BadGrandma

My fastest was about 45mph on my single. Bruce and I hit 52 mph on our tandem on a long straight hill leading into Chillicothe. But for the last 4 years I don't go any faster than 20-22mph (gotta get disc brakes).

tshelver

Recumbent trikes are the answer...

Not really measured top speed much in my life (on bicycles that is), but it very much depends on the bike, the surface and visibility.
Another big variable is the rider. I have ridden (and raced a bit) sport motorcycles most of my life, and there is a huge difference between how riders handle incidents at speed, even on the same type of bike: usually a combination of skill and a familiarity with riding at speed.

When I lived in Lyme, NH, there was one hill I could regularly hit in the 40s (mph on computer and GPS) on my recumbent trike. Once I even did it towing a trailer full of groceries (which was almost totally in the trikes's slipstream). Great surface, excellent visibility with a slight bend towards the bottom, just stay steady on the controls. IMHO quite doable on any bike in good condition and with good stability (that is, not possible on my MTB ...).

Trike was an ICE Q with rear suspension, similar to today's Sprint, but with a wider track.

I rode the same trike in the Philippines. One favourite weekly ride was up into the mountains to fetch milk, a 75 to 90 km round trip. On the way back there was a 3.5 km descent where I regularly could coast well past my max peddling speed: Here, you can also do a Google street view.
Never measured the actual speed, but the warming flag on the trike pulled out twice due to wind pressure. Once a motorcycle rider I had passed told me at the bottom that he had been doing well over 60 kph on some of the straights and not catching up.
I usually covered the distance faster than any of the cars or motorcycles on the road: the cars got stuck behind traffic, and the bikes were limited by greasy / dirty road surfaces.

But I would NOT attempt that same descent on a 2 wheeler (motorcycle or bicycle) at the same speed. Surface was just too variable, and traffic was also an issue. The trike let me do apply variable braking to the front wheels, as usually the inside wheel would lock up when braking in a corner: the same braking on a 2 wheeler would have you down in an instant.
Plus you could recover from front or rear slides on the trike, not so easy to do with a 2-wheeler.

MikeyMK

The problem with taking my tadpole recumbent trike to high speeds is that it has no suspension.

I've got a 24in x 2.35in Schwalbe Big Apple tyre on the back but my front wheels are a daft size (16 3/8 English) so i'm limited to skinny Schwalbe Marathon tyres.

I have 2.0in Big Apples in 18in and the tyre bead is a frustrating 6mm bigger, obviously they won't seat on the rim. 18in rims with 36 spoke holes are proving tough to find, 16s impossible, so that'd mean new brakes to replace my 36h drums, too.
Halving the spokes to 18 doesn't compute.
I can't use 20in rims as that'd really limit my steering, unless i fabricate blocks to widen the track - if i was gonna do that i'd go for longitudinally operating suspension arms (Classic VW Beetle style).

My short wheelbase e-tandem is blisteringly quick. Fat tyres, air suspension, it doesn't matter what gets in it's way, it irons out half-kerbs at over 40mph head-on, bricks, raised manhole covers, stairs.. To imagine riding the tadpole like that is just ludicrous, it'd be wrecked in minutes. And so would i.

cyccommute 

You are braver than my wife ever was. When we had a 2 year old, we did a trip in the Taos area. On the way back down from Angel Fire (I think), I was fully prepared to go as fast as possible (while pulling said child in a trailer). When we hit about 45, my wife started shouting "We are going to die! Slow down!". I did.

Said child, on the other hand, had no problem with speed. While still tied into the kid crank, she laid down (on her back) to watch the clouds rush by on a 40+ mph descent down into Norris Geyser Basin. She was also the one who did 55 mph with me on the tandem at 6 years old. She's still pretty fearless 30+ years later.

jefscolnago

Over 50 a couple of times; over 55 once - all the same hill (straight) into Carversville, PA. Speed is relevant, though and anything over 40 is fast anywhere, when you consider about 2 square inches (or so) of contact between the tires and the pavement. A good example of this is another road with curves and a 42 mph top speed. All I can say is it brings me closer to God as I pray that I don't have a spoke break on me. (Or any other catastrophic failure... That's a prayer I have a LOT anywhere, but much louder going into that first curve and coming out the last!)

canklecat

As you gain experience and comfort with speed, sometimes nothing seems fast enough. But the one time I drafted a truck and got up over 50 mph, that seemed like enough.

