Bob McCarthy wrote:
On 4 Feb 2006 18:55:35 -0800, "Nate Knutson"
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?