Innsbruck to sancandido without a car

Not too difficult. You can see the options at https://www.suedtirolmobil.info/en/#/
It covers trains from Innsbruck Hbf.

Thanks Sam but on 29 September it gave me no choice of a bus or a train. This is what Im running into. Very difficult indeed.

When you see that, it is obvious that there is a rail repair/construction project going on during your travel date. In this case, looks like the rail line is closed between Bressanone and Brunico, so a replacement bus is provided. At Brunico, you get back on the train for the continuation to San Candido. This is normal. It happens all the time. Rail lines need to be repaired periodically, and you drew the short straw.

From what I can see, this stoppage will continue until at least mid December.

The Pustertal railway is closed in different installments for a whole year, as they are upgrading the signal system and building a short link from the Pustertal railway in order to send trains directly to Brixen station, instead of going to Fortezza and reversing direction there.

I understand at present there is a substitute bus from Brixen station (not Fortezza) to Brunico and works east of Brunico should be already over. So you are likely to do your trip in four steps, Innsbruck-Brenner on OeBB train, Brenner-Brixen on an Italian train, Brixen-Brunico by bus, Brunico-San Candido on train.

The OBB website/app gives the correct options and timings.

The rail replacement bus ride is 52 minutes.

It also gives another 2 seat option on scheduled bus 960X to Arnbach then train, or the odd through train from Innsbruck to Brixen, all of which options can be through ticketed by OBB.