Tomorrow at 11am he will become Prime Minister. Abruptly, the road ahead, steep, twisting and scattered with pot-holes, is his responsibility.
The cycle-racing metaphor, and other unguarded comments during the campaign, suggest that Mr Jospin knows that elements of the Socialist programme are unlikely to survive contact with reality. Even before the second round of the election, Socialist leaders were dampening public expectations: all would depend on their budgetary "margin of manoeuvre"; perhaps the mandatory reduction in the working week to 35 hours would mean some slight loss of pay after all.
Mr Jospin has promised, above all, to create a different governing culture, one in which politicians "tell the truth and do what they say they are going to do". He knows that another failure by the Left - by any government after five zig-zags of political direction in 20 years - could do serious damage to French democracy.
On the far-right, Jean-Marie Le Pen waits confidently for another political disaster. The centre-right, humiliated on Sunday, may be ready to implode. Dissident parts of both the Gaullist RPR and the UDF alliance may, in extremis, be prepared to think the unthinkable and do deals with the National Front.
Mr Jospin is an honest, competent, likeable man. He got off to a brisk start yesterday after being formally offered the premiership by a chastened and severely weakened President Jacques Chirac at the Elysee Palace.
Mr Jospin promised to announce his government by the end of the week. It is likely to include at least two Communist ministers and some old Socialist favourites - perhaps Jacques Delors or Jack Lang - as well as several rising stars such as Mr Delors' daughter, Martine Aubry, and the Mayor of Strasbourg, Catherine Trautmann.
But even before the demands arrive from the Communists and other allies in the left majority, Mr Jospin must know that he cannot easily deliver the promises made by his own party. Preserve the single currency; but soften the Maastricht guidelines. Create 700,000 subsidised jobs at a final cost of pounds 3bn a year; but allow no increase in the total tax take. Reduce VAT on some items and social charges on business; but soften the last government's welfare reforms and abandon the sell-off of France Telecom.
It will probably fall to Dominique Strauss-Kahn, the Socialists' economic spokesman, who invented this programme, to try to make it work as Finance Minister.
In Britain, Labour inherited good growth, low inflation and low unemployment. In France, Mr Jospin inherits high unemployment (12.8 per cent), stuttering growth and a half-chewed, anti-state, supply-side revolution. Will he abandon this entirely, or complete parts of it?
During the campaign, Mr Jospin said the principal requirement was to boost domestic demand. He promised a conference in the first month between government, employers and unions to push up wages. He said the deflationary policies of the Alain Juppe government were self-defeating; reducing growth, reducing tax income, increasing government spending and forcing further cuts. There is some truth in the criticism. Ceasing the deflationary efforts to squeeze the French foot in the glass slipper of Maastricht may help a little.
But what if EMU implodes, or is delayed, forcing up interest rates, cutting the foreign investment in France which was beginning to pick up?
Tony Blair in Britain and Bill Clinton in the US were able to position themselves as the inheritors, and humanisers, of an anti-state revolution which had succeeded but left many victims in its wake. The revolution has not yet happened in France. Some on the French left argue that they will able to invent a new way, mixing piecemeal state reform with greater concern for the human costs of globalisation and computerisation. Others admit that the Socialists are still inventing policy on the hoof.
Mr Jospin has placed a great stress on abandoning the monarchical, patronising style of previous governments. If he delivers on at least this promise, it will help. But he will not be judged by it. He will be judged by his success in delivering growth and jobs.
Tremor shakes Right, page 10 and 11Reuse content