The B838 is a very short, unsigned road connecting the A814 and A83 in Arrochar.
The road starts on the S1 A814 on the shore of Loch Long and climbs steeply beside the parish church along Church Road. On reaching the church the road TOTSOs left onto a road that is even narrower than what has gone before; but its still called Church Road. The road runs above the village centre, passing a few houses before a fairly straight run lined with bushes takes the road to its end on the A83 as it cuts across Glen Tarbert to the A82 and Loch Lomond. It was perhaps a useful short cut in the past, but is now unsigned and largely unused by anyone but locals.