Storer joined the team from the Mitchelton-Scott feeder team (now Mitchelton-BikeExchange) in 2018, and finished fifth overall at that year's Tour de Yorkshire, followed by fifth on the GC at the Tour of Slovenia. Later in the season, he was selected for, and finished, his first Grand Tour – the Vuelta a España – and is again riding this season's Vuelta.
"I'm happy to extend my contract with the team after two good years with them so far," Storer said on the Sunweb website. "The team has a plan for my development, and that's an approach that suits me. I'm confident about the structure we have made going forward.
"Working closely together with the team in this way works well for me, and I'm looking forward to continuing in this way in the coming years," said the 22-year-old.
Tusveld also arrived at Sunweb in 2018, having spent the previous season with Pro Continental squad Roompot-Nederlandse Loterij.
Like Storer, 25-year-old Tusveld is currently riding the second Grand Tour of his career at the Vuelta, having also ridden it last season. In between, however, the Dutchman crashed heavily on the opening stage of this year's Paris-Nice in March, fracturing his jaw and leaving him on the sidelines until June, when he returned to racing at the Critérium du Dauphiné.
"After my accident in March, I knew I would be out for a long time," Tusveld said. "I was very happy with the confidence the team has in me, as they immediately came to me to tell me that I could sign a new contract with them.
"I feel at home and in the right place with the team, and hope to be important for them in not only in the Vuelta but also during the following years," he said.
Sunweb coach Marc Reef said that the team was very pleased to be able to retain both riders.
"Martijn has had a really difficult year after his crash in Paris–Nice, but he's worked hard to come back," said Reef. "We have big trust in his capabilities as a rider, and we're happy to extend his contract."
Going forward, Reef said the aim is for Tusveld to continue to ride in support of the team's leaders at Grand Tours and one-week races.
"We'll also focus on his general development, as we feel that he's a rider who still has a lot more potential in both climbing and in time trials," he said.
In Storer's case, Reef said that the team still views him as a young rider, despite him being in his second year with them, but one with "big talent and a lot of potential".
"We're going to work hard not only on Michael's physical level and attributes but also with our experts in all aspects of cycling to help him develop. We believe that his potential will come to fruition over the coming years that he is with us," Reef said.