It's one of the first things you learn in trick cycling and not that bad, really.
As soon as you know the failure modes of each trick and how to deal with each you're pretty safe. This one only has some that are easily caught. That speed, on the other hand...
Last time I discussed this I was told that the bike in question here is fixed gear and in such a race you're not allowed to take your feet of the pedals.
On it's face the hypothesis that riders are optimizing for aerodynamics on descent is suspect. The peloton breaks up because the critical limit is the performance envelop of the bike's steering geometry, braking and contact patches. It's not that aerodynamics don't matter at all, it's that good enough is good enough. The margins are elsewhere. Everyone can go fast enough to carry too much speed into a turn and have a bad day.
Other positions...provide more equal distribution of body weight over both wheels
This is a suspect optimization premise. Weight distributed to the rear wheel means less weight on the steering wheel and greater eccentric forces when steering...i.e. a reduced front wheel contact patch required to resist higher eccentric loads.
An interesting difference between the photographs and the 3D models is pedal position. The photographs show high-low. The models use a midpoint. The high-low position puts the high foot next to the seat post where weight shift steering will create the least torque on the frame and the feet stay "under" the rider as much as possible shortening the levers creating stiffness.
It looks like Froome's position maximized the amount of force he could exert to keep the handle bars steady and center of mass low -- when going downhill the further forward the rider, the lower their center of mass (all things being equal).
> Everyone can go fast enough to carry too much speed into a turn and have a bad day.
But if you want to beat someone going downhill you need to get to the turn as fast as possible and then brake. On a steep enough hill aerodynamics are the only thing that determine how fast you go on the straight - you don't even pedal because your legs can't keep up.
That depends on the gearing. I remember pedaling madly up to 80kph in 12th gear, and after reaching that sliding into that Pantani thing, to coast out as long as possible. Which wasn't that long where i rode, 2 minutes max, maybe.
Very interesting, but also needed a mention of the crazy "discesista" that was Paolo Savoldelli [1], I think he won a Giro one year based on a crazy descent like that.
In his case I don't think it was only a question of aerodynamics, it never is, it was also that he seemed to know best how much risks he could take when entering a curve (similar to how Formula 1 cars used to be in the past, nowadays they're too "computerized" for that to matter that much anymore).
He is one of my favourite all time descenders on the road. Absolutely fearless and precise. I wish professional road cycling gave the discipline of descending the respect it deserves.
Good point. Case in point: Cancellara's masterful descent here [1]. It's one of the least aerodynamic (I'm certain I can get more aero on a straight descent), but I would get dropped hard on the first curve. Especially on curvy descents, it's all about taking the right line at the right speed. But I am happy to see Froome's position is not even that aero. It certainly looked unstable.
The skill of these "descent specialists" always reminds me of racing skateboards down hills, which is a combination of the "descent aerodynamics" of cycling and the "edge of grip" of racing cars.
I participated for a while, and it is a really fun way to access the "edge of grip" of racing cars, which isn't really accessible in cycling (bicycles don't often survive a loss of traction on the front wheel!)
If you're interested, here is a nice intro [1] to the sport, and an example of a [2] final race heat in a European Alp setting, with similar aerials to cycling coverage. The skill is the combination of drafting, strategy, cornering and straight line speed.
First video reminds me of inline skates parallel slide on the crappy asphalt I've done while "in the zone". From downhill to full stop, no protection at all, perfect control, extremely happy that slided with wheels not with face.
Love this :) Let’s not put aside the fact that F1 drivers spend days testing courses on simulators, so they know exactly what speed they can handle corners at.
The article is keen to stress that going super aero on the descents for amateurs is best avoided.
I second this. A lot of descending skill gets learned in teenage years. Those that grow up in hilly areas enter adulthood with innate ability that those who grow up in flat areas struggle to emulate. You can't just take chances.
For absolute amateurs wanting to descend like the kings of The Tour on charity rides the trick is to have properly inflated tyres, so that means using a track pump and not some small hand pump. The track pump has a guage and the tyre has a figure to inflate to.
