Bicycle Mechanics - Will a BB used for a triple crank work with a double?

Just ordered an FSA carbon compact crankset. I currently have an Ultegra triple crankset installed. I am assuming my BB length must be 118 mm? Will I need to pick up a shorter BB like a 110 mm? I already have the front and rear double derailluers. Thanks.

Just ordered an FSA carbon compact crankset. I currently have an Ultegra triple crankset installed. I am assuming my BB length must be 118 mm? Will I need to pick up a shorter BB like a 110 mm? I already have the front and rear double derailluers. Thanks.

It would be best to have the correct spindle length to optomize your chain line and shifting. Without seeing your bike, I wouldn't be able to determine whether 110 mm is the correct length. Best to go to a local shop to determine this. The other factor involves the front double derailleur. The derailleur cage probably won't swing out far enough to complete a shift to the large chainring.

It would be best to have the correct spindle length to optomize your chain line and shifting. Without seeing your bike, I wouldn't be able to determine whether 110 mm is the correct length. Best to go to a local shop to determine this. The other factor involves the front double derailleur. The derailleur cage probably won't swing out far enough to complete a shift to the large chainring.There are only 2 lengths for an ultegra BB. 118.5 for the triple and 109.5 for the double. The short one gives the correct chainline with the double crank,and the double FD might not have enough throw to shift to the big ring of the double when used with the 118.5 spindle.

Thanks for the replies. I will pick up a 109.5