50 mph on a Schwinn Le Tour Luxe on a straight downhill years ago.
Use to do 43 mph downhill on a winding road (35 mph speed limit) on my daily commute until a few JAMs started passing me, then cutting me off. So I started keeping my speed at 35 mph to better manage not crashing when the JAMs do their stupid stuff. So the JAMs desire to race past me has now resulted in them having to go slower most of the time.

57 MPH coming down off of a mountain in the finger lakes region of NY. Its easier to hit those speeds with some confidence on a low recumbent with disc brakes.
45 MPH on one hill on my commute when I ride my current recumbent. 30-35mph with my normal fixed gear commuter.
Craig

47.5 mph going down Mt. Mitchell in NC. I was a teenager at the time and don't think I would ever try that again!

I just revisted thread and realize this is for top speed overall, not just top speed on commute - unless of course some folks have amazing commute routes! Confused as this is in commuting forum.

So to update, my fastest non-commute speed is just under 50mph, aided in this case by downhill of course.

Al

35mph on an MTB with slicks on Lake Boone Trail Rd in Raleigh in 1992. 31mph at 127rpm the other day on the way to work (on a 1/4 mile downhill, not very long). The one time I remember flying down really long hill (like a mile or longer) was in the 1980s and I didn't have a bike computer.

The Garmin said that I did 49.5 down a big hill last week, but I think that's a calculation error. The top speed is usually between 30-35, which sounds MUCH more realistic.

Other than that, my previous top speed has been 46 down a BIG long downhill in SW Ohio. Too scary for me. I think that 40 is as fast as I want to go.

I used to be happy flying at at 40+. Now, being older and having more imagination, I get worried at about 32.

I've hit over 55MPH twice
First, I was coming down nice long fairly steep hills both times.
Second, I was riding my low, very aerodynamic recumbent.
I max out pedaling a little over 40MPH on a down hill, with a 53x11 gear on a 26x1 tire. Beyond that I have to let gravity do the work.
If you are riding a 26x1 then I can guess it is an MTB style bike. Even crouched down these are very poor aerodynamically due to an upright riding position an wide handlebar. A road bike in the tuck position is much more aero and my previously mentioned recumbent is much better than that. In both cases I hit my high speeds the hills were steep but not so steep you couldn't ride up it at a good pace. I imagine most cyclists who have hit 50+ on a road bike have been coming down some crazy steep hills to do so.
Craig

53 mph downhill on a tandem...with no disc brakes.

Needless to say, it took us a while to stop.

32??? When I ride my recumbent (not my fixed gear commuter), 32 is achievable on flat ground. 45 happens on any decent hill and 50 is where it starts to get fun.
Ofcourse with my fixed gear commuter my legs don't allow much over 30mph.
Craig

I cranked out 51.something going down River Mountain Rd in Little Rock. I was pushing the big gear as hard as I could.

I think i hit 24mph once.

49 on a fixed gear ... i have witnesses

44 mph on This bike with street tires and a larger front chainring.

Oww, what kind of gear were you running, or did you cheat and pull your feet off the pedals?

Craig

56 mph on the downhill section of the TT at the 1989 junior regional time trial championships in Eastern Long Island. Some guy name George H, or something like that won, and he's pretty famous now, rides for this "Discovery" team.

I finished 11th.

I pulled the pedals off at 40 mph and reattached them around 25 mph

riding a 42x13 on 700c x 25 tires

58mph, i was 14 years old, on a 70's Schwinn, down a steep hill. The speedo was accurate, we checked the calibration with a car
more recent top speed is about 37mph, down a wimpy hill on my commuter mtb. Thats' SPINNIN those cranks!

51mph down Old Stage Road, coasting. Helps to have a heavy bike and weigh 180lbs.

I need to get a bigger chainring as I can outspin my 46x11 on my Superlight on a very slight descent and on the flat with a tailwind.

Yeah, there are a few fibs on this thread, no biggie. (As an old stayer and derny racer, I'd like to know what gear was on the bike of the fellow who claimed to have done 65 MPH behind a Goldwing... )

As others have more-or-less pointed out, though, gearing doesn't matter on the downhill. On a steep enough descent, aerodynamics becomes the whole ball of wax and if you can get enough of your fat arse out of the way, you'll go fast. Nobody's pedalling at these speeds unless they've purposefully selected gears for it. (You'd be amazed at the size gears necessary to pedal at 65 MPH...)

At any rate, there are mountain roads in Northern and Southern California, and in Colorado, where I know for a fact that one can exceed 60 MPH. I am sure there are similar roads in many other states that I haven't personally been on. Tell the truth, I don't really see the "bragging rights" of going fast down a hill. Gravity did all the work; all the rider did was, well, nothing. Didn't pedal, didn't brake... you should be just as proud for sitting on the toilet and reading Bicisport.

I hit 47.2 on my loaded touring bike coming off a pass in Montana back in '83. Nice smooth surface, steep hill, no traffic, stiff tailwind, sun setting behind me (so excellent visibility), I was going near 45 mph for a couple miles there. My cyclocomputer has told me I've hit higher speeds once or twice since then, but never for more than a few seconds.

In this area there a plenty of descents long and straight enough to get to 50+mph. My top speed wasn't sustained for more than a few seconds. I'm not crazy, I like to descend at about 35-40 mph tops but sometimes you just have to let it run or burn up your brakes. Pedaling is kind of useless at that speed, better to get out of the wind. I can get pretty low and kind of aero so I usually pass people on the downhills. The uphills though are another matter.

I was coasting at 32 mph this am. I think it's around 35 that I start thinking 'I should really be wearing more leather'

That thought quickly goes away on the ascent of same hill in mid-summer.
Al