I have been carrying out an overhaul of a old Mercier steel frame made in the sixties and part of the job has involved trying to upgrade the groupset to a 'modern' setup including ergolevers, better brake calipers, closed shell bottom bracket etc.
Well the bottom bracket is proving to be a right pain in the a%$£. Before I had managed to get the old one off (which wasn't easy) I measured the shell width (68mm) and therefore concluded it was an english type. Therefore I got an british thread BB and when I tried to fit it I found that the end cap went on fine but the main piece didn't. The thread was wrong (the end cap could go on both sides without a problem). Therefore the conclusion was 'its an Italian thread' so I ordered one. However, I got that today and it doesn't fit - its too wide (the diameter of the italian one seems to be bigger than the british thread one).
Can anyone explain what is going on here ? I'd rather not use the old BB (which was the old style with ball bearings everywhere) as there was masses of play in it (its wrecked).
I have been carrying out an overhaul of a old Mercier steel frame made in the sixties and part of the job has involved trying to upgrade the groupset to a 'modern' setup including ergolevers, better brake calipers, closed shell bottom bracket etc.
Well the bottom bracket is proving to be a right pain in the a%$£. Before I had managed to get the old one off (which wasn't easy) I measured the shell width (68mm) and therefore concluded it was an english type. Therefore I got an british thread BB and when I tried to fit it I found that the end cap went on fine but the main piece didn't. The thread was wrong (the end cap could go on both sides without a problem). Therefore the conclusion was 'its an Italian thread' so I ordered one. However, I got that today and it doesn't fit - its too wide (the diameter of the italian one seems to be bigger than the british thread one).
Can anyone explain what is going on here ? I'd rather not use the old BB (which was the old style with ball bearings everywhere) as there was masses of play in it (its wrecked).
cheers
Matt.
You will need to make the measurements and know what the threading is. Or you could install a Mavic Bottom bracket that doesn't use any of the threads, but requires a tool to shape the shell. Take your frame to a shop and have them measure it and stop the guessing. Possibilities are: British 1.370 x 24 tpi – RH & LH Italian – 36mm x 24 tpi French – 35mm x 1mm Swiss – 35mm x 1mm – RH & LH Raleigh Super Corsa –1.370 x 26 tpi – RH & LH Chater Lea – 1.450 x 26 tpi – RH & LH
Based on what you have discovered so far it may be French, but please don't use my statement as another "bad guess".
Well the bottom bracket is proving to be a right pain in the a%$£. Before I had managed to get the old one off (which wasn't easy) I measured the shell width (68mm) and therefore concluded it was an english type. Therefore I got an british thread BB and when I tried to fit it I found that the end cap went on fine but the main piece didn't. The thread was wrong (the end cap could go on both sides without a problem). Therefore the conclusion was 'its an Italian thread' so I ordered one. However, I got that today and it doesn't fit - its too wide (the diameter of the italian one seems to be bigger than the british thread one)..
Is there anything written on the old bottom bracket?
Not only is there a big difference in diameter of an English and Italian bottom bracket, English BBs have a left hand thread on the right (drive side), and Italian is a right hand thread.
Which way did the old one come out? I suppose if you got the English left cup to screw in both sides, it's a right hand thread.
Is there anything written on the old bottom bracket?
Not only is there a big difference in diameter of an English and Italian bottom bracket, English BBs have a left hand thread on the right (drive side), and Italian is a right hand thread.
Which way did the old one come out? I suppose if you got the English left cup to screw in both sides, it's a right hand thread.
Yeah, Like the OP said, If ya have to guess, French is the pick. But he has aleady made 2 wrong ones.
To answer a few of the queries, I am able to take the end cup (the bit that isn't most of the bracket) from a campag mirage british thread bottom bracket and screw it into both sides of the shell. It fits nice and snug and therefore not skipping threads.
From this I can confirm that the thread is italian (i.e. the thread goes the same way, as you look at it, on each side rather than the opposite way as you would see for british thread). However in my limited experience it seems that the diameter of the bracket seems to differ between italian and british thread BBs (can someone confirm that) the italian one seems slightly wider. This isn't the first time I have noticed this, I was previously sent an italian threaded ultegra BB for a different frame and I noticed that it was that little bit wider in the diameter.
Its not stamped 35mmx1mm infact it has no marking on it at all but as I have said above I have managed to get some end caps to fit correctly.
To answer a few of the queries, I am able to take the end cup (the bit that isn't most of the bracket) from a campag mirage british thread bottom bracket and screw it into both sides of the shell. It fits nice and snug and therefore not skipping threads.
From this I can confirm that the thread is italian (i.e. the thread goes the same way, as you look at it, on each side rather than the opposite way as you would see for british thread).
It's not Italian.Italian thread diameter is 36mm and an english 34.8mm or french 35mm would drop right into it. French is 68mm shell width, and right hand both sides,and threads are similar enough that an english cup from the non drive side would thread in either side.The OP gave you the threading specs, and if you don't buy it, check witth Sheldon Browns stuff at www.harriscyclery.com
