Need to shorten stem
 

I purchased a Trek 7500fx. I really like the bike. It feels great except for the fact that I am more comfortable if I pull my hands back on the bars so that just my fingers are wrapped around them. I think a shorter stem will help. There are many stems for sale out there and I would like to take advantage of getting a good deal on one. How do I tell what stem I have now? I know it is a Bontrager but that is all I know. There seems to be three different numbers for each stem. How much shorter should I go considering where I seem to be most comfortable? Is this something that I should just leave to my local bike shop?

If it is a new bike purchaed from your local shop , you can ask if you can swap stems. Alot of times they will work with you in that respect.

if i am right you should be able to adjust the stem up and down which may help. if you look on the underside of the stem there should be a 6mm alen key bolt, loosen it till the stem become floppy and then move it up or down as yuo desire (don't forget to adjust the handlebars aswell because the stem adjustment will cause a tilt)