You'll be able to send a parcel 'poste restante' for collection at almost any Post Office in Spain - some brief info at the link below:

http://www.travel-spain.net/barcelona/mail.htm

Or you could check whether you could post it direct to your accommodation. I have no knowledge or expertise when it comes to motor bikes so don't know if yours is the sort that panniers can be fitted on or not but posting the equivalent of a suitcase full of clothes is going to be pricey. Depending on how you will spend your time once you get there, it could even be cheaper to simply buy what you need when you get there! Before committing yourself, I suggest that you pack-up a trial parcel and take it along to your local Post Office and ask them to weigh it and confirm what the probable cost will be and then make the decision as to whether this is a cost effective plan. At least these days there won't be any hassle with customs duties etc.

Also, remember that you'll need to plan for either ditching your clothes or paying to post them back home. Main post offices here also provide a poste restante service but I'm not sure whether sub-post offices do. So when you take the trial parcel chceck this out and they should be able to look up for you what the return postal costs from Spain would be along with the charges for the poste restante service at each end.

I know that it might sound a bit strange but if you google on 'camino de santiago' you'll find that there are lots of other people who need to send of parcels of clothes to Spain! It's a frequent discussion point amongst people walking the pilgrimage routes to Santiago who want to be able to regularly pick up parcels of clean clothes and post the dirty ones home - I think it would be lot a less hassle for them to just pack some travel wash but there you go

SM

Hi sorry for the late reply ...

Get in touch with Offex w w w. offexspain. com

You can post your package to a UK address (a PO box at a UK airport) and they will ship it over to their depot in Arroyo where you can collect it ... then do the same on your return ...