Islington Festival: Eine Brise/(Fleeting Action for 111 Cyclists) Upper Street, London

The human form is closest to perfection when riding a bicycle. Think of what happens when you walk: to send you forward in a straight line, your feet move up and down, your muscles tense to cushion the pavement's impact, your arms and shoulders swing wide and forward to balance you over the swivel of your hips. So much energy wasted. On a bicycle, all this effort is changed into pure motion; the stuttering, grunting language of corns, bunions and fallen arches is translated into some unearthly poetry. You are no longer earthbound: gravity conspires with you to pull you towards your goal.

Some sense of this is contained in the title of Mauricio Kagel's Eine Brise ("A Breeze"), a "Fluchtige Aktion fur 111 Radfahrer" ("Fleeting Action for 111 Cyclists"), which received its British premiere on Saturday afternoon in Islington, north London, in a co-production between Almeida Opera and the Islington Festival. In fact, this was Eine Kleine Brise: though not exactly a chamber version, this was tailored to reduced forces, weather and mechanical defects having cut the number of participants to somewhere in the low nineties.

In conception, the work is simple: the cyclists, moving in a strictly delineated formation, separated from each other by one and half metres in front and to the side, move swiftly past an audience on a straight road. As each cyclist passes a designated point, he/ she must ring his bell or toot his horn - one short burst, followed by a longer one, and then a longer still; at the next marker, the cyclists begin to sing or whistle a pattern of three rising notes; at the next, they must flutter or shush; finally they ring and toot again, as they disappear into the distance. It lasts around 90 seconds.

In practice, maintaining such a tight formation is difficult. That the day's two performances came off without accident, and managed to maintain a firm hold on Kagel's conception was astounding - particularly difficult given the crowded conditions on Upper Street. The credit must go largely to the brilliant direction of Stephen Montague, a keen cyclist who has worked with the composer.

As for how far the piece achieved its intended effects, I'm not ideally placed to comment, having been one of the cyclists. Kagel conceived of the piece being performed in front of small audiences bunched together at one point along a long, straight route, with the cyclists moving past very swiftly. On Saturday, with the audience strung out along the route and little room for the pack to accelerate, much of the hoped for sense of evanescence - of noise only vanishingly embodied - was inevitably lost. Most spectators seem to have been amused, some at least enchanted by the jangling and susurrations; and Stephen Montague declared himself satisfied that the composer would have been pleased. Perhaps that's all any musician can hope for.