Euro BB is a euro BB is a euro BB--or is it?

Bike: Thorn Raven Tour with eccentric BB shell.
Problem: Drive-side bottom bracket race will not thread into eccentric
shell.

I thought that all Euro BB threads are the same and that I could use
any brand on the market. I'm thinking not since I've tried two
different bottom brackets ( an IRD sealed cartridge and Primo Powerbite
euro ) without good results.
I stopped by the local bike shop today to see what they thought. They
pulled a Shimano sealed cartridge BB off the shelf and it threaded in
without difficulty? Now I'm confused. Is the Thorn eccentric
eccentric BB only capable of using a Shimano sealed cartridges?

Thanks and best regards,

David

wrote:
Bike: Thorn Raven Tour with eccentric BB shell.
Problem: Drive-side bottom bracket race will not thread into eccentric
shell.



Not to sound simple- but you do realize that the right-hand side cup is
left-hand threaded, don't you? In order to screw in the the cup, you
need to turn it counter-clockwise.

Jeff

Yes, I do realize that the right-hand side cup is left-hand threaded.
Even armed with this knowledge the BB bracket still will not thread
into place.

David

wrote:

Yes, I do realize that the right-hand side cup is left-hand threaded.
Even armed with this knowledge the BB bracket still will not thread
into place.

Consider that while "Euro" usually refers to ISO/British standard
threading, there are several other European BB thread standards about
the same overall size. The most common "other" standard is Italian
36mm x 24tpi, but there are also French 35mm x 1mm and Raleigh-specific
26tpi types with some specimens still in circulation.

Italian and French can be sorted out on cursory examination because
they use RH threads on both sides. 26tpi Raleigh threads won't mesh
with the 24tpi threading on ISO BBs, 1" threaded fork steerers, or
freewheel threads; but they will mesh with the 26tpi threads on 1-1/8"
threaded fork steerers.

Chalo Colina

wrote:
Yes, I do realize that the right-hand side cup is left-hand threaded.
Even armed with this knowledge the BB bracket still will not thread
into place.

David

OK- you said that you'd tried an IRD and a Primo BB's, and that the
Thorn's shell is a machined aluminum eccentric, right? I would guess
that the IRD and the Primo BB's have aluminum cups, and the Shimano
BB's that were successfully installed were steel. In my experience, the
steel BB's are a little more tolerant to misalignment when you're
trying to get the first thread started.

I would try the IRD or Primo cups again, holding them steady with
whatever is the proper installation tool. I'd hold the cup against the
shell and turn it *clockwise* until the ends of the threads clicked
past each other, then turn it counterclockwise smoothly for one full
turn (it might help to lie the frame on its side on the floor).

I think you've got a case of tolerances stacking up against one
another- the Thorn shell is on the small side and the IRD and Primo
cups are a bit large.

Jeff

I wrote:

Consider that while "Euro" usually refers to ISO/British standard
threading, there are several other European BB thread standards about
the same overall size.

I see now that you mention the Primo Powerbite Euro BB. That is made
in only one thread standard, ISO. So it sounds like you may have
bruised threads, burs, or some other similar problem with the bearing
cups on your Primo BB. If you have a 24tpi thread file or any small
jeweler's files available, you can try to touch up the leading edge of
the threads on the bearing cups, but otherwise you should probably
pursue the matter with the merchant.

Chalo

Chalo wrote:
wrote:


Consider that while "Euro" usually refers to ISO/British standard
threading, there are several other European BB thread standards about
the same overall size. The most common "other" standard is Italian
36mm x 24tpi, but there are also French 35mm x 1mm and Raleigh-specific
26tpi types with some specimens still in circulation.

Italian and French can be sorted out on cursory examination because
they use RH threads on both sides. 26tpi Raleigh threads won't mesh
with the 24tpi threading on ISO BBs, 1" threaded fork steerers, or
freewheel threads; but they will mesh with the 26tpi threads on 1-1/8"
threaded fork steerers.

Chalo Colina


Hiya, Chalo!

Yeah, I thought of that, too, but since he said he tried a Primo and an
IRD, I figured he wasn't using anything too old.

Jeff

Thanks Jeff for the info---

I forgot to mention that I'm able to get the drive-side started
threaded in a few turns before it just stops and does not go any
further. Perhaps I could take the eccentric shell in to the shop and
have the threads chased? Also, the other side of the shell threads
just fine. This leaves me thinking the threads are buggered-up some on
the drive-side.

On 20 Jul 2005 20:05:42 -0700, wrote:

Thanks Jeff for the info---

I forgot to mention that I'm able to get the drive-side started
threaded in a few turns before it just stops and does not go any
further. Perhaps I could take the eccentric shell in to the shop and
have the threads chased? Also, the other side of the shell threads
just fine. This leaves me thinking the threads are buggered-up some on
the drive-side.

Aluminum threads on both? Better use a lubricant, or they may grab.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

wrote:
Thanks Jeff for the info---

I forgot to mention that I'm able to get the drive-side started
threaded in a few turns before it just stops and does not go any
further. Perhaps I could take the eccentric shell in to the shop and
have the threads chased? Also, the other side of the shell threads
just fine. This leaves me thinking the threads are buggered-up some on
the drive-side.

OK- now I get it. Yes, chase the threads. As Chalo said, a burr or
buggered thread will give you plenty of grief.

Jeff