I bought a Nashbar AL-1 road bike awhile back (didn't want to invest too much, wasn't sure I'd be too into road) and so far it's been great. However, I want to switch from a triple to a compact crankset. I currently have an isis bb and the compacts I'm looking at also take an isis, so is it simply a matter of off with the old and on with the new or is there a width difference that precludes using the same one? Thanks

No. In your case ISIS road double bottom brackets are 108mm wide and triple 118mm. I also wouldn't count on being able to get a triple front derailleur to work with a double crank due to the chain line and geometry differences. I couldn't get a Campagnolo Racing-T front derailleur to shift an FSA 50-34 compact double consistently without dropping the chain although the correct CT double derailleur worked flawlessly.

Assuming 10 cogs throw an 11-21, 12-23, or 13-26 cassette on there for good spacing. With 9 try 11-19, 12-21, or 13-23. If you never use the small ring you can run a full size double. Otherwise stick with the triple - the compact will involve _MANY_, _MANY_ more double shifts.

Triple cranks look goofy, just like pie plate sized rear cogs. If you can't get rid of both of them forget about looking cool.

This doesn't hold if you're a bike company. You can usually sell a compact double (especially the contemporary 52-36) to the people who would otherwise want 53-39 or 53-39-30, cut your SKUs, and increase your profit margins.

Thanks for the prompt reply Drew, I'll pick up a new bb when I order the crankset. To be honest I haven't even considered doing anything with my cassette, but you've got me thinking now that I'd be well served to educate myself on gear ratios and the math involved.