BMX Bike building

Discussion in 'Cycling Equipment' started by Bob McCarthy, Feb 4, 2006.

  1. Bob McCarthy

    Bob McCarthy Guest

    We're attempting to build a BMX bike from scratch, and are having a
    heck of a time of it; nothing seems to fit together.

    Frame is a Hyper Assault Pro XL

    Bottom bracket threading - can't seem to get the crank into the BB.
    Both the frame and cranks advertise Euro BB. Which side is CW tighten,
    and which side is CCW tighten?

    Seat tube ID is listed as 26.8 mm, though there appears to be too much
    'slop' after the tube is inserted - can't tighten the downtube. Are we
    missing a part for this?

    Thanks in advance for any info you can provide.
     
    Tags:


  2. Nate Knutson

    Nate Knutson Guest

    Bob McCarthy wrote:
    > We're attempting to build a BMX bike from scratch, and are having a
    > heck of a time of it; nothing seems to fit together.
    >
    > Frame is a Hyper Assault Pro XL
    >
    > Bottom bracket threading - can't seem to get the crank into the BB.
    > Both the frame and cranks advertise Euro BB. Which side is CW tighten,
    > and which side is CCW tighten?


    The right side is CCW to tighten, left is CW. You can always determine
    this on anything threaded by looking at the angle of the threads.

    > Seat tube ID is listed as 26.8 mm, though there appears to be too much
    > 'slop' after the tube is inserted - can't tighten the downtube. Are we
    > missing a part for this?


    What you mean by "can't tighten the downtube" is unclear because
    'downtube' is the term for the tube connecting the headtube to the BB.
    If the opening and the post are both nomimally 26.8 and there's much
    looseness at all, then it's a tolerance problem. The best place to
    start in solving that would be to determine what the frame and post are
    actually measuring currently. If the post is too small you can get a
    different post, use a shim, or get the one you have knurled. If the
    frame opening is too wide, that's more of a pain. You could use a shim,
    warranty the frame, try a larger size post if the problem is REALLY bad
    (but normally this wouldn't work), or try a 26.8 post that's been
    knurled, which is something for a good shop to do. The shim solution is
    inelegant and shouldn't be necessary but works.

    > Thanks in advance for any info you can provide.
     
  3. Bob McCarthy

    Bob McCarthy Guest

    On 4 Feb 2006 18:55:35 -0800, "Nate Knutson" <[email protected]>
    wrote:

    >
    >Bob McCarthy wrote:
    >> We're attempting to build a BMX bike from scratch, and are having a
    >> heck of a time of it; nothing seems to fit together.
    >>
    >> Frame is a Hyper Assault Pro XL
    >>
    >> Bottom bracket threading - can't seem to get the crank into the BB.
    >> Both the frame and cranks advertise Euro BB. Which side is CW tighten,
    >> and which side is CCW tighten?

    >
    >The right side is CCW to tighten, left is CW. You can always determine
    >this on anything threaded by looking at the angle of the threads.


    Both the frame and the bearing cup state they are Euro BB, but the
    fit just isn't there. TRhe cup is just too big to fit easily. Are
    there different thread sizes for Euro BB's?

    >> Seat tube ID is listed as 26.8 mm, though there appears to be too much
    >> 'slop' after the tube is inserted - can't tighten the downtube. Are we
    >> missing a part for this?

    >
    >What you mean by "can't tighten the downtube" is unclear because
    >'downtube' is the term for the tube connecting the headtube to the BB.
    >If the opening and the post are both nomimally 26.8 and there's much
    >looseness at all, then it's a tolerance problem. The best place to
    >start in solving that would be to determine what the frame and post are
    >actually measuring currently. If the post is too small you can get a
    >different post, use a shim, or get the one you have knurled. If the
    >frame opening is too wide, that's more of a pain. You could use a shim,
    >warranty the frame, try a larger size post if the problem is REALLY bad
    >(but normally this wouldn't work), or try a 26.8 post that's been
    >knurled, which is something for a good shop to do. The shim solution is
    >inelegant and shouldn't be necessary but works.


