Which cyclist hill descent position is superior? (2017)
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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...
(unable to find a decent-quality clip of karen knight, who i have seen spin a 16' sea kayak on a dime with a canoe paddle with no above-water motion.)
You can see him use his feet to slow down the wheel before putting his feet back on the pedals.
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).
none of this weight torque stuff on the cranks has any meaningful impact when descending in mostly straight lines
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.
Here is a video of Frome descending.[0] There are some hard corners by 6km. He's back up in the saddle and choosing lines through them.
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).
[1] https://www.youtube.com/watch?v=E4Kd8XIKoiY&feature=youtu.be...
https://www.eurosport.com/cycling/re-cycle-when-sean-kelly-s...
Niccolo Bonifazio descending the cipressa https://youtu.be/Wb5G-18YLeI
But if your aerodynamics changes too much, then so will your lines.
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.
[1] https://www.youtube.com/watch?v=bnzch12ntag [2] https://youtu.be/NQbyutzJbsQ?t=225
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.
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.
https://www.sciencedirect.com/science/article/pii/S016761051...
But yeah, that shouldn't stop everybody else from using a modern frame.
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.
Your lead in meters would increase, but not necessarily in time difference?
At least that’s what I’ve learned amateur racing in a completely different sport.
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.
1. Some positions look super forced. Do cyclists really hold their body in this position?
2. When it is going down steep my major concern is to be TOO fast, not too slow. I mean what kind of speed to they have on they way down?
In fact, when I was in my mid teens, I cycled over this mountain in France. https://en.wikipedia.org/wiki/Mont_Ventoux
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.
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.
There is a good answer to this question here:
https://bicycles.stackexchange.com/questions/10231/why-dont-...
Cycling has some dumb rules (e.g. sock length), but banning aerobars in mass start races is not among them.
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.)
1) Increased safety
2) More entertaining racing (not much success here so far)
3) Reducing the cost so that it is economically sustainable even for smaller teams.
Still, the current cars are the fastest F1 cars ever.
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.
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.
It's one of the reasons I love the sport.
As others have mentioned, F1 is probably the closest today.
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.
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.
Been popping wheelies trying to climb some of the hills here in Seattle in the lowest gear (22/34).