2017 Tour de France, Stage 4 crash

Sprints can be hectic and split decisions are made at high speed. Riders do not want to cause a crash, but risks are taken that sometimes do not work out. The fourth stage was a sprint finish with a crash at just under 200 meters to go, which resulted in an unfair disqualification of the most popular rider, Peter Sagan. Keep in mind that the following event takes about 7 seconds, from 300 meters to go to just under 200 meters to go. And with 300 meters to go, there is only about 20 seconds left to the race; a sprinters focus will be on what's out front and will not be turning his head to see anything behind him, so anything behind 180 degrees of peripheral vision will be unknown to him.

At the time of this writing, there were two videos that showed the overhead and front views of this incident, which the following images are taken from. Unfortunately the overhead shots have trees that obscure some critical points of the events.

As the riders approached 300 meters to go, they were close to single file, with Sagan in 5th, Demare 6th, and Cavendish 7th.

A few meters later, the third place rider, Kristoff, accelerated and moved to the right.

This causes the train behind to follow the drift to the right.

Demare in blue saw the action and veered to his right to get around the crowd, shifting more momentum to the right and Cavendish more in Sagan's slipstream than Demare's.

Greipel (in red) can be seen elbowing Bouhanni (also in red) with his right elbow as Demare came even with Sagan and Cavendish is looking to be on Sagan's wheel.

As Bouhanni untangled himself, Demare moved further right to avoid him, those around him also moving right.

Demare moved far to the right as Sagan also moved right to avoid Bouhanni, oblivious to Cavendish.

Now with Demare slightly forward of Sagan, he could move further right to try to get on his wheel, still oblivious to Cavendish.

As the tree obscures a critical point, we can see Cavendish realizing he was getting pinched to the barriers and started to turn towards Sagan who can not see behind him. Even if Sagan knew that Cavendish was approaching on his right, he was moving faster than Bouhanni and could have collided with him by moving left.

After emerging from the tree, Cavendish had advanced upon Sagan with his left shoulder in Sagan's rib and arm pit; the first realization the Cavendish was there. Sagan's arms were in a normal sprint position and Cavendish was already leaning towards his crash. The sudden forces on Sagan's side would have caused him to naturally lean back into that force, appearing like an intentional quick hook and change of lane.

Feeling contact under his tricep, Sagan started to raise his elbow as Cavendish's brake lever rubbed the under side of his forearm.

Sagan's elbow then went higher, moving away from Cavendish to give clearance to Cavendish's brake lever, not to block or push, as Cavendish is already doomed to crash. If Cavendish was not already so off balance, Sagan's elbow raise would have taken pressure off of Cavnedish's brake lever which would have helped Cavendish to retain control to hopefully stay upright.

Sagan's elbow then started to come back down once Cavendish is not in contact. Sagan's left leg came out to try to bring him back away from the barriers.

Sagan worked to regain balance after the collision as Cavendish fell back. And what's with that big red triangle sticking out from the barriers waiting for riders to smack and break bones with? Notice Bouhanni's left leg sticking out to keep balance as he coasted for two pedal strokes due to Demare cutting across and contacting his wheel (and Demare knew Bouhanni was there). With only Kristoff ahead of Demare, no obstructions, and 150 meters left, there was no safety reason to swerve left. The coasting by Bouhanni allowed Greipel to pass Bouhanni by the finish. If Bouhanni had not coasted and hit Demare, there would have been a crash that may have taken down Demare, Bouhanni, Greipel, and Sagan, so Demare's move was much more intentional and dangerous. If only Cavendish had coasted, rather than continuing into a high risk slot, there would have been no crash.

This does not indicate that Sagan intentionally rode dangerously. Cavendish was heading for a diminishing slot and had too much speed to avoid getting trapped. He tried leaning into Sagan, but unfortunately Sagan could not react quickly enough to open up the hole and had no idea the situation was developing. Although Sagan is a very serious rider, everyone knows he rides for fun and is not mean spirited. Sprinting often involves being assertive and taking risks, but Sagan should not be found guilty of intentional dangerous riding in this situation. To have him expelled from the Tour de France for this incident is unjust and a major loss to the fans as well.

Greipel's intentional hooking of Bouhanni was a more dangerous move (and initiated the shift further to the right of those involved), as was Demare's final 150 meters moving from the barriers to the center of the road at the finish line and cutting Bouhanni off in the process (where in an interview after the race, Bouhanni states he touched Demare's wheel).

Cavendish had collided with a large red obstacle placed along the barriers by the organizers. Is it possible this fractured Candish's right scapula?

And there's a very important tidbit of data that everyone had been unaware of (except by one very smart friend of mine). The finish took place in Vittel France on the Avenue Georges Clemenceau. I mapped the race video with street view from one kilometer to go, to make sure the following pictures were at the correct location and some of the paint from the Street View has worn off as compared to the video from 7/4/2017. The incident happened soon after a Pizzeria-Hotel-Bar on the left side of the road that is not in any of the pictures.
That road is 2 lanes plus a center turn lane, but the race blocked off the left lane for officials at the finish line, so barricades left 2 lanes open on the right (yes, the finish could have been 50% wider). The barricades were placed just off the street, above the curb on the right side. You can see the tree on the right that blocked the overhead view at the time Cavendish and Sagan tangle. These can be compared by seeing the first of the chevrons in the center lane just past the white triangle. However, if you zoom in a bit closer, you'll discover a storm grate at the exact point under the tree which is right where Cavendish began to have difficulty.
View as you approach tree.
Hard to see any problem ahead. 
Grate adjacent to the tree.
View from across the street.
Close up.
Would this cause a problem for you at 40 mph? 

