Schwinn Homegrown Model Identifier Forums General Stuff Homegrown Talk 2000 Orange Homegrown – trying to replace bottom bracket and crankset

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  • #1725
    ta373
    Member

    Hi – I’m 100% new to all of this, but really like this bike, and would like to replace the bottom bracket and crankset. Managed to snap my chain, and bend up the chain ring pretty badly.

    I ignornatly purchased a new crankset thinking I could just swap out – but my bottom bracket style isn’t compatible with what I purchaed.

    Turns out, the bottom bracket was also cross threaded.

    I’d love to update all of the above – but I’m honestly unsure of what to order/where to start – I’ve not worked on bikes before.

    Happy to toss a bit of money at it, just don’t know what direction to toss the money!

    #5600
    bikeric
    Member

    The right side bottom bracket (behind the gears) is Reverse-threaded.  That means you must rotate the wrench “Righty” to “Loosy”.  The left side is normally threaded so “Lefty” – “Loosy”.

    The bottom bracket width is 73mm, so get the bottom bracket for the crankset you purchased.  If you truely think the previous bottom bracket was cross-threaded, you should take the bike to a bike shop so they can chase the threads of the bottom bracket with the proper tap.

    Good Luck!!

    #5605
    ta373
    Member

    Thank you very much for the help! I don’t have the wrench for the bottom bracket yet – I misspoke when I said it was cross threaded – it’s not the BB that’s cross threaded (into the frame) but rather the crank arms that are cross threaded (specifically the left one) into the BB.

    I’m struggling to come up to speed with terms – what would be the correct bottom bracket wrench to remove this BB? 

    I’m also struggling to find a replacement BB and crankset – again, awash in terminolgy/sizes/brands. Other than a 73MM BB (thanks to you!) – I’m a little clueless as to how to piece together a good BB/crankset pairing.

    Turns out the one that I got (via some neighborly help from a buddy down the road) is HUUUUUGE in comparison to my current one – like basically a 1:1 gearing on the smallest chainring.

    I dig the bike, but I’m a little embarassed at how little I know about how to pull out the parts that aren’t working, and swap em for decent replacement ones.

    #5606
    tomatoadmin
    Keymaster

    If you can post some pictures of your current setup that will help us diagnose your problem. Depending on the crankset you have, the crank arms interface with a square taper spindle, splined spindle, or are two-piece, where the spindle is integrated into one crank arm. The spindle interface will dictate which crank arm puller you should use, or if you have what should be self-extracting bolts.

    #5608
    ta373
    Member

    Hey all, thanks very much for the help thus far. Here’s a shot of the bottom bracket/frame with the crank off.

    Since I bent the smallest chain ring, and the other two are worn, I’m hoping to do the bottom bracket, and chain ring – which I’m guessing, means, I need to get all componsents out of the frame – but the only two I’m able to name are: bottom bracket, and crank.

    Not sure if I should be looking to swap out/purchase more?

    I’ve attached the pic of the bottom bracket with the crank off.

    ta373-pastedgraphic1.jpg

    #5611
    bikeric
    Member

    I personally like the Park Tool BBT-22.  There is much sand hiding the internal splines, but they are there and you will need an internal spline tool for the opposite side.  The side pictured: Rotate Left to Loosen.  Opposite side: Rotate Right to Loosen.  I’m honestly surprised you were able to remove the (XT?) crankarms because they require a special oversize button if using the standard tool. 

    https://www.parktool.com/product/bottom-bracket-tool-bbt-22

    What you pictured is a Shimano Octalink V2 bottom bracket.  My guess is you had a Shimano XT M751 crankset.  What crankset did you purchase to replace it with?  Need to know that information to make sure you get the proper bottom bracket.

    #5612
    ta373
    Member

    Managed to get it off thanks to your recommendation!

    The current bottom bracket is a Shimano BB-ES70, BC 1.37×24.

    I have no allegiance to this BB, unless yall tell me I should?

    I was going to try and just get a new BB and crankset – but don’t know where to start on that. If I’m going to do that, is the current BB relevant?

    ta373-image.jpeg

    #5615
    bikeric
    Member

    It’s strange that the bike had a 68mm bottom bracket installed.  The frame should have had a 73mm, but maybe that explains the visible rust where the loose side cup did not fully cover the inner shell.

    What matters now is matching the proper bottom bracket axle to the crankset.  There are multiple options with differenct axle splines/diameter etc….

     

    #5616
    chas60422
    Member

    replacing the bottom bracket and crankset may be hard to do.  Get calipers or a ruler and measure the width of the bottom bracket shell.  That will tell you for sure if its 68 or 73 mm.  Most cranks use a spindle that is attached to one of the crank arms.  Your current BB has the spindle part of the BB.  

    You also need to make sure you have the correct # of chainrings.  Is it a 3, 2, or 1 (doubt 1).  Then make sure the ring sizes are the same.  

    It’s possible that you might be able to replace the chainring and not the whole bb and crank set up.  Take your crank to a good local bike store with a repair dept and have them look at the chainrings.  Its highly possible all you need to do is replace the chainrings and not anything else.  In fact the chain rings wear out along with the chain and rear cassette and all need to be replaced at some time or another.  If the crank arm spider arms are fine, then just replace the chainrings and you’re back riding.

     

    One thing to consider that finding parts to replace older components can be quite costly and easy to fall into a money pit.  However, if you’re wanting to be more modern and upgrade to a 1x 11 or 12 speed, now is a good time to do so.  Again you will need to replace the BB, crank, chain, rear cassette, and rear derailluer if you go 1×11 or 12.  

    #5617
    chas60422
    Member

    for replacing your old BB and new crank make sure you get a 68/73 mm English threaded BB and a 24 mm spindle crank.  Some cranks comes with the BB.

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