Why 397 is Chris Froome's winning Giro d'Italia number

397 watts ... that’s the number behind Chris Froome’s stunning attack on the Colle delle Finestre which blew the Giro d’Italia apart.

Froome became the first British rider to win the Giro d’Italia and the first cyclist in 35 years to hold all three Grand Tour titles.

And it was all down to his blistering performance on a 9.3% gradient over 3.02km of the Finestre, in which Froome averaged 397 watts of power at an average cadence of 95rpm.

The attack came 10 km into the Finestre with 80km of racing left and was followed by a descent with an average speed of 53.4km/h.

The feat resulted in Froome winning Stage 19 by 3’00” from Richard Carapaz (Movistar Team).

Read our Stage 19 report.

Chris Froome captured his historic win for Velon

Froome ended up winning the Giro by 46 seconds from second-placed Tom Dumoulin (Team Sunweb) and 4'57" from third-placed Miguel Angel Lopez (Astana Pro Team) after three weeks of pulsating racing.

He was one of 144 riders whose power, speed, heart rate and cadence Velon tracked throughout the Giro and we've brought the Team Sky rider's numbers together so you can see the key numbers on his road to Rome.

Stage 3

Froome endured a difficult to start to the Giro, crashing before the race had even started while recceing Stage 1's time trial course.

He consequently spent Stages 2 and 3 sheltered in the peloton recovering and expending as little energy as possible. In his first 30km of Stage 3, he averaged 36.6km/h and 183 watts, hitting maximums of 596 watts and 57.7km/h.

Read our Stage 3 report.

Stage 14

Froome had looked a shadow of his normal self for the first 13 stages of the Giro and was 3'20" adrift of Mitchelton-SCOTT rider Simon Yates's overall lead in 12th place overall.

But he then sprang to life with a superb solo victory on Monte Zoncolan on Stage 14. The victory was built on a 1.3km attack in which he averaged 465 watts and 12.4km/h on a 15.4% gradient.

Read our Stage 14 report.

Stage 19

A day after his win on the Zoncolan, Froome struggled on Stage 15 and lost time, dropping back to 3'22" adrift of Yates's overall race lead. 

However, by Stage 19 he was back in top form and turned the race on its head with his attack on the Colle delle Finestre with 80km to go with his 397 watts average over a time of 11'03" on a 3.02km section of the 9.3% gradident ascent.

Froome held a lead of about 40 seconds going over the summit but then more than doubled that advantage with and astonishing descent down the other side. He negotiated the 11.2km descent in 12'15", hitting a maximum of 80.1km/h.

Froome then extended his gap over the chasers by powering up the day's next climb, to Sestriere, negotiating the 6.3km ascent at 23.2km/h.

He stretched his gap even further on the final climb to the summit finish in Bardonecchia to win the stage by 3'00" and take the overall lead by 40" from second-placed Dumoulin.

For the full 5h12'26" of the 184km stage, he averaged 35.3km/h and hit a maximum speed of 84.9km/h.

Read our Stage 19 report.

Stage 20

Now very much back to his best and in the Maglia Rosa, Froome just had to defend on the final mountain stage of the race, Stage 20's summit finish in Cervinia.

The 214km stage ended with three back-to-back category-one climbs and Froome had to ride at a fierce tempo on the approach to the first of them. In a 31'09" stretch, he averaged 48.2km/h and 280 watts, hitting maximums of 68.4km/h and 860 watts.

In the first 3km of the second climb, the Col Saint Pantaléon, which averaged 6.1%, Froome averaged 21.9km/h and 380 watts and reached maximums of 41.0km/h and 540 watts.


Once over the top of the climb, he descended down the other side at a maximum speed of 71.9km/h.

Inevitably, Froome came under heavy pressure on the final climb to Cervinia as Dumoulin attacked no fewer than four times. 

In order to keep shutting Dumoulin's moves down, Froome was forced in one 9'08" spell to average 420 watts and 21.0km/h on an 8.8% gradient, reaching mximums of 41.0km/h and 760 watts.

Within that 9'08", there was a particularly intense 3'00" period in which Froome averaged an even higher 450 watts and 24.1km/h.

His two hardest efforts were as follows:

- Effort #1: 33” at 540W and 23.2km/h (13% gradient)
- Effort #2: 30” at 540W and 24.4km/h (11 %)

Froome ended the stage win averages of 280 watts and 37.3km/h, with a normalised power of 325 watts.

Read our Stage 20 report.

Stage 21

Froome now just had to take it easy on the final stage in Rome to complete overall victory - and he did just that, averaging just 100 watts in the final 2.5km of the race.

Read our Stage 21 report.

Time to celebrate in Rome (Justin Setterfield/Getty Images)