Originally Posted by
G_I_B_B_O_N
The model number is: FD-4503. Thanks for the tip on angling. I'll read through Sheldon's page on it and give it a try.
Took a couple quick pictures. Hopefully this helps. The contact with the chain isn't firm, but just enough that it's constant.
That Tiagra is usually paired with 52t outer rings, but it should handle the triple reasonably well.
However, as I suspected, that crankarm looks like it's sitting outboard a bit. While I'm not there to measure chainline, I'd guesstimate that it's about 4mm further out than it could be - meaning that the BB spindle is too long or the crank's chainring offset is just unsuitable for this particular frame.
Replacing the crank and BB together is probably the best course of action to take here (and make sure the mechanic understands that copying the BB width of the Octalink on it now is
not correct). If you haven't already, give the gearing some thought.
One last thing: Even though external-bearing BBs are nice, they're not necessarily the first thing you'll find at a remote bike shop in an emergency. If you plan to do touring in remote areas where picking and choosing an LBS isn't an option, I'd recommend sticking with a simple JIS square taper BB spindle and crankarm. That's the most common crank you'll find at any bike shop - especially those way out in the middle of nowhere. You can even cannibalize a thrift store bike for a crank arm or a cup-and-cone BB in the absolute worst-case scenario. While I wouldn't expect a new crank to come to this, I
have had two cranks bent into boomerangs after being hit (in one case, I was hit by another rider, so it's not just automobiles that pose an issue here).
-Kurt