I should have said its a 2011 frame, and the front forks are bent which is why they're in the bin. The rear cassette is 9 speed shimano slx.
Ah! That changes much, and favorably! You no longer have to worry so much about compatibility of components.
First thing I would do is determine the original frame's intended use -- sport-touring? Touring? Cyclo-cross? That geometry and intended use will give you a good starting point for evaluating your build. Not every bike has geometry optimized for touring, with or without a load.
Once that is determined, I would check the frame very closely for any damage. Usually, an impact forceful enough to bend the forks often results in a bulge appearing on the underside of the top- and downtubes and sometimes paint-flaking on the tops of both those same tubes. If there is any sign of damage in those places, then I would be reluctant to proceed further.
If the frame is sound and fit for the purpose, then I'd feel much better about proceeding.
You asked...
On the stem, how short can you go? What problems would a very short stem create?
As far as
fitting a stem, you
can go as short as is available. Downhill bikes are coming out with stems that are perilously close to zero-reach, with the clamp parked nearly atop the steerer, but those are for a specialized purpose. As far as how short you
should go, two immediate concerns are 1) handling and 2) clearance (particularly between handlebars and knees). Both are somewhat problematic to predict in advance. A stem with too-long reach tends to give a "tiller" effect to the steering and places much more of the rider's weight over the front hub, which does not always result in the best handling. The common concern with a stem having extremely short reach is it does not provide enought leverage to safely steer the bike, and this can be made worse with a heavy front touring load or bad roads. I'm not convinced this is the case in reality, as leverage is more generally determined by the width of the handlebars as that moment arm is what provides the leverage, not the stem offset or reach.
I can share that I have had success in days past fitting bikes for other people by installing stems as short as 50mm and 60mm. In the "olden days" of the 1970s and 1980s, bikes commonly came with the same length top tube and varied only in the length of the seat tube. The only way to "fit" a bicycle was to alter stem reach and hope it would be enough, as many production frames only came in sizes "Small", "Medium" and "Large" (21", 23", 25" c-t seat tubes). Even when used with handlebars bags, I never had reports of poor handling that were attributable to short stem reach, whereas I have sometimes has reports of problems when reach was "too long".
In my own personal experience, I currently run quill stems with 80mm reach on several of my single bikes with no problem, and I am currently using a Kalloy Uno stem with 90mm reach on the Nomad (and brake levers placed about 1cm higher than usual); the Sherpa had a shorter top tube and used a 110mm stem that resulted in the same effective handlebar placement.
An adjustable stem would go far in helping you dial-in your desired position before committing to a stem with fixed reach and angles. Many good ones are available at relatively low cost, and would be a good first step toward determing what your needs are. That's the course I'd take.
Hope this helps,
Dan.
