Riding fixed gear is like driving without brake lights

Just so as not to appear too flippant, lazybeard...

My pedalling slows if I'm stopping.
I position myself, indicate clearly and make frequent eye contact with other road users around and behind me.
I only stop when I need to - ie. at lights and crossings - along with the rest of the traffic of which I'm very much a part.
Sudden stops are extremely rare.

All ways to show drivers and other cyclists my intentions.

So far (in over 15 years) I've never once been rear-ended by a motor vehicle. Nor have I heard of it happening to friends. (I do know one or two who've gone in to the back of a bus though, usually after the pub.) As EEI rightly says " When something slows down it goes slower. Period."

Not sure what you mean by giving freewheelers "a heads-up" - how does being told that they (or drivers?) may or may not see that you're slowing, in any way protect you? It's rather disingenuous to make such a bold (and to many of us inaccurate) statement and then moan that we're being defensive and/or not taking your "fact" seriously.

Would it be right to assume your friend here had a rear-ending experience?

Since you ask, Miss Mouse, no - I've never had a rear-ending experience, and I'm glad you haven't been rear ended by a motor vehicle. Have you ever been rear-ended by a bike?

I'm a much less experienced fixed rider than you. When I started 7 months ago, I had a couple of ped-freezing-on-zebra incidents in the first couple of months. I found it mildly irritating, but I didn't stop to think why it was happening until I went out on a ride with some freewheeling mates. Early on in the ride, my close-following friend was forced to take evasive action: "I didn't realize you were slowing down because you don't stop pedalling." That's when it dawned that the crossing-hesitant peds and our near rear-ending incident were down to the same thing - my constant pedalling disguised my deceleration.

Both me and my mate were arguably at fault here. But once there was awareness of this disguised deceleration effect, there were no more incidents. If I knew about it before the ride, I could have told him, and the incident would have been avoided. How could that not help? I would have found that information useful.

As you and EEI rightly say "When something slows down it goes slower. Period." This is true. But people like you and EEI are not the problem. You are experienced and aware cyclists who aren't about to run into the back of anything. The problem is the "nodder" who is pumping along 2ft behind you, who was dumb enough to be deceived by your pedalling approach to the crossing earlier in the day when he was a pedestrian, and so is quite likely to be deceived again.

I think it helps to be aware - especially if you are just learning - that if you are riding fixed gear, the unusual mechanics of the bike mean that you can give out signals which may be misinterpreted by less experienced road users (ever get out of the saddle to slow down?). Because you are constantly pedalling, you will send out one less (fewer!) deceleration signal when you slow. This is just a fact. Might this have potential safety implications, and by extension a positive effect on the way you ride? Maybe it will underline the importance of developing sophisticated signalling tactics like the ones you and BringMeMyFix describe.

That's what I think. However, I am still open to the possibility that I am talking bullshit so bottomlessly stupid that it is too physically painful for a reasonable person to even consider. If someone would be kind enough to explain why.