Used bike question - Aluminium vs. Steel
 

Hi !
I'm thinking about buying a second hand bike frame. The options are:
1. Trek 970 (Steel, True temper I guess), I'm not sure about the model but rather "old"
2. Cannondale F2000 SL (CAAD 3,Aluminium) model 2000-2001
Both of the frames are great looking, no dents, no cracks.
I'm thinking about doing XC and perhaps a race or two.
The frames cost is the same.
I was thinking about the F2000 but I know that aluminium is easy to brake and habe a limited life span. Still will serve me much longer but is ~800 grams heavier.

What do you say ??

Do you have a 3rd choice? Unless you've got a stack of parts lying around, it may not be worth it to build up an old Trek. Aluminum is no easier to break than steel, but if you're just doing XC, that shouldn't be an issue. The important thing to be aware of with the Cannondale is that if it doesn't come with a working Headshok, you'll either have to buy one ($$$) or get the adaptors to convert the head tube to 1-1/8 so you can run a regular fork. That's my 2 cents.

The steel frame will have a failure mode of rust. The fatigue life(cracks) factor is minimal. So, if it has no rust you can pretty much depend on it.
The F2000 will have a fatigue limit like most aluminum XC frames. 4-5 hard xc seasons will be about when the inspections have to get more thorough. I am running a 01 XTC right now that had a dropout crack(aircraft shops fix aluminum nicely ;) ) but the main tubes are fine. It would be useful to check the history of the F2000. If it was used lighty to moderately than it is not that big a concern. If it was in full time race duty or owned by an urban stunt guy, look carefully. It sounds like it was treated nicely, so the choice is prefference.