I dunno, Jay, but you can, depending on the crankset, get a spacer and shift the cranks over enough to clear the boom - I did it on my baron way back when and it shifted great.
 
If that doesn't work I have a new ultralight 10 speed KMC chain I might trade you for  a 9 speed if you have it.  I may be converting my carbent to a 9 speed.

Quote from aikigreg on Feb 22^nd, 2011, 5:30pm:

 
Greg, thanks for your input. I guess a triple crankset suitable for a 73 mm bottom bracket could be used in conjunction with a spacer and 68 mm bottom bracket. Part of the problem I'm having is caused by the boom almost being bottomed out (I'm short). The derailleur cage is actually contacting the boom receiver, instead of the boom. So, cage movement is even more limited. I don't plan on climbing any steep hills with the Baron, so I want to try a compact crank, instead of another triple.
 
I wonder if a 10-speed chain would be compatible with my Baron's 9-speed cassette? I don't have a new 9-speed chain to trade. The chain on the Baron currently has 723 miles on it.  
 
Curious as to why you want to convert your Carbent to 9 speed? I've never been able to keep the 10-speed Ultegra bar end shifter/rear derailleur combo on my Carbent in adjustment. Wonder if a SRAM 10-speed, "Exact Shift" combo would be better?  

Quote from power_bent on Feb 22^nd, 2011, 5:36pm:

 
Tom, I installed an ISIS triple crankset and heavy, 128 mm (super wide), mountain bike bottom bracket and could get the drailleur to access the small ring. I screwed up the bottom bracket when I removed it to try an external bearing bottom bracket and carbon triple crankset. Instead of buying another 128 mm bottom bracket, I want to try another external bearing bottom bracket and light compact crankset.  

Rode over to Dallas Bike Works at WRL, this afternoon, and talked to one of their mechanics. He said a 9-speed chain would be compatible with a 10-speed compact crankset. He suggested use of a 10-speed front derailleur for smoother shifting. Subsequently, I pulled the trigger on a new 165 mm Ultegra compact crankset w/bottom bracket for just $130 on E-Bay. Hope it works on the Baron.