I have the Trek 7300 and I had the same problem. I bought the trekking bars from Nashbar and they have worked great. I'm a bigger guy as well and I figured there to be about 5 hand positions on them. I looked at it as they were $16 and if they didn't work I would look elsewhere. I can feel them flex a bit when I go over really bumpy roads and trails but they haven't moved in the stem yet and I've had them for 3 months now.