About the Carnet we do have one so that shouldn't be a problem.

It looks like the best option so far is to fly into Nepal with the bike, then ride into India for a few months then come back to Nepal and ship the bike to Vladivostok to ride back to Europe.

Now start the fun part, finding a shipping company...

That should be do-able... but shipping the bike is a proverbial pain in the behind, even when everything works out like it should! Plus it costs some money, too, so I´d keep it to a minimum.

If you´re prepared to go to Vladivostok, then I guess you won´t be doing it in midwinter? There are two should I say "main" overland-routes from India to Europe, too, around the north and south side of Afghanistan.

Northern route necessitates to cross into China from North Pakistan, but only for a few days, so probably helps with the costs (it is still not cheap, and needs to be arranged months in advance!)... and it goes through some very high mountain areas, so not do-able in the winter.

But the southern route: Pakistan-Iran-Turkey-Europe, long as you have the carnet for Pakistan and possibly for Iran as well, should definitely be do-able. It is almost a year-round route even for bikes, except eastern Turkey and northern parts of Iran can get chilly (but winter over there is much shorter than on the Vladivostok-Europe route, for example!) Areas in Pakistan adjacent to Iran are a bit sketchy, and more or less the same goes for areas across the border on Iranian side, but you can go through in just a couple of days if you want. Some nationalities may have problems to get visas for these two countries, and you may have police escorts through some areas.

(ok this was more like route planning – sorry for going a bit off-topic!)