robertj298 

I've had half a dozen bikes that have had uniglide freewheels None of
them have ever shifted very smoothly .Usually the shift is very abrupt
and rather noisy. They do shift fine though. The only one I have that shifts smooth
and quietly is the Ironman that I switched to a more modern freewheel and
new chain.

T-Mar

A modern, Hyperglide compatible freewheel with its ramps and different tooth profiles to facilitate chain release and pick-up will shift more quietly than Uniglide for a given situation. It's a case of more modern technology. Hyperglide will even shift under very high drivetrain loads. It won't sound pleasan but it will shift under loads that Uniglide won't.

Retoocs

Hyperglide cassette and chain are designed so the chain, when it shifts, can be on two cogs at the same time. Pre-hypeglide cassettes and freewheels, and chains for that matter, cannot engage two cogs at the same time. The chain rides on top of the teeth before dropping into place.

dddd

Abrupt and noisy, ...compared to what other freewheels?

Uniglide cogs were the best-shifting cogs, right up until the Hyperglide cogs replaced them (Hyperglide was intended to allow full-power shifting while the rider moved an indexed shifter at the handlebars, which could be dangerous if there was any unexpected slippage when the rider was off of the saddle).

Imo, Uniglide cogs still are the very best cogs for use with modern chain and friction shifters. They allow a higher chain tension to be maintained during shifting that other non-Hyperglide cogs can not match.
Suntour cogs are the next-best imo, so also allow at least some driving torque to be maintained during the shift event.

Uniglide cogs used with modern chain (of the "UG Narrow" design that Shimano invented) give just the right amount of audible feedback that allows the rider to be assured that, once completed, any friction shift could be relied on to safely transmit full power (unlike Hyperglide cogs which can ghost-shift without much if any warning if the centering of the derailer under the cog isn't perfect).

Steel Charlie

Since '84 or so when I put the 7400 6-spd group on the Caylor, I've never worried about the shifting. The SIS was a new world that has never grown old and still functions flawlessly three decades later.

"Abrupt and noisy, ...compared to what other freewheels?" Amen

And I never used those POS Shimano chains. Sedis then and KMC now.

Personally, I think the OP should worry about something important - - but that might just be me, eh?

dmark 

Not as smooth as Hyperglide but nothing like Accushift for "clunky".

robertj298 

Abrupt and noisy compared to a modern freewheel which I assume would be hyperglide. I would compare the difference
to popping the clutch on a standard transmission car to easing the clutch out. My Ironman with a modern chain and freewheel shifts
soo smooth and quiet it's hard to tell when it goes into the next gear.