Two Harvard entrepreneurs are bidding for a part of the runners' market this fall with yet another piece of jogging paraphernalia.

Winthrop House juniors David Sultan and Paul Kang have culminated two months of sporadic summer work with the publication of their Charles River Runner's Map, designed to help local runners measure their daily romps by the Charles.

The map hit bookshelves in five stores in Harvard Square 10 days ago, but early reports indicate slow sales so far. Sultan concedes sales have not been spectacular but says revenue should pick up with warmer weather next spring.

Stan Silver, a graduate student at MIT, helped design the map while living and working with Kang last summer.

Sultan says he conceived the map while running last spring. "Every time I went running. I would think of a new thing to put in the map," he says.

After combing local running stores last year Sultan said he found mimeographed maps that he felt poorly approximated distances. He and Kang agreed to collect the capital for a new map, and Silver joined in later that summer.

The map traces 22 miles of roads and paths along the Charles and around Fresh Pond. It includes a mileage chart giving round-trip distances between 12 bridges on the river and an accompanying pace chart.

Sultan says the map measures recently modified courses along the Charles, making previous maps of the river obsolete. Kang and Silver measured the courses with bicycle odometers.

Tutor Harry J. Holzmer of Winthrop House is one of the first to use Sultan and Kang's guide for training. "It gives a very nice breakdown of the mileage," he says, adding. "It's hard to make any progress if you don't know how fast or how far you are running."