On a charity ride with properly inflated tyres and some ability to take the correct line it is possible to cruise past people that are in a full aero tuck and pedalling furiously. The chances are that those you pass have all the gear but haven't got that tyre pressure detail right.
Clearly this won't work when riding with people who are pro or have ambition to be pro. But there is great joy to be had when freewheeling down a hill on a boring flat bar old man's bike with mudguards and steel components to pass fully lycra-d riders with fully aero carbon fibre steeds.
I've only ever been the most amateur of cyclists, but I find the "Pantani" position (or perhaps the nearest facsimile of it that I can perform) is the most comfortable and stable for descending steep hills at speed. With my stomach on the saddle, I never worry about pitching forward and my arms are aero yet still able to steer.
I can do high speed descents faster on a slick tired mountain bike than on a road bike simply because the added mass bumps up the terminal velocity so it's less of a struggle. You're not proving much beating roadies with a heavier rig.
As an amateur the aero tuck looks like a tempting way to get a marginal gain in speed on the descents. It costs no money and does not demand superhuman fitness. It is easy. But if you get it wrong you get hurt.
My point was that an easier marginal gain is the tyre pressures. So often overlooked, tyre pressures are often gauged by feel for the rider to think their tyres are rock hard for them to actually be half inflated.
If you don't have fitness or an expensive bike then the air in tyres idea is better than the aero tuck for getting some speed.
Regarding your anecdotal MTB speed experience, you have changed quite a few variables - suspension might better suit the road surface, disc brakes might give you quicker braking, the upright bars might help you pick a better line, the smaller wheels might be more aero, the higher bottom bracket might enable you to pedal out of tight turns, the situational awareness from the upright position might give you more confidence on the road and familiarity with the MTB rather than the Sunday special road bike might also be part of the apparent speed gain.
At the macro level this optimization to a local minimum is interesting, but on a larger view it's just sad. Using a recumbent, one doesn't need to bend into a favourable position, one already is in the optimal position. The fact that bicycle races prescribe this aerodynamically and ergonomically suboptimal frame type is damaging to the larger cycling community.
Road and track races are all about closely packed pelotons going around tight turns very fast. Recumbents have very poor cornering compared to standard bicycles, and would not be safe. The performance advantage of most recumbents is often overstated as well, because the rider is in a reclining position at maybe a 30-40 degree angle.
A rider on a standard racing bike can get their backs horizontal in the drops.
Respectfully, I think you're both right. Certainly recumbent bikes are aerodynamically efficient, but it's worth considering that in a bike race one also needs to ride uphill, and the instability of a recumbent at slow speeds would be a disadvantage here. I haven't checked, but I suspect most hill climb records would be held by traditional bike frames.
I don't think recumbents (at least high-racers) are necessarily unstable at slow speeds. My understanding was that the fundamental problem with recumbents in racing is that, going uphill, aerodynamics matters less. What really matters is applying torque efficiently. And humans are designed to apply torque vertically: we're good at it. So while on the straightaways and downhill recumbents cannot be beaten, they are poor at climbing.
What's frustrating is that we'll never get to see serious comparisons of the two, or of interesting combinations of them, in real races because UCI banned recumbents for the worst of reasons a hundred years ago.
Sadly, the stranglehold UCI has on organised cycling around the globe is not going to go away anytime soon, pandemic or not. The rise of "gravel" riding and races is proof that we can have more fun when the UCI isn't involved.
I think that races on recumbents would be comparably boring. Because there are fewer tactical options when drag is reduced. So I can understand why there are races on the classical frame.
But yeah, that shouldn't stop everybody else from using a modern frame.
Under heading: "Four conclusions" and as part of conlusion "1. Froome did not win because his descent position was aerodynamically superior" it says: ". . . When you have a lead when you start descending while others are still climbing at lower speed, your lead only increases until the others start descending."
Your lead in meters would increase, but not necessarily in time difference?
