Huffman, a former Astana rider, and Britton were part of a five-rider break that went clear early on the stage to Santa Clarita, building up a huge advantage on a day that had been expected to provide a bunch sprint.
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The chase was frantic over the final 20km, with the peloton hitting speeds of 60kmh on flat roads in pursuit of the break.
But it wasn’t enough, with Huffman jumping early to cross the line with a comfortable lead, as Britton came around Lennard Hofstede to take second.
13 seconds behind it was Peter Sagan who led hom the bunch sprint ahead of John Degenkolb (Trek-Segafredo) and Kittel.
Despite the action at the front of the race, there was no change at the top of GC with Rafal Majka (Bora-Hansgrohe) maintaining his two second lead over George Bennett (LottoNL-Jumbo).
How it happened
The fourth stage of the Tour of California featured a 159.5km stage from Santa Barbara to Santa Clarita, and offered a chance for the sprinters ahead Thursday’s summit finish and Friday’s time trial, so it was a slight surprise to see a four-man breakaway take a maximum lead of nine minutes at one point in the stage.
In the move were two riders from Rally Cycling in Rob Britton and Evan Huffman, who were joined by Gavin Mannion (United Healthcare), Lennard Hofstede (Team Sunweb), and Mathias Le Turnier (Cofidis).
The fivesome managed to hold their sizeable advantage for much of the hilly part of the stage, but once into the flat final third the gap began to tumble.
Entering into the final 50km and their lead was down to 4-30, with Katusha-Alpecin and Quick-Step Floors, working for Alexander Kristoff and Marcel Kittel respectively, responsible for much of the damage.
There was a sense of panic on the front of the peloton as riders began to realise that the breakaway could succeed, although a series of uphill drags began to make the break lose time.
But entering in to the final 10km and the break still held a lead of 1-45, but that was falling quickly as Quick-Step and Katusha continued to work on the front.
At the back of the race Andrew Talansky (Cannondale-Drapac) suffered an unfortunately timed mechanical, but was able to regain contact with the peloton with 5km to go.
The stage win looked destined to go to the break, but Team Sky weren’t giving up just, setting a fast pace that briefly split the peloton in a brief crosswind section, but with most of the contenders safely in the front group.
With 800m to go Huffman jumped clear of the break, and was able to hold off the charge of the other breakaway riders, as team-mate Britton came around Hofstede to deliver a famous 1-2 finish for Rally.
Tour of California 2017, stage four: Santa Barbara to Santa Clarita (159.5km)
1. Evan Huffman (USA) Rally Cycling, in 3-41-52
2. Rob Britton (Can) Rally Cycling
3. Lennard Hofstede (Ned) Team Sunweb
4. Mathias Leturnier (Fra) Cofidis
5. Gavin Mannion (USA) United Healthcare, all at same time
6. Peter Sagan (Svk) Bora-Hansgrohe, at 13 secs
7. John Degenkolb (Ger) Trek-Segafredo
8. Marcel Kittel (Ger) Quick-Step Floors
9. Alexander Kristoff (Nor) Katusha-Alpecin
10. Simone Consonni (Ita) UAE Team Emirates, all at same time
General classification after stage four
1. Rafal Majka (Pol) Bora-Hansgrohe, in 16-04-48
2. George Bennett (NZl) Team LottoNl-Jumbo, at 2 secs
3. Ian Boswell (USA) Team Sky, at 14 secs
4. Lachlan Morton (Aus) Dimension Data, at 16
5. Robert Gesink (Ned) Team LottoNl-Jumbo, at 45 secs
6. Brent Bookwalter (USA) BMC Racing Team, at 48 secs
7. Sam Oomen (Ned) Team Sunweb
8. Andrew Talansky (USA) Cannondale-Drapac
9. Vegard Stake Laengen (Nor) UAE Team Emirates
10. Maximilian Schachmann (Ger) Quick-Step Floors, all at same time