The decline could also be because riders have bought, bought, bought for the past few years and now have a shed full, like me.
Look no further than the C2W scheme for the market becoming saturated with nearly new and recent stuff. Because people have got into the mindset that they are getting a bargain, because they can get the Taxman to subsidise their purchase, they are buying bikes more frequently than they would do otherwise, and this has flooded the market.
Cycling is very much a minority activity, and the vast majority of the population are not even looking for adult bikes, either new or used. That means you've got the same pool of cyclists out there, but the pool of bikes is being constantly added to by repeated C2W purchases. The demand stays the same but the supply increases, so you get price falls.
I agree there are some buyers who genuinely make their heads rule their hearts and buy second hand on value grounds.
Seems to me such buyers are very much in the minority, and will often be found hanging around internet forums - you sound like such a buyer.
Another illustration of this theory is the extremely low resale prices of children's bikes.
As one of those value-oriented buyers myself, there are several reasons why I buy secondhand. The obvious one is price, even though I can easily afford to buy new.
Other reasons are the types of bikes I like, or rather don't like, which restricts my choice new. There is also a perceived hassle factor with secondhand, in case the bike needs attention. However, judging by a lot of postings on here, new bikes are, if anything, likely to be worse in that respect than old ones costing a fraction of the price!
Kids bikes are generally at the low price end of the market, and are perceived as too cheap to be bothered with trying to save money on by many buyers. I always rode secondhand ones when I was young though, until I got my first new racer.
Don't know the percentage - not necessarily the raeson though.
They might not want the suposedly latest best advances.
Experienced cyclists can grab a bargain, will have no worries replacing bits that are closer to wearing out.
and they might not be much closer to wearing out than a new model.
I could have got my Hewitt for under half the price with hardly any wear at all.
There are lots of second hand bikes around more immaculate than any new bikes entrusted to my careless hands for a couple of weeks.
In my experience the paintwork on old bikes is often far better than new as well.
I can certainly agree with those comments, having bought some really nice lugged steel machines for just a few pennies in the pound of their original cost. Sometimes, before actually collecting a bargain bike, I have wondered why it didn't go for more, and expected to find issues - but my purchase experiences have been positive overall.
Raleigh paint from the late 80's and 90's was certainly very tough (usually stoved powder coat, AFAIK), and my Dawes MTB and road frame finishes have also held up well. Have got an early 90's donor Dawes with pretty poor paint though (but it cost peanuts). Raleigh quality was probably more consistently good, Dawes seems more variable.