Please will you stop squeaking; Dance

Twyla Tharp's Diabelli Barbican, London Traboule Highbury Fields, London

It was the 1820s equivalent of a celebrity recipe book. One Mr Diabelli - Viennese publisher and amateur musician - invited 51 composers of the day to write one variation each on a theme of his own creation (a silly little plunkety-plunk waltz). The proceeds of the publication were to "succour the widows of the late wars".

Schubert obliged. An 11-year-old whiz-kid called Liszt obliged. But the great Beet-hoven, by then ill and deaf, grumpily declined. Perhaps he thought the project demeaning. Then he seems to have changed his mind, coming up with not one, but a socking 33 variations on Mr Diabelli's tune. The result is a towering masterpiece which manages by turns to mock its gimmicky origins and reach up to heaven. Tender, teasing, transcendental, sometimes violent in its revolutionary fervour, Beethoven's response finds a whole world in a speck of dust.

Then along comes Twyla Tharp, who thinks she can gild the lily. The prospect sounded enticing enough: a performance of Beethoven's Opus 120 by pianist Nikolai Demidenko, alongside nine dancers meting out Tharp's choreographic riposte. Expectations were high. The Barbican Concert Hall sold out. And for the first 20 minutes of the hour-long work it seemed Tharp had struck gold. Her magpie style - a slinky mix of ballet and jazz-dance strewn with motifs from street and social dances - is a perfect medium for humour. Where Beethoven makes jokes with thematic material, she's in clover. For the mock-pompous Variation 1 we got toy soldiers with swinging arms and piggy-back battles. Later on, head-butting, leap-frog and a cheeky smacked bottom. The pianist Alfred Brendel - in his essay "Must Classical Music Be Entirely Serious?" - invented titles for each variation. Tharp clearly found these useful: "Cheerful Spook" (No 15); "Swivelling and Stamping" (No 7) and "The Virtuoso at Boiling Point" (No 23) were directly translated into dance. When the music goes contrapuntal, Tharp offers busy circuit-boards of criss-crossing movement. All very clever. When the music goes slow she responds with dreamy duets, but sometimes tries to create textures of her own (a girl bobbing up and down to repeated chords was particularly odd). At worst, she creates distracting complexity where the music is clear as glass; too much effortful craft trying to match effortless genius. After half an hour I was silently begging the dancers to stop and go home. This is music that demands, if not consumes, every particle of concentration, and in the end the dance was merely an irritant. If Twyla Tharp had one ounce of humility she would have cleared the platform of dancers and done nothing at all for the most sublime variations. But no. The appalling squeak-squeak of leather dance slippers continued to assault the ear through moments that, musically, would have held us on the edge of tears. Did no one foresee this extraneous noise? It undermined the whole project, finally. Yet Beethoven survived, thanks to the supreme artistry of the pianist. Demidenko delivered hammer blows and launched sky-rockets with equal mastery, and his tender playing would have melted the gates of heaven. If there was ever any kind of contest, Tharp was left at the starting post.

The Islington Festival has been promoting another circus find from France in a petite big top on Highbury Fields. Last year it had a sexy trapeze act serving the audience beer on tap from the central tent pole. This year it has a raggle-taggle bunch of jugglers who based their hour-long show, Traboule, on characters observed in "Le Traboule" - Lyon's labyrinthine cardboard city. There seemed some confusion over this title: my ticket was printed with the word "Trouble", which was possibly just as appropriate.

The appearance of four rattling, hinged structures made of scrap wood sets the dossers' aesthetic: these are makeshift, mobile homes of four odd characters around whom the action revolves - a splendid Mohican, a nicotine-addicted dandy, a gibbering hypochondriac in grimy bandages, and a little guy who wants to be big, but whose attempts to make a grand impression amount to twirling toothbrushes round one finger.

Fierce competition cues some terrific feats of stilt-walking on outsized splints knocked together from old pallets. A bizarre episode where each one metamorphoses, naked, into a fantasy insect had the girls behind me in stitches, on account of their homemade cod-pieces. One appeared to have his member stuffed into a sock. Anarchic, off-beat, immaculately skilled; Traboule shows that circus can still hold some surprises.

`Traboule': Highbury Fields, N5 (0171 689 0200) today