT buy an ISIS splined BB & crank.

    BTW. My recollection is that Biopace was more common about 25+ years ago ... a traditional BB with "loose" bearings ... 113mm asymmetrical spindle with a "double" crankset.
     
  8. robsy

    robsy New Member

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    English threaded cups? Does that rule out Shimano?


     
  9. alfeng

    alfeng Well-Known Member

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    Shimano makes English threaded BBs/(cups) ... probably, more than 90% of the Bottom Brackets Shimano produces have English threading.
     
  10. robsy

    robsy New Member

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    I see that cranksets are sold according to weather the bike is 8,9 or 10 speed. As my bike is just 7 speed can I buy a crankset which is meant for 9 speed, or 10 speed for that matter?
    Thanks
     
  11. alfeng

    alfeng Well-Known Member

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    You can use almost any crank & BB combination on your bike which your budget allows.
     
  12. kdelong

    kdelong Well-Known Member

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    The reason cranksets are sold like that is because the Chainrings are different thicknesses. The chain used on a 10 speed bike is thinner than the chain used on an 8 speed bike, so the chain rings have to be thinner. Since you are riding a 7-speed, the chain will be thicker and may be used with any of these cranksets.

    As for the BB, check with your local bike shop. They should be able to set you up with the correct BB. If it is a Dawes, it is English threaded.
     
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