Good question lol

I am not sure it is needed to be honest. In my nature to be over kill when it comes to engineering I guess

I do however think its worth fitting the bottom one, as it helps take the load on the luggage blog with a heavy ladened bag. That is where I think my solution scores over the one that just has the two clips going around the bracket and attaching to the head tube. Mine has been rock solid for over a year and sometimes I carry eight pints of milk and couple of bottles of cider/wine with not problems.

Next time I do some work to the bike I may remove the top jubilee clip. Thanks for making me think about it

PS When you cut the slots for the middle clip make sure you get them as near to the flat face inside the block as you can. Also once the clip is inserted try and push the part inside as flat against the flat surface as you can. The mounting block itself is made from quite dense material and cutting these slots does not seem to weaken it at all. I also found that the semi circle round profile on the back of the block fitted my head tube diameter really well. That may not be the same with all head tube sizes/diameters. Oh and finally I think I had to trim the release lever a little on the back as it fowled the jubliee clip when I pushed it to release the bag.

Regards

Jerry