Frederiek Nolf died in his sleep at the Ritz-Carlton hotel in Doha, Qatar, last night.
The 21-year-old Topsport Vlaanderen rider is thought to have suffered a heart attack, but that has not been confirmed. He was due to celebrate his 22nd birthday next week.
Thursday's fifth stage has been cancelled.
Nolf had crossed the line in 90th position at the end of Wednesday's fourth stage.
After hearing the news that the young Belgian had died, the decision was taken to cancel the stage. However, the riders were taken to the start where they took off their helmets and bowed their heads to observe a minute's silence as a mark of respect.
Tomorrow's final stage is expected to take place.
Cycling Weekly's reporter Alasdair Fotheringham spoke to riders and key figures after hearing the news.
?It?s terrible when you lose such a young healthy guy. I don?t know him personally, but I rode with the team together last week."
Roger Hammond Cervélo rider
?It?s terrible. Nobody?s thinking very much about the race. I didn?t know him personally but when something like this happens to somebody in the same race in the same hotel, you can?t really get any closer."
Jeremy Hunt Cervélo rider
"I?m not the right man to talk a lot. It's difficult to know which words I can use to express myself and my sadness, I find it terrible, and we?ll just have to keep going."
"If you crash that?s something different, but this is awful. He?s just died, awful news. No explanation possible, no words to say."
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