Do bike shops do genuine January sales?
Not certain about the economics of bike selling but I would guess might go something like this:
-kids bikes: sales heavily biased to Christmas. Guess you might pick up a bargain kid's bike in January
-adult bikes: less obviously skewed towards Christmas. Probably kept fairly steady around year, esp. with C2W schemes, but I would guess peak in sales would occur in Spring. Little incentive for shops to offer a sale in January.
Next year's models start coming in around September-October. You can find some deals on this year's remaining stock at present, but would be surprised whether there will be much left by January.