brands such as carrera and boardman have suffered from being
halfords exclusives not because there's anything wrong with the bikes themselves, but because of snobbery about halfords or, more pointedly, at the inconstancy of service provided, as even a good bike, set up poorly, is no fun to ride.
The Boardman brand suffered so much that Halfords bought it for a bargain £20,000,000.
As for inconsistency of service - it's a received wisdom. The silent majority of successful sales are unheralded. If Halfords are so piss poor why did their sales increase by 6.5% last year, driven mainly by bicycle sales?
Carrera have not suffered from being a Halfords exclusive. It is an in house brand owned by Halfords just like Apollo. In the past Carerra frames were made by Merida. The Carerra range are excellent value and I've yet to read a poor review of any of them. You might be confusing them with an Italian brand of expensive road bikes which has no connection whatsoever with Halfords or Porsche for that matter.
As for brand cache I'm sure that Pinarello will not lose sleep over the potential global loss of market through them being sold by Halfords and losing an element of their exclusivity. At the end of the day the Pinarello is a mass produced bike just like the the Carerras and Boardmans. It's cache depends more upon marketing, sponsorship and received wisdom about superiority than through retail outlets.
A minority of cycling snobs might care about them Halfords but the average person in the high street will still see them as an unaffordable brand and go ahead and buy Apollo, Carrera and Boardman bikes that share the showroom with the Pinarellos.