OK, I have some boots to try on whose length is probably towards the top end of what I should be going for. I'll make a decision whether to keep them on the basis of the shell fit, but it needs to be accurate. If I have 15mm or less behind the heel, I'll keep them, but a mm or two more and I'll send them back. So, I want as accurate a figure as I can get, which leads me to some questions:
1. Do I do this with a footbed in the shell or without? I've heard both versions.
2. How lightly should my toes be touching the fronts of the boots? Barely touching, or so I can actually feel the fronts?
3. How upright should my shin be?
4. What should I use to measure the gap, and exactly where should I measure it? The area behind the heel is very curved (as indeed is the heel), so any object of measured width I push down there is likely to butt up against other surfaces as well, unless it's very short and therefore nigh on impossible to hold in place down there! I've heard people say use dowel - how long a piece of dowel do you use (assuming I've understood correctly and it's dowel of known diameter we're talking about)?
As you can perhaps tell, I've been trying to get a shell fit myself, but with results which vary by more than a couple of mm each time - which is the difference between keeping the boots and sending them back.
Hope someone can help! If only my feet were 2mm shorter or longer, I wouldn't be exactly on the cusp and faced with such a dilemma. What encourages me is the thought that if these really are too long, then necessarily the size down must not be too short, however it initially feels, and should be able to be made to fit. The boots are Head Raptor Project RS, incidentally, size 27/27.5 shell. The boot size is given as 27.5, the liner has 270 printed on the back, but the footbeds (which I would not use if I kept the boots, I'd use my own) say 27.5, so I'm still not certain what makes this a 27.5 instead of a 27.0.