We don't have any long steep descents, straight or curved. Just a few moderate straight downhills of 1/2 mile or less where it's easy to do 30-35 mph barely pedaling or even coasting if you're tucked. I've topped out at 40 mph on both road bikes, mostly due to gearing. With the 50/13 top gear combo on one bike and 52/14 on the other, I'm spun out at 130 rpm right at 40 mph. If I was better coordinated I might go a little faster, but that fast cadence starts to feel a bit wobbly on fast descents unless the pavement is smooth.

Only one of our relatively fast descents has good smooth pavement, but it's less than 1/2 a mile long so it's a sprint to reach maximum speed before running out of real estate. My fastest speed on that descent is on my hybrid, rather than road bikes, mostly because the hybrid has 11-32 cassette so the 50T big chain ring can reach over 40 mph at a comfortable cadence. And with a hefty tailwind the more upright riding position can help a bit.

Going fast in a straight line is no big deal. But add some curves and it's a whole nuther game. Emma Pooley is a mountain goat, a strong climber, but admitted she was terrified of descents and had to work with a coach specifically on that technique in order to be competitive.

Recently I rode with a friend who was trying a new-to-him TT/tri-bike. He was anxious to try the aero bars. I picked a circuit route with some rollers but also long flat sections. On the fastest, longest straight downhill he tucked into the aero bars and coasted ahead of me easily while I was pedaling. I'm not confident enough to use my clip on aero bars on that descent, so I get into the drops and stay as low as possible. It's only an undulating 2%, but I'm not comfortable using aero bars on any descents. I'll use 'em on flats and moderate inclines.

mahamil2

Same here for the motorcycles. Different ride!

DaveSSS 

I have several hills that are good for 48-54 mph, depending on the wind. It's rare if I don't hit at least 48 on every one of my routes. Horsetooth Lake has a couple of hills that have 10-12% slope that can get you over 50. Heading south out of Carter lake will get me to 50 on a good day. The exception is riding from my house west of Loveland, to Estes Park. It's over 22 miles of climbing, but none of is all that steep. The steepest area only gets me up to about 43 on the way home.

I'm geared for the hills and only spin up to 38. Gravity has to do the rest.

Digger Goreman

By govt machines, 27mph. My coworker says he trailed me at 33mph one morning (I did not spin out). A few weeks ago, I did spin out on a new, steepish downhill. So I'm guessing 40mph. Ride was stable, so no worries. I think cornering, at speed, bothers me more....

BlazingPedals

I don't have a speed limit. Or at least if I do, I haven't found it yet. Hurtling down a hill feet first, inches off the ground, is the biggest rush I know. I will hit the brakes for a curve that I can't see around, though.

SethAZ 

As far as I know my fastest downhill cycling speed that I've recorded by gps was 50.8mph. That scared the crap out of me. Some typical hills that I'll descend on occasional group rides I'll typically get up to upper 30s, perhaps low 40s due to gravity alone after spinning out in the lower 30s. That doesn't scare me. So, somewhere between around 40-50mph I hit my pucker factor. I don't hit these speeds very often, since where I do the vast majority of my riding it's pretty flat.

Litespud

depends on how familiar I am with the road. I used to have a steep 1/2 mile descent that I would routinely hit 46-7 mph, but I was younger and dumber then - These days I have no interest in approaching those sorts of speeds even if I could. I did a hilly group ride last year and I barreled into some decreasing-radius off-camber turns that tested the limits of my brakes and my nerves. At this stage, if I’m interested in looking at the stats for a ride, the average speed is way more important to me than the max speed. But I’d be OK up to maybe 40 mph if I knew the road

chaadster

For me, having top equipment which I can trust, the bike set up and maintained properly, and of course trust in my own skills, allows me to descend without a speed limit. My home terrain is rolling, but I'm heavy, so it's rare I won't crack 30mph on any given ride, but I'm also regularly in the 40s and 50s on my travels for training camps. Having a helmet with an aero visor, like Giro Air Attack, makes hitting high speeds more comfortable and calm.

Back in the '90s when I was living in Avon, CO, I'd descend on dirt on the MTB in the Holy Cross logging speeds on the old Cateye Mity in the 50mph range, and saw 60mph for the first time coming down pavement on Wildwood or Paintbrush roads; pretty sure it was Wildwood first, but I had a 60T crank setup for the bike in those days, because I was looking for it. In the modern data-logging era, I broke 60mph in 2014 down outside Bloomington, IN shooting down to Monroe dam: https://www.strava.com/activities/148262639/overview

taco2ewsday

Fastest ever was 50 as detected by whatever wired Cateye speedometer I had back ~25 years ago on the down-slope of the Brooklyn Bridge Manhattan bound. if you know the area the pucker moment is stopping before getting to the train station entrance, Since I've gotten back into riding 36 mph is my max

bruce19

Back in the day I was on the last leg of a trip from Sebago Lake in ME to my home near UCONN. It was about 250 mi. in 2 1/2 days. Hit a downhill in CT at 53 mph. If I have a line of sight, speed doesn't bother me all that much. Yesterday, on a 31 mi. ride I hit a corner which is a slight downhill at 40 mph. Turning 74 in June. You would think I'd know better.

