it depends on what is chasing me...

38.1mph on a flat road in my 52x13 with a monster 25mph sustained tailwind directly at my back.

My top speed flat with no wind is about 25mph, but I'm really pushing it. Normal cruising speed is 15-20mph.

With a tail wind going downhill, I've managed to run out of gears around 36mph.

edit: this is a Trek Allant, loaded up for commuting, 700x32 tires.

44 MPH on a downhill because I had to brake for slower cars.

No pics? Didn't happen!!!

It is interesting to note that the recumbent holds the record here but that makes sense.

My sons and I were riding across part of Manitoulin Island and going into Westbay from Little Current is down a hill. The boys were probably 14 and 16yrs and we were coasting down into Westbay at about 50kph. My youngest, at the front, slowly caught and passed an OPP car (Ontario Provincial Police), the posted limit was 50kmh, and he was scared that the police officer was going to pull him over for speeding. Didn't happen and we had a blast.

mach 0.03

I took the speedo meter off my mountain bike when I did endurance races, it just made me sad, and my commuter has never had one. Math says I spin out in the low 20s on the commuter. The calculator says I average about 16mph from unlocking the chain to opening my front door on my commute.

In other places? Descending Laramie Pass I was in the mid 50s. There was a 2mph difference between full-crouch-chin-touching-the-stem and just being low in the drops. Took me 45 minutes to climb that pile of rock, and less than 10 minutes to get back down it. In the flattest-of-the-flat in Oklahoma, I could usually break 40 on the down-hill-and-down-wind side of the only hill in town, where the road went over the train tracks. But only when the wind was 20knots or better. On flat-with-no-wind, I can hit 35, but not stay there long enough to make the effort worthwhile. And I've seen 750knots ground speed one day riding the jetstream, and mach 1.05 one afternoon in California, but neither of those involved wheels touching ground, and both were burning hydrocarbons.

Wait. That's like only 23 mph....

Well, my speedo reads out to mach 5. The dial can be hard to read on the bottom end.

48 mph down Texas St. (14% grade) in the dark at 5:45 am. 35 mph on my fixed gear path racer.

uphill, 3-6 mph

On a race oriented road bike, 41.2 mph down hill on a one lane paved farm road in rural TN.
On another race oriented road bike, 31.4 mph dead flat road with no wind, in Dallas Tx.
On a ss (53x16), 36.7 mph, downhill, with a backpack, commuting from work.

46 mph on a paved downhill on the mt bike, too fast for the sane.

Man you guys got to get out on a tandem. My wife and I hit 62mph coming down one of the passes on the Logan to Jackson race. Here in the rocky mountains one of our favorite rides has a decent where if the wind is not blowing we reach 58mph. If the wind is blowing its scary as hell and we slow it down to 45 or so. LOL We can regularly reach speeds of 38 to 40mph on only a very slight decent. Nothing like pedaling out a 54-11 gear.

Wow, all that on your daily commute? And you commute by bike with your wife, that sure is convenient.

That's cool your wife is into cycling, I wish mine was. So you got your tandem to go fast down hill, we know that the extra weight of two riders and a heavier tandem that's entirely possible; but, how your speed going up those same hills? I've past tandem riders climbing hills, but then they would go past me coming down hills. It seems to me the same reason that makes them go down hill fast...weight...slows them down going up hill.

62mph=99km/h, on a bicycle ??...I guess madness has no limits.

All I know is I am amazed at bicycle racers. I average 12 on my commuter (Trek 520) and 14-15 on my road bike (Trek Madone)while just fun riding. Rarely do I all out push myself at my age. So when I see these racers average 30 mph or more, it amazes me. I can't imagine averaging 30 mph over a 5 or 6 hour time span.

They must be in a rush to get to (or from) work.

In my case, it was actually 42. 42 mph -- going down a huge hill. I do not ever plan to go that fast on a bicycle again - at least not without a suit of armour on.

BTW: My top normally commuting speed is about 20 mph, with an average about 14 mph.

