Install Bottom Bracket backwards?
 

Any reason I can't install a cartridge BB backwards? Why, you ask?

Hehe- I want a compact crank on my homebuilt recumbent. The present "boom" is from an old ten-speed with an old-style BB. It accomadates an aged full-size triple crank, but that makes my overall gear ratios just a tad too high. I have a nice Alivio compact crank, but it won't work on the present BB and spindle, it won't seat deep enough, and the front DR wont adjust to accomodate it.

So, I have an old Cro-mo Trek frame that was trashed by the frat boys. Seattube and BB still OK, but this would mean reversing the BB to have the "long" end of the spindle (where the crank mounts) on the proper side of the bike. (the downtube is bent.)

(This is one ugly critter, BTW, but functional. It's a test-bed for version 2.0)

If it's a cup and cone bottom bracket, you could just flip the spindle. Whether or not this helps is a different matter... Sometimes this is an effective tool for getting fixed-gear chainline pretty close on the cheap, sometimes not. You'll have to measure your spindle to see how this affects things...

Most every modern bottom bracket, including the one that's meant to work with your Alivio compact crank, uses a symmetrical spindle. There ain't no "long end" on these units. The cranks might go on the bottom bracket that's in the Trek, but the offset was designed for a symmetrical spindle. They're cheap. Take the plunge.

I'm actually embarrassed. I had already cut the frame segment away and was simply looking at it wrong. The "short" side of the spindle takes the crank, and the long side goes on the left. I was holding it wrong...

This bit of cro-mo frame should give me a slightly-lighter boom, and the compact crank should lower my overall gear ratios to the point I want 'em. The only fly in the ointment will be mounting the front DR on the rather bent portion of the frame. I think it will go right under the damaged part, though.

Some of the Shimano brackets are non-symmetrical. A 107 and a 110 extend equal length on the drive side but the 110 is 3 mm longer on the non-drive side. This lets you fiddle a bit with the chainline if need be.

Campy has asymmetrical cartridges. Phil Wood has a plethora of em

With shimano cartridge type,No workee in english threaded BB unless you have the specific ones where both cups can be separated from the cartridge,allowing the carridge to be flipped.