It is the ultimate compliment to a rider that his presence or absence from a race fundamentally changes its shape, affecting the tactics of all his main rivals to the point where they ride more to negate than they do to win. Arguably there are maybe only four or five riders among the current generation who command this ultimate level of fear and respect: Alberto Contador on the big climbs of the Grand Tours, Mark Cavendish in the sprints, the 2011 model Philippe Gilbert on punchy finishes such as the Ardennes Classics. And in the hard-man races which demand a combination of both physical and indomitable will-power: Fabian Cancellara.

When the Swiss champion crashed in the feed zone of last Sunday’s Ronde van Vlaanderen, fracturing his collarbone in four places, you could almost hear the frantic chatter over team radios as the directeur sportifs of each team frantically recalibrated their tactics. Instead of riding to contain Cancellara’s expected charge, the race became more about positioning their men for the decisive split to set up a small sprint finish – eventually won by the resurgent Tom Boonen, who was the pre-race co-favourite along with Cancellara.

Cancellara’s retirement fundamentally changed the shape of the Ronde, just as his absence from Sunday’s Paris-Roubaix – which had been pencilled in as another clash of the titans with Boonen – casts the teams’ race planning in an entirely different light.

Here at VeloVoices Towers we’ve been scratching our heads all week about the impact of Cancellara’s absence. Here are the key questions we’ve been asking ourselves, and what we think the answers are.

How did such a bad crash happen in the feed zone?

Tim: It appears that Cancellara’s crash occurred when he hit a stray bidon in the road. In any such accident where a rider is suddenly upended, collarbone injuries upon landing are common. And it’s not the first time this season that a humble drinks bottle has taken out a big name. Alejandro Valverde retired from the recent Volta a Catalunya when he too was felled by a bidon in the feed zone, while world champion Mark Cavendish was taken out of the Dwars door Vlaanderen when a bottle was thrown into his front wheel.

Despite being the slowest part of a race, crashes in the feed zone are not uncommon. It can be something of a disorganised free-for-all, as the entire peloton scrambles in a confined space to find their team personnel and grab their musette. Consequently, riders are not focussing on the road as much as they would ordinarily do. In their eagerness to get under way again, bidons, musettes and other paraphernalia are easily dropped or casually discarded – the feed zone is not a tidy place! – leaving plenty of opportunities for a rider to end up in the wrong place at the wrong time and be brought down. Such crashes happen more frequently than one might think, but often these are relatively minor falls which occur to relatively minor riders who pick themselves up, dust themselves down and get back on their bikes. Not so in the unfortunate Cancellara’s case.

How will this affect the tactics of the upcoming Classics?

Jack: It’s going to make the races much easier for the other riders, particularly the better sprinters like Tom Boonen or Peter Sagan [although Sagan has pulled out of Paris-Roubaix – Ed]. No one in the peloton has the strength of Cancellara to accelerate away from the bunch 50km from the finish and win alone on some of the toughest terrain in cycling.

We’re less likely to see anyone try such a daring manoeuvre, and we can expect more movement later in the race, possibly from a rider like Alessandro Ballan or Filippo Pozzato, who looked so strong in Flanders last weekend. This is a duo who aren’t as strong in a sprint, but will look to try to win with a late, punchy attack.

What does this mean for Tom Boonen?

Who are the other key favourites for Paris-Roubaix now?

Sheree: Cancellara’s exclusion doesn’t alter the list of other contenders but maybe it does give them a bit more confidence that this year they might be the one to strike it lucky. Or at least they might have thought that before Boonen’s all-conquering performance in Flanders. His OPQS team are on an all-time high and with so many early notches on their bedpost and other cards to play such as Sylvain Chavanel, they are the team to beat.

The list of other contenders must include Farnese Vini’s Filippo Pozzato, while BMC have God of Thunder Thor Hushovd, the evergreen George Hincapie and Alessandro Ballan. Garmin-Barracuda have the defending champion Johann Vansummeren, Omloop Het Nieuwsblad winner Sep Vanmarcke and Martijn Maaskant. Or will Matti Breschel make the breakthrough with Rabobank?