It is quite important to be aero when leading, or otherwise when isolated in a descent, in order to gain speed while being able to rest. Others that are riding in a group may have a sub-optimal position in a descent and pedal to compensate. They will be able to rest on the flat anyway by relaying each others at the front.
One thing to keep in mind is race strategy. If the opponent in front of you is out of sight, its very hard to catch up again. Even if both are otherwise identical.
At least that’s what I’ve learned amateur racing in a completely different sport.
Agreed. Imagine two objects with the same velocity profile, but offset by a certain number of seconds. They'll take the same amount of time to reach a given displacement from when they set off.
On longer straight sections in descents, one can also very narrowly grip the bars near the stem. This lets you tuck your arms in front of your torso. Pedaling when you're doing ~70 kph or more can be counterproductive too. It's a lot of work for almost no speed, and it makes you less aerodynamic.
A narrow grip results in less torque if you need to control steering. It's true that will be faster, until and unless you lose control. Then it is extremely dangerous. It also positions your hands away from the brake levers (on road bikes).
It’s no worse than the Froome position, which is about as bad as you can get for braking. You don’t want or need to be applying a lot of force to the handlebars at speed, so it’s not a big deal that you don’t need to have a lot of torque on the handlebars. At high speeds, you really want to be controlling the bike by shifting your weight slightly.
As for the tight in position, It’s actually pretty easy to move your hands from the beside the stem position out to the brakes as long as you’re paying some attention to the road ahead.
They never account for fatigue. On long descents your neck and arms will get tired. The downward back is especially stressful on your neck to hold your head so you can see forward. This means changing to a less aero position to rest your neck and arms. Some positions may be less aero but also put less strain on a rider that may be 4 hours into a race already.
Because of draconian UCI rules put in place to satisfy political whims of the 1930s, we are required to consider only positions like these rather than other, much more aerodynamic ones. The danger lies in people starting to think that these are good positions. They are not: they are horrible. But professionals are forced to use them in racing.
Once you are at the apex, it is down for like 20km. Your biggest worries will be your breaks. We were a group of youngster and some had back pedal brakes. Most of them went up in smoke. They had to use a rope to drag a small tree behind the bike as a way to slow motion in the end. No kidding.
I mean, you drag a small tree beyond you to slow your speed. If your back pedal braked has become fully dysfunctional and your consumer grade front wheel cantilever brakes is all you have left for a 20km descent, good luck!
This was a while ago. As far as I remember there was no bike shop on the mountain. Also doubt it would be easy to add a disk brake on a bike that has a back pedal brake.
When bicycling downhill during good weather, on known routes and acceptable traffic I always tried to reach anywhere between 80 to 85 kph, and one time even reached 93kph!
That Pantani position was something I instinctively went for.
Of course that was eons ago, nowadays I'm happy to peak 65kph on flat grounds without headwind, when on a street bike. Which is rarely the case, since I'm mostly riding some vintage city/touring bike for practical reasons, which limits me to something like 45kph if I push it, and when I don't want to be sweaty it's more like 35kph.
Interestingly nobody ever thought of Peter Sagan of a good downhill racer. The very best sprinter of course. But his position looked strange, not as strange as Froome's or Pantani's though. And I never thought he'd won any race because of his downhill advances. Only because of his sprinting abilities. Strong bias. But he always had a strong technical team behind him, and that shows.
I suspect using triathlon bars exceeds the performance of every tested position. Unfortunately there are not allowed by the UCI for inline races. Progress is very slow in some areas ...
Cycling is a sport about strategy and athletic power, not about technology. What a bike looks like is fixed so that the best rider wins instead of the best bike winning. You can build a more aerodynamic bike. You can build a lighter bike. The progress would be relentless and all money would be invested there if the rules allowed it. So they don't.
It's the same for many sports. You could use aluminum bats in major league baseball. They don't because they simply work too well. In addition to killing the pitcher if you hit a line drive at him, every hit would be a home run. They'd have to make the stadiums larger and add more outfielders. Why bother? Then they'd make the bats even more powerful, and the process would repeat again. So they just use wood bats.
There are plenty of opportunities to race streamlined recumbent bikes, by the way, it's just not the ruleset in play for the Tour de France. (And of course you can use a TT bike in the time trials.)
While that's true, I do wish there would be some "no technological limits" athletic events where they could go all out on technology just to see what the extreme would look like.
I think formula 1 comes closest in that regard. There is some insane engineering that is done by top teams. I believe carbon fiber, ABS, disc brakes all came from f1.
A large part is also for looking for something that passes the letter of the rules, but not the spirit - a loophole.
The Mercedes F1 DAS system they intend to race this year when the season gets underway is just the latest example, but see also the 6 wheeled car, the fan car, getting around the ground effect ban, double diffuser, blown exhaust etc. etc.
They do - but they also have scores of super smart engineers who each year manage to find a certain something - be it a loophole, or just something nobody else thought of.
See DAS this year, F Duct in the early 2010s, the 2009 Double Diffusers (when they were technically banned), Blown diffuser, CF layups that cause the front wing to flex under load etc. etc.
Why tri bars should be unsafe? You have control of the steering, control of the brakes and your back is flat which increases comfort. Aerodynamically speaking your cross section is quite smaller.
Your control is greatly reduced in aerobars, but more importantly, your ability to defend your space is hugely reduced, which makes riding in a pack extremely dangerous. This video explains why having the ability to protect your bars prevents crashes: https://www.youtube.com/watch?v=sRIsWzrMmBs
Cycling has some dumb rules (e.g. sock length), but banning aerobars in mass start races is not among them.
This. Aero bars are nice for flats and descents. I wouldn't want to have to do a tough climb without drop bars or at least flat bars. And I definitely wouldn't want to ride in a pack with drop bars with my hands not on them. That sounds like a great way to wreck.
When you are on the the aero-bars your hands are not on the brakes and the your ability to perform accurate steering adjustments is greatly compromised.
Yes. Getting the upper body tucked narrowly is superior to basically everything here.
However, full-size tri/TT bars aren't even allowed in triathlons where drafting is permitted. Only recently have reduced-length aerobars been permitted in drafting-allowed races (aerobars no longer than the drop bars/hoods).
Full Tri/TT bars aren't allowed in UCI races because they poke out in front of the bars and hoods; there is some concern they could stab someone in a crash. UCI races allow drafting. The shorter aero bars are relatively new and there is certainly some resistance to change in UCI. I don't know how long it has been since UCI reduced the minimum weight limit but it's been 6.8 kg for quite some time.
Additionally, tri/tt bars reduce your steering stability, which is potentially very bad on a fast descent like this. Usually tri/TT bars do not have brakes on the extension arms — neither for clip-on aero bars for road bikes, nor dedicated tri/TT handlebars.
Anyway, I have aero bars myself and ride in that position going fast on flats and modest descents. But I go back to a wide, near-the-brakes position above 30 mph.
Tri bars are definitely the fastest that I’ve ever descended by quite a bit. Neither were in race
conditions, once was on a mtb with road tires and aero like bars in upstate ny, and once on a tandem with aero bars on the US route that STP takes once crossing into Oregon.
Both times I hit 55mph, and the bike was rock solid riding at that speed on the aero bars.
The fastest descents I’ve done without tri bars has been in the 45 mph range, but I’m sure faster is possible with the right hills.
Don't single out cycling. Doping is rampant and risk free (when it comes to the risk of being caught) in every professional sport. They decided to do something about it in cycling while most sport federations (with maybe the exception of the UFC) prefer to turn a blind eye. There is much more incentive to dope in soccer, NFL, NBA or tennis and about zero risk of ever being caught if you're not a complete idiot about it.
It's safe to say cycling is one of the cleanest sports now and wasn't the dirtiest in the past. Sure you still have compounds that are detectable for like 3-4 hours and you still have designer drugs which are not detectable yet but at least you have to deal with an organization willing to test and use biological passport while for example in soccer everyone works together so it's easy to dope and get those 100 high paced games per season done.
https://m.youtube.com/watch?v=3Iz7ZMALaCY