Converting French BB to English
10-25-09, 06:51 PM
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Converting French BB to English
Is there a good way to convert a french BB to english?
Will running my english tap through to the trick, or should I fill with brass and cut new threads?
Will running my english tap through to the trick, or should I fill with brass and cut new threads?
10-25-09, 10:45 PM
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I think you'll end up with a mess on the fixed cup side since french is right hand thread and english is left hand thread. I don't know if brass will be a lasting solution. If the french threads are in good shape, I'd figure out a way to use a crank that can utilize one of the many french bottom brackets available.
10-25-09, 10:49 PM
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There are not many options for French bottom brackets (unless you have a deep parts bin) and the most economical and sound solution would be to buy a French threaded cartridge from velo orange.
You can retap Raleigh threaded bb's to standard and usually have things work well because the threading is the same as to right and left but French bb's are right and right like Italian bottom brackets (which are 2 mm larger in diameter).
You can retap Raleigh threaded bb's to standard and usually have things work well because the threading is the same as to right and left but French bb's are right and right like Italian bottom brackets (which are 2 mm larger in diameter).
10-25-09, 10:50 PM
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Bicycle Repair Man !!!
There is also the Phil Wood solution but that is very pricey.
10-26-09, 05:44 AM
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BSC diameter is 1.37"=34.8mm so 0.1mm smaller in radius than French (35mm). So on top of the cross LH vs RH thread on the drive side, you'll have a bit less material to dig in. As far as I know it is not recommended, but I've heard many people doing it. If it is a long lasting solution I don't know.
10-26-09, 08:55 AM
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Why do you need to change the threading?
10-26-09, 08:59 AM
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There is one alternative solution, which is to find some Italian taps and get the Italian to English conversion sleeves that Ceeway sells. I've never tried this, seems like it would work fine. Since Italian is nearly obsolete, it might be worth getting some taps and a supply of the sleeves for doing repairs. Back in the day, tapping a stripped bb to Italian was a very common repair.
11-25-19, 12:51 AM
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11-25-19, 04:32 PM
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His last post was in 2016, so it's not likely that he will see your question. I am pretty sure he means he flowed brass in there with a torch
11-25-19, 04:48 PM
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/You'd need at least a fuel/oxygen flame to get hot enough to effectively melt brass into something with the mass of a bottom bracket shell. If it were my bike, I'd either go with the threadless cartridge (the easiest path), or ream and tap the shell for Italian threads. Either approach would leave the paint intact as well.
