I sagged our club's Climb to Kiaser ride this summer. I carried a floor pump, some tools, BIG jug of water, firtst aid kit, and a couple of big beach towels, one for riders who wanted to wipe down, the other for them to sit on and not get the seat of my truck all sweaty. Some spare gels and a six pack of soda wouldn't be a bad idea to carry. Mostly I just drove my assigned sections (not the major climbs) a few times to let riders know SAG support was available, I had signs taped to the bumpers and windows so they could see who I was. I drove with the flashers on if I was doing under 35 mph so other drivers would know something was going on up ahead. Mostly I enjoyed the scenery and watching theses awsome cyclist climb hills I wouldn't dream of climbing.
cytoman