From a retailer point of view it's difficult.
I work for a camping/outdoors retailer and we sometimes get slated for a restrictive returns policy.
It's something we are continually reviewing as we want to be fair, as if it works for our customers they become repeat customers even if there has been a problem. But you would not believe the amount of 100% perfect tents that we receive back with dubious faults. Usually within a month - i.e. outside the normal Distance Selling "change of mind" rights but just long enough to have taken the family on a 2 week camping trip....
It means that we sometimes upset genuine people who have got a leaky seam, whilst we insist on getting the item back (can be a £1000+ item at top end) and inspecting it, which can include blasting it with a pressure spray, but if we just accepted any return back, then we'd just be a free tent hire.
Personally I think if you buy a bike and ride it around, then if you decide you don't like it, it's your job to sell it on as best you can. IF it has no faults. In a perfect world perhaps it could be 80% refunded as a goodwill gesture, then sold on with 20% off