By Bill Wilson
Business reporter, BBC News
Just over two weeks after the Tour de France set off in a Grand Depart blaze of glory from London, a pack has broken away from the main body of the race.
Rabobank removed their cyclist Rasmussen when he was leading
However, this speedy group is not a peloton of top cyclists - doped-up or otherwise.
It is a phalanx of leading brands asking themselves what connection, if any, they want with this now-tainted sporting event in the wake of the latest scandals over performance-enhancing drugs and blood doping.
It could mean a crisis for the sport in terms of attracting sponsors, who provide important financial backing for cycling teams consisting of up to 70 personnel and a host of attendant vehicles and demands.
But for corporations eager for television exposure, stepping off the bicycle could be seen as the best way of saving their brands from being tarnished by cheating scandals.
BLOOD DOPING EXPLAINED
What is it?
Administration of red blood cells to increase the blood's oxygen-carrying capacity
How is it done?
Injection with someone else's red blood cells; removing own blood, storing it and returning it once body has replaced it
Why do it?
The better the blood's oxygen-carrying capacity, the greater one's endurance
Blood clots, overload of circulatory system, kidney damage, transmission of infectious diseases such as HIV
Chances of being caught:
Test can only detect it if the blood comes from a donor
Richard Moore is managing director of sponsorship consultants Capitalize and is a board member for the European Sponsorship Association.
His firm is involved in cycling, with T-Mobile - which sponsors a Tour de France team - among his clients.
"The sport of cycling is going to take some hits," he says.
"For new companies considering it as a marketing opportunity, they might now think sponsoring cycling is too risky and look elsewhere.
"Sponsors want to back clean sport, clean teams, sporting values and athletes who play by the rules.
"For sponsors, it will be disappointing to find these things happening in the Tour in such a high-profile way."
His comments come after German truckmaker Man backed out as a sponsor and a pair of German television stations dropped their coverage of the Tour.
Carmaker Audi and global sportskit maker Adidas are reconsidering their sponsorship, as are several others.
In Switzerland, bicycle manufacturer BMC says it is reconsidering its partnership with team Astana, after its star rider was ejected.
"We do not want to have anything to do with doping," says Andreas Georgiadis of ISH International Sport Holding, which co-ordinates BMC's sponsorship activities.
Team Cofidis was withdrawn by its sponsors after a drug shock
And Mr Moore says sponsors which remain in cycling - and the Tour de France in particular - will want to consider their future move.
"I would not be surprised that people would want to get around the table and discuss the problems.
"It is understandable that sponsors want to consider their options. It does not necessarily mean they are going to turn their back on the sport, as long as cycling is seen to be taking strong measures to tackle these problems."
Two teams have withdrawn from the Tour after members were caught in doping scandals.
The whole Astana team withdrew when its star, Alexandre Vinokourov, tested positive for blood doping after winning Saturday's time-trial stage of the Tour de France.
That was followed by Team Cofidis withdrawing - on the demands of its chief sponsor - after team member Cristian Moreni failed a drugs test.
That strong action was matched by similar moves by other sponsors of teams, the bank Rabobank and telecoms firm T-Mobile.
Tour de France leader Michael Rasmussen was sacked by his Rabobank team and withdrawn from the race.
Patrik Sinkewitz was suspended by his team over a Spanish test
The Dane, 33, had been at the centre of controversy since it was revealed he missed out-of-competition drugs tests.
And earlier in the Tour, Patrik Sinkewitz, who was found to have tested positive for elevated levels of testosterone in drug tests made in June, was suspended by his T-Mobile team.
Another cyclist, Jan Ullrich, had previously been suspended by the T-Mobile team on the eve of the 2006 Tour after being named in an official inquiry into blood doping in Spain.
Meanwhile, Rabobank describes the Rasmussen episode as "a dark page" in its history.
The team's sponsor says the team will carry out extra doping tests on its riders at the Tour and that it had already decided to do so before Rasmussen's dismissal.
"The cyclists are not under suspicion, but as a sponsor, we want to be absolutely sure that our team is competing in good health," says Thomas van Rijckevorsel, a member of the Rabo Cycling Team's supervisory board.
It is not all doom and gloom on the sponsor front, as US firms have not been as quick to distance themselves from the event as their European counterparts.
Trek Bicycle has said it will continue its sponsorship of the Discovery Channel team, which it helps to kit out, after saying it believes the Discovery team is clean.
Kitmaker Nike and Discovery Communications say they are standing by the team as well.
Sponsors are essential for the backing they give to Tour teams
Computer Sciences, a California company that sponsors Team CSC, has said it will also continue its involvement in cycling.
And according to UK cyclist David Millar, who served a two-year ban for doping, the fact that sponsors are taking strong action is a "really positive thing".
"Rabobank are assuming their responsibilities," he says.
"You've got to remember this is a sponsor that's been in the sport for years and supports the national team, from a schoolboy junior level right through to professional.
"And the fact that they're doing something like this, I think, is a very strong statement and a very big step and I hope everyone is learning from it."