Shimano Uniglide & Hyperglide

[hamster]

They ramped both sides of the sprocket. Allegedly it needs a different chain, but it all seems fine with SRAM or KMC chains. Frankly IG seems a bit pointless as the difference was imperceptible to me.

 

[SammyS]

IG chain 8-speed pin width was 7.1mm HG was 7.4mm
One significant compatibility issue is always to avoid using a HG chain with an IG-only crank set.
The chain will release from the large (outer) chain rings too easily while in the larger rear cog. It may be possible that the chain drops off the outer ring without shifting the lever, when under full power.