front derailleur question when swapping cranksets
02-16-12, 04:40 PM
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front derailleur question when swapping cranksets
hi, i've got a bike with a road drive train configuration and another with a mountain, and i want to swap the two drive trains.
the bike that now has a two chainring crankset has a shimano bar end front shifter, set on friction. if i put a triple chainring crankset on that bike, and leave the shifter on, would i be able to use the existing front derailleur, adjusting the set screws to expand the range of motion? and how will i know if the bottom bracket currently installed with the double chainring crankset would work with the new triple? what indicators can i look for to see if the bottom bracket works or not with the new triple crankset? thanks a lot, really appreciate the help,
jeff
https://bicycletouringoncarfreepaths.org/
the bike that now has a two chainring crankset has a shimano bar end front shifter, set on friction. if i put a triple chainring crankset on that bike, and leave the shifter on, would i be able to use the existing front derailleur, adjusting the set screws to expand the range of motion? and how will i know if the bottom bracket currently installed with the double chainring crankset would work with the new triple? what indicators can i look for to see if the bottom bracket works or not with the new triple crankset? thanks a lot, really appreciate the help,
jeff
https://bicycletouringoncarfreepaths.org/
02-16-12, 05:06 PM
#2
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Are both BB shells the same width?
IF both bikes have the same dropout spacing, just swap the BB's with the crank.
That would "probably" still work if they don't have the same spacing, but not give an ideal chain line.
Else, you could just install the crank and see where it ends up.
Else, you could remove both BB's and read the size.
You might mention WHAT bikes you have to see if there are any interchangeability issues such as ISO vs JIS, Bracket width etc.
With the FDERs-
You might be able to use the existing setup.
It depends on how much travel the FDER has, how it's "centered" over the triple (spindle length) and what's the size difference between the before/after rings.
Provide more details with what you have.
IF both bikes have the same dropout spacing, just swap the BB's with the crank.
That would "probably" still work if they don't have the same spacing, but not give an ideal chain line.
Else, you could just install the crank and see where it ends up.
Else, you could remove both BB's and read the size.
You might mention WHAT bikes you have to see if there are any interchangeability issues such as ISO vs JIS, Bracket width etc.
With the FDERs-
You might be able to use the existing setup.
It depends on how much travel the FDER has, how it's "centered" over the triple (spindle length) and what's the size difference between the before/after rings.
Provide more details with what you have.
Last edited by Bill Kapaun; 02-16-12 at 05:52 PM.
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