If you're having problems on a bike then a bike fit can make a huge difference. Evans Cycles do a basic one for £45 which covers all the important areas.
And Baub - a couple of the guys I cycle with also ride in a group where there are a couple of 80-somethings who have transitioned to E-bikes, which basically just assist up the hills. You'd be hard-pressed to know they weren't conventional bikes.