    My apologies for the terminpolgy. I meant the tube that is attached to
    the seat. Both the tube manufacturer and the bike manufacturer state
    the seat tube size is 26.8, but there's just too much room in the
    tube.

    >> Thanks in advance for any info you can provide.
     
  4. Nate Knutson

    Nate Knutson Guest

    Bob McCarthy wrote:
    > On 4 Feb 2006 18:55:35 -0800, "Nate Knutson" <[email protected]>
    > wrote:
    >
    > >
    > >Bob McCarthy wrote:
    > >> We're attempting to build a BMX bike from scratch, and are having a
    > >> heck of a time of it; nothing seems to fit together.
    > >>
    > >> Frame is a Hyper Assault Pro XL
    > >>
    > >> Bottom bracket threading - can't seem to get the crank into the BB.
    > >> Both the frame and cranks advertise Euro BB. Which side is CW tighten,
    > >> and which side is CCW tighten?

    > >
    > >The right side is CCW to tighten, left is CW. You can always determine
    > >this on anything threaded by looking at the angle of the threads.

    >
    > Both the frame and the bearing cup state they are Euro BB, but the
    > fit just isn't there. TRhe cup is just too big to fit easily. Are
    > there different thread sizes for Euro BB's?


    Nope. Euro is always the same 1.375" x 24tpi size, in either a
    nominally 68mm or 73mm wide shell.

    Part of the background here is that "Euro" is BMX's word for the
    regular ISO bottom brackets found on most current adult bikes. There
    are and have been numerous other somewhat similar threaded BB sizes, of
    which only Italian is still somewhat common (used mostly on a few road
    bikes).

    Italian is slightly larger (36mm x 24tpi, about 1 mm wider than ISO).
    Since this is a race frame, one thing could be going on here is that
    you've found yourself with an Italian BB cartridge. Also, both cups
    thread in clockwise on Italian BB's.

    > >> Seat tube ID is listed as 26.8 mm, though there appears to be too much
    > >> 'slop' after the tube is inserted - can't tighten the downtube. Are we
    > >> missing a part for this?

    > >
    > >What you mean by "can't tighten the downtube" is unclear because
    > >'downtube' is the term for the tube connecting the headtube to the BB.
    > >If the opening and the post are both nomimally 26.8 and there's much
    > >looseness at all, then it's a tolerance problem. The best place to
    > >start in solving that would be to determine what the frame and post are
    > >actually measuring currently. If the post is too small you can get a
    > >different post, use a shim, or get the one you have knurled. If the
    > >frame opening is too wide, that's more of a pain. You could use a shim,
    > >warranty the frame, try a larger size post if the problem is REALLY bad
    > >(but normally this wouldn't work), or try a 26.8 post that's been
    > >knurled, which is something for a good shop to do. The shim solution is
    > >inelegant and shouldn't be necessary but works.

    >
    > My apologies for the terminpolgy. I meant the tube that is attached to
    > the seat. Both the tube manufacturer and the bike manufacturer state
    > the seat tube size is 26.8, but there's just too much room in the
    > tube.


    You do have a seat collar for the bike, right?
     
  5. Bob McCarthy

    Bob McCarthy Guest


    >> Both the frame and the bearing cup state they are Euro BB, but the
    >> fit just isn't there. TRhe cup is just too big to fit easily. Are
    >> there different thread sizes for Euro BB's?


    >Nope. Euro is always the same 1.375" x 24tpi size, in either a
    >nominally 68mm or 73mm wide shell.
    >
    >Part of the background here is that "Euro" is BMX's word for the
    >regular ISO bottom brackets found on most current adult bikes. There
    >are and have been numerous other somewhat similar threaded BB sizes, of
    >which only Italian is still somewhat common (used mostly on a few road
    >bikes).
    >
    >Italian is slightly larger (36mm x 24tpi, about 1 mm wider than ISO).
    >Since this is a race frame, one thing could be going on here is that
    >you've found yourself with an Italian BB cartridge. Also, both cups
    >thread in clockwise on Italian BB's.


