[Retric]

People do ski faster than that but low friction means slower deceleration which is a huge reason it’s even possible to learn reasonably safely. This applies to basically all high speed winter sports and is under appreciated by most viewers. Similarly landing from a jump or fall on a hill the force vectors mean people are mostly sliding on the surface resulting in significantly less forceful impacts.

Biking at 45-48 MPH is rare, dangerous, and free of tripping hazards which I think are a much larger concern. Further, people also add extra protection for downhill MTB such as a back protector, thick gloves, goggles, helmets with neckbrace, padded clothing, and knee pads. Yet it also has similar benefits from being on steep hills.

[Lio]

> Biking at 45-48 MPH is rare, dangerous,

Not sure where you get that from. Amateur road cyclists can pretty easily reach 50MPH given a long enough hill and do so pretty uneventfully.

That's dressed in just shorts, jersey, helmet and fingerless gloves.

A professional racing cyclist could easily break 60MPH on closed roads and even 80MPH on occasion.

For someone like Tom Pidcock who knows[1]. In the linked video he's topping out at about 100kph (60mph) but it's worth noting that that's without being allowed to sit on the top tube of this bike. They banned that (even though it wasn't linked to any crashes).

The bike manufactures will eventually just add dropper posts to all pro road bikes and those speeds will go up again.

https://www.youtube.com/watch?v=3f4Pp4oYh28

[Retric]

Rare as in what percentage of the time is someone on a bike going 45+ MPH?

I’d be surprised if it’s more than 1% for more than a handful of people. An ultra elite athlete on a normal bike can hit that on level ground in an absolute sprint, but you can’t sprint for very long. Going downhill requires time spent going up the hill.

The women’s 1 hour speed record is 30.6MPH, the men’s is 35.3 MPH. So sure downhill, rolling start, or motor-paced people can reach extreme speeds but they really aren’t doing so for hours a day. Streamlined recumbent bicycle can do it far more easily but that’s niche territory.

[pixl97]

The amount of time that standard cars reach 100MPH is rare, and it is dangerous. Professional racing drivers have cars that reach 200MPH+, it is insanely dangerous and all kinds of specialized equipment is in place to keep the driver from dying.

You seem to be conflating that if someone reaches a particular speed it is safe which the whole 'velocity squared' doesn't give two damns about. The energy you have to safely dissipate increases very quickly.

[Lio]

No, I don’t think I am conflating that at all.

I’m not a professional rider. Nothing special about me.

Yet on a small hill near my house, with a maximum gradient of maybe 8%, I regularly hit 40mph.

When I need to I’m able to safely decelerate uneventfully.

It’s really not that rare. It happens every ride. I get to the bottom and I just go on with my day.

You won’t suddenly loose control if go past a arbitrary speed. Just read the road conditions and act accordingly.

This is not something only professionals do whilst wearing body armour. That’s an obviously silly suggestion to anyone that regularly rides a bike.

If you must make a car analogy then a better one would be crashing at 80mph on a motorway. If you do it will be life changing.

The same thing applies on a bike going 40mph but I happily do both when I think it’s appropriate to the conditions.

[lloeki]

> Biking at 45-48 MPH is rare, dangerous, and free of tripping hazards which I think are a much larger concern

Two decades ago I was doing downhill MTB. On a road section it was quite frequent for me to reach those speeds†; and that's with a MTB (tuned to that end), friends†† with road bikes reached these speeds with ease, some of them regularly hit 80-90kph on specific sections.

One of the wide hairpin turns happened to be littered with gravel, and as I was banking for the turn the bike wheels started zipping off laterally as it the ground was ice, propelling both of us sideways at full speed towards the downward outer bank.

Luckily a) I had slowed down to approach the turn so I was going more like 45-50kph and b) the bike had much less ground grip than my body so it flied away while body-ground friction (painfully) slowed me down to a stop before I hit any tree or rock down the bank. Sheer luck had it that I walked away from the event with only a few bruises and a lot of scratches (one of my elbows still bears burn scars)

† Top recorded speed ever was 74 kph, at which point gear ratio was such that `cat pedalling > /dev/null`

†† c.a 1995-1999 they biked regularly with the then young Julien Absalon (I only biked with him once): https://en.wikipedia.org/wiki/Julien_Absalon.

[Retric]

‘On specific sections’ doesn’t mean people are spending a lot of time doing something. If you’re going downhill at 45+ MPH you quickly run out of hill.

I doubt the total time by any bike rider over 45 MPH was 0.1% of the total time people ride bikes.

[LargoLasskhyfv]

I do that on flat grounds with a roadbike, and can hold that for about 5 minutes, then falling back to about 60 to 65 kph, which I can hold for an hour, after which I usually am where I wanted to be. Rarely doing longer rides anymore. Usually at sea level.

That thing where you are 'running out of hill fast' I'm doing comfortably with 80 to 85 kph, and sometimes when in a 'real crazy' mood, and weather is allowing it (strong gusty winds, and possibility of black ice NOT good) with 90 to 95 kph. Though I'm really having to pedal like mad then, like in 1st gear, even faster.

Usually anywhere between 2000 to 4300m above sea level.

Got myself 2 really nice roadbikes recently, after having ridden an antique citybike with only 3 gears for almost 2 decades now.

It's like I'm young again! Unbelievable! :-)

[Retric]

> Can hold that for about 5 minutes, then falling back to about 60 to 65 kph.

If you’re suggesting doing 60 to 65 kph for an hour on a normal road bike after 5 minutes of 75 kph, I simply don’t believe you.

The world record 1 hour time on ultra flat indoor terrain set in 2014 was 51.852 km (32.219 mi). It’s climbed since then but your suggestion of ~63 kph for a full hour on a roadbike comes off as silly unless your using serious electric assistance.

[LargoLasskhyfv]

I believe that you don't believe me, because that's what I always got. Except when on rare ocasssions ppl followed me with a car or motorbike. OR I pushed them to ride like they couldn't believe when they rode with me, which was also rare.

Can't do anything about it. Shrug. :-)

[LargoLasskhyfv]

A long time ago, 1989 or 1990 I went with 65kph into a larger roundabout at around 4 AM, with only one car in it, a Citroën 2CV. As usual, the thing was SLOW. I thought I'd could overtake it left, while staying behind it, but not much. What I didn't think of was the possibility that it would brake right there and then to exit into a small private driveway directly adjacent to the roundabout, instead of the regular exits.

So I touched the thick rubber lip of its back bumper at its far right side, almost the corner with my front wheel, while already being banked right by about 30 to 45 degrees (because turning right in a wide bow from the entering main street).

INSTANT STOP and I FLEW over the back of that f...ing thing.

In that moment I felt surprise, and anger, for being so stupid, but also thought in ultrafast-forward about anything I could think of to dampen the crash.

Which was to spread the energy of impact as much as possible around my whole body, execpt my head, and separate like hell from my roadbike.

I actually managed that while doing a summersault, not by myself, been already catapulted into it, still attached to bike, but got free of the pedals, and managed to spread out my arms and legs while flying feet forward, and somehow stay oriented like that.

BAM! Hit the road with my back at least a dozen meters away from 'lift-off', could have been 20 to 25 meters also. Can't tell anymore.

Hands outstretched, palms flat down. Head UP, chin toward my breast. Soles of my shoes also flat down, legs slightly bent upwards at the knees.

OOOF! Couldn't breath for a while, that just didn't work anymore, even if I tried. That went on for about 30 seconds, then I managed to gasp, and then it was gone. It didn't hurt, I just couldn't.

My palms tingled. The soles of my feet too. Like hell. But only for about a minute or so. Then that was gone, too.

In utter incomprehension I sat up and checked my hands, arms, ribs, legs, head. Nothing. Everything still attached, not broken, no blood, while the chalk white faces from that 2CV emerged, running toward me, shocked.

I told them to get their damned 2cv out of the roundabout, to avoid another crash, grabbed my bike from the street where it lay a few meters away, and went to the sidewalk, still debating with the shocked people that I wouldn't need an ambulance, that nothing bad happened, and they could calm down now.

No torn clothes. Yay for Levis 501 and Nomex45p Bomber Jacket CWU!1!! But the roadbike was trash. Not even the frontwheel, as I'd have expected, but the whole frame and fork bent diagonally sideways in a hard to describe way.

Did walk the rest of the way home, after removing the saddle, very light bell with a nice ring, tachometer, its sensor, cable and fixings.

Sitting on a bench in a park next to a river, thinking: Insane, insane, this can't be, can't have happenend like that, can't can't...

Moving on, still a few kilometers to walk, through forest. Sun rises. Still thinking can't be, can't be, like in an endless loop.

Went to bed at about 6AM after checking for bruises, swelling but nothing to be seen or felt. Used the next day to get me another roadbike (used) for 2000 Deutsche Mark ;-)