I would lean toward modern components, yes. I like this design :

http://www.businesscycles.com/graphics/cr7710.JPG

it has really soft lines without harsh edges that could create high stress areas. the carbon
crank is a prime exaple of bad design. they merged two different materials in a high stress area.
each material has different properties and flexes differently under loads. Its like a
steel stem with a aluminium handlebar. the hard steal eats through the alu pretty quickly.
a couple of years ago it was agreed that carbon fibre is not the right material for cranks
and suddenly they are everywhere. I saw a steel frame with glued and bolted on carbon
seatstays. whats the point? what are those people thinking? why not make a frame
where each tube is made from sections of carbon, titanium and scandium. that would give them
the marketing edge.

Bloody Hell!! That's a frightening reality :D

the reason i put the old D/A cranks on my bike was because i got 'em for like, $20, and i couldn't afford anything new at the time. i've got some sugino75s on my other bike right now, and i'll probably end up going with those again.

the new dura ace cranks are nice looking, and i'm sure they're great, but i have a big problem with octalink.

i didnt mean that these cranks are the only one to buy. just this type of design as opposed to
the hard edges skinny design of older cranks.

Jimv is absolutely right..I remember seeing a number of these cracks on cranks in the 70's..when you use the round file to remove just enough material to eliminate the crack..you've eliminated what is called in engineering terms a "stress riser". Kinda like..give a crack an inch and it will take a mile. If it's no longer there, it won't progress up the spider any further.

The problem with this is, there may be structural damage that can't be seen that will eventually fail too. And if something has already begun to crack, especially if it's old, chances are it past it's useful life.

I'm a cheap bastard, but sometimes you have to know when to retire a part to the junk bin. Dental work is generally more expensive than a new set of cranks.

Sure..in some cases with a crack it's best to retire the part..in this instance though I'm thoroughly familiar with the crack and crank in question. The area where the crack started at the spider is thinner and sharper than the rest of the crankarm/spider. Therefore, the removal of a small amount of material enough to eliminate the crack, leaving a rounded profile will solve the problem. If this thinner material had been removed at the factory, the crack would have never started.

I absolutely agree. I have always felt that this was an error in tooling design rather than structural design. Having said that, I think that if anyone is uncertain about the safety of this approach then by all means simply replace the part. I have however, made this 'repair' with great success more than once ... and I'm no light-weight at 250 lbs. Naturally if you find one of these cranks without the crack, it's definitely a good idea to remove the sharp edge as a preventative measure.... I guess that goes without saying.

Jim

Ok, so funny you guys should mention aluminum catastrophically failing....

Check out what happened to my bianchi tourer's stem while my friend was riding it.

The only warning it gave was some creaking the night before between pubs.

Soooo, yeah - I wouldn't use a cracked crankarm.