If I remember correctly it is mid-30's down a big hill near here, which I avoid. I go up it (much slower) but I generally don't like to go that fast and therefore don't want to wear out my brakes.

Trek 520
Flat no load about 28.
Loaded panniers downhill 42 (35mph speed limit, and cars still have to pass me)
My other downhill I'm to chicken to tuck it. Too steep with an S turn on the bottom.

My actual top speed where I crank up the effort is about 21mph. Good pavement, etc. I've not tried to sustain it for any length of time though.

I think it's just a matter of getting used to it Terrapin. My daily commute starts off down a 3/4 mile hill where I hit 42 mph without pedaling if I tuck, and a out 39 or 40 if I don't tuck. It doesn't feel fast at all anymore. My biggest fear is people pulling out of driveways or side streets, because they misjudge my speed. One day someone pulled out from a side street, and instead of slamming on the brakes I just pulled out passed them on the left...not real smart on my part but one of those things you just do in the moment.

New top speed this past weekend. Down a psycho hill, no pedaling, on my Sirrus. In mph.

http://bikeforums.net/attachment.php...hmentid=312235

Interesting topic. I don't have computers on all my bikes (and usually don't turn them on when I do), but sometimes I record my rides with Cyclemeter/iPhone so I went back through the history. I've only had the app for a year, so this is fairly recent data.

The fastest I've descended was on my mountain bike (with slick tires), 41 mph tucked on a downhill part of Highway 50 during a circumnavigation of Lake Tahoe last summer. We were riding in the traffic lanes, watching our helmet mirrors, when cars approached (typical car speed is 60 mph there) we'd move to the right, they'd pass, and we'd swing back into the center of the lane. I didn't want to ride 40 mph in the narrow shoulder with storm drains and debris, too dangerous.

As far as max routine speed under my own power on my daily commute, I usually sprint up the eastern approach of the bridge I take (Burnside Br.) and on a good day, no headwind, if I feel strong, am not carrying much in the messenger bag, time the lights and hit the start of the approach around 20 mph, I can crack 30 mph (max recorded so far 32 mph). That is going up a slight grade (guessing 1-2%?), and I blow up by the mid-point of the bridge, so maybe a 200 meter effort. Going home, two of my routes put me on major streets without bike lanes (NE Sandy, NE Broadway) where I try to ride as close to car speed as possible. That puts me around 30 mph (max recorded so far 31 mph), between stop lights. At that pace, I am going about as fast as the slowest cars, so I'm not holding up traffic too badly. But I'm grateful when traffic slows for lights, because I can't keep up that speed for more than a few blocks. If there is a headwind, I can't do it at all.

The max sustained speed that I can keep up for, say, a couple miles, is about 25 mph. Has to be no wind, and I'll be in the drops. I'm not "cruising", but am working hard.

On long rides, I can average about 17 mph if the route isn't hilly. On Seattle to Portland last year, I averaged 17.03 mph on day 1 to Centralia which is 99 miles (fresh legs, almost entirely flat), but only 15.99 mph on day 2 to Portland which is 104 miles (tired, rolling hills, long grind on highway 30). On the 50 mile training rides for STP I averaged 16.5 to 17.5 mph. Going around Lake Tahoe, the average was only 15.15 mph, that is 73 miles (on mountain bike, some pretty hilly parts at Emerald Bay and then on Highway 28). This excludes stops, using the app's automatic stop detection. On each of those rides, I recorded a max speed around 29-31 mph (except the Tahoe ride), but those were probably descents of rollers, not self-propelled on the flats, because I don't remember sprinting on those longish ride days.

Looks like to sprint 30 mph up a 1% grade I have to put out about 750 watts, to ride 30 mph for a few blocks on flat road needs about 600 watts, to sustain 25 mph that is about 325 watts. So that tells me the power I can output for a couple minutes is what a pro rider can output for an hour or more :-(.

55kph on the flats and 90kph on a descent.

listing a top speed on a descent has the competitiveness of a high school physics egg drop experiment.