15t sprocket (cog) for modern Brompton 3spd?
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15t sprocket (cog) for modern Brompton 3spd?
Is there enough clearance for a 15t cog on modern (mine's 2007) 3spd sturmey archer bromptons?
I searched a bit, but from the ~10 year old archives that said only a 14t would work. There is a tight clearance between the frame and cog.
The Brompton manual says that this should work, but this breaks the data from the folding society archives :
==========
REAR SPROCKETS: for geared hub (to ISO 10230): non-derailleur, ½" x 13T x 3mm thick (but for lower gearing, use a 14T or 15T sprocket): derailleur, special Brompton sprockets, 13T and 15T only.
==========
Any easy source for the part in the US? I'm not familiar with their interchangeability with other more common parts (ie BMX).
I searched a bit, but from the ~10 year old archives that said only a 14t would work. There is a tight clearance between the frame and cog.
The Brompton manual says that this should work, but this breaks the data from the folding society archives :
==========
REAR SPROCKETS: for geared hub (to ISO 10230): non-derailleur, ½" x 13T x 3mm thick (but for lower gearing, use a 14T or 15T sprocket): derailleur, special Brompton sprockets, 13T and 15T only.
==========
Any easy source for the part in the US? I'm not familiar with their interchangeability with other more common parts (ie BMX).
#2
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Any standard hub gear cog will fit on the splines.
I'm not sure about cog size on a modern Brommie, our two are '98 and '99. I think they changed the chain tensioner a few years back to give room for a slightly larger cog.
I'm not sure about cog size on a modern Brommie, our two are '98 and '99. I think they changed the chain tensioner a few years back to give room for a slightly larger cog.
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LWab, I can't seem to identify what are the standard hub gear cog that will be compatible. Do you have suggestions? From the little reading I've done, this seems to be a possible mod on the newer Bromptons that have more clearance with the tensioner and possibly chain stays.
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https://groups.yahoo.com/group/BromptonTalk/
EDIT:
Ah - I just checked and it appears that this very question has just been asked. Jasong obviously got there without help.
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It's a $25 modification (or less if you find an old larger crankset) that you can do in 10 minutes (you may need a longer chain).