Rode the Olde Muskingum all the way from 40 corners to Canal Fulton and back, on September 10, 2014. My bicycle is not a trail bike and it was rough going. That said, on a beautiful if humid morning, I saw exactly 5 people and 2 dogs on the trail in about an hour. Most hikers use the Ohio and Erie Canal trail on the other side of the river.
You can access it anywhere that a public road crosses the trail. 40 corners; High Mill (park at the Tavern); Butterbridge Rd. and Canal Fulton's numerous trail parking areas. One always has to cross the river to get to this trail from the main one, the towpath trail.
Olde Muskingum seems like it was at one time a rail line, because there are RR type mileposts and some other relics all around. Massive concrete bridge over a stream, for example. The Corman RR tracks run parallel this trail all the way, but on higher ground.
There are a few bumpy patches on the trail. Some low areas stay wet for days. Mostly packed earth which is very smooth when dry, with areas of crushed limestone and some loose gravel at intervals. There is some soft sand pack near High Mill where I almost lost it.
I have been riding the Canal trails for years, from Valley View to Zoar Village. This Olde Musk trail is real find. Private, almost.