Or maybe we’re in for another surprise. What about Astana’s Maxim Iglinsky, who finished second to Fabulous Fabian in Strade Bianche? Or the German armada: Andre Greipel (Lotto-Belisol) and Argos-Shimano’s John Degenkolb? Or how about former winner Stuart O’Grady or Tomas Vaitkus from GreenEDGE?

What’s Plan B for RadioShack now for Sunday’s Hell of the North?

Sheree: Step forward Gregory Rast, RadioShack-Nissan’s Plan B for Paris-Roubaix. Team manager Johan Bruyneel has tried to throw us off the scent with comments such as the following right after last weekend’s Ronde van Vlaanderen:

Once your leader goes down it becomes difficult. If Fabian didn’t have his crash I feel confident he would have been in the final with the rest of the favorites. I think he had a good chance to win it. But that is all ‘if’. It’s a big disappointment for him and for the entire Classics team. They have worked very hard all winter to be ready for this race and next week’s Paris-Roubaix and now they are gone.

The team’s best-placed rider at the Ronde was another former Swiss champion, Rast, in 11th place. But more importantly he finished fourth in last year’s Paris-Roubaix. He only just missed the podium in the charge to the line in the famed velodrome, being edged out for second and third by Cancellara and Maarten Tjallingii (Rabobank) respectively, after latching on to Vansummeren’s winning move.

Rast will be strongly supported by New Zealand powerhouse Hayden Roulston, who’s already confirmed:

It’s a huge disappointment to not have Fabian, I feel very sorry for him, but we’re all professionals and we’ll do the best we can.

How will Cancellara bounce back?

Kitty: One thing that Cancellara has proved over and over is that, not only is he physically strong, but he is mentally strong. He has a huge appetite to win and to constantly challenge himself, but he also seems to wear his ambition lightly. It must have been hugely disappointing for him not to be able to perform in the races he was targeting, but it proves how well-balanced he is too. He sent charming tweets and even tweeted pictures of the candy counter at the hospital on Twitter almost as soon as he got out of surgery.

At his press conference on Tuesday he said:

A crash is part of cycling, and in a way it’s also part of life. I have been working really hard in the last four months to be in the best shape possible for the big races, and I’m confident that I would have performed well. However, I’m glad I only broke my collarbone and that I’m OK for the rest. I’ll be back!

Or, as he said in his filmed message to fans: “I will come back and we will kick some ass again.”

He is planning to return at the Tour of Bavaria at the end of May, then probably the Tour de Suisse as his usual build-up to the Tour de France, then on to London for the Olympics. The crash – and his second child expected this summer – is going to give him that much more motivation to do well in London. He’s obviously going to be targeting the time trial, but he will desperately want to win the road race as well.

I wouldn’t rule him out of the World Championships either. Let’s not forget that in a sprint-friendly course last year he was fourth, narrowly missing out on the podium to Andre Greipel. The right course, the right conditions, the right frame of mind – damn, he’d look great in that rainbow jersey.

Closing thoughts

Just as Cancellara’s abrupt retirement last Sunday left many fans feeling slightly robbed of the potentially titanic showdown with Tom Boonen, his absence from Paris-Roubaix also leaves a massive void. But , as Jack says, it potentially makes the race that much more unpredictable and exciting. Will Boonen continue his exceptional spring form? Or will we see another surprise winner like Vansummeren last year? As one door closes, several others might just open for those who are brave, astute and fast enough to seize the opportunity when it arises.

While we all wish Fabian a swift recovery from his injury and recognise that Paris-Roubaix will be a different race without him, it will still be just as exciting. Even without Spartacus, Paris-Roubaix is simply epic. Don’t miss it.

Paris-Roubaix takes place on Sunday 8th April. Live coverage and highlights will be shown in the UK by Eurosport. For other channels check cyclingfans.com. VeloVoices will also be live-tweeting the race.