Bicycle Tutor

When coasting and you then put the foot down, I'd like there to be an immediate tension on the pedals, but instead there is a tiny free rotation and then the tension kicks in.

would you know what's wrong?
Is it the chain, something else? The chain itself doesn't look too saggy.
Am I in the wrong gear?

I'm new to bike repair, fyi. so any ideas would be good thanks

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Replying to myself, the other time you can notice this, is if you back peddle a bit, and then immediatly front peddle. There's a slight 'free wheel' gap between the tension coming back on, compared to what you would expect.

There will always be some free motion when switching from coasting to pedalling due to:

* pedal bearings are not infinitely stiff
* BB bearings are not infinitely stiff
* there is a slight gap between the chain roller and the chain ring
* there is a slight gap between each chain pin and roller
* slight gap between the chain roller and the cogs
* the freewheel/freehub pawls require slight motion to engage
* the spokes are not infinitely stiff
* the tire has some compliance.

A Fixie has less free play, but there is still some noticeable.

After a service I noticed that the free motion was less. I was wondering what was fixed (I didn't mention it to the mechanic to fix).

So are any of the above tunable?
Or was it just pumping the tyre .. which I generally have soft alright ..

The bearings are tuneable; except "sealed" BBs

Chains and sprockets are wear items.

Tire pressure is.