I took a test overnight trip into the mountains west of Denver this weekend. I have a front lowrider rack with about 11 lbs in each pannier. I also have a handlebar bag with about 6 lbs of stuff. My rear panniers are about 10 lbs each. I'm riding a 12 year old Trek 970 mtn bike with a rigid fork.
This setup handles great on flat ground or downhills (got up to 42mph with no problems). However, when I'm climbing uphill at slow speeds I find it problematic to keep the front wheel in a straight line. It keeps pulling to one side or the other and I was constantly working to keep from weaving all over the road. I wouldn't say it was dangerous or terribly worrisome, but I'm wondering if there is anything I can do to improve my slow speed handling while going uphill.
It seems like moving the front panniers rearward a bit might help, but the panniers are almost as far back as they go. I'm gonna try adjusting them to move them as far back as I can. Any other suggestions?