I am looking at getting a used steel bike specifically a colnago Tecnos 2000. Well looking at bottom brackets I have seen 3 sizes 68, 70 and 73. Well I know English is 68, and I thought Italian was 73 but Shimano calls Italian 70. I've contacted one owner about it but all he may know is he had a Italian threaded BB not what size it was. Any help would be greatly appreciated.
Cycling Equipment · Public discussion
Bottom Bracket ? Help, Italian v. English
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- Cycling Equipment
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- 27 May 2004
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- 27 May 2004
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- neilthemeal
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Quoted post said:
Originally posted by neilthemeal
I am looking at getting a used steel bike specifically a colnago Tecnos 2000. Well looking at bottom brackets I have seen 3 sizes 68, 70 and 73. Well I know English is 68, and I thought Italian was 73 but Shimano calls Italian 70. I've contacted one owner about it but all he may know is he had a Italian threaded BB not what size it was. Any help would be greatly appreciated.Road bottom brackets generally are available with either British or Italian threads.
The length, distance from one cup face to the other of a road frame bottom bracket shell that is English threaded is 68 mm.
Road frames also come with Italian threaded bottom bracket shells. An Italian threaded BB comes in 70 mm length.Mountain bikes almost always come with English threaded shells. The exact thread measurement is the same as road bikes, 34.8mm (1.37 inches) x 24 threads per inch. However, mountain bikes come with two different bottom bracket shell lengths; 68 or 73 mm. 68 mm is the most popular but 73 mm is catching on. Both often require different bottom brackets even though spindle length and cup threading is the same.
PS. An English BB shell diameter is 34.8mm while an Italian BB shell diameter is 36mm. Both have 24 threads per inch.
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Quoted post said:
Originally posted by neilthemeal
I am looking at getting a used steel bike specifically a colnago Tecnos 2000. Well looking at bottom brackets I have seen 3 sizes 68, 70 and 73. Well I know English is 68, and I thought Italian was 73 but Shimano calls Italian 70. I've contacted one owner about it but all he may know is he had a Italian threaded BB not what size it was. Any help would be greatly appreciated.Check out:
http://www.sheldonbrown.com/gloss_bo-z.html
and look at the excellent table under Bottom Brackets.
As a rule Italian is 70mm width with 36mm X 24 tpi threading with both sides right-threaded.
73 is usually an oversized MTB design
There are some bastardized designs out there but most conform.
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