New Shorter Bottom Bracket
Kiblams
Posts: 2,423
Good Evening, I have a quick question regarding replacing my current BB (68x121.5 apparently) as the chainline is all messed up between the chainrings and my rear sprockets.
Currently the cranks are sitting just over 10mm from the frame and the single chainring that I use lines up with the second smallest gear on the back, and as I am sure you can imagine the chain has a very stressed angle on it when I use the larger sprockets on the back.
So the thing that I need to know is will buying a 68x107 BB be too small as I have 20mm (10 either side) to play with or am I confused. I guess I should also ask if you think that moving the front ring 10mm inwards will have a major effect on the chainline?
Thanks guys.
Currently the cranks are sitting just over 10mm from the frame and the single chainring that I use lines up with the second smallest gear on the back, and as I am sure you can imagine the chain has a very stressed angle on it when I use the larger sprockets on the back.
So the thing that I need to know is will buying a 68x107 BB be too small as I have 20mm (10 either side) to play with or am I confused. I guess I should also ask if you think that moving the front ring 10mm inwards will have a major effect on the chainline?
Thanks guys.
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Comments
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Good article on sizing here:
http://www.sheldonbrown.com/bbsize.html
The 107 should drop the chainset 7mm inwards. A close call.0 -
Brilliant!
Cheers Supersonic, I use that site quite a bit, not sure why I didn't head there first.0
