36 x 24F thread
 

Hello guys and gals,


I have a question regarding bottom brackets. I have a 1991 Specialized Allez Comp, with carbon fiber frame, Shimano 105 groupset and downtube shifters. The bottom bracket is a Campagnolo 36 x 24F, with 11 loose steel bearings and a Shimano D-3H spindle, 130mm. I would like to install a new bottom bracket, a Shimano 105 SC (sealed mechanism) unit, with a 36 x 24T thread.


My question is: does the 36 x 24F thread equals to the 36 x 24T thread ? Any chances of cross threading and damaging the frame threads ?


Thank you !

Rodrigo

The French word for threaded is Fileté, so I would guess they put T for thread. The answer is yes, same thing.

36x24 tpi is an Italian threading size. I am somewhat surprised that it is found in your bike. However, one repair for damaged English bottom bracket threads is to re-tap them for Italian.

Or, was your frame made by Alan or Vitus?

If the threads are clean, you should be able to fit the new bottom bracket in the frame by hand.

Hi Milo,

Thanks for the information, I didn´t know that. I´m gonna write it down and save it, thanks !

Rod

Hi Clifford,

I don´t know if the frame was tapped, I´ve bought the bike with the bottom bracket already there. I had to buy a HCW-4 park tool wrench to service it, 36x24 tpi is not that common here in Brazil.

The frame is a 1991 Specialized with bonded carbon tubes, could it be a "Vitus inspired" solution ?

Rod

In this case, since it's an Italian threading standard on cups manufactured in Italy, the 'F' stands for 'filetto', which is the Italian word for 'threads'.

(Puts it in to google translate for Spanish)

Roscado! I was hoping as one of the romance languages, it would be similar but apparently not!

Well, we call it "fio de rosca" in brazilian portuguese, something like " filetto of roscado". It is interesting how the words get so close related.
Regards,
Rod

I don't think Specialized ever hooked up with either ALAN or Vitus to rebrand/sell bikes....
The theory about a BB shell threading repair makes sense as Ital
ian threading for BB's are larger ID than BSC.....

Given the era, it almost certainly a repaired shell but I wouldn't necessarily rule out Italian threading for Brazilian bicycles. After all, Italian threading was the standard in Mexico during the pre-ISO era. I've also seen vintage bicycles from Argentina and Chile with Italian threading. It all seems to come down to the native country of the immigrants or companies who developed the bicycle industry in the particular country. If they were from Italy, the traditional threading standard could be Italian. It would be interesting to know the threading standard on a pre-ISO era, Brazilian manufactured bicycle, such as a Caloi. Neither French nor Italian would surprise me.

OP do both BB cups tighten to the right and loosen to the left?

Yes T-Mar, you are right ! Here in Brazil, bicycles like Monark, Phillips, Goricke, Peugeot and Caloi were major players on the bicycle industry. Caloi was a huge brand during the 70´s, 80´s and 90´s (I´ve had several road and MTB models, as a kid and teenager). Monark and Peugeot were good brands with a loyal following, there are a lot of classic bikes still around.

Old Caloi framesets have 34,7mm bottom brackets, with hellish cotter pins cranksets (one-piece cranks were common too) and italian threading. Some Caloi framesets (so called "Professionals") were actually made in Italy, with Gipiemme and Campagnolo pieces. Only professional cycling teams got them, they are really nice and very well made.

Regards,
Rod

Yes, both bottom brackets tighten to the right, clockwise. The previous owner of the Epic frameset almost got them soldered, guy must have Popeye forearms !

:thumb: