IBG is for chilly days, probably <10c depending on how hot you run. Stick it on first thing, maybe as the tempo/temperature rises, you can take it off and stow it.
Rain gilet is for days where it might piss down but you want to ride anyway. I wouldn't take the rain gilet out on a cold day for example, not without something more substantial underneath it.
maveco
TBH they are for different things.
IBG is for chilly days, probably <10c depending on how hot you run. Stick it on first thing, maybe as the tempo/temperature rises, you can take it off and stow it.
Rain gilet is for days where it might piss down but you want to ride anyway. I wouldn't take the rain gilet out on a cold day for example, not without something more substantial underneath it.