I have used Interparcel twice recently to send items sold on the forum.
Thus far they have failed to collect items on the correct day (on either occasion) and I am still waiting for a parcel to be collected way past the expected delivery date.
They seem pleasant enough when/if you can speak to them and they book you for 'same day' delivery but tbh, it isn't really good enough.
Just thought this might be of interest if anyone is thinking of using them.
fyi frames are on their restricted list so can't be sent at all via their own branded economy services and if sent via others, City Link etc they are only covered for the basic £50 or whatever it is regardless how much extra you pay, I found this out the other day and they refunded me the next day. I then attempted to send via parcel monkey, don't start me on that lot! Used Parcel Force in the end, cost more but got there next day and was insured.
I tend to use Parcel Force now through Postage Supermarket for sending larger stuff out-
www.postagesupermarket.com
and while they're not the cheapest (it usually ends up costing around £20 for next day delivery for something like a frame or exhaust system) I've had no problems with them so far. It's easy to get a quick idea of how much it'll cost to send as well.