Thanks Bryn, I've been in touch with the ebay seller he seems to know what hes talking about and the £120 ish price is most appealing, when i asked him about m\cycle suitability i got this reply:-
"These units are factory Newly overhauled but although we have mentioned this on the listing there is nothing on the box or instructions to say this. The unit comes complete and with all factory seals and stickers and fully warranted by Garmin. You have to register the unit online to activate the update.
The 2620 does have a hardrive so is a moving part. However people that want to use satnav on bike usually have touring bikes which have softer suspension (probably better than a car). So these are not a problem to use. You will come across a lot of people on the net who currently use a 2620 on their bike and very happy.
Kind regards,
Harry"
Thanks for your input.