Grate even with front of Demare's front wheel.
Grate even with center of Demare's front wheel.
Cavendish at grate.
Cavendish's front wheel has moved away from the curb quickly, leaning into Sagan.
Cavendish coasting as Sagan keeps balance by leaning into side forces.
Cavendish coasts for about half a second just prior to the grate and prior to colliding with Sagan (notice his left foot is down in all of the above sequence, while everyone else still pedals).
Thus it may have been entirely possible for Cavendish to squeeze through the gap between the barriers and Sagan, except the surprise grate forced him to move into Sagan (and/or slow down when he needed to close the gap on Demare). He may have reacted instinctually when the grate approached and moved left (or his wheel became caught in a part of the grate), contacting Sagan, who would then end up leaning into him to counter-act the force on his right side, thus causing him to swerve a bit more to the right and further into Cavendish, probably abruptly, appearing like a hook.
Watch in slow motion starting from 1:37 in on YouTube where you can see his wheels bounce as he goes over the grate and then starts to crash.

In Summary:
Sagan did what any other sprinter would have done in similar circumstances; there was no violence or unsportsmanlike conduct involved and in fact the elbow raise that was used to crucify him was intended to help avoid contact. If the race organizers had done a proper job to use all three available lanes and put the barriers over the hazardous storm grates, there probably would have been no accident; thus once again, rider safety was not a priority. For the riders, the accident was precipitated by Demare, but his proximity to the barriers was precipitated by Griepel who elbowed Bouhanni, forcing Bouhanni to untangle from Griepel by moving more right than originally intended, which forced Demare closer to the barriers. Although Cavendish started on Demare's wheel, as Demare began to pass Sagan, Cavendish placed himself somewhat behind Sagan (not directly behind Demare, photos at 4h53'40"), leaving himself invisible to Sagan and not asserting his stake to Demare's wheel. This is where Cavendish made his mistake, as he should have had committed himself to Demare and done a quick acceleration to put himself right behind Demare which would have also made him visible to Sagan. Instead, his indecision left the door open for Sagan to take the opportunity to swing into Demare's slipstream when it presented itself (4h53'44") and that's when Cavendish also sees that one opportunity to win may be for him to squeeze through on Sagan's right. Yet Cavendish should fully be aware that Sagan will try to take Demare's wheel and that will leave inadequate room for him to pass Sagan unless he can jump quickly enough to get into the hole before Sagan can move over, then force himself with a shoulder to prevent Sagan from taking Demare's wheel. It was a brutish risk, but he didn't accelerate quickly enough and space ran out before he could get his shoulders even with Sagan's, possibly due to a sewer grate interfering with his plans. Knowing prior to the crash that his positioning had already closed the door on likely success to come up beside the barrier, he should have let Sagan lead him out and pop around him at the line, since there was still about 150 meters to do so. These are tricky, split second decisions that can not be replayed, and this time Cavendish didn't make the best choices and paid the price.

Cavendish was so eager for the win that he took a gamble that his dive for a hole would work out (somewhat like the amazing Chris Hoy in the Olympics), but he lost the gamble. After the race, Cavendish should have manned up and admitted the accident was mostly from his own decisions. Although he saw Sagan's elbow well in front of him, he knew damn well that it was in no way a cause of the accident. To instead insinuate that Sagan's elbow was somehow a factor was disingenuous and unsportsmanlike conduct. This surely influenced the decision that unfairly targeted Sagan. I was rooting for Cavendish at the last Olympics, but was shocked to see his apparent intentional wiping out of a rider that also knocked down the current leader that could have given Cavendish the gold; Cavendish was not given any penalty and finished with a silver medal at the Olympics.

And many people also accused Sagan of causing the crash with 1.5 km to go. Not so. If you view the NBCSN link on YouTube, at 1:49 you'll see the rider slightly ahead and to the left of Sagan touched the back wheel of the rider in front of him and fell into Sagan (you can see his left side from an above view taken from the right side, so he was leaning heavily when he contacted Sagan). He bounced off of Sagan to the left and went down, taking a bunch of others as well.

I have stopped watching this year's Tour de France. The GC race was just an aside for me, as the sprints were the main attraction. With the most exciting sprinters removed, the remaining sprints and green jersey competition are tarnished. This jury decision will drastically hurt the Tour, Cycling's credibility, and long term profitability for the sport overall. Political motivations are also inferred (a French race disqualifies the strongest rider so that a French rider with more serious violations is not sanctioned, awarded the win and the green jersey). Sagan (or any other riders involved) were not consulted in the decision and the jury brazenly stated that no appeal could be admitted. There was no need to hurry to make a decision, since the next racing did not start until the following day. There needs to be reform in the case of penalties and consequences for jury decisions that appear biased. The bias in this case is that the officials did not want it to become evident that they again had an unsafe course and demonized Sagan's elbow to distract. If it's not an honest race, it's not worth watching.