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Double crankset on triple BB?(6 posts)

Double crankset on triple BB?bobdiz
Oct 1, 2002 8:14 PM
I have a triple crankset and am thinking of going with a double instead. Manufacturers recommend the shorter spindle bottom bracket with the double, although I have the longer BB. Would there be a problem with this?

Anyone want to trade a double setup for a triple? Mine are 105, 175mm length, 68mm BB width with less than 100 miles on them.

-Bob
re: Double crankset on triple BB?Juanmoretime
Oct 2, 2002 1:36 AM
Bob, if you don't change your bottom bracket your chainline will be way off with the double. It may shift OK but you might be creating more friction on your drive train than if you had the correct bottom bracket. This could cause accelerated drive train wear.
re: Double crankset on triple BB?Rusty Coggs
Oct 2, 2002 4:37 AM
It would be the same as one would get by using a triple crank and BB ,but only using the large and middle rings. Most use the granny very little anyway.
shifting problemDougSloan
Oct 2, 2002 6:46 AM
If you use a front derailleur designed for the double, it may not be able to shift to the outer ring, as it will be too far away. If you keep the triple front derailleur, there may not be enough adjustability in the stop screws to keep the chain on.

BB's are relatively cheap. Do it right or just keep what you have.

Doug
re: shifting problemMike Prince
Oct 2, 2002 8:26 AM
Had same issue when I set up my bike and the chainline was off. My first thought was, OK let's get a triple BB. Chainline was fixed but my double FD didn't have enough "swing" to reach the big ring. I guess that I could have taken a dremel to the FD to increase its travel, but buying a new BB and FD (if you have a triple now) is really the answer.
You may be able to solve the shifting problemdzrider
Oct 2, 2002 8:40 AM
Try taking the bottom bracket axle out, turning it around, and putting it back in. This was possible with older stuff and may still be so.