Just curious.

I doubt much at all. I might've gained maybe one or two, but it makes hill climbs, take offs, and pedaling when tired easier.

I think I'm stealing this from another of the five million friggin threads that people have posted about clipless pedals because they didn't bother to use the search function:

Switching to clipless? It enabled me to do the Kessell Run in under twelve parsecs!

That's fast enough for ya..

I'm so fast with my clipless pedals that I get up to relativistic speeds - I can go cycling for weeks, and when I get back only a few minutes have elapsed. It's also almost completely eliminated right hooks.

Seriously, little, if any, difference in speed, but I find it much easier to ride, and the shoes are stiffer and more comfortable for riding.

I've seen claims for anywhere from 0 to 5 mph. I really doubt anyone is 5 mph quicker with clipless. For me personally, I'm faster in specific situations but it doesn't make that great of difference overall.

It isn't about speed but comfort. However, sprinting is much easier.
I'm still going to go with 0.03 mph

My "plateform" pedals were made of really cheap paper plates, so my avg speed increased by 17 mph when I finally made the switch to metal clipless ones.

I doubt there's any speed gain at all, unless you're traveling long distances without stopping.

I ride in the city, and I don't ride fast at all, but it's much easier for me to get going at a green light faster than someone with clipless. They might go slightly faster, but it takes them longer to get going too, what with having to clip in and all.

1.75 mph

Nothing in MPH, but an ocean of joy when I hop off a curb and the point of my saddle doesn't get rammed into my grundle when a foot slips off the pedal

clever clipless riders don't have to clip out at all at red lights, they just balance the bike at a standstill. i haven't mastered the technique yet, but i'm definitely getting better.

Clipping back in is easy with a little practice. I find there's no time penalty there. And being clipped in makes quick acceleration easier, so there you go.

I know riders who ride 10,000 miles a year and still can't trackstand.
I am by no means perfect but can sort of do it from time to time.

I can usually do it on my geared bike, but not on my fixed.. which seems backwards..

SPDs are pretty easy and quick to clip in; just mash on the pedals and go. But I have seen many riders admiring their shoes while they take their time to accelerate.

Best guess is .75 mph. At least .50 and any claim of results over 1.50 is very suspect. Part of the differences will depend on how much the rider pulls with clipless.

I'd say 1 mph, but if I had some dice to role, they might give me a different answer. Seriously, I think there's a few mph gain in average speed in my case. I live in Hilltown, so your mileage may vary. I'll see if I can get an answer from my GPS data, though.

The longest I've proven to myself that I can track stand is about 30 seconds. Most lights are longer than that, but major thoroughfares through residential districts that rich people don't live in, have long red lights. Whenever I come to a light and have to stop for it, I'll balance until the light turns, or I can't hold it anymore. The more practice I get, the better I seem to be at it. But I've been doing this for years; even before I went clipless, I used clips, and still preferred to keep my feet on the pedals.

This. And it helps your endurance as you tend to pedal more efficiently. The pedal stroke is no longer a square when you are clipped in. I find it helps most in my climbing.

.03937 furlongs per fortnight, or thereabouts, plus or minus 3j+5. Or is it 8.3 tesla per kilojoule? Now I don't remember.

I'm still transitioning to clipless and I don't know that it's responsible for any increase in speed but like the others accelerating is easier. In the city for those short stop & go sections (roughly a furlong or less) I'll keep one foot uncliped (I have platform on one side spd on the other).

Clipless won't make you that much faster except maybe for climbing hills and hard acceleration (no risk of slipping off). But your average speeds are not likely to change significantly.

A "furlong" sighting! And in the wild no less!

Anywhere from 0.03 mph to 12.225 mph.