You can wear three-quarter length bib tights almost year round - apart from that fortnight in June we call summer and the odd sub-zero day in winter - but they're especially good in spring and autumn, when you want to keep your knees warm but don't need all-over insulation.
These ones are what we've come to expect from Decathlon: pretty good and very cheap. They use a six-panel construction, with a leg-gripper and a synthetic chammy.
The straps are mostly mesh, but are rather narrow so that the 'improved ventilation' from this feature isn't a big deal. They're not quite as comfortable as the 3/4-length Lusso bib tights we've tested and they're not Roubaix-lined so they're not as snug. However, they're cheaper and a lot lighter, not just because they're thinner but because they reach less high up the torso and there's no partial, to-the-waist zip - which, incidentally, makes pitstops even trickier. So long as you don't expect to wear them in the middle of winter, these are good bib tights.