Lukevintagebike

Hi!

I just had my old bike painted and in hindsight, with too little research, bought a 105 Shimano groupset. The BB shell is right-threaded on both sides so that's why I got the Italian BB. It now turns out that it's a French thread that I'm dealing with. Now it's impossible to find a new BB that works with a new 105 crank and that fits in the old BB shell (68mm long, 34mm in diameter). Since I really want to avoid sending those 105 parts back and to buy new/old stock, I'm quite stuck now. The only possibility I see is to ream and redo the orginal threads in the BB shell, and then try to get the 70mm BB to fit the 68mm shell.

If there is any suggestion, I would gladly hear it.

Thanks in advance and greetings from Belgium

cny-bikeman

Check threadless bottom brackets.

Kontact

Italian is only .5mm larger in radius, so that might not be enough when the threads are deeper than 1mm. They are both 24TPI, so that might be possible. That's a machine ship job, not a bike shop.

You could also have your 105 bb turned down to French thread, which might be a lot easier since they are small and aluminum.

Phil Wood makes Shimano style external BBs with French thread:
Phil Wood & Co.

Pricey, but you can probably service the bearings on the PW BB.

Kontact

How are you going to make a threadless BB for an external BB crank? Is there a product you had in mind?

fietsbob

yes Phil is a good square taper BB , made in California..
they make separate mounting rings

to use their cartridge assembly in any bike ,
with the appropriate mounting ring choice..

French held out for their own metric standard,
eventually had to fall in with the rest ..

You might look for loose ball BB from earlier years ..
a 1/4" ball is common to all those types.
so you may be able to source french thread cups and a japan BB spindle....

You have to send the external bearing crankset and bearings , back.
they only make the bearings in British or Italian thread , not french

and go back to older components .. sorry, time has moved on.
now to export the French bike biz have to use other standards,
to sell abroad.

good luck with the 3rd place match with England..





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Kontact

The OP doesn't want square taper - there are plenty available in French thread.

Phil Wood makes external French thread BBs so he can use his external BB crank.

fietsbob

dear sisyphus, rather than pushing that boulder uphill forever,
buy an italian or british threaded frame ..


(in Belgium I expect those Phil parts cost a whole pile of Euros)





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dedhed

https://www.bikeforums.net/bicycle-m...m-bracket.html

cny-bikeman

Whoops - too rushed, not paying attention!

Dan Burkhart 

I once heard of someone who executed a successful hack by running right hand English taps in both sides of a French BB shell and using two adjustable cups. The diameter and threading should be close enough to work, but I have not tried this myself to confirm.
I would think the right cup would need to be loctited in place. Sounds plausible enough to try.

squirtdad

maybe velo orange french bottom bracket? 103 to 122 mm spindle length? https://velo-orange.com/collections/...e-alloy-cups-1

Dan Burkhart 

Well, would you look at that. Not a horrible price for such a low demand item either.

Kontact

How is the OP going to mount a 105 Hollowtech crank on that?

squirtdad

ahh read it that OP had 105 italian bb.......wans was thinking square taper... not that OP had a 105 group...... reading comprehension

The OP does not mention if he has a stem and seatpost, if not that will be another bit of fun if they are French size

OP: IMHO you will go crazy trying to cludge this.... either new frame or if this frame is really special, send the group back and put something together to fit the frame

dedhed

In people's defense the OP never really stated what generation of 105 he bought or that he needed an external bearing BB other than saying "new" regarding the group.

realistically his only options are Phil or a different crank that uses a square taper in a length available.

Asi

NO!
Italian thread 36mm x 24tpi (1.05833mm spacing pitch)
French is 35mm x 1mm spacing pitch.
While they are pretty close it's really not compatible. French thread can (in theory) be rethreaded for Italian but it will mess up the threads because of the pitch difference and those 0.06mm difference add at every thread. So after 10mm of threads is 0.6mm difference, which is halfway the original pitch so the tap will effectively strip that thread at about 10mm depth. There will be only a few good-decent threads left - don't do it) - also the shell width is not enough.

Thread-less BB's need a larger hole and there is not enough metal on the BB shell to do so. But there are some that require 35mm hole which is the best bet since it will only cut out the threads not weakening the BB shell.

Find FRENCH BB. There are plenty on square taper and there are some decent square taper cranks. Nothing wrong with that. You are not expecting a light racing bike, right?

Kontact

Like I said, ask a machine shop. However:

I don't see how having to add two 1mm spacers under the cups could possibly be an impediment.

3alarmer

...If I understand the OP correctly, you bought a new 105, outboard bearing Hollowtech crankset, and your newly painted frame is French threaded in the shell.

While it's certainly possible to ream and re-thread the shell to fit your Italian cups, I think you're going to run into additional issues when you need to space the cups out wider with the 68 mm shell width to accommodate your Italian specced crank shaft in your new crank set. If nothing else, it will move your crank arms out by either a skosh on both sides, or on the outboard side if you elect to try maintaining the current chainline by installing the drive side bearing with no spacer. I can't imagine you'll end up being able to do this cheaper and easier than just getting a different crank that fits the French standard frame. One of the unfortunate downsides of outboard bearing cranks is they are more resistant to adaptation for unique situations like yours.

If, OTOH, you're talking about an earlier version of 105, with a square taper BB, I think you've already got plenty of good recommendations.

xlbs

https://velo-orange.com/collections/bottom-brackets

Asi

Well from the looks of it, tapping to italian thread looks to be a suitable solution after-all (apart from finding the right French BB for your cranks).

I've did a sketch and the threads don't look that mangled. They interfere just a bit from time to time.

The real resulting thread profile is in green in model2, while in model 1 with red is french thread and blue is italian thread.

fietsbob

FWIW VO is the Importer, in Maryland USA

Maybe there is another source in Europe for what is undoubtedly made by a Taiwan company..

yea not the latest external bearing hollowtech cranks.. sorry..




with a repaint .. one can lay in molten brass filling the thread , then the rethread pitch mismatch can be cured
with good metal when done .. carefully..





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BillyD

Please pardon the disruption. Carry on.