When deciding what to take, I evaluate the chances of needing something and the ability to make due without it if I don't take it and something does happen to go wrong. I took a spare tire on my Black Hills trip primarily because I would be riding the Mickelson Trail, which is rough in places and presents areas with limited or no opportunities to even get a ride from someone should something go wrong. I had also planned to head to a very remote area of Nebraska using some dirt roads. In contrast, I would not dream of talking a spare tire on one of favorite three-day getaways to S. Jersey which is all on paved roads and which is never far from civilization. If worse came to worst, I could get "rescued" by a friend or even possibly catch a cab part of the way home. And where does it end? Spare crank just in case? What if the handlebars crack? Spare saddle in case the rails break?


In the case of the OP's particular trip (100 total miles in two days on a trail), and assuming the bikes are well maintained as I wrote in my post, what are the odds of needing, say, stuff to fix a chain or cable even if he had the technical know how to do it? I would say extremely slim to none. More than 44,000 bike miles crossing the country with a small group. Not one chain or cable issue among the lot of us. Throw out the one guy who was cheap and refused to spend money on quality tires, I would be surprised if we had even 30 flats between the remaining 12 of us. I know I only had two. And no ne experienced any mechanical problem that prevented them from getting to a LBS, even when that meant a couple of days of riding.


Just my philosophy, and it's worked so far over 15K loaded miles. To each his own.