Sidi wire sizing woes

Try some Bonts? You can heat them in the oven and mould them to your feet.

Long time Sidi user here. Two things.
1. The wires are built on a different last to many other Sidis. The wires are a bit wider in the forefoot and less "pointy Italian" like. So if the wires don't fit maybe try another model and vice-versa.
2. Definitely worth trying some insoles to fine tune the fit. Don't bother with Sidi's own alternative insoles; they're rubbish (I tried them). There are some outrageously expensive carbon / mouldable options available (I have some), but Specialized do a range of insoles with 3 different degrees of arch support and they're only £20 a pair and actually pretty good, (I have some of these too).

tried very hard to like/fit some carbon vernice but no joy. i too had heel lift
or numb feet from having to tighten them too much.

then tried giro and found pinched toes, then spiuk ... que shafts of light from
heaven - perfect.
i now have the zs15rc for "best bike" use and the zs15r for cack days, oh and
some northwave winter boots for ... errr ... winter

Been trying Genius 6.6 and wires over last month. Have always used the older Genius models and loved how they fit like a glove in a 42.5

Both of these models seem to have issues for me:

Wires are tight and toes come up on pedal upstroke all in a 43

6.6 are looser and have tongue irritating ankle and front of top of shoe presses against the big toes on both feet (sort of bends onto toes and does not hold shape) all in a 43

Been playing with different insoles and shims

Try putting an insole arch support thing in your size 43 Sidi - tightening up the waist of the shoe holds you further back into the heel.

got some lake cx236c which are boa laced. nice and tight on the heel
but pinch the little toe area which is odd as the toe box is bigger than
my sidi's. my genius 6.6's are "slipper" like and have been
from new.

thanks for that unbiased advice actually because I was considering that they may just not be right. The worst thing I think about cycling shoes is it's useless even trying them on. Standing up in a shop is nothing like 8 hours in the saddle!
I ordered from Wiggle and they do 365 day returns (which is brilliant). They're new condition so will try a size up on the rollers and go from there.

I must admit I mainly went for them because of the stigma attached to them being 'the best', I didn't really try any others because I wanted them. Who else does a decent shoe with wire adjustment (because that is brilliant I think).

It's like any shoe, cycling or not, they either fit or they don't irrespective of the make. For me sidi are 100% perfect I have 6 pairs going back over 20yrs and they are like slippers. I tried some bontranger for a change and I had the same issues you are having with sidi. Yes they are awesome to look at and the build quality is top notch, but if they don't fit perfectly don't keep them.

Interesting thread as I have the same shoes, and find a very similar problem. I find my feet become very achy especially on the instep, probably because the shoes are too tight. So I loosen the shoes, and then I lose any strength in the shoe as my feet are a bit too loose. I do wonder whether they are right for me.

I am going to send back and go for a size up, but bear in mind that there is 3mm between every half size... And if you look at the sole on the half size, it's the same as the lesser size. My point being - these are handmade. No 43.5 is the same size as another 43.5.

It's tricky because they're £300 and I want them to fit like a glove. However, they fit worse than my £70 Shimanos. My bad, their bad, italian bad? Who knows.

If you're really in love with the Wires (not to mention the sadness at losing out on £250) you get get a silicone heel cup to fit into the sole, also available at your local cobbler's. Sometimes they're a bit thick so if that's too tight of a fit you could get a custom heel cup made by a shoe orthotic place (in the US you can get one through a physio referral but not sure how it's done in the UK).

Suede heel grips, a few pounds at any cobblers.

I tried to buy SiDI Genius 6.6 Carban Lite Vernice Shoes. I tried a few other SiDi models as well, but none would fit..

I got so fed up trying shoes in the end I went for these: SPECIALIZED COMP ROAD CYCLING SHOE.

Ok they may be chalk and cheese but these fit me so well. SiDi shoes are fantastic in almost every way, but for me the fit was way off, especially around the heel.