    BTW, thanks so much for your info; we really appreciate it.

    We're having some success getting them in to the frame, but they don't
    seem to fit too well. The cartridges are reverse threaded (one CW, the
    other CCW) Here is the crank bought:
    http://www.danscomp.com/cgi-bin/hazel.cgi?action=DETAIL&item=451023


    >> My apologies for the terminolgy. I meant the tube that is attached to
    >> the seat. Both the tube manufacturer and the bike manufacturer state
    >> the seat tube size is 26.8, but there's just too much room in the
    >> tube.

    >
    >You do have a seat collar for the bike, right?


    Er, we will tomorrow. Since we bought the frame separately from all
    the other parts, no 'assembly' instructions came with any of the
    parts. We don't know what we're missing. In other words, we don't know
    what we don't know.

    Again, thanks!
     
  6. Nate Knutson

    Nate Knutson Guest

    Bob McCarthy wrote:
    > >> Both the frame and the bearing cup state they are Euro BB, but the
    > >> fit just isn't there. TRhe cup is just too big to fit easily. Are
    > >> there different thread sizes for Euro BB's?

    >
    > >Nope. Euro is always the same 1.375" x 24tpi size, in either a
    > >nominally 68mm or 73mm wide shell.
    > >
    > >Part of the background here is that "Euro" is BMX's word for the
    > >regular ISO bottom brackets found on most current adult bikes. There
    > >are and have been numerous other somewhat similar threaded BB sizes, of
    > >which only Italian is still somewhat common (used mostly on a few road
    > >bikes).
    > >
    > >Italian is slightly larger (36mm x 24tpi, about 1 mm wider than ISO).
    > >Since this is a race frame, one thing could be going on here is that
    > >you've found yourself with an Italian BB cartridge. Also, both cups
    > >thread in clockwise on Italian BB's.

    >
    > BTW, thanks so much for your info; we really appreciate it.
    >
    > We're having some success getting them in to the frame, but they don't
    > seem to fit too well. The cartridges are reverse threaded (one CW, the
    > other CCW) Here is the crank bought:
    > http://www.danscomp.com/cgi-bin/hazel.cgi?action=DETAIL&item=451023


    So those are normal Euro cranks.

    First of all, grease the BB threads if you haven't already.

    It's somewhat easy to cross-thread BB cups. Be careful about this - a
    good tip is to always start threading in the cup by hand. If it's
    possible that you've done something to damage the threads, like
    cross-thread a cup, be really cautious. If this is the case or the
    threads seem excessively rough in general, it would probably be worth
    it to have a shop look at it and chase the threads using a special tool
    (if they deem it a good idea). This would cost around $15 and make the
    cups go in and out easily.

    Keep in mind that crossthreaded BB cups can really mess up a frame,
    especially an aluminum one, which I'm pretty sure yours is.

    OTOH, it's very common for BB cups to have much more friction than
    ideal going in. Obviously, it helps to have a good feel for this.

    Also, if the cups are pre-treated with a threadlocking compound, that
    will add a lot of friction.

    > >> My apologies for the terminolgy. I meant the tube that is attached to
    > >> the seat. Both the tube manufacturer and the bike manufacturer state
    > >> the seat tube size is 26.8, but there's just too much room in the
    > >> tube.

    > >
    > >You do have a seat collar for the bike, right?

    >
    > Er, we will tomorrow. Since we bought the frame separately from all
    > the other parts, no 'assembly' instructions came with any of the
    > parts. We don't know what we're missing. In other words, we don't know
    > what we don't know.
    >
    > Again, thanks!
     
  7. Bob McCarthy

    Bob McCarthy Guest

    Brought the bike to the local shop - good guys there. In an instant
    they saw that the threading for the BB wasn't done properly - first
    two thread lines were bad. They took the old BB out and reamed out the
    frame. So much for Chinese bicycle craftsmanship, or at least the
    factory that made the Hyper model I now have.

    Also, the seat tube is not as specified (26.8), it's 28-something.
    Needed a shim to make it fit. Only 5 bucks, but still, it shouldn't be
    necessary. Now, I need to deal with the folks at Dan's Comp regarding
    a bad bearing that was needlessly stripped due to the faulty
    craftsmanship of the frame.

    More to come...

    On 4 Feb 2006 21:39:01 -0800, "Nate Knutson" <[email protected]>
    wrote:

    >
    >Bob McCarthy wrote:
    >> >> Both the frame and the bearing cup state they are Euro BB, but the
    >> >> fit just isn't there. TRhe cup is just too big to fit easily. Are
    >> >> there different thread sizes for Euro BB's?

    >>
    >> >Nope. Euro is always the same 1.375" x 24tpi size, in either a
    >> >nominally 68mm or 73mm wide shell.
    >> >
    >> >Part of the background here is that "Euro" is BMX's word for the
    >> >regular ISO bottom brackets found on most current adult bikes. There
    >> >are and have been numerous other somewhat similar threaded BB sizes, of
    >> >which only Italian is still somewhat common (used mostly on a few road
    >> >bikes).
    >> >
    >> >Italian is slightly larger (36mm x 24tpi, about 1 mm wider than ISO).
    >> >Since this is a race frame, one thing could be going on here is that
    >> >you've found yourself with an Italian BB cartridge. Also, both cups
    >> >thread in clockwise on Italian BB's.

    >>
    >> BTW, thanks so much for your info; we really appreciate it.
    >>
    >> We're having some success getting them in to the frame, but they don't
    >> seem to fit too well. The cartridges are reverse threaded (one CW, the
    >> other CCW) Here is the crank bought:
    >> http://www.danscomp.com/cgi-bin/hazel.cgi?action=DETAIL&item=451023

    >
    >So those are normal Euro cranks.
    >
    >First of all, grease the BB threads if you haven't already.
    >
    >It's somewhat easy to cross-thread BB cups. Be careful about this - a
    >good tip is to always start threading in the cup by hand. If it's
    >possible that you've done something to damage the threads, like
    >cross-thread a cup, be really cautious. If this is the case or the
    >threads seem excessively rough in general, it would probably be worth
    >it to have a shop look at it and chase the threads using a special tool
    >(if they deem it a good idea). This would cost around $15 and make the
    >cups go in and out easily.
    >
    >Keep in mind that crossthreaded BB cups can really mess up a frame,
    >especially an aluminum one, which I'm pretty sure yours is.
    >
    >OTOH, it's very common for BB cups to have much more friction than
    >ideal going in. Obviously, it helps to have a good feel for this.
    >
    >Also, if the cups are pre-treated with a threadlocking compound, that
    >will add a lot of friction.
    >
    >> >> My apologies for the terminolgy. I meant the tube that is attached to
    >> >> the seat. Both the tube manufacturer and the bike manufacturer state
    >> >> the seat tube size is 26.8, but there's just too much room in the
    >> >> tube.
    >> >
    >> >You do have a seat collar for the bike, right?

    >>
    >> Er, we will tomorrow. Since we bought the frame separately from all
    >> the other parts, no 'assembly' instructions came with any of the
    >> parts. We don't know what we're missing. In other words, we don't know
    >> what we don't know.
    >>
    >> Again, thanks!
     
  8. Bob McCarthy

    Bob McCarthy Guest

    Good news!!

    Kudos to Dan's Comp for their customer service. I spoke to them Monday
    AM, describing the problem. The person reviewed my order, asked which
    side the bearing was on, and said they would drop one to me. Should be
    at my house in 2 to 5 business days.

    "Thanks" says I.

    Tuesday comes, and the bearing is at the house. Greased it and put it
    into the bike. Fits like buttah.

    Hats off to Dan's Comp. Mistakes can happen to anyone/any company.
    It's how you handle the problems that will keep me coming back.

    And Nate, a BIG THANK YOU for all your assistance; couldn't have done
    it without you.

    Bob


    On Sun, 05 Feb 2006 22:23:19 GMT, Bob McCarthy <[email protected]>
    wrote:

    >Brought the bike to the local shop - good guys there. In an instant
    >they saw that the threading for the BB wasn't done properly - first
    >two thread lines were bad. They took the old BB out and reamed out the
    >frame. So much for Chinese bicycle craftsmanship, or at least the
    >factory that made the Hyper model I now have.
    >
    >Also, the seat tube is not as specified (26.8), it's 28-something.
    >Needed a shim to make it fit. Only 5 bucks, but still, it shouldn't be
    >necessary. Now, I need to deal with the folks at Dan's Comp regarding
    >a bad bearing that was needlessly stripped due to the faulty
    >craftsmanship of the frame.
    >
    >More to come...
    >
    >On 4 Feb 2006 21:39:01 -0800, "Nate Knutson" <[email protected]>
    >wrote:
    >
    >>
    >>Bob McCarthy wrote:
    >>> >> Both the frame and the bearing cup state they are Euro BB, but the
    >>> >> fit just isn't there. TRhe cup is just too big to fit easily. Are
    >>> >> there different thread sizes for Euro BB's?
    >>>
    >>> >Nope. Euro is always the same 1.375" x 24tpi size, in either a
    >>> >nominally 68mm or 73mm wide shell.
    >>> >
    >>> >Part of the background here is that "Euro" is BMX's word for the
    >>> >regular ISO bottom brackets found on most current adult bikes. There
    >>> >are and have been numerous other somewhat similar threaded BB sizes, of
    >>> >which only Italian is still somewhat common (used mostly on a few road
    >>> >bikes).
    >>> >
    >>> >Italian is slightly larger (36mm x 24tpi, about 1 mm wider than ISO).
    >>> >Since this is a race frame, one thing could be going on here is that
    >>> >you've found yourself with an Italian BB cartridge. Also, both cups
    >>> >thread in clockwise on Italian BB's.
    >>>
    >>> BTW, thanks so much for your info; we really appreciate it.
    >>>
    >>> We're having some success getting them in to the frame, but they don't
    >>> seem to fit too well. The cartridges are reverse threaded (one CW, the
    >>> other CCW) Here is the crank bought:
    >>> http://www.danscomp.com/cgi-bin/hazel.cgi?action=DETAIL&item=451023

    >>
    >>So those are normal Euro cranks.
    >>
    >>First of all, grease the BB threads if you haven't already.
    >>
    >>It's somewhat easy to cross-thread BB cups. Be careful about this - a
    >>good tip is to always start threading in the cup by hand. If it's
    >>possible that you've done something to damage the threads, like
    >>cross-thread a cup, be really cautious. If this is the case or the
    >>threads seem excessively rough in general, it would probably be worth
    >>it to have a shop look at it and chase the threads using a special tool
    >>(if they deem it a good idea). This would cost around $15 and make the
    >>cups go in and out easily.
    >>
    >>Keep in mind that crossthreaded BB cups can really mess up a frame,
    >>especially an aluminum one, which I'm pretty sure yours is.
    >>
    >>OTOH, it's very common for BB cups to have much more friction than
    >>ideal going in. Obviously, it helps to have a good feel for this.
    >>
    >>Also, if the cups are pre-treated with a threadlocking compound, that
    >>will add a lot of friction.
    >>
    >>> >> My apologies for the terminolgy. I meant the tube that is attached to
    >>> >> the seat. Both the tube manufacturer and the bike manufacturer state
    >>> >> the seat tube size is 26.8, but there's just too much room in the
    >>> >> tube.
    >>> >
    >>> >You do have a seat collar for the bike, right?
    >>>
    >>> Er, we will tomorrow. Since we bought the frame separately from all
    >>> the other parts, no 'assembly' instructions came with any of the
    >>> parts. We don't know what we're missing. In other words, we don't know
    >>> what we don't know.
    >>>
    >>> Again, thanks!
     
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