[SaltyNC]

Old school contact cement works great on leather, too, but it's a pain to apply. Works best if done a little at a time, but needs cure time before pressing pieces together, so can make for a long job and light head from the fumes. I used it to adhere the M5 weighted shift knob leather boot to the plastic hoop. I applied to plastic then leather. Let cure a little, then pressed together -- did about 1 inch at a time. Once the two pieces touch, it is game over, but holds like it is welded.

Edit: Just re-read Stickmon's post about the hot sun. Contact cement may not be best for areas that get really hot in the sun as it can become workable again. On my boot, it's never been a problem, but it's tucked down and not exposed to the direct sun.

Salty