Chuckles1

Haven't found it yet. I just put 28c road tires on my cyclocross bike for the first time, and I'm amazed how much faster it is. Cateye says I've hit 45 or better several times this year, always on familiar roads. As long as road, wheels, and tires are good, I feel safe enough. On less familiar roads, I brake before exceeding 30mph unless I can see a lot of road ahead.

Rides4Beer

I hit 47-50mph on almost every ride, there's a short -15% hill on my regular route, love to hammer it going into the hill, tuck and hit the sweeper at the bottom at full speed, it's a blast. If it's windy, or I'm tired and just taking it easy, I'll still hit 43-45mph with no effort. As mentioned, the more often you do it, the more comfortable you get. I'm very comfortable at 40+mph and really only get a lil pucker factor when hitting 50+. Current speed PR is 55mph, and that was just a comfortable long smooth descent during Six Gap last year, didn't even realize I had hit 55 until after the ride. lol

Comfort level is also relative to how well I know the road, I'm much less cavalier on unknown roads, there are way too many hairpin turns around here that will sneak up on you. But once I know the road, then it's on. Being a bigger guy, I love to take advantage of descents, and hate having to hit my brakes when in a group.

Notso_fastLane

Oddly enough, I feel more comfortable/safe on two wheels (recumbent) than I do on three (velomobile).

Having said that, the aerodynamics in the velomobile are so much better for going fast downhill. They are both geared such that I spin out around 48 mph. After that it's all gravity.

On my bent, 'terminal velocity' on my favorite hill is 54 mph. In my velo, my new record (set just a couple weeks ago) is 68 mph. I'm doing some work to improve the aerodynamics a bit, and I think I should be able to break 70 mph. The conditions need to be right for the velo though, I can't do those kinds of speeds if there's a crosswind. The steering gets a bit...twitchy...in a strong crosswind that the 2 wheeler just doesn't really feel.

Interestingly, I did the same run on my motorcycle (CBR600), entering the top of the hill at ~50 mph and coasting. The terminal velocity of the motorcycle (~400 lb) is the same as my recumbent. Go figure.

A little disclaimer: I road race motorcycles, so 100+ is not at all unusual for me. Turn two at Pacific raceways was ~85 mph with my knee on the ground at almost full lean.

On my CBR, I've seen 165 mph indicated. Realistically, I was probably only going about 160.

tomato coupe

I would have thought someone who races motorcycles would gravitate towards traditional road bikes, rather than recumbents.

rumrunn6

32 but that hill is probably not safe due to entering traffic from side streets. I need to find a better hill. but at 61 my stupid fearless 20s are far behind me

Oneder

Once and a while I will let loose and go about 50 mph downhill if there are not too many people around, but I generally go pretty slow by most people's standards. It is healthier to go at a moderate pace if you are doing it for exercise otherwise you are just spiking tons of cortisol and burning muscle tissue to produce sugar for your muscles to work hard.

Notso_fastLane

I'm also old.

And I've found my >average< speed has gone up since switching to recumbent. Climbing is a little slower, but overall, my bent (and especially my velo) is faster.

August West

I just set a new PR of 60 mph last week, actually 59.8 but I'm rounding up This was coming back down off a cat 2 climb after struggling to make it to the top into a 25+ mph wind. Normally on this stretch of road I hit the low 40's but with a tailwind the speed just kept going up. Probably way faster than I have any business going but the pavement is only 9 months old, long straights, gradual curves, no trees so sight lines are great, next to no traffic and the wind was directly at my back so it wasn't blowing me all over the road. I didn't really even feel that fast since the effective wind speed in my face was probably only about around 30 mph.

Last ride 76 

The fastest you've seen professional riders go in the TDF, is not the same as "faster than any professional rider can go".

A simple way to go faster is to draft behind a vehicle going faster, though I don't recommend doing it behind a semi-truck, the suction is quite frightening and can be deadly.

Last ride 76 

If you're going to do it...