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Thread: gear ratios

  1. #1
    Senior Member mburgess86's Avatar
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    gear ratios

    Probably a dumb question but my wife has a 80s Takara 10 speed with down tube shifters and she would like to be able to climb easier. Is there a way to put a triple chain ring on her bike or change the chain ring sizes to make things easier? Any tips are appreciated.

    this is a picture of the bike if this helps.. http://www.flickr.com/photos/mburges...in/photostream

  2. #2
    26 tpi nut. sailorbenjamin's Avatar
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    I'd put a triple on it myself. Look at the back of the crank. Is there a 3rd set of holes where you can put another chainring on? If not you can get them on ebay or the for sale section here.
    A new (or used) freewheel with bigger sprockets is a simple thing to do, too. Easier than the triple but the triple gives you more range. They come with as many as 34 teeth but 32 is more common.
    I have spoken.

  3. #3
    Senior Member mburgess86's Avatar
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    cool that helps thank you!

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    that crank looks like it may be a Sakae CR with a 110 BCD. which means you could probably replace the chainrings (possibly both) with something with fewer teeth than you currently have (the front derailleur may have to be readjusted and a length of chain removed). chainrings in 110BCD, if that is indeed what it is, can be had dirt cheap, like 10-15 dollars delivered, on ebay.

    a closer shot of the crank would be helpful.



    BTW, here's a shot of a Sakae CR crank in 110 BCD (w/o chainrings)...

  5. #5
    Gearhead old's'cool's Avatar
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    Converting to a triple is usually feasible but there can be pitfalls. If you're not experienced with bikes and machines in general, it might help to find someone locally who is, to help (i.e. a friend or bike co-op; you don't want to pay a LBS to engineer a triple conversion for you). Or if you're willing to roll your sleeves up and learn from experience, you can dive in and see what happens. We'll be here to help.
    Things to consider in a triple conversion:
    Front derailleur range - can the existing FD acommodate the tooth difference, and the lateral movement required?
    Rear derailleur chain wrapping ability - can the existing RD wrap the additional tooth difference resulting from the new small chainring?
    chainstay clearance - does the frame, existing bottom bracket, and chosen triple crankset, in combination, allow clearance between the small chainring and the chainstay?
    If the answer to any of these is no, additional replacement components that alleviate the respective fitment issues will need to be identified and purchased.

    there is a secondary issue, chain length; it may be necessary to modify (most likely shorten) the chain, in order to optimize length for the new drivetrain. That is not a big deal, just requires an inexpensive chain tool and moderate skill to use it.

    That said, I have done 3 triple conversions, and the only component I've had to upgrade other than the crankset, in one instance, was an FD, which did not have enough lateral range for the triple crankset.
    Geoff
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  6. #6
    Senior Member RobbieTunes's Avatar
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    +1 if that's a Sakae CR with 110 BCD. Tons of chainrings to make it a compact.
    Performance's clearance bin had them for $10 the other day...

    Robbie ♪♫